9 .Nd User interface for firewall, traffic shaper, packet scheduler,
12 .Ss FIREWALL CONFIGURATION
21 .Op Ar rule | first-last ...
29 .Brq Cm delete | zero | resetlog
33 .Cm set Oo Cm disable Ar number ... Oc Op Cm enable Ar number ...
37 .Ar number Cm to Ar number
39 .Cm set swap Ar number number
45 .Brq Cm firewall | altq | one_pass | debug | verbose | dyn_keepalive
48 .Brq Cm firewall | altq | one_pass | debug | verbose | dyn_keepalive
51 .Oo Cm set Ar N Oc Cm table Ar name Cm create Ar create-options
53 .Oo Cm set Ar N Oc Cm table
57 .Oo Cm set Ar N Oc Cm table Ar name Cm modify Ar modify-options
59 .Oo Cm set Ar N Oc Cm table Ar name Cm swap Ar name
61 .Oo Cm set Ar N Oc Cm table Ar name Cm add Ar table-key Op Ar value
63 .Oo Cm set Ar N Oc Cm table Ar name Cm add Op Ar table-key Ar value ...
65 .Oo Cm set Ar N Oc Cm table Ar name Cm atomic add Op Ar table-key Ar value ...
67 .Oo Cm set Ar N Oc Cm table Ar name Cm delete Op Ar table-key ...
69 .Oo Cm set Ar N Oc Cm table Ar name Cm lookup Ar addr
71 .Oo Cm set Ar N Oc Cm table Ar name Cm lock
73 .Oo Cm set Ar N Oc Cm table Ar name Cm unlock
75 .Oo Cm set Ar N Oc Cm table
79 .Oo Cm set Ar N Oc Cm table
83 .Oo Cm set Ar N Oc Cm table
87 .Oo Cm set Ar N Oc Cm table
90 .Ss DUMMYNET CONFIGURATION (TRAFFIC SHAPER AND PACKET SCHEDULER)
92 .Brq Cm pipe | queue | sched
98 .Brq Cm pipe | queue | sched
99 .Brq Cm delete | list | show
113 .Ss STATEFUL IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
115 .Oo Cm set Ar N Oc Cm nat64lsn Ar name Cm create Ar create-options
117 .Oo Cm set Ar N Oc Cm nat64lsn Ar name Cm config Ar config-options
119 .Oo Cm set Ar N Oc Cm nat64lsn
124 .Oo Cm set Ar N Oc Cm nat64lsn
128 .Oo Cm set Ar N Oc Cm nat64lsn Ar name Cm stats Op Cm reset
129 .Ss STATELESS IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
131 .Oo Cm set Ar N Oc Cm nat64stl Ar name Cm create Ar create-options
133 .Oo Cm set Ar N Oc Cm nat64stl Ar name Cm config Ar config-options
135 .Oo Cm set Ar N Oc Cm nat64stl
139 .Oo Cm set Ar N Oc Cm nat64stl
143 .Oo Cm set Ar N Oc Cm nat64stl Ar name Cm stats Op Cm reset
144 .Ss XLAT464 CLAT IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
146 .Oo Cm set Ar N Oc Cm nat64clat Ar name Cm create Ar create-options
148 .Oo Cm set Ar N Oc Cm nat64clat Ar name Cm config Ar config-options
150 .Oo Cm set Ar N Oc Cm nat64clat
154 .Oo Cm set Ar N Oc Cm nat64clat
158 .Oo Cm set Ar N Oc Cm nat64clat Ar name Cm stats Op Cm reset
159 .Ss IPv6-to-IPv6 NETWORK PREFIX TRANSLATION
161 .Oo Cm set Ar N Oc Cm nptv6 Ar name Cm create Ar create-options
163 .Oo Cm set Ar N Oc Cm nptv6
167 .Oo Cm set Ar N Oc Cm nptv6
171 .Oo Cm set Ar N Oc Cm nptv6 Ar name Cm stats Op Cm reset
172 .Ss INTERNAL DIAGNOSTICS
179 .Ss LIST OF RULES AND PREPROCESSING
192 utility is the user interface for controlling the
196 traffic shaper/packet scheduler, and the
197 in-kernel NAT services.
199 A firewall configuration, or
203 numbered from 1 to 65535.
204 Packets are passed to the firewall
205 from a number of different places in the protocol stack
206 (depending on the source and destination of the packet,
207 it is possible for the firewall to be
208 invoked multiple times on the same packet).
209 The packet passed to the firewall is compared
210 against each of the rules in the
213 (multiple rules with the same number are permitted, in which case
214 they are processed in order of insertion).
215 When a match is found, the action corresponding to the
216 matching rule is performed.
218 Depending on the action and certain system settings, packets
219 can be reinjected into the firewall at some rule after the
220 matching one for further processing.
222 A ruleset always includes a
224 rule (numbered 65535) which cannot be modified or deleted,
225 and matches all packets.
226 The action associated with the
232 depending on how the kernel is configured.
234 If the ruleset includes one or more rules with the
241 the firewall will have a
243 behaviour, i.e., upon a match it will create
245 i.e., rules that match packets with the same 5-tuple
246 (protocol, source and destination addresses and ports)
247 as the packet which caused their creation.
248 Dynamic rules, which have a limited lifetime, are checked
249 at the first occurrence of a
254 rule, and are typically used to open the firewall on-demand to
255 legitimate traffic only.
262 for all packets (not only these matched by the rule) but
269 .Sx STATEFUL FIREWALL
272 Sections below for more information on the stateful behaviour of
275 All rules (including dynamic ones) have a few associated counters:
276 a packet count, a byte count, a log count and a timestamp
277 indicating the time of the last match.
278 Counters can be displayed or reset with
282 Each rule belongs to one of 32 different
286 commands to atomically manipulate sets, such as enable,
287 disable, swap sets, move all rules in a set to another
288 one, delete all rules in a set.
289 These can be useful to
290 install temporary configurations, or to test them.
293 for more information on
296 Rules can be added with the
298 command; deleted individually or in groups with the
300 command, and globally (except those in set 31) with the
302 command; displayed, optionally with the content of the
308 Finally, counters can be reset with the
314 The following general options are available when invoking
316 .Bl -tag -width indent
318 Show counter values when listing rules.
321 command implies this option.
323 Only show the action and the comment, not the body of a rule.
327 When entering or showing rules, print them in compact form,
328 i.e., omitting the "ip from any to any" string
329 when this does not carry any additional information.
331 When listing, show dynamic rules in addition to static ones.
333 When listing, show only dynamic states.
334 When deleting, delete only dynamic states.
336 Run without prompting for confirmation for commands that can cause problems if misused,
339 If there is no tty associated with the process, this is implied.
342 command with this flag ignores possible errors,
343 i.e., nonexistent rule number.
344 And for batched commands execution continues with the next command.
346 When listing a table (see the
348 section below for more information on lookup tables), format values
350 By default, values are shown as integers.
352 Only check syntax of the command strings, without actually passing
355 Try to resolve addresses and service names in output.
357 Be quiet when executing the
367 This is useful when updating rulesets by executing multiple
371 .Ql sh\ /etc/rc.firewall ) ,
372 or by processing a file with many
374 rules across a remote login session.
375 It also stops a table add or delete
376 from failing if the entry already exists or is not present.
378 The reason why this option may be important is that
379 for some of these actions,
381 may print a message; if the action results in blocking the
382 traffic to the remote client,
383 the remote login session will be closed
384 and the rest of the ruleset will not be processed.
385 Access to the console would then be required to recover.
387 When listing rules, show the
389 each rule belongs to.
390 If this flag is not specified, disabled rules will not be
393 When listing pipes, sort according to one of the four
394 counters (total or current packets or bytes).
396 When listing, show last match timestamp converted with
399 When listing, show last match timestamp as seconds from the epoch.
400 This form can be more convenient for postprocessing by scripts.
402 .Ss LIST OF RULES AND PREPROCESSING
403 To ease configuration, rules can be put into a file which is
406 as shown in the last synopsis line.
410 The file will be read line by line and applied as arguments to the
414 Optionally, a preprocessor can be specified using
418 is to be piped through.
419 Useful preprocessors include
425 does not start with a slash
427 as its first character, the usual
429 name search is performed.
430 Care should be taken with this in environments where not all
431 file systems are mounted (yet) by the time
433 is being run (e.g.\& when they are mounted over NFS).
436 has been specified, any additional arguments are passed on to the preprocessor
438 This allows for flexible configuration files (like conditionalizing
439 them on the local hostname) and the use of macros to centralize
440 frequently required arguments like IP addresses.
441 .Ss TRAFFIC SHAPER CONFIGURATION
447 commands are used to configure the traffic shaper and packet scheduler.
449 .Sx TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
450 Section below for details.
452 If the world and the kernel get out of sync the
454 ABI may break, preventing you from being able to add any rules.
455 This can adversely affect the booting process.
460 to temporarily disable the firewall to regain access to the network,
461 allowing you to fix the problem.
463 A packet is checked against the active ruleset in multiple places
464 in the protocol stack, under control of several sysctl variables.
465 These places and variables are shown below, and it is important to
466 have this picture in mind in order to design a correct ruleset.
467 .Bd -literal -offset indent
470 +----------->-----------+
472 [ip(6)_input] [ip(6)_output] net.inet(6).ip(6).fw.enable=1
475 [ether_demux] [ether_output_frame] net.link.ether.ipfw=1
477 +-->--[bdg_forward]-->--+ net.link.bridge.ipfw=1
483 times the same packet goes through the firewall can
484 vary between 0 and 4 depending on packet source and
485 destination, and system configuration.
487 Note that as packets flow through the stack, headers can be
488 stripped or added to it, and so they may or may not be available
490 E.g., incoming packets will include the MAC header when
494 but the same packets will have the MAC header stripped off when
501 Also note that each packet is always checked against the complete ruleset,
502 irrespective of the place where the check occurs, or the source of the packet.
503 If a rule contains some match patterns or actions which are not valid
504 for the place of invocation (e.g.\& trying to match a MAC header within
508 the match pattern will not match, but a
510 operator in front of such patterns
514 match on those packets.
515 It is thus the responsibility of
516 the programmer, if necessary, to write a suitable ruleset to
517 differentiate among the possible places.
519 rules can be useful here, as an example:
520 .Bd -literal -offset indent
521 # packets from ether_demux or bdg_forward
522 ipfw add 10 skipto 1000 all from any to any layer2 in
523 # packets from ip_input
524 ipfw add 10 skipto 2000 all from any to any not layer2 in
525 # packets from ip_output
526 ipfw add 10 skipto 3000 all from any to any not layer2 out
527 # packets from ether_output_frame
528 ipfw add 10 skipto 4000 all from any to any layer2 out
531 (yes, at the moment there is no way to differentiate between
532 ether_demux and bdg_forward).
534 Also note that only actions
543 frames and all other actions act as if they were
546 Full set of actions is supported for IP packets without
551 action does not divert
555 In general, each keyword or argument must be provided as
556 a separate command line argument, with no leading or trailing
558 Keywords are case-sensitive, whereas arguments may
559 or may not be case-sensitive depending on their nature
560 (e.g.\& uid's are, hostnames are not).
562 Some arguments (e.g., port or address lists) are comma-separated
564 In this case, spaces after commas ',' are allowed to make
565 the line more readable.
566 You can also put the entire
567 command (including flags) into a single argument.
568 E.g., the following forms are equivalent:
569 .Bd -literal -offset indent
570 ipfw -q add deny src-ip 10.0.0.0/24,127.0.0.1/8
571 ipfw -q add deny src-ip 10.0.0.0/24, 127.0.0.1/8
572 ipfw "-q add deny src-ip 10.0.0.0/24, 127.0.0.1/8"
575 The format of firewall rules is the following:
576 .Bd -ragged -offset indent
579 .Op Cm set Ar set_number
580 .Op Cm prob Ar match_probability
582 .Op Cm log Op Cm logamount Ar number
592 where the body of the rule specifies which information is used
593 for filtering packets, among the following:
595 .Bl -tag -width "Source and dest. addresses and ports" -offset XXX -compact
596 .It Layer2 header fields
598 .It IPv4 and IPv6 Protocol
599 SCTP, TCP, UDP, ICMP, etc.
600 .It Source and dest. addresses and ports
604 .It Transmit and receive interface
606 .It Misc. IP header fields
607 Version, type of service, datagram length, identification,
611 .It IPv6 Extension headers
612 Fragmentation, Hop-by-Hop options,
613 Routing Headers, Source routing rthdr0, Mobile IPv6 rthdr2, IPSec options.
615 .It Misc. TCP header fields
616 TCP flags (SYN, FIN, ACK, RST, etc.),
617 sequence number, acknowledgment number,
625 When the packet can be associated with a local socket.
627 Whether a packet came from a divert socket (e.g.,
629 .It Fib annotation state
630 Whether a packet has been tagged for using a specific FIB (routing table)
631 in future forwarding decisions.
634 Note that some of the above information, e.g.\& source MAC or IP addresses and
635 TCP/UDP ports, can be easily spoofed, so filtering on those fields
636 alone might not guarantee the desired results.
637 .Bl -tag -width indent
639 Each rule is associated with a
641 in the range 1..65535, with the latter reserved for the
644 Rules are checked sequentially by rule number.
645 Multiple rules can have the same number, in which case they are
646 checked (and listed) according to the order in which they have
648 If a rule is entered without specifying a number, the kernel will
649 assign one in such a way that the rule becomes the last one
653 Automatic rule numbers are assigned by incrementing the last
654 non-default rule number by the value of the sysctl variable
655 .Ar net.inet.ip.fw.autoinc_step
656 which defaults to 100.
657 If this is not possible (e.g.\& because we would go beyond the
658 maximum allowed rule number), the number of the last
659 non-default value is used instead.
660 .It Cm set Ar set_number
661 Each rule is associated with a
664 Sets can be individually disabled and enabled, so this parameter
665 is of fundamental importance for atomic ruleset manipulation.
666 It can be also used to simplify deletion of groups of rules.
667 If a rule is entered without specifying a set number,
670 Set 31 is special in that it cannot be disabled,
671 and rules in set 31 are not deleted by the
673 command (but you can delete them with the
674 .Nm ipfw delete set 31
676 Set 31 is also used for the
679 .It Cm prob Ar match_probability
680 A match is only declared with the specified probability
681 (floating point number between 0 and 1).
682 This can be useful for a number of applications such as
683 random packet drop or
686 to simulate the effect of multiple paths leading to out-of-order
689 Note: this condition is checked before any other condition, including
696 .It Cm log Op Cm logamount Ar number
697 Packets matching a rule with the
699 keyword will be made available for logging in two ways:
700 if the sysctl variable
701 .Va net.inet.ip.fw.verbose
702 is set to 0 (default), one can use
707 This pseudo interface can be created manually after a system
708 boot by using the following command:
709 .Bd -literal -offset indent
710 # ifconfig ipfw0 create
713 Or, automatically at boot time by adding the following
717 .Bd -literal -offset indent
721 There is zero overhead when no
723 is attached to the pseudo interface.
726 .Va net.inet.ip.fw.verbose
727 is set to 1, packets will be logged to
731 facility up to a maximum of
736 is specified, the limit is taken from the sysctl variable
737 .Va net.inet.ip.fw.verbose_limit .
738 In both cases, a value of 0 means unlimited logging.
740 Once the limit is reached, logging can be re-enabled by
741 clearing the logging counter or the packet counter for that entry, see the
745 Note: logging is done after all other packet matching conditions
746 have been successfully verified, and before performing the final
747 action (accept, deny, etc.) on the packet.
749 When a packet matches a rule with the
751 keyword, the numeric tag for the given
753 in the range 1..65534 will be attached to the packet.
754 The tag acts as an internal marker (it is not sent out over
755 the wire) that can be used to identify these packets later on.
756 This can be used, for example, to provide trust between interfaces
757 and to start doing policy-based filtering.
758 A packet can have multiple tags at the same time.
759 Tags are "sticky", meaning once a tag is applied to a packet by a
760 matching rule it exists until explicit removal.
761 Tags are kept with the packet everywhere within the kernel, but are
762 lost when packet leaves the kernel, for example, on transmitting
763 packet out to the network or sending packet to a
767 To check for previously applied tags, use the
770 To delete previously applied tag, use the
774 Note: since tags are kept with the packet everywhere in kernelspace,
775 they can be set and unset anywhere in the kernel network subsystem
778 facility), not only by means of the
784 For example, there can be a specialized
786 node doing traffic analyzing and tagging for later inspecting
788 .It Cm untag Ar number
789 When a packet matches a rule with the
791 keyword, the tag with the number
793 is searched among the tags attached to this packet and,
794 if found, removed from it.
795 Other tags bound to packet, if present, are left untouched.
797 When a packet matches a rule with the
799 keyword, the ALTQ identifier for the given
804 Note that this ALTQ tag is only meaningful for packets going "out" of IPFW,
805 and not being rejected or going to divert sockets.
806 Note that if there is insufficient memory at the time the packet is
807 processed, it will not be tagged, so it is wise to make your ALTQ
808 "default" queue policy account for this.
811 rules match a single packet, only the first one adds the ALTQ classification
813 In doing so, traffic may be shaped by using
814 .Cm count Cm altq Ar queue
815 rules for classification early in the ruleset, then later applying
816 the filtering decision.
821 rules may come later and provide the actual filtering decisions in
822 addition to the fallback ALTQ tag.
826 to set up the queues before IPFW will be able to look them up by name,
827 and if the ALTQ disciplines are rearranged, the rules in containing the
828 queue identifiers in the kernel will likely have gone stale and need
830 Stale queue identifiers will probably result in misclassification.
832 All system ALTQ processing can be turned on or off via
837 .Cm disable Ar altq .
839 .Va net.inet.ip.fw.one_pass
840 is irrelevant to ALTQ traffic shaping, as the actual rule action is followed
841 always after adding an ALTQ tag.
844 A rule can be associated with one of the following actions, which
845 will be executed when the packet matches the body of the rule.
846 .Bl -tag -width indent
847 .It Cm allow | accept | pass | permit
848 Allow packets that match rule.
849 The search terminates.
850 .It Cm check-state Op Ar :flowname | Cm :any
851 Checks the packet against the dynamic ruleset.
852 If a match is found, execute the action associated with
853 the rule which generated this dynamic rule, otherwise
854 move to the next rule.
857 rules do not have a body.
860 rule is found, the dynamic ruleset is checked at the first
867 is symbolic name assigned to dynamic rule by
872 can be used to ignore states flowname when matching.
875 keyword is special name used for compatibility with old rulesets.
877 Update counters for all packets that match rule.
878 The search continues with the next rule.
880 Discard packets that match this rule.
881 The search terminates.
882 .It Cm divert Ar port
883 Divert packets that match this rule to the
887 The search terminates.
888 .It Cm fwd | forward Ar ipaddr | tablearg Ns Op , Ns Ar port
889 Change the next-hop on matching packets to
891 which can be an IP address or a host name.
892 The next hop can also be supplied by the last table
893 looked up for the packet by using the
895 keyword instead of an explicit address.
896 The search terminates if this rule matches.
900 is a local address, then matching packets will be forwarded to
902 (or the port number in the packet if one is not specified in the rule)
903 on the local machine.
907 is not a local address, then the port number
908 (if specified) is ignored, and the packet will be
909 forwarded to the remote address, using the route as found in
910 the local routing table for that IP.
914 rule will not match layer2 packets (those received
915 on ether_input, ether_output, or bridged).
919 action does not change the contents of the packet at all.
920 In particular, the destination address remains unmodified, so
921 packets forwarded to another system will usually be rejected by that system
922 unless there is a matching rule on that system to capture them.
923 For packets forwarded locally,
924 the local address of the socket will be
925 set to the original destination address of the packet.
928 entry look rather weird but is intended for
929 use with transparent proxy servers.
930 .It Cm nat Ar nat_nr | global | tablearg
933 (for network address translation, address redirect, etc.):
935 .Sx NETWORK ADDRESS TRANSLATION (NAT)
936 Section for further information.
937 .It Cm nat64lsn Ar name
938 Pass packet to a stateful NAT64 instance (for IPv6/IPv4 network address and
939 protocol translation): see the
940 .Sx IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
941 Section for further information.
942 .It Cm nat64stl Ar name
943 Pass packet to a stateless NAT64 instance (for IPv6/IPv4 network address and
944 protocol translation): see the
945 .Sx IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
946 Section for further information.
947 .It Cm nat64clat Ar name
948 Pass packet to a CLAT NAT64 instance (for client-side IPv6/IPv4 network address and
949 protocol translation): see the
950 .Sx IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
951 Section for further information.
953 Pass packet to a NPTv6 instance (for IPv6-to-IPv6 network prefix translation):
955 .Sx IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
956 Section for further information.
957 .It Cm pipe Ar pipe_nr
961 (for bandwidth limitation, delay, etc.).
963 .Sx TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
964 Section for further information.
965 The search terminates; however, on exit from the pipe and if
969 .Va net.inet.ip.fw.one_pass
970 is not set, the packet is passed again to the firewall code
971 starting from the next rule.
972 .It Cm queue Ar queue_nr
976 (for bandwidth limitation using WF2Q+).
982 Discard packets that match this rule, and if the
983 packet is a TCP packet, try to send a TCP reset (RST) notice.
984 The search terminates.
986 Discard packets that match this rule, and if the
987 packet is a TCP packet, try to send a TCP reset (RST) notice.
988 The search terminates.
989 .It Cm skipto Ar number | tablearg
990 Skip all subsequent rules numbered less than
992 The search continues with the first rule numbered
995 It is possible to use the
997 keyword with a skipto for a
1000 Skipto may work either in O(log(N)) or in O(1) depending
1001 on amount of memory and/or sysctl variables.
1003 .Sx SYSCTL VARIABLES
1004 section for more details.
1005 .It Cm call Ar number | tablearg
1006 The current rule number is saved in the internal stack and
1007 ruleset processing continues with the first rule numbered
1010 If later a rule with the
1012 action is encountered, the processing returns to the first rule
1015 rule plus one or higher
1016 (the same behaviour as with packets returning from
1021 This could be used to make somewhat like an assembly language
1023 calls to rules with common checks for different interfaces, etc.
1025 Rule with any number could be called, not just forward jumps as with
1027 So, to prevent endless loops in case of mistakes, both
1031 actions don't do any jumps and simply go to the next rule if memory
1032 cannot be allocated or stack overflowed/underflowed.
1034 Internally stack for rule numbers is implemented using
1036 facility and currently has size of 16 entries.
1037 As mbuf tags are lost when packet leaves the kernel,
1039 should not be used in subroutines to avoid endless loops
1040 and other undesired effects.
1042 Takes rule number saved to internal stack by the last
1044 action and returns ruleset processing to the first rule
1045 with number greater than number of corresponding
1048 See description of the
1050 action for more details.
1056 and thus are unconditional, but
1058 command-line utility currently requires every action except
1061 While it is sometimes useful to return only on some packets,
1062 usually you want to print just
1065 A workaround for this is to use new syntax and
1068 .Bd -literal -offset indent
1069 # Add a rule without actual body
1070 ipfw add 2999 return via any
1072 # List rules without "from any to any" part
1076 This cosmetic annoyance may be fixed in future releases.
1078 Send a copy of packets matching this rule to the
1080 socket bound to port
1082 The search continues with the next rule.
1083 .It Cm unreach Ar code Op mtu
1084 Discard packets that match this rule, and try to send an ICMP
1085 unreachable notice with code
1089 is a number from 0 to 255, or one of these aliases:
1090 .Cm net , host , protocol , port ,
1091 .Cm needfrag , srcfail , net-unknown , host-unknown ,
1092 .Cm isolated , net-prohib , host-prohib , tosnet ,
1093 .Cm toshost , filter-prohib , host-precedence
1095 .Cm precedence-cutoff .
1098 code may have an optional
1101 If specified, the MTU value will be put into generated ICMP packet.
1102 The search terminates.
1103 .It Cm unreach6 Ar code
1104 Discard packets that match this rule, and try to send an ICMPv6
1105 unreachable notice with code
1109 is a number from 0, 1, 3 or 4, or one of these aliases:
1110 .Cm no-route, admin-prohib, address
1113 The search terminates.
1114 .It Cm netgraph Ar cookie
1115 Divert packet into netgraph with given
1117 The search terminates.
1118 If packet is later returned from netgraph it is either
1119 accepted or continues with the next rule, depending on
1120 .Va net.inet.ip.fw.one_pass
1122 .It Cm ngtee Ar cookie
1123 A copy of packet is diverted into netgraph, original
1124 packet continues with the next rule.
1127 for more information on
1132 .It Cm setfib Ar fibnum | tablearg
1133 The packet is tagged so as to use the FIB (routing table)
1135 in any subsequent forwarding decisions.
1136 In the current implementation, this is limited to the values 0 through 15, see
1138 Processing continues at the next rule.
1139 It is possible to use the
1141 keyword with setfib.
1142 If the tablearg value is not within the compiled range of fibs,
1143 the packet's fib is set to 0.
1144 .It Cm setdscp Ar DSCP | number | tablearg
1145 Set specified DiffServ codepoint for an IPv4/IPv6 packet.
1146 Processing continues at the next rule.
1147 Supported values are:
1193 Additionally, DSCP value can be specified by number (0..63).
1194 It is also possible to use the
1196 keyword with setdscp.
1197 If the tablearg value is not within the 0..63 range, lower 6 bits of supplied
1199 .It Cm tcp-setmss Ar mss
1200 Set the Maximum Segment Size (MSS) in the TCP segment to value
1204 should be loaded or kernel should have
1205 .Cm options IPFIREWALL_PMOD
1206 to be able use this action.
1207 This command does not change a packet if original MSS value is lower than
1209 Both TCP over IPv4 and over IPv6 are supported.
1210 Regardless of matched a packet or not by the
1212 rule, the search continues with the next rule.
1214 Queue and reassemble IPv4 fragments.
1215 If the packet is not fragmented, counters are updated and
1216 processing continues with the next rule.
1217 If the packet is the last logical fragment, the packet is reassembled and, if
1218 .Va net.inet.ip.fw.one_pass
1219 is set to 0, processing continues with the next rule.
1220 Otherwise, the packet is allowed to pass and the search terminates.
1221 If the packet is a fragment in the middle of a logical group of fragments,
1223 processing stops immediately.
1225 Fragment handling can be tuned via
1226 .Va net.inet.ip.maxfragpackets
1228 .Va net.inet.ip.maxfragsperpacket
1229 which limit, respectively, the maximum number of processable
1230 fragments (default: 800) and
1231 the maximum number of fragments per packet (default: 16).
1233 NOTA BENE: since fragments do not contain port numbers,
1234 they should be avoided with the
1237 Alternatively, direction-based (like
1241 ) and source-based (like
1243 ) match patterns can be used to select fragments.
1245 Usually a simple rule like:
1246 .Bd -literal -offset indent
1247 # reassemble incoming fragments
1248 ipfw add reass all from any to any in
1251 is all you need at the beginning of your ruleset.
1253 Discard packets that match this rule, and if the packet is an SCTP packet,
1254 try to send an SCTP packet containing an ABORT chunk.
1255 The search terminates.
1257 Discard packets that match this rule, and if the packet is an SCTP packet,
1258 try to send an SCTP packet containing an ABORT chunk.
1259 The search terminates.
1262 The body of a rule contains zero or more patterns (such as
1263 specific source and destination addresses or ports,
1264 protocol options, incoming or outgoing interfaces, etc.)
1265 that the packet must match in order to be recognised.
1266 In general, the patterns are connected by (implicit)
1268 operators -- i.e., all must match in order for the
1270 Individual patterns can be prefixed by the
1272 operator to reverse the result of the match, as in
1274 .Dl "ipfw add 100 allow ip from not 1.2.3.4 to any"
1276 Additionally, sets of alternative match patterns
1278 can be constructed by putting the patterns in
1279 lists enclosed between parentheses ( ) or braces { }, and
1282 operator as follows:
1284 .Dl "ipfw add 100 allow ip from { x or not y or z } to any"
1286 Only one level of parentheses is allowed.
1287 Beware that most shells have special meanings for parentheses
1288 or braces, so it is advisable to put a backslash \\ in front of them
1289 to prevent such interpretations.
1291 The body of a rule must in general include a source and destination
1295 can be used in various places to specify that the content of
1296 a required field is irrelevant.
1298 The rule body has the following format:
1299 .Bd -ragged -offset indent
1300 .Op Ar proto Cm from Ar src Cm to Ar dst
1304 The first part (proto from src to dst) is for backward
1305 compatibility with earlier versions of
1309 any match pattern (including MAC headers, IP protocols,
1310 addresses and ports) can be specified in the
1314 Rule fields have the following meaning:
1315 .Bl -tag -width indent
1316 .It Ar proto : protocol | Cm { Ar protocol Cm or ... }
1317 .It Ar protocol : Oo Cm not Oc Ar protocol-name | protocol-number
1318 An IP protocol specified by number or name
1319 (for a complete list see
1320 .Pa /etc/protocols ) ,
1321 or one of the following keywords:
1322 .Bl -tag -width indent
1324 Matches IPv4 packets.
1326 Matches IPv6 packets.
1335 option will be treated as inner protocol.
1343 .Cm { Ar protocol Cm or ... }
1346 is provided for convenience only but its use is deprecated.
1347 .It Ar src No and Ar dst : Bro Cm addr | Cm { Ar addr Cm or ... } Brc Op Oo Cm not Oc Ar ports
1348 An address (or a list, see below)
1349 optionally followed by
1355 with multiple addresses) is provided for convenience only and
1356 its use is discouraged.
1357 .It Ar addr : Oo Cm not Oc Bro
1358 .Cm any | me | me6 |
1359 .Cm table Ns Pq Ar name Ns Op , Ns Ar value
1360 .Ar | addr-list | addr-set
1362 .Bl -tag -width indent
1364 Matches any IP address.
1366 Matches any IP address configured on an interface in the system.
1368 Matches any IPv6 address configured on an interface in the system.
1369 The address list is evaluated at the time the packet is
1371 .It Cm table Ns Pq Ar name Ns Op , Ns Ar value
1372 Matches any IPv4 or IPv6 address for which an entry exists in the lookup table
1374 If an optional 32-bit unsigned
1376 is also specified, an entry will match only if it has this value.
1379 section below for more information on lookup tables.
1381 .It Ar addr-list : ip-addr Ns Op Ns , Ns Ar addr-list
1383 A host or subnet address specified in one of the following ways:
1384 .Bl -tag -width indent
1385 .It Ar numeric-ip | hostname
1386 Matches a single IPv4 address, specified as dotted-quad or a hostname.
1387 Hostnames are resolved at the time the rule is added to the firewall list.
1388 .It Ar addr Ns / Ns Ar masklen
1389 Matches all addresses with base
1391 (specified as an IP address, a network number, or a hostname)
1395 As an example, 1.2.3.4/25 or 1.2.3.0/25 will match
1396 all IP numbers from 1.2.3.0 to 1.2.3.127 .
1397 .It Ar addr Ns : Ns Ar mask
1398 Matches all addresses with base
1400 (specified as an IP address, a network number, or a hostname)
1403 specified as a dotted quad.
1404 As an example, 1.2.3.4:255.0.255.0 or 1.0.3.0:255.0.255.0 will match
1406 This form is advised only for non-contiguous
1408 It is better to resort to the
1409 .Ar addr Ns / Ns Ar masklen
1410 format for contiguous masks, which is more compact and less
1413 .It Ar addr-set : addr Ns Oo Ns / Ns Ar masklen Oc Ns Cm { Ns Ar list Ns Cm }
1414 .It Ar list : Bro Ar num | num-num Brc Ns Op Ns , Ns Ar list
1415 Matches all addresses with base address
1417 (specified as an IP address, a network number, or a hostname)
1418 and whose last byte is in the list between braces { } .
1419 Note that there must be no spaces between braces and
1420 numbers (spaces after commas are allowed).
1421 Elements of the list can be specified as single entries
1425 field is used to limit the size of the set of addresses,
1426 and can have any value between 24 and 32.
1428 it will be assumed as 24.
1430 This format is particularly useful to handle sparse address sets
1431 within a single rule.
1432 Because the matching occurs using a
1433 bitmask, it takes constant time and dramatically reduces
1434 the complexity of rulesets.
1436 As an example, an address specified as 1.2.3.4/24{128,35-55,89}
1437 or 1.2.3.0/24{128,35-55,89}
1438 will match the following IP addresses:
1440 1.2.3.128, 1.2.3.35 to 1.2.3.55, 1.2.3.89 .
1441 .It Ar addr6-list : ip6-addr Ns Op Ns , Ns Ar addr6-list
1443 A host or subnet specified one of the following ways:
1444 .Bl -tag -width indent
1445 .It Ar numeric-ip | hostname
1446 Matches a single IPv6 address as allowed by
1449 Hostnames are resolved at the time the rule is added to the firewall
1451 .It Ar addr Ns / Ns Ar masklen
1452 Matches all IPv6 addresses with base
1454 (specified as allowed by
1460 .It Ar addr Ns / Ns Ar mask
1461 Matches all IPv6 addresses with base
1463 (specified as allowed by
1468 specified as allowed by
1470 As an example, fe::640:0:0/ffff::ffff:ffff:0:0 will match
1472 This form is advised only for non-contiguous
1474 It is better to resort to the
1475 .Ar addr Ns / Ns Ar masklen
1476 format for contiguous masks, which is more compact and less
1480 No support for sets of IPv6 addresses is provided because IPv6 addresses
1481 are typically random past the initial prefix.
1482 .It Ar ports : Bro Ar port | port Ns \&- Ns Ar port Ns Brc Ns Op , Ns Ar ports
1483 For protocols which support port numbers (such as SCTP, TCP and UDP), optional
1485 may be specified as one or more ports or port ranges, separated
1486 by commas but no spaces, and an optional
1491 notation specifies a range of ports (including boundaries).
1495 may be used instead of numeric port values.
1496 The length of the port list is limited to 30 ports or ranges,
1497 though one can specify larger ranges by using an
1501 section of the rule.
1505 can be used to escape the dash
1507 character in a service name (from a shell, the backslash must be
1508 typed twice to avoid the shell itself interpreting it as an escape
1511 .Dl "ipfw add count tcp from any ftp\e\e-data-ftp to any"
1513 Fragmented packets which have a non-zero offset (i.e., not the first
1514 fragment) will never match a rule which has one or more port
1518 option for details on matching fragmented packets.
1520 .Ss RULE OPTIONS (MATCH PATTERNS)
1521 Additional match patterns can be used within
1523 Zero or more of these so-called
1525 can be present in a rule, optionally prefixed by the
1527 operand, and possibly grouped into
1530 The following match patterns can be used (listed in alphabetical order):
1531 .Bl -tag -width indent
1532 .It Cm // this is a comment .
1533 Inserts the specified text as a comment in the rule.
1534 Everything following // is considered as a comment and stored in the rule.
1535 You can have comment-only rules, which are listed as having a
1537 action followed by the comment.
1541 .It Cm defer-immediate-action | defer-action
1542 A rule with this option will not perform normal action
1544 This option is intended to be used with
1548 as the dynamic rule, created but ignored on match, will work
1553 .Cm defer-immediate-action
1554 create a dynamic rule and continue with the next rule without actually
1555 performing the action part of this rule.
1556 When the rule is later activated via the state table, the action is
1559 Matches only packets generated by a divert socket.
1560 .It Cm diverted-loopback
1561 Matches only packets coming from a divert socket back into the IP stack
1563 .It Cm diverted-output
1564 Matches only packets going from a divert socket back outward to the IP
1565 stack output for delivery.
1566 .It Cm dst-ip Ar ip-address
1567 Matches IPv4 packets whose destination IP is one of the address(es)
1568 specified as argument.
1569 .It Bro Cm dst-ip6 | dst-ipv6 Brc Ar ip6-address
1570 Matches IPv6 packets whose destination IP is one of the address(es)
1571 specified as argument.
1572 .It Cm dst-port Ar ports
1573 Matches IP packets whose destination port is one of the port(s)
1574 specified as argument.
1576 Matches TCP packets that have the RST or ACK bits set.
1577 .It Cm ext6hdr Ar header
1578 Matches IPv6 packets containing the extended header given by
1580 Supported headers are:
1586 any type of Routing Header
1588 Source routing Routing Header Type 0
1590 Mobile IPv6 Routing Header Type 2
1594 IPSec authentication headers
1596 and IPsec encapsulated security payload headers
1598 .It Cm fib Ar fibnum
1599 Matches a packet that has been tagged to use
1600 the given FIB (routing table) number.
1601 .It Cm flow Ar table Ns Pq Ar name Ns Op , Ns Ar value
1602 Search for the flow entry in lookup table
1604 If not found, the match fails.
1605 Otherwise, the match succeeds and
1607 is set to the value extracted from the table.
1609 This option can be useful to quickly dispatch traffic based on
1610 certain packet fields.
1613 section below for more information on lookup tables.
1614 .It Cm flow-id Ar labels
1615 Matches IPv6 packets containing any of the flow labels given in
1618 is a comma separated list of numeric flow labels.
1619 .It Cm dst-mac Ar table Ns Pq Ar name Ns Op , Ns Ar value
1620 Search for the destination MAC address entry in lookup table
1622 If not found, the match fails.
1623 Otherwise, the match succeeds and
1625 is set to the value extracted from the table.
1626 .It Cm src-mac Ar table Ns Pq Ar name Ns Op , Ns Ar value
1627 Search for the source MAC address entry in lookup table
1629 If not found, the match fails.
1630 Otherwise, the match succeeds and
1632 is set to the value extracted from the table.
1634 Matches IPv4 packets whose
1636 field contains the comma separated list of IPv4 fragmentation
1637 options specified in
1639 The recognized options are:
1641 .Pq Dv don't fragment ,
1643 .Pq Dv more fragments ,
1645 .Pq Dv reserved fragment bit
1647 .Pq Dv non-zero fragment offset .
1648 The absence of a particular options may be denoted
1652 Empty list of options defaults to matching on non-zero fragment offset.
1653 Such rule would match all not the first fragment datagrams,
1655 This is a backward compatibility with older rulesets.
1657 Matches all TCP or UDP packets sent by or received for a
1661 may be specified by name or number.
1663 Matches all TCP or UDP packets sent by or received for the
1664 jail whose ID or name is
1666 .It Cm icmptypes Ar types
1667 Matches ICMP packets whose ICMP type is in the list
1669 The list may be specified as any combination of
1670 individual types (numeric) separated by commas.
1671 .Em Ranges are not allowed .
1672 The supported ICMP types are:
1676 destination unreachable
1684 router advertisement
1688 time-to-live exceeded
1700 address mask request
1702 and address mask reply
1704 .It Cm icmp6types Ar types
1705 Matches ICMP6 packets whose ICMP6 type is in the list of
1707 The list may be specified as any combination of
1708 individual types (numeric) separated by commas.
1709 .Em Ranges are not allowed .
1711 Matches incoming or outgoing packets, respectively.
1715 are mutually exclusive (in fact,
1719 .It Cm ipid Ar id-list
1720 Matches IPv4 packets whose
1722 field has value included in
1724 which is either a single value or a list of values or ranges
1725 specified in the same way as
1727 .It Cm iplen Ar len-list
1728 Matches IP packets whose total length, including header and data, is
1731 which is either a single value or a list of values or ranges
1732 specified in the same way as
1734 .It Cm ipoptions Ar spec
1735 Matches packets whose IPv4 header contains the comma separated list of
1736 options specified in
1738 The supported IP options are:
1741 (strict source route),
1743 (loose source route),
1745 (record packet route) and
1748 The absence of a particular option may be denoted
1751 .It Cm ipprecedence Ar precedence
1752 Matches IPv4 packets whose precedence field is equal to
1755 Matches packets that have IPSEC history associated with them
1756 (i.e., the packet comes encapsulated in IPSEC, the kernel
1757 has IPSEC support, and can correctly decapsulate it).
1759 Note that specifying
1761 is different from specifying
1763 as the latter will only look at the specific IP protocol field,
1764 irrespective of IPSEC kernel support and the validity of the IPSEC data.
1766 Further note that this flag is silently ignored in kernels without
1768 It does not affect rule processing when given and the
1769 rules are handled as if with no
1772 .It Cm iptos Ar spec
1773 Matches IPv4 packets whose
1775 field contains the comma separated list of
1776 service types specified in
1778 The supported IP types of service are:
1781 .Pq Dv IPTOS_LOWDELAY ,
1783 .Pq Dv IPTOS_THROUGHPUT ,
1785 .Pq Dv IPTOS_RELIABILITY ,
1787 .Pq Dv IPTOS_MINCOST ,
1789 .Pq Dv IPTOS_ECN_CE .
1790 The absence of a particular type may be denoted
1793 .It Cm dscp spec Ns Op , Ns Ar spec
1794 Matches IPv4/IPv6 packets whose
1796 field value is contained in
1799 Multiple values can be specified via
1800 the comma separated list.
1801 Value can be one of keywords used in
1803 action or exact number.
1804 .It Cm ipttl Ar ttl-list
1805 Matches IPv4 packets whose time to live is included in
1807 which is either a single value or a list of values or ranges
1808 specified in the same way as
1810 .It Cm ipversion Ar ver
1811 Matches IP packets whose IP version field is
1813 .It Cm keep-state Op Ar :flowname
1814 Upon a match, the firewall will create a dynamic rule, whose
1815 default behaviour is to match bidirectional traffic between
1816 source and destination IP/port using the same protocol.
1817 The rule has a limited lifetime (controlled by a set of
1819 variables), and the lifetime is refreshed every time a matching
1823 is used to assign additional to addresses, ports and protocol parameter
1825 It can be used for more accurate matching by
1830 keyword is special name used for compatibility with old rulesets.
1832 Matches only layer2 packets, i.e., those passed to
1837 .Fn ether_output_frame .
1838 .It Cm limit Bro Cm src-addr | src-port | dst-addr | dst-port Brc Ar N Op Ar :flowname
1839 The firewall will only allow
1841 connections with the same
1842 set of parameters as specified in the rule.
1844 of source and destination addresses and ports can be
1846 .It Cm lookup Bro Cm dst-ip | dst-port | dst-mac | src-ip | src-port | src-mac | uid | jail Brc Ar name
1847 Search an entry in lookup table
1849 that matches the field specified as argument.
1850 If not found, the match fails.
1851 Otherwise, the match succeeds and
1853 is set to the value extracted from the table.
1855 This option can be useful to quickly dispatch traffic based on
1856 certain packet fields.
1859 section below for more information on lookup tables.
1860 .It Cm { MAC | mac } Ar dst-mac src-mac
1861 Match packets with a given
1865 addresses, specified as the
1867 keyword (matching any MAC address), or six groups of hex digits
1868 separated by colons,
1869 and optionally followed by a mask indicating the significant bits.
1870 The mask may be specified using either of the following methods:
1871 .Bl -enum -width indent
1875 followed by the number of significant bits.
1876 For example, an address with 33 significant bits could be specified as:
1878 .Dl "MAC 10:20:30:40:50:60/33 any"
1882 followed by a bitmask specified as six groups of hex digits separated
1884 For example, an address in which the last 16 bits are significant could
1887 .Dl "MAC 10:20:30:40:50:60&00:00:00:00:ff:ff any"
1889 Note that the ampersand character has a special meaning in many shells
1890 and should generally be escaped.
1892 Note that the order of MAC addresses (destination first,
1894 the same as on the wire, but the opposite of the one used for
1896 .It Cm mac-type Ar mac-type
1897 Matches packets whose Ethernet Type field
1898 corresponds to one of those specified as argument.
1900 is specified in the same way as
1902 (i.e., one or more comma-separated single values or ranges).
1903 You can use symbolic names for known values such as
1904 .Em vlan , ipv4, ipv6 .
1905 Values can be entered as decimal or hexadecimal (if prefixed by 0x),
1906 and they are always printed as hexadecimal (unless the
1908 option is used, in which case symbolic resolution will be attempted).
1909 .It Cm proto Ar protocol
1910 Matches packets with the corresponding IP protocol.
1912 Upon a match, the firewall will create a dynamic rule as if
1915 However, this option doesn't imply an implicit
1919 .It Cm recv | xmit | via Brq Ar ifX | Ar if Ns Cm * | Ar table Ns Po Ar name Ns Oo , Ns Ar value Oc Pc | Ar ipno | Ar any
1920 Matches packets received, transmitted or going through,
1921 respectively, the interface specified by exact name
1925 by IP address, or through some interface.
1928 may be used to match interface by its kernel ifindex.
1931 section below for more information on lookup tables.
1935 keyword causes the interface to always be checked.
1942 then only the receive or transmit interface (respectively)
1944 By specifying both, it is possible to match packets based on
1945 both receive and transmit interface, e.g.:
1947 .Dl "ipfw add deny ip from any to any out recv ed0 xmit ed1"
1951 interface can be tested on either incoming or outgoing packets,
1954 interface can only be tested on outgoing packets.
1959 is invalid) whenever
1963 A packet might not have a receive or transmit interface: packets
1964 originating from the local host have no receive interface,
1965 while packets destined for the local host have no transmit
1967 .It Cm set-limit Bro Cm src-addr | src-port | dst-addr | dst-port Brc Ar N
1970 but does not have an implicit
1974 Matches TCP packets that have the SYN bit set but no ACK bit.
1975 This is the short form of
1976 .Dq Li tcpflags\ syn,!ack .
1978 Matches packets that are associated to a local socket and
1979 for which the SO_USER_COOKIE socket option has been set
1980 to a non-zero value.
1981 As a side effect, the value of the
1982 option is made available as
1984 value, which in turn can be used as
1989 .It Cm src-ip Ar ip-address
1990 Matches IPv4 packets whose source IP is one of the address(es)
1991 specified as an argument.
1992 .It Cm src-ip6 Ar ip6-address
1993 Matches IPv6 packets whose source IP is one of the address(es)
1994 specified as an argument.
1995 .It Cm src-port Ar ports
1996 Matches IP packets whose source port is one of the port(s)
1997 specified as argument.
1998 .It Cm tagged Ar tag-list
1999 Matches packets whose tags are included in
2001 which is either a single value or a list of values or ranges
2002 specified in the same way as
2004 Tags can be applied to the packet using
2006 rule action parameter (see it's description for details on tags).
2007 .It Cm tcpack Ar ack
2009 Match if the TCP header acknowledgment number field is set to
2011 .It Cm tcpdatalen Ar tcpdatalen-list
2012 Matches TCP packets whose length of TCP data is
2013 .Ar tcpdatalen-list ,
2014 which is either a single value or a list of values or ranges
2015 specified in the same way as
2017 .It Cm tcpflags Ar spec
2019 Match if the TCP header contains the comma separated list of
2022 The supported TCP flags are:
2031 The absence of a particular flag may be denoted
2034 A rule which contains a
2036 specification can never match a fragmented packet which has
2040 option for details on matching fragmented packets.
2041 .It Cm tcpmss Ar tcpmss-list
2042 Matches TCP packets whose MSS (maximum segment size) value is set to
2044 which is either a single value or a list of values or ranges
2045 specified in the same way as
2047 .It Cm tcpseq Ar seq
2049 Match if the TCP header sequence number field is set to
2051 .It Cm tcpwin Ar tcpwin-list
2052 Matches TCP packets whose header window field is set to
2054 which is either a single value or a list of values or ranges
2055 specified in the same way as
2057 .It Cm tcpoptions Ar spec
2059 Match if the TCP header contains the comma separated list of
2060 options specified in
2062 The supported TCP options are:
2065 (maximum segment size),
2067 (tcp window advertisement),
2071 (rfc1323 timestamp) and
2073 (rfc1644 t/tcp connection count).
2074 The absence of a particular option may be denoted
2078 Match all TCP or UDP packets sent by or received for a
2082 may be matched by name or identification number.
2084 For incoming packets,
2085 a routing table lookup is done on the packet's source address.
2086 If the interface on which the packet entered the system matches the
2087 outgoing interface for the route,
2089 If the interfaces do not match up,
2090 the packet does not match.
2091 All outgoing packets or packets with no incoming interface match.
2093 The name and functionality of the option is intentionally similar to
2094 the Cisco IOS command:
2096 .Dl ip verify unicast reverse-path
2098 This option can be used to make anti-spoofing rules to reject all
2099 packets with source addresses not from this interface.
2103 For incoming packets,
2104 a routing table lookup is done on the packet's source address.
2105 If a route to the source address exists, but not the default route
2106 or a blackhole/reject route, the packet matches.
2107 Otherwise, the packet does not match.
2108 All outgoing packets match.
2110 The name and functionality of the option is intentionally similar to
2111 the Cisco IOS command:
2113 .Dl ip verify unicast source reachable-via any
2115 This option can be used to make anti-spoofing rules to reject all
2116 packets whose source address is unreachable.
2118 For incoming packets, the packet's source address is checked if it
2119 belongs to a directly connected network.
2120 If the network is directly connected, then the interface the packet
2121 came on in is compared to the interface the network is connected to.
2122 When incoming interface and directly connected interface are not the
2123 same, the packet does not match.
2124 Otherwise, the packet does match.
2125 All outgoing packets match.
2127 This option can be used to make anti-spoofing rules to reject all
2128 packets that pretend to be from a directly connected network but do
2129 not come in through that interface.
2130 This option is similar to but more restricted than
2132 because it engages only on packets with source addresses of directly
2133 connected networks instead of all source addresses.
2136 Lookup tables are useful to handle large sparse sets of
2137 addresses or other search keys (e.g., ports, jail IDs, interface names).
2138 In the rest of this section we will use the term ``key''.
2139 Table name needs to match the following spec:
2141 Tables with the same name can be created in different
2143 However, rule links to the tables in
2146 This behavior can be controlled by
2147 .Va net.inet.ip.fw.tables_sets
2151 section for more information.
2152 There may be up to 65535 different lookup tables.
2154 The following table types are supported:
2155 .Bl -tag -width indent
2156 .It Ar table-type : Ar addr | iface | number | flow | mac
2157 .It Ar table-key : Ar addr Ns Oo / Ns Ar masklen Oc | iface-name | number | flow-spec
2158 .It Ar flow-spec : Ar flow-field Ns Op , Ns Ar flow-spec
2159 .It Ar flow-field : src-ip | proto | src-port | dst-ip | dst-port
2161 Matches IPv4 or IPv6 address.
2162 Each entry is represented by an
2163 .Ar addr Ns Op / Ns Ar masklen
2164 and will match all addresses with base
2166 (specified as an IPv4/IPv6 address, or a hostname) and mask width of
2171 is not specified, it defaults to 32 for IPv4 and 128 for IPv6.
2172 When looking up an IP address in a table, the most specific
2175 Matches interface names.
2176 Each entry is represented by string treated as interface name.
2177 Wildcards are not supported.
2179 Matches protocol ports, uids/gids or jail IDs.
2180 Each entry is represented by 32-bit unsigned integer.
2181 Ranges are not supported.
2183 Matches packet fields specified by
2185 type suboptions with table entries.
2187 Matches MAC address.
2188 Each entry is represented by an
2189 .Ar addr Ns Op / Ns Ar masklen
2190 and will match all addresses with base
2197 is not specified, it defaults to 48.
2198 When looking up an MAC address in a table, the most specific
2202 Tables require explicit creation via
2206 The following creation options are supported:
2207 .Bl -tag -width indent
2208 .It Ar create-options : Ar create-option | create-options
2209 .It Ar create-option : Cm type Ar table-type | Cm valtype Ar value-mask | Cm algo Ar algo-desc |
2210 .Cm limit Ar number | Cm locked | Cm missing | Cm or-flush
2216 Table algorithm to use (see below).
2218 Maximum number of items that may be inserted into table.
2220 Restrict any table modifications.
2222 Do not fail if table already exists and has exactly same options as new one.
2224 Flush existing table with same name instead of returning error.
2227 so existing table must be compatible with new one.
2230 Some of these options may be modified later via
2233 The following options can be changed:
2234 .Bl -tag -width indent
2235 .It Ar modify-options : Ar modify-option | modify-options
2236 .It Ar modify-option : Cm limit Ar number
2238 Alter maximum number of items that may be inserted into table.
2241 Additionally, table can be locked or unlocked using
2249 can be swapped with each other using
2252 Swap may fail if tables limits are set and data exchange
2253 would result in limits hit.
2254 Operation is performed atomically.
2256 One or more entries can be added to a table at once using
2259 Addition of all items are performed atomically.
2260 By default, error in addition of one entry does not influence
2261 addition of other entries.
2262 However, non-zero error code is returned in that case.
2265 keyword may be specified before
2267 to indicate all-or-none add request.
2269 One or more entries can be removed from a table at once using
2272 By default, error in removal of one entry does not influence
2273 removing of other entries.
2274 However, non-zero error code is returned in that case.
2276 It may be possible to check what entry will be found on particular
2282 This functionality is optional and may be unsupported in some algorithms.
2284 The following operations can be performed on
2289 .Bl -tag -width indent
2293 Removes all entries.
2295 Shows generic table information.
2297 Shows generic table information and algo-specific data.
2300 The following lookup algorithms are supported:
2301 .Bl -tag -width indent
2302 .It Ar algo-desc : algo-name | "algo-name algo-data"
2303 .It Ar algo-name : Ar addr: radix | addr: hash | iface: array | number: array | flow: hash | mac: radix
2305 Separate Radix trees for IPv4 and IPv6, the same way as the routing table (see
2311 Separate auto-growing hashes for IPv4 and IPv6.
2312 Accepts entries with the same mask length specified initially via
2313 .Cm "addr:hash masks=/v4,/v6"
2314 algorithm creation options.
2315 Assume /32 and /128 masks by default.
2316 Search removes host bits (according to mask) from supplied address and checks
2317 resulting key in appropriate hash.
2318 Mostly optimized for /64 and byte-ranged IPv6 masks.
2320 Array storing sorted indexes for entries which are presented in the system.
2321 Optimized for very fast lookup.
2323 Array storing sorted u32 numbers.
2325 Auto-growing hash storing flow entries.
2326 Search calculates hash on required packet fields and searches for matching
2327 entries in selected bucket.
2329 Radix tree for MAC address
2334 feature provides the ability to use a value, looked up in the table, as
2335 the argument for a rule action, action parameter or rule option.
2336 This can significantly reduce number of rules in some configurations.
2337 If two tables are used in a rule, the result of the second (destination)
2340 Each record may hold one or more values according to
2342 This mask is set on table creation via
2345 The following value types are supported:
2346 .Bl -tag -width indent
2347 .It Ar value-mask : Ar value-type Ns Op , Ns Ar value-mask
2348 .It Ar value-type : Ar skipto | pipe | fib | nat | dscp | tag | divert |
2349 .Ar netgraph | limit | ipv4
2351 rule number to jump to.
2355 fib number to match/set.
2357 nat number to jump to.
2359 dscp value to match/set.
2361 tag number to match/set.
2363 port number to divert traffic to.
2365 hook number to move packet to.
2367 maximum number of connections.
2369 IPv4 nexthop to fwd packets to.
2371 IPv6 nexthop to fwd packets to.
2376 argument can be used with the following actions:
2377 .Cm nat, pipe, queue, divert, tee, netgraph, ngtee, fwd, skipto, setfib ,
2385 action, the user should be aware that the code will walk the ruleset
2386 up to a rule equal to, or past, the given number.
2390 Section for example usage of tables and the tablearg keyword.
2392 Each rule or table belongs to one of 32 different
2395 Set 31 is reserved for the default rule.
2397 By default, rules or tables are put in set 0, unless you use the
2399 attribute when adding a new rule or table.
2400 Sets can be individually and atomically enabled or disabled,
2401 so this mechanism permits an easy way to store multiple configurations
2402 of the firewall and quickly (and atomically) switch between them.
2404 By default, tables from set 0 are referenced when adding rule with
2405 table opcodes regardless of rule set.
2406 This behavior can be changed by setting
2407 .Va net.inet.ip.fw.tables_sets
2409 Rule's set will then be used for table references.
2411 The command to enable/disable sets is
2412 .Bd -ragged -offset indent
2414 .Cm set Oo Cm disable Ar number ... Oc Op Cm enable Ar number ...
2421 sections can be specified.
2422 Command execution is atomic on all the sets specified in the command.
2423 By default, all sets are enabled.
2425 When you disable a set, its rules behave as if they do not exist
2426 in the firewall configuration, with only one exception:
2427 .Bd -ragged -offset indent
2428 dynamic rules created from a rule before it had been disabled
2429 will still be active until they expire.
2431 dynamic rules you have to explicitly delete the parent rule
2432 which generated them.
2435 The set number of rules can be changed with the command
2436 .Bd -ragged -offset indent
2439 .Brq Cm rule Ar rule-number | old-set
2443 Also, you can atomically swap two rulesets with the command
2444 .Bd -ragged -offset indent
2446 .Cm set swap Ar first-set second-set
2451 Section on some possible uses of sets of rules.
2452 .Sh STATEFUL FIREWALL
2453 Stateful operation is a way for the firewall to dynamically
2454 create rules for specific flows when packets that
2455 match a given pattern are detected.
2456 Support for stateful
2457 operation comes through the
2458 .Cm check-state , keep-state , record-state , limit
2464 Dynamic rules are created when a packet matches a
2470 rule, causing the creation of a
2472 rule which will match all and only packets with
2476 .Em src-ip/src-port dst-ip/dst-port
2481 are used here only to denote the initial match addresses, but they
2482 are completely equivalent afterwards).
2488 This name is used in matching together with addresses, ports and protocol.
2489 Dynamic rules will be checked at the first
2490 .Cm check-state, keep-state
2493 occurrence, and the action performed upon a match will be the same
2494 as in the parent rule.
2496 Note that no additional attributes other than protocol and IP addresses
2497 and ports and :flowname are checked on dynamic rules.
2499 The typical use of dynamic rules is to keep a closed firewall configuration,
2500 but let the first TCP SYN packet from the inside network install a
2501 dynamic rule for the flow so that packets belonging to that session
2502 will be allowed through the firewall:
2504 .Dl "ipfw add check-state :OUTBOUND"
2505 .Dl "ipfw add allow tcp from my-subnet to any setup keep-state :OUTBOUND"
2506 .Dl "ipfw add deny tcp from any to any"
2508 A similar approach can be used for UDP, where an UDP packet coming
2509 from the inside will install a dynamic rule to let the response through
2512 .Dl "ipfw add check-state :OUTBOUND"
2513 .Dl "ipfw add allow udp from my-subnet to any keep-state :OUTBOUND"
2514 .Dl "ipfw add deny udp from any to any"
2516 Dynamic rules expire after some time, which depends on the status
2517 of the flow and the setting of some
2521 .Sx SYSCTL VARIABLES
2523 For TCP sessions, dynamic rules can be instructed to periodically
2524 send keepalive packets to refresh the state of the rule when it is
2529 for more examples on how to use dynamic rules.
2530 .Sh TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
2532 is also the user interface for the
2534 traffic shaper, packet scheduler and network emulator, a subsystem that
2535 can artificially queue, delay or drop packets
2536 emulating the behaviour of certain network links
2537 or queueing systems.
2540 operates by first using the firewall to select packets
2541 using any match pattern that can be used in
2544 Matching packets are then passed to either of two
2545 different objects, which implement the traffic regulation:
2546 .Bl -hang -offset XXXX
2552 with given bandwidth and propagation delay,
2553 driven by a FIFO scheduler and a single queue with programmable
2554 queue size and packet loss rate.
2555 Packets are appended to the queue as they come out from
2557 and then transferred in FIFO order to the link at the desired rate.
2561 is an abstraction used to implement packet scheduling
2562 using one of several packet scheduling algorithms.
2565 are first grouped into flows according to a mask on the 5-tuple.
2566 Flows are then passed to the scheduler associated to the
2568 and each flow uses scheduling parameters (weight and others)
2569 as configured in the
2572 A scheduler in turn is connected to an emulated link,
2573 and arbitrates the link's bandwidth among backlogged flows according to
2574 weights and to the features of the scheduling algorithm in use.
2579 can be used to set hard limits to the bandwidth that a flow can use, whereas
2581 can be used to determine how different flows share the available bandwidth.
2583 A graphical representation of the binding of queues,
2584 flows, schedulers and links is below.
2585 .Bd -literal -offset indent
2586 (flow_mask|sched_mask) sched_mask
2587 +---------+ weight Wx +-------------+
2588 | |->-[flow]-->--| |-+
2589 -->--| QUEUE x | ... | | |
2590 | |->-[flow]-->--| SCHEDuler N | |
2592 ... | +--[LINK N]-->--
2593 +---------+ weight Wy | | +--[LINK N]-->--
2594 | |->-[flow]-->--| | |
2595 -->--| QUEUE y | ... | | |
2596 | |->-[flow]-->--| | |
2597 +---------+ +-------------+ |
2600 It is important to understand the role of the SCHED_MASK
2601 and FLOW_MASK, which are configured through the commands
2602 .Dl "ipfw sched N config mask SCHED_MASK ..."
2604 .Dl "ipfw queue X config mask FLOW_MASK ..." .
2606 The SCHED_MASK is used to assign flows to one or more
2607 scheduler instances, one for each
2608 value of the packet's 5-tuple after applying SCHED_MASK.
2609 As an example, using ``src-ip 0xffffff00'' creates one instance
2610 for each /24 destination subnet.
2612 The FLOW_MASK, together with the SCHED_MASK, is used to split
2614 As an example, using
2615 ``src-ip 0x000000ff''
2616 together with the previous SCHED_MASK makes a flow for
2617 each individual source address.
2618 In turn, flows for each /24
2619 subnet will be sent to the same scheduler instance.
2621 The above diagram holds even for the
2623 case, with the only restriction that a
2625 only supports a SCHED_MASK, and forces the use of a FIFO
2626 scheduler (these are for backward compatibility reasons;
2627 in fact, internally, a
2629 pipe is implemented exactly as above).
2631 There are two modes of
2639 mode tries to emulate a real link: the
2641 scheduler ensures that the packet will not leave the pipe faster than it
2642 would on the real link with a given bandwidth.
2645 mode allows certain packets to bypass the
2647 scheduler (if packet flow does not exceed pipe's bandwidth).
2648 This is the reason why the
2650 mode requires less CPU cycles per packet (on average) and packet latency
2651 can be significantly lower in comparison to a real link with the same
2657 mode can be enabled by setting the
2658 .Va net.inet.ip.dummynet.io_fast
2660 variable to a non-zero value.
2661 .Ss PIPE, QUEUE AND SCHEDULER CONFIGURATION
2667 configuration commands are the following:
2668 .Bd -ragged -offset indent
2669 .Cm pipe Ar number Cm config Ar pipe-configuration
2671 .Cm queue Ar number Cm config Ar queue-configuration
2673 .Cm sched Ar number Cm config Ar sched-configuration
2676 The following parameters can be configured for a pipe:
2678 .Bl -tag -width indent -compact
2679 .It Cm bw Ar bandwidth | device
2680 Bandwidth, measured in
2683 .Brq Cm bit/s | Byte/s .
2686 A value of 0 (default) means unlimited bandwidth.
2687 The unit must immediately follow the number, as in
2689 .Dl "dnctl pipe 1 config bw 300Kbit/s"
2691 If a device name is specified instead of a numeric value, as in
2693 .Dl "dnctl pipe 1 config bw tun0"
2695 then the transmit clock is supplied by the specified device.
2696 At the moment only the
2698 device supports this
2699 functionality, for use in conjunction with
2702 .It Cm delay Ar ms-delay
2703 Propagation delay, measured in milliseconds.
2704 The value is rounded to the next multiple of the clock tick
2705 (typically 10ms, but it is a good practice to run kernels
2707 .Dq "options HZ=1000"
2709 the granularity to 1ms or less).
2710 The default value is 0, meaning no delay.
2712 .It Cm burst Ar size
2713 If the data to be sent exceeds the pipe's bandwidth limit
2714 (and the pipe was previously idle), up to
2716 bytes of data are allowed to bypass the
2718 scheduler, and will be sent as fast as the physical link allows.
2719 Any additional data will be transmitted at the rate specified
2723 The burst size depends on how long the pipe has been idle;
2724 the effective burst size is calculated as follows:
2731 .It Cm profile Ar filename
2732 A file specifying the additional overhead incurred in the transmission
2733 of a packet on the link.
2735 Some link types introduce extra delays in the transmission
2736 of a packet, e.g., because of MAC level framing, contention on
2737 the use of the channel, MAC level retransmissions and so on.
2738 From our point of view, the channel is effectively unavailable
2739 for this extra time, which is constant or variable depending
2741 Additionally, packets may be dropped after this
2742 time (e.g., on a wireless link after too many retransmissions).
2743 We can model the additional delay with an empirical curve
2744 that represents its distribution.
2745 .Bd -literal -offset indent
2746 cumulative probability
2756 +-------*------------------->
2759 The empirical curve may have both vertical and horizontal lines.
2760 Vertical lines represent constant delay for a range of
2762 Horizontal lines correspond to a discontinuity in the delay
2763 distribution: the pipe will use the largest delay for a
2766 The file format is the following, with whitespace acting as
2767 a separator and '#' indicating the beginning a comment:
2768 .Bl -tag -width indent
2769 .It Cm name Ar identifier
2770 optional name (listed by "dnctl pipe show")
2771 to identify the delay distribution;
2773 the bandwidth used for the pipe.
2774 If not specified here, it must be present
2775 explicitly as a configuration parameter for the pipe;
2776 .It Cm loss-level Ar L
2777 the probability above which packets are lost.
2778 (0.0 <= L <= 1.0, default 1.0 i.e., no loss);
2780 the number of samples used in the internal
2781 representation of the curve (2..1024; default 100);
2782 .It Cm "delay prob" | "prob delay"
2783 One of these two lines is mandatory and defines
2784 the format of the following lines with data points.
2786 2 or more lines representing points in the curve,
2787 with either delay or probability first, according
2788 to the chosen format.
2789 The unit for delay is milliseconds.
2790 Data points do not need to be sorted.
2791 Also, the number of actual lines can be different
2792 from the value of the "samples" parameter:
2794 utility will sort and interpolate
2795 the curve as needed.
2798 Example of a profile file:
2799 .Bd -literal -offset indent
2804 0 200 # minimum overhead is 200ms
2810 #configuration file end
2814 The following parameters can be configured for a queue:
2816 .Bl -tag -width indent -compact
2817 .It Cm pipe Ar pipe_nr
2818 Connects a queue to the specified pipe.
2819 Multiple queues (with the same or different weights) can be connected to
2820 the same pipe, which specifies the aggregate rate for the set of queues.
2822 .It Cm weight Ar weight
2823 Specifies the weight to be used for flows matching this queue.
2824 The weight must be in the range 1..100, and defaults to 1.
2827 The following case-insensitive parameters can be configured for a
2830 .Bl -tag -width indent -compact
2831 .It Cm type Ar {fifo | wf2q+ | rr | qfq | fq_codel | fq_pie}
2832 specifies the scheduling algorithm to use.
2833 .Bl -tag -width indent -compact
2835 is just a FIFO scheduler (which means that all packets
2836 are stored in the same queue as they arrive to the scheduler).
2837 FIFO has O(1) per-packet time complexity, with very low
2838 constants (estimate 60-80ns on a 2GHz desktop machine)
2839 but gives no service guarantees.
2841 implements the WF2Q+ algorithm, which is a Weighted Fair Queueing
2842 algorithm which permits flows to share bandwidth according to
2844 Note that weights are not priorities; even a flow
2845 with a minuscule weight will never starve.
2846 WF2Q+ has O(log N) per-packet processing cost, where N is the number
2847 of flows, and is the default algorithm used by previous versions
2850 implements the Deficit Round Robin algorithm, which has O(1) processing
2851 costs (roughly, 100-150ns per packet)
2852 and permits bandwidth allocation according to weights, but
2853 with poor service guarantees.
2855 implements the QFQ algorithm, which is a very fast variant of
2856 WF2Q+, with similar service guarantees and O(1) processing
2857 costs (roughly, 200-250ns per packet).
2859 implements the FQ-CoDel (FlowQueue-CoDel) scheduler/AQM algorithm, which
2860 uses a modified Deficit Round Robin scheduler to manage two lists of sub-queues
2861 (old sub-queues and new sub-queues) for providing brief periods of priority to
2862 lightweight or short burst flows.
2863 By default, the total number of sub-queues is 1024.
2864 FQ-CoDel's internal, dynamically
2865 created sub-queues are controlled by separate instances of CoDel AQM.
2867 implements the FQ-PIE (FlowQueue-PIE) scheduler/AQM algorithm, which similar to
2869 but uses per sub-queue PIE AQM instance to control the queue delay.
2873 inherits AQM parameters and options from
2877 inherits AQM parameters and options from
2880 Additionally, both of
2884 have shared scheduler parameters which are:
2885 .Bl -tag -width indent
2888 specifies the quantum (credit) of the scheduler.
2890 is the number of bytes a queue can serve before being moved to the tail
2892 The default is 1514 bytes, and the maximum acceptable value
2896 specifies the hard size limit (in unit of packets) of all queues managed by an
2897 instance of the scheduler.
2898 The default value of
2900 is 10240 packets, and the maximum acceptable value is 20480 packets.
2903 specifies the total number of flow queues (sub-queues) that fq_*
2904 creates and manages.
2905 By default, 1024 sub-queues are created when an instance
2906 of the fq_{codel/pie} scheduler is created.
2907 The maximum acceptable value is
2911 Note that any token after
2915 is considered a parameter for fq_{codel/pie}.
2916 So, ensure all scheduler
2917 configuration options not related to fq_{codel/pie} are written before
2922 In addition to the type, all parameters allowed for a pipe can also
2923 be specified for a scheduler.
2925 Finally, the following parameters can be configured for both
2928 .Bl -tag -width XXXX -compact
2929 .It Cm buckets Ar hash-table-size
2930 Specifies the size of the hash table used for storing the
2932 Default value is 64 controlled by the
2935 .Va net.inet.ip.dummynet.hash_size ,
2936 allowed range is 16 to 65536.
2938 .It Cm mask Ar mask-specifier
2939 Packets sent to a given pipe or queue by an
2941 rule can be further classified into multiple flows, each of which is then
2945 A flow identifier is constructed by masking the IP addresses,
2946 ports and protocol types as specified with the
2948 options in the configuration of the pipe or queue.
2949 For each different flow identifier, a new pipe or queue is created
2950 with the same parameters as the original object, and matching packets
2955 are used, each flow will get the same bandwidth as defined by the pipe,
2958 are used, each flow will share the parent's pipe bandwidth evenly
2959 with other flows generated by the same queue (note that other queues
2960 with different weights might be connected to the same pipe).
2962 Available mask specifiers are a combination of one or more of the following:
2964 .Cm dst-ip Ar mask ,
2965 .Cm dst-ip6 Ar mask ,
2966 .Cm src-ip Ar mask ,
2967 .Cm src-ip6 Ar mask ,
2968 .Cm dst-port Ar mask ,
2969 .Cm src-port Ar mask ,
2970 .Cm flow-id Ar mask ,
2975 where the latter means all bits in all fields are significant.
2978 When a packet is dropped by a
2980 queue or pipe, the error
2981 is normally reported to the caller routine in the kernel, in the
2982 same way as it happens when a device queue fills up.
2984 option reports the packet as successfully delivered, which can be
2985 needed for some experimental setups where you want to simulate
2986 loss or congestion at a remote router.
2988 .It Cm plr Ar packet-loss-rate
2991 .Ar packet-loss-rate
2992 is a floating-point number between 0 and 1, with 0 meaning no
2993 loss, 1 meaning 100% loss.
2994 The loss rate is internally represented on 31 bits.
2996 .It Cm queue Brq Ar slots | size Ns Cm Kbytes
3001 Default value is 50 slots, which
3002 is the typical queue size for Ethernet devices.
3003 Note that for slow speed links you should keep the queue
3004 size short or your traffic might be affected by a significant
3006 E.g., 50 max-sized Ethernet packets (1500 bytes) mean 600Kbit
3007 or 20s of queue on a 30Kbit/s pipe.
3008 Even worse effects can result if you get packets from an
3009 interface with a much larger MTU, e.g.\& the loopback interface
3010 with its 16KB packets.
3014 .Em net.inet.ip.dummynet.pipe_byte_limit
3016 .Em net.inet.ip.dummynet.pipe_slot_limit
3017 control the maximum lengths that can be specified.
3019 .It Cm red | gred Ar w_q Ns / Ns Ar min_th Ns / Ns Ar max_th Ns / Ns Ar max_p
3021 Make use of the RED (Random Early Detection) queue management algorithm.
3026 point numbers between 0 and 1 (inclusive), while
3030 are integer numbers specifying thresholds for queue management
3031 (thresholds are computed in bytes if the queue has been defined
3032 in bytes, in slots otherwise).
3033 The two parameters can also be of the same value if needed.
3036 also supports the gentle RED variant (gred) and ECN (Explicit Congestion
3037 Notification) as optional.
3040 variables can be used to control the RED behaviour:
3041 .Bl -tag -width indent
3042 .It Va net.inet.ip.dummynet.red_lookup_depth
3043 specifies the accuracy in computing the average queue
3044 when the link is idle (defaults to 256, must be greater than zero)
3045 .It Va net.inet.ip.dummynet.red_avg_pkt_size
3046 specifies the expected average packet size (defaults to 512, must be
3048 .It Va net.inet.ip.dummynet.red_max_pkt_size
3049 specifies the expected maximum packet size, only used when queue
3050 thresholds are in bytes (defaults to 1500, must be greater than zero).
3053 .It Cm codel Oo Cm target Ar time Oc Oo Cm interval Ar time Oc Oo Cm ecn |
3055 Make use of the CoDel (Controlled-Delay) queue management algorithm.
3057 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
3058 microseconds (us) can be specified instead.
3059 CoDel drops or marks (ECN) packets
3060 depending on packet sojourn time in the queue.
3063 (5ms by default) is the minimum acceptable persistent queue delay that CoDel
3065 CoDel does not drop packets directly after packets sojourn time becomes
3072 (100ms default) before dropping.
3075 should be set to maximum RTT for all expected connections.
3077 enables (disabled by default) packet marking (instead of dropping) for
3078 ECN-enabled TCP flows when queue delay becomes high.
3080 Note that any token after
3082 is considered a parameter for CoDel.
3083 So, ensure all pipe/queue
3084 configuration options are written before
3091 .Va net.inet.ip.dummynet.codel.target
3093 .Va net.inet.ip.dummynet.codel.interval
3094 can be used to set CoDel default parameters.
3096 .It Cm pie Oo Cm target Ar time Oc Oo Cm tupdate Ar time Oc Oo
3097 .Cm alpha Ar n Oc Oo Cm beta Ar n Oc Oo Cm max_burst Ar time Oc Oo
3098 .Cm max_ecnth Ar n Oc Oo Cm ecn | Cm noecn Oc Oo Cm capdrop |
3099 .Cm nocapdrop Oc Oo Cm drand | Cm nodrand Oc Oo Cm onoff
3100 .Oc Oo Cm dre | Cm ts Oc
3101 Make use of the PIE (Proportional Integral controller Enhanced) queue management
3103 PIE drops or marks packets depending on a calculated drop probability during
3104 en-queue process, with the aim of achieving high throughput while keeping queue
3106 At regular time intervals of
3109 (15ms by default) a background process (re)calculates the probability based on queue delay
3113 (15ms by default) and queue delay trends.
3114 PIE approximates current queue
3115 delay by using a departure rate estimation method, or (optionally) by using a
3116 packet timestamp method similar to CoDel.
3118 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
3119 microseconds (us) can be specified instead.
3120 The other PIE parameters and options are as follows:
3121 .Bl -tag -width indent
3124 is a floating point number between 0 and 7 which specifies the weight of queue
3125 delay deviations that is used in drop probability calculation.
3126 0.125 is the default.
3129 is a floating point number between 0 and 7 which specifies is the weight of queue
3130 delay trend that is used in drop probability calculation.
3131 1.25 is the default.
3132 .It Cm max_burst Ar time
3133 The maximum period of time that PIE does not drop/mark packets.
3135 default and 10s is the maximum value.
3136 .It Cm max_ecnth Ar n
3137 Even when ECN is enabled, PIE drops packets instead of marking them when drop
3138 probability becomes higher than ECN probability threshold
3140 , the default is 0.1 (i.e 10%) and 1 is the maximum value.
3142 enable or disable ECN marking for ECN-enabled TCP flows.
3143 Disabled by default.
3144 .It Cm capdrop | nocapdrop
3145 enable or disable cap drop adjustment.
3146 Cap drop adjustment is enabled by default.
3147 .It Cm drand | nodrand
3148 enable or disable drop probability de-randomisation.
3149 De-randomisation eliminates
3150 the problem of dropping packets too close or too far.
3151 De-randomisation is enabled by default.
3153 enable turning PIE on and off depending on queue load.
3154 If this option is enabled,
3155 PIE turns on when over 1/3 of queue becomes full.
3156 This option is disabled by
3159 Calculate queue delay using departure rate estimation
3167 Note that any token after
3169 is considered a parameter for PIE.
3170 So ensure all pipe/queue
3171 the configuration options are written before
3175 variables can be used to control the
3179 .Sx SYSCTL VARIABLES
3180 section for more details.
3183 When used with IPv6 data,
3185 currently has several limitations.
3186 Information necessary to route link-local packets to an
3187 interface is not available after processing by
3189 so those packets are dropped in the output path.
3190 Care should be taken to ensure that link-local packets are not passed to
3193 Here are some important points to consider when designing your
3197 Remember that you filter both packets going
3201 Most connections need packets going in both directions.
3203 Remember to test very carefully.
3204 It is a good idea to be near the console when doing this.
3205 If you cannot be near the console,
3206 use an auto-recovery script such as the one in
3207 .Pa /usr/share/examples/ipfw/change_rules.sh .
3209 Do not forget the loopback interface.
3214 There are circumstances where fragmented datagrams are unconditionally
3216 TCP packets are dropped if they do not contain at least 20 bytes of
3217 TCP header, UDP packets are dropped if they do not contain a full 8
3218 byte UDP header, and ICMP packets are dropped if they do not contain
3219 4 bytes of ICMP header, enough to specify the ICMP type, code, and
3221 These packets are simply logged as
3223 since there may not be enough good data in the packet to produce a
3224 meaningful log entry.
3226 Another type of packet is unconditionally dropped, a TCP packet with a
3227 fragment offset of one.
3228 This is a valid packet, but it only has one use, to try
3229 to circumvent firewalls.
3230 When logging is enabled, these packets are
3231 reported as being dropped by rule -1.
3233 If you are logged in over a network, loading the
3237 is probably not as straightforward as you would think.
3238 The following command line is recommended:
3239 .Bd -literal -offset indent
3241 ipfw add 32000 allow ip from any to any
3244 Along the same lines, doing an
3245 .Bd -literal -offset indent
3249 in similar surroundings is also a bad idea.
3253 filter list may not be modified if the system security level
3254 is set to 3 or higher
3257 for information on system security levels).
3259 .Sh PACKET DIVERSION
3262 socket bound to the specified port will receive all packets
3263 diverted to that port.
3264 If no socket is bound to the destination port, or if the divert module is
3265 not loaded, or if the kernel was not compiled with divert socket support,
3266 the packets are dropped.
3267 .Sh NETWORK ADDRESS TRANSLATION (NAT)
3269 support in-kernel NAT using the kernel version of
3273 should be loaded or kernel should have
3274 .Cm options IPFIREWALL_NAT
3277 The nat configuration command is the following:
3278 .Bd -ragged -offset indent
3283 .Ar nat-configuration
3287 The following parameters can be configured:
3288 .Bl -tag -width indent
3289 .It Cm ip Ar ip_address
3290 Define an ip address to use for aliasing.
3292 Use ip address of NIC for aliasing, dynamically changing
3293 it if NIC's ip address changes.
3295 Enable logging on this nat instance.
3297 Deny any incoming connection from outside world.
3299 Try to leave the alias port numbers unchanged from
3300 the actual local port numbers.
3302 Traffic on the local network not originating from a RFC 1918
3303 unregistered address spaces will be ignored.
3305 Like unreg_only, but includes the RFC 6598 (Carrier Grade NAT)
3308 Reset table of the packet aliasing engine on address change.
3310 Reverse the way libalias handles aliasing.
3312 Obey transparent proxy rules only, packet aliasing is not performed.
3314 Skip instance in case of global state lookup (see below).
3315 .It Cm port_range Ar lower-upper
3316 Set the aliasing ports between the ranges given. Upper port has to be greater
3320 Some special values can be supplied instead of
3322 in nat rule actions:
3323 .Bl -tag -width indent
3325 Looks up translation state in all configured nat instances.
3326 If an entry is found, packet is aliased according to that entry.
3327 If no entry was found in any of the instances, packet is passed unchanged,
3328 and no new entry will be created.
3330 .Sx MULTIPLE INSTANCES
3333 for more information.
3335 Uses argument supplied in lookup table.
3338 section below for more information on lookup tables.
3341 To let the packet continue after being (de)aliased, set the sysctl variable
3342 .Va net.inet.ip.fw.one_pass
3344 For more information about aliasing modes, refer to
3348 for some examples of nat usage.
3349 .Ss REDIRECT AND LSNAT SUPPORT IN IPFW
3350 Redirect and LSNAT support follow closely the syntax used in
3354 for some examples on how to do redirect and lsnat.
3355 .Ss SCTP NAT SUPPORT
3356 SCTP nat can be configured in a similar manner to TCP through the
3359 The main difference is that
3361 does not do port translation.
3362 Since the local and global side ports will be the same,
3363 there is no need to specify both.
3364 Ports are redirected as follows:
3365 .Bd -ragged -offset indent
3371 .Cm redirect_port sctp
3372 .Ar ip_address [,addr_list] {[port | port-port] [,ports]}
3378 configuration can be done in real-time through the
3381 All may be changed dynamically, though the hash_table size will only
3386 .Sx SYSCTL VARIABLES
3388 .Sh IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
3389 .Ss Stateful translation
3391 supports in-kernel IPv6/IPv4 network address and protocol translation.
3392 Stateful NAT64 translation allows IPv6-only clients to contact IPv4 servers
3393 using unicast TCP, UDP or ICMP protocols.
3394 One or more IPv4 addresses assigned to a stateful NAT64 translator are shared
3395 among several IPv6-only clients.
3396 When stateful NAT64 is used in conjunction with DNS64, no changes are usually
3397 required in the IPv6 client or the IPv4 server.
3400 should be loaded or kernel should have
3401 .Cm options IPFIREWALL_NAT64
3402 to be able use stateful NAT64 translator.
3404 Stateful NAT64 uses a bunch of memory for several types of objects.
3405 When IPv6 client initiates connection, NAT64 translator creates a host entry
3406 in the states table.
3407 Each host entry uses preallocated IPv4 alias entry.
3408 Each alias entry has a number of ports group entries allocated on demand.
3409 Ports group entries contains connection state entries.
3410 There are several options to control limits and lifetime for these objects.
3412 NAT64 translator follows RFC7915 when does ICMPv6/ICMP translation,
3413 unsupported message types will be silently dropped.
3414 IPv6 needs several ICMPv6 message types to be explicitly allowed for correct
3416 Make sure that ND6 neighbor solicitation (ICMPv6 type 135) and neighbor
3417 advertisement (ICMPv6 type 136) messages will not be handled by translation
3420 After translation NAT64 translator by default sends packets through
3421 corresponding netisr queue.
3422 Thus translator host should be configured as IPv4 and IPv6 router.
3423 Also this means, that a packet is handled by firewall twice.
3424 First time an original packet is handled and consumed by translator,
3425 and then it is handled again as translated packet.
3426 This behavior can be changed by sysctl variable
3427 .Va net.inet.ip.fw.nat64_direct_output .
3428 Also translated packet can be tagged using
3430 rule action, and then matched by
3432 opcode to avoid loops and extra overhead.
3434 The stateful NAT64 configuration command is the following:
3435 .Bd -ragged -offset indent
3444 The following parameters can be configured:
3445 .Bl -tag -width indent
3446 .It Cm prefix4 Ar ipv4_prefix/plen
3447 The IPv4 prefix with mask defines the pool of IPv4 addresses used as
3448 source address after translation.
3449 Stateful NAT64 module translates IPv6 source address of client to one
3450 IPv4 address from this pool.
3451 Note that incoming IPv4 packets that don't have corresponding state entry
3452 in the states table will be dropped by translator.
3453 Make sure that translation rules handle packets, destined to configured prefix.
3454 .It Cm prefix6 Ar ipv6_prefix/length
3455 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3456 to represent IPv4 addresses.
3457 This IPv6 prefix should be configured in DNS64.
3458 The translator implementation follows RFC6052, that restricts the length of
3459 prefixes to one of following: 32, 40, 48, 56, 64, or 96.
3460 The Well-Known IPv6 Prefix 64:ff9b:: must be 96 bits long.
3463 prefix can be used to handle several IPv6 prefixes with one NAT64 instance.
3464 The NAT64 instance will determine a destination IPv4 address from prefix
3466 .It Cm states_chunks Ar number
3467 The number of states chunks in single ports group.
3468 Each ports group by default can keep 64 state entries in single chunk.
3469 The above value affects the maximum number of states that can be associated with single IPv4 alias address and port.
3470 The value must be power of 2, and up to 128.
3471 .It Cm host_del_age Ar seconds
3472 The number of seconds until the host entry for a IPv6 client will be deleted
3473 and all its resources will be released due to inactivity.
3476 .It Cm pg_del_age Ar seconds
3477 The number of seconds until a ports group with unused state entries will
3481 .It Cm tcp_syn_age Ar seconds
3482 The number of seconds while a state entry for TCP connection with only SYN
3484 If TCP connection establishing will not be finished,
3485 state entry will be deleted.
3488 .It Cm tcp_est_age Ar seconds
3489 The number of seconds while a state entry for established TCP connection
3493 .It Cm tcp_close_age Ar seconds
3494 The number of seconds while a state entry for closed TCP connection
3496 Keeping state entries for closed connections is needed, because IPv4 servers
3497 typically keep closed connections in a TIME_WAIT state for a several minutes.
3498 Since translator's IPv4 addresses are shared among all IPv6 clients,
3499 new connections from the same addresses and ports may be rejected by server,
3500 because these connections are still in a TIME_WAIT state.
3501 Keeping them in translator's state table protects from such rejects.
3504 .It Cm udp_age Ar seconds
3505 The number of seconds while translator keeps state entry in a waiting for
3506 reply to the sent UDP datagram.
3509 .It Cm icmp_age Ar seconds
3510 The number of seconds while translator keeps state entry in a waiting for
3511 reply to the sent ICMP message.
3515 Turn on logging of all handled packets via BPF through
3519 is a pseudo interface and can be created after a boot manually with
3522 Note that it has different purpose than
3525 Translators sends to BPF an additional information with each packet.
3528 you are able to see each handled packet before and after translation.
3530 Turn off logging of all handled packets via BPF.
3531 .It Cm allow_private
3532 Turn on processing private IPv4 addresses.
3533 By default IPv6 packets with destinations mapped to private address ranges
3534 defined by RFC1918 are not processed.
3535 .It Cm -allow_private
3536 Turn off private address handling in
3541 To inspect a states table of stateful NAT64 the following command can be used:
3542 .Bd -ragged -offset indent
3550 Stateless NAT64 translator doesn't use a states table for translation
3551 and converts IPv4 addresses to IPv6 and vice versa solely based on the
3552 mappings taken from configured lookup tables.
3553 Since a states table doesn't used by stateless translator,
3554 it can be configured to pass IPv4 clients to IPv6-only servers.
3556 The stateless NAT64 configuration command is the following:
3557 .Bd -ragged -offset indent
3566 The following parameters can be configured:
3567 .Bl -tag -width indent
3568 .It Cm prefix6 Ar ipv6_prefix/length
3569 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3570 to represent IPv4 addresses.
3571 This IPv6 prefix should be configured in DNS64.
3572 .It Cm table4 Ar table46
3575 contains mapping how IPv4 addresses should be translated to IPv6 addresses.
3576 .It Cm table6 Ar table64
3579 contains mapping how IPv6 addresses should be translated to IPv4 addresses.
3581 Turn on logging of all handled packets via BPF through
3585 Turn off logging of all handled packets via BPF.
3586 .It Cm allow_private
3587 Turn on processing private IPv4 addresses.
3588 By default IPv6 packets with destinations mapped to private address ranges
3589 defined by RFC1918 are not processed.
3590 .It Cm -allow_private
3591 Turn off private address handling in
3596 Note that the behavior of stateless translator with respect to not matched
3597 packets differs from stateful translator.
3598 If corresponding addresses was not found in the lookup tables, the packet
3599 will not be dropped and the search continues.
3600 .Ss XLAT464 CLAT translation
3601 XLAT464 CLAT NAT64 translator implements client-side stateless translation as
3602 defined in RFC6877 and is very similar to statless NAT64 translator
3604 Instead of lookup tables it uses one-to-one mapping between IPv4 and IPv6
3605 addresses using configured prefixes.
3606 This mode can be used as a replacement of DNS64 service for applications
3607 that are not using it (e.g. VoIP) allowing them to access IPv4-only Internet
3608 over IPv6-only networks with help of remote NAT64 translator.
3610 The CLAT NAT64 configuration command is the following:
3611 .Bd -ragged -offset indent
3620 The following parameters can be configured:
3621 .Bl -tag -width indent
3622 .It Cm clat_prefix Ar ipv6_prefix/length
3623 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3624 to represent source IPv4 addresses.
3625 .It Cm plat_prefix Ar ipv6_prefix/length
3626 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3627 to represent destination IPv4 addresses.
3628 This IPv6 prefix should be configured on a remote NAT64 translator.
3630 Turn on logging of all handled packets via BPF through
3634 Turn off logging of all handled packets via BPF.
3635 .It Cm allow_private
3636 Turn on processing private IPv4 addresses.
3639 instance will not process IPv4 packets with destination address from private
3640 ranges as defined in RFC1918.
3641 .It Cm -allow_private
3642 Turn off private address handling in
3647 Note that the behavior of CLAT translator with respect to not matched
3648 packets differs from stateful translator.
3649 If corresponding addresses were not matched against prefixes configured,
3650 the packet will not be dropped and the search continues.
3651 .Sh IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
3653 supports in-kernel IPv6-to-IPv6 network prefix translation as described
3657 should be loaded or kernel should has
3658 .Cm options IPFIREWALL_NPTV6
3659 to be able use NPTv6 translator.
3661 The NPTv6 configuration command is the following:
3662 .Bd -ragged -offset indent
3671 The following parameters can be configured:
3672 .Bl -tag -width indent
3673 .It Cm int_prefix Ar ipv6_prefix
3674 IPv6 prefix used in internal network.
3675 NPTv6 module translates source address when it matches this prefix.
3676 .It Cm ext_prefix Ar ipv6_prefix
3677 IPv6 prefix used in external network.
3678 NPTv6 module translates destination address when it matches this prefix.
3679 .It Cm ext_if Ar nic
3680 The NPTv6 module will use first global IPv6 address from interface
3683 It can be useful when IPv6 prefix of external network is dynamically obtained.
3687 options are mutually exclusive.
3688 .It Cm prefixlen Ar length
3689 The length of specified IPv6 prefixes.
3690 It must be in range from 8 to 64.
3693 Note that the prefix translation rules are silently ignored when IPv6 packet
3694 forwarding is disabled.
3695 To enable the packet forwarding, set the sysctl variable
3696 .Va net.inet6.ip6.forwarding
3699 To let the packet continue after being translated, set the sysctl variable
3700 .Va net.inet.ip.fw.one_pass
3703 Tunables can be set in
3709 before ipfw module gets loaded.
3710 .Bl -tag -width indent
3711 .It Va net.inet.ip.fw.default_to_accept : No 0
3712 Defines ipfw last rule behavior.
3713 This value overrides
3714 .Cd "options IPFW_DEFAULT_TO_(ACCEPT|DENY)"
3715 from kernel configuration file.
3716 .It Va net.inet.ip.fw.tables_max : No 128
3717 Defines number of tables available in ipfw.
3718 Number cannot exceed 65534.
3720 .Sh SYSCTL VARIABLES
3723 variables controls the behaviour of the firewall and
3725 .Pq Nm dummynet , bridge , sctp nat .
3726 These are shown below together with their default value
3727 (but always check with the
3729 command what value is actually in use) and meaning:
3730 .Bl -tag -width indent
3731 .It Va net.inet.ip.alias.sctp.accept_global_ootb_addip : No 0
3734 responds to receipt of global OOTB ASCONF-AddIP:
3735 .Bl -tag -width indent
3737 No response (unless a partially matching association exists -
3738 ports and vtags match but global address does not)
3741 will accept and process all OOTB global AddIP messages.
3744 Option 1 should never be selected as this forms a security risk.
3746 establish multiple fake associations by sending AddIP messages.
3747 .It Va net.inet.ip.alias.sctp.chunk_proc_limit : No 5
3748 Defines the maximum number of chunks in an SCTP packet that will be
3750 packet that matches an existing association.
3751 This value is enforced to be greater or equal than
3752 .Cm net.inet.ip.alias.sctp.initialising_chunk_proc_limit .
3754 a DoS risk yet setting too low a value may result in
3755 important control chunks in
3756 the packet not being located and parsed.
3757 .It Va net.inet.ip.alias.sctp.error_on_ootb : No 1
3760 responds to any Out-of-the-Blue (OOTB) packets with ErrorM packets.
3761 An OOTB packet is a packet that arrives with no existing association
3764 and is not an INIT or ASCONF-AddIP packet:
3765 .Bl -tag -width indent
3767 ErrorM is never sent in response to OOTB packets.
3769 ErrorM is only sent to OOTB packets received on the local side.
3771 ErrorM is sent to the local side and on the global side ONLY if there is a
3772 partial match (ports and vtags match but the source global IP does not).
3773 This value is only useful if the
3775 is tracking global IP addresses.
3777 ErrorM is sent in response to all OOTB packets on both
3778 the local and global side
3782 At the moment the default is 0, since the ErrorM packet is not yet
3783 supported by most SCTP stacks.
3784 When it is supported, and if not tracking
3785 global addresses, we recommend setting this value to 1 to allow
3786 multi-homed local hosts to function with the
3788 To track global addresses, we recommend setting this value to 2 to
3789 allow global hosts to be informed when they need to (re)send an
3791 Value 3 should never be chosen (except for debugging) as the
3793 will respond to all OOTB global packets (a DoS risk).
3794 .It Va net.inet.ip.alias.sctp.hashtable_size : No 2003
3795 Size of hash tables used for
3797 lookups (100 < prime_number > 1000001).
3800 size for any future created
3802 instance and therefore must be set prior to creating a
3805 The table sizes may be changed to suit specific needs.
3806 If there will be few
3807 concurrent associations, and memory is scarce, you may make these smaller.
3808 If there will be many thousands (or millions) of concurrent associations, you
3809 should make these larger.
3810 A prime number is best for the table size.
3812 update function will adjust your input value to the next highest prime number.
3813 .It Va net.inet.ip.alias.sctp.holddown_time : No 0
3814 Hold association in table for this many seconds after receiving a
3816 This allows endpoints to correct shutdown gracefully if a
3817 shutdown_complete is lost and retransmissions are required.
3818 .It Va net.inet.ip.alias.sctp.init_timer : No 15
3819 Timeout value while waiting for (INIT-ACK|AddIP-ACK).
3820 This value cannot be 0.
3821 .It Va net.inet.ip.alias.sctp.initialising_chunk_proc_limit : No 2
3822 Defines the maximum number of chunks in an SCTP packet that will be parsed when
3823 no existing association exists that matches that packet.
3825 will only be an INIT or ASCONF-AddIP packet.
3826 A higher value may become a DoS
3827 risk as malformed packets can consume processing resources.
3828 .It Va net.inet.ip.alias.sctp.param_proc_limit : No 25
3829 Defines the maximum number of parameters within a chunk that will be
3832 As for other similar sysctl variables, larger values pose a DoS risk.
3833 .It Va net.inet.ip.alias.sctp.log_level : No 0
3834 Level of detail in the system log messages (0 \- minimal, 1 \- event,
3835 2 \- info, 3 \- detail, 4 \- debug, 5 \- max debug).
3837 option in high loss environments.
3838 .It Va net.inet.ip.alias.sctp.shutdown_time : No 15
3839 Timeout value while waiting for SHUTDOWN-COMPLETE.
3840 This value cannot be 0.
3841 .It Va net.inet.ip.alias.sctp.track_global_addresses : No 0
3842 Enables/disables global IP address tracking within the
3845 upper limit on the number of addresses tracked for each association:
3846 .Bl -tag -width indent
3848 Global tracking is disabled
3850 Enables tracking, the maximum number of addresses tracked for each
3851 association is limited to this value
3854 This variable is fully dynamic, the new value will be adopted for all newly
3855 arriving associations, existing associations are treated
3856 as they were previously.
3857 Global tracking will decrease the number of collisions within the
3860 of increased processing load, memory usage, complexity, and possible
3863 problems in complex networks with multiple
3865 We recommend not tracking
3866 global IP addresses, this will still result in a fully functional
3868 .It Va net.inet.ip.alias.sctp.up_timer : No 300
3869 Timeout value to keep an association up with no traffic.
3870 This value cannot be 0.
3871 .It Va net.inet.ip.dummynet.codel.interval : No 100000
3874 AQM interval in microseconds.
3875 The value must be in the range 1..5000000.
3876 .It Va net.inet.ip.dummynet.codel.target : No 5000
3879 AQM target delay time in microseconds (the minimum acceptable persistent queue
3881 The value must be in the range 1..5000000.
3882 .It Va net.inet.ip.dummynet.expire : No 1
3883 Lazily delete dynamic pipes/queue once they have no pending traffic.
3884 You can disable this by setting the variable to 0, in which case
3885 the pipes/queues will only be deleted when the threshold is reached.
3886 .It Va net.inet.ip.dummynet.fqcodel.flows : No 1024
3887 Defines the default total number of flow queues (sub-queues) that
3889 creates and manages.
3890 The value must be in the range 1..65536.
3891 .It Va net.inet.ip.dummynet.fqcodel.interval : No 100000
3894 scheduler/AQM interval in microseconds.
3895 The value must be in the range 1..5000000.
3896 .It Va net.inet.ip.dummynet.fqcodel.limit : No 10240
3897 The default hard size limit (in unit of packet) of all queues managed by an
3901 The value must be in the range 1..20480.
3902 .It Va net.inet.ip.dummynet.fqcodel.quantum : No 1514
3903 The default quantum (credit) of the
3906 The value must be in the range 1..9000.
3907 .It Va net.inet.ip.dummynet.fqcodel.target : No 5000
3910 scheduler/AQM target delay time in microseconds (the minimum acceptable
3911 persistent queue delay).
3912 The value must be in the range 1..5000000.
3913 .It Va net.inet.ip.dummynet.fqpie.alpha : No 125
3916 parameter (scaled by 1000) for
3919 The value must be in the range 1..7000.
3920 .It Va net.inet.ip.dummynet.fqpie.beta : No 1250
3923 parameter (scaled by 1000) for
3926 The value must be in the range 1..7000.
3927 .It Va net.inet.ip.dummynet.fqpie.flows : No 1024
3928 Defines the default total number of flow queues (sub-queues) that
3930 creates and manages.
3931 The value must be in the range 1..65536.
3932 .It Va net.inet.ip.dummynet.fqpie.limit : No 10240
3933 The default hard size limit (in unit of packet) of all queues managed by an
3937 The value must be in the range 1..20480.
3938 .It Va net.inet.ip.dummynet.fqpie.max_burst : No 150000
3939 The default maximum period of microseconds that
3941 scheduler/AQM does not drop/mark packets.
3942 The value must be in the range 1..10000000.
3943 .It Va net.inet.ip.dummynet.fqpie.max_ecnth : No 99
3944 The default maximum ECN probability threshold (scaled by 1000) for
3947 The value must be in the range 1..7000.
3948 .It Va net.inet.ip.dummynet.fqpie.quantum : No 1514
3949 The default quantum (credit) of the
3952 The value must be in the range 1..9000.
3953 .It Va net.inet.ip.dummynet.fqpie.target : No 15000
3958 in unit of microsecond.
3959 The value must be in the range 1..5000000.
3960 .It Va net.inet.ip.dummynet.fqpie.tupdate : No 15000
3965 in unit of microsecond.
3966 The value must be in the range 1..5000000.
3967 .It Va net.inet.ip.dummynet.hash_size : No 64
3968 Default size of the hash table used for dynamic pipes/queues.
3969 This value is used when no
3971 option is specified when configuring a pipe/queue.
3972 .It Va net.inet.ip.dummynet.io_fast : No 0
3973 If set to a non-zero value,
3978 operation (see above) is enabled.
3979 .It Va net.inet.ip.dummynet.io_pkt
3980 Number of packets passed to
3982 .It Va net.inet.ip.dummynet.io_pkt_drop
3983 Number of packets dropped by
3985 .It Va net.inet.ip.dummynet.io_pkt_fast
3986 Number of packets bypassed by the
3989 .It Va net.inet.ip.dummynet.max_chain_len : No 16
3990 Target value for the maximum number of pipes/queues in a hash bucket.
3992 .Cm max_chain_len*hash_size
3993 is used to determine the threshold over which empty pipes/queues
3994 will be expired even when
3995 .Cm net.inet.ip.dummynet.expire=0 .
3996 .It Va net.inet.ip.dummynet.red_lookup_depth : No 256
3997 .It Va net.inet.ip.dummynet.red_avg_pkt_size : No 512
3998 .It Va net.inet.ip.dummynet.red_max_pkt_size : No 1500
3999 Parameters used in the computations of the drop probability
4000 for the RED algorithm.
4001 .It Va net.inet.ip.dummynet.pie.alpha : No 125
4004 parameter (scaled by 1000) for
4007 The value must be in the range 1..7000.
4008 .It Va net.inet.ip.dummynet.pie.beta : No 1250
4011 parameter (scaled by 1000) for
4014 The value must be in the range 1..7000.
4015 .It Va net.inet.ip.dummynet.pie.max_burst : No 150000
4016 The default maximum period of microseconds that
4018 AQM does not drop/mark packets.
4019 The value must be in the range 1..10000000.
4020 .It Va net.inet.ip.dummynet.pie.max_ecnth : No 99
4021 The default maximum ECN probability threshold (scaled by 1000) for
4024 The value must be in the range 1..7000.
4025 .It Va net.inet.ip.dummynet.pie.target : No 15000
4030 AQM in unit of microsecond.
4031 The value must be in the range 1..5000000.
4032 .It Va net.inet.ip.dummynet.pie.tupdate : No 15000
4037 AQM in unit of microsecond.
4038 The value must be in the range 1..5000000.
4039 .It Va net.inet.ip.dummynet.pipe_byte_limit : No 1048576
4040 .It Va net.inet.ip.dummynet.pipe_slot_limit : No 100
4041 The maximum queue size that can be specified in bytes or packets.
4042 These limits prevent accidental exhaustion of resources such as mbufs.
4043 If you raise these limits,
4044 you should make sure the system is configured so that sufficient resources
4046 .It Va net.inet.ip.fw.autoinc_step : No 100
4047 Delta between rule numbers when auto-generating them.
4048 The value must be in the range 1..1000.
4049 .It Va net.inet.ip.fw.curr_dyn_buckets : Va net.inet.ip.fw.dyn_buckets
4050 The current number of buckets in the hash table for dynamic rules
4052 .It Va net.inet.ip.fw.debug : No 1
4053 Controls debugging messages produced by
4055 .It Va net.inet.ip.fw.default_rule : No 65535
4056 The default rule number (read-only).
4058 .Nm , the default rule is the last one, so its number
4059 can also serve as the highest number allowed for a rule.
4060 .It Va net.inet.ip.fw.dyn_buckets : No 256
4061 The number of buckets in the hash table for dynamic rules.
4062 Must be a power of 2, up to 65536.
4063 It only takes effect when all dynamic rules have expired, so you
4064 are advised to use a
4066 command to make sure that the hash table is resized.
4067 .It Va net.inet.ip.fw.dyn_count : No 3
4068 Current number of dynamic rules
4070 .It Va net.inet.ip.fw.dyn_keepalive : No 1
4071 Enables generation of keepalive packets for
4073 rules on TCP sessions.
4074 A keepalive is generated to both
4075 sides of the connection every 5 seconds for the last 20
4076 seconds of the lifetime of the rule.
4077 .It Va net.inet.ip.fw.dyn_max : No 8192
4078 Maximum number of dynamic rules.
4079 When you hit this limit, no more dynamic rules can be
4080 installed until old ones expire.
4081 .It Va net.inet.ip.fw.dyn_ack_lifetime : No 300
4082 .It Va net.inet.ip.fw.dyn_syn_lifetime : No 20
4083 .It Va net.inet.ip.fw.dyn_fin_lifetime : No 1
4084 .It Va net.inet.ip.fw.dyn_rst_lifetime : No 1
4085 .It Va net.inet.ip.fw.dyn_udp_lifetime : No 5
4086 .It Va net.inet.ip.fw.dyn_short_lifetime : No 30
4087 These variables control the lifetime, in seconds, of dynamic
4089 Upon the initial SYN exchange the lifetime is kept short,
4090 then increased after both SYN have been seen, then decreased
4091 again during the final FIN exchange or when a RST is received.
4093 .Em dyn_fin_lifetime
4095 .Em dyn_rst_lifetime
4096 must be strictly lower than 5 seconds, the period of
4097 repetition of keepalives.
4098 The firewall enforces that.
4099 .It Va net.inet.ip.fw.dyn_keep_states : No 0
4100 Keep dynamic states on rule/set deletion.
4101 States are relinked to default rule (65535).
4102 This can be handly for ruleset reload.
4103 Turned off by default.
4104 .It Va net.inet.ip.fw.enable : No 1
4105 Enables the firewall.
4106 Setting this variable to 0 lets you run your machine without
4107 firewall even if compiled in.
4108 .It Va net.inet6.ip6.fw.enable : No 1
4109 provides the same functionality as above for the IPv6 case.
4110 .It Va net.inet.ip.fw.one_pass : No 1
4111 When set, the packet exiting from the
4115 node is not passed though the firewall again.
4116 Otherwise, after an action, the packet is
4117 reinjected into the firewall at the next rule.
4118 .It Va net.inet.ip.fw.tables_max : No 128
4119 Maximum number of tables.
4120 .It Va net.inet.ip.fw.verbose : No 1
4121 Enables verbose messages.
4122 .It Va net.inet.ip.fw.verbose_limit : No 0
4123 Limits the number of messages produced by a verbose firewall.
4124 .It Va net.inet6.ip6.fw.deny_unknown_exthdrs : No 1
4125 If enabled packets with unknown IPv6 Extension Headers will be denied.
4126 .It Va net.link.ether.ipfw : No 0
4127 Controls whether layer2 packets are passed to
4130 .It Va net.link.bridge.ipfw : No 0
4131 Controls whether bridged packets are passed to
4134 .It Va net.inet.ip.fw.nat64_debug : No 0
4135 Controls debugging messages produced by
4138 .It Va net.inet.ip.fw.nat64_direct_output : No 0
4139 Controls the output method used by
4142 .Bl -tag -width indent
4144 A packet is handled by
4147 First time an original packet is handled by
4152 Then translated packet is queued via netisr to input processing again.
4154 A packet is handled by
4156 only once, and after translation it will be pushed directly to outgoing
4160 .Sh INTERNAL DIAGNOSTICS
4161 There are some commands that may be useful to understand current state
4162 of certain subsystems inside kernel module.
4163 These commands provide debugging output which may change without notice.
4165 Currently the following commands are available as
4168 .Bl -tag -width indent
4170 Lists all interface which are currently tracked by
4172 with their in-kernel status.
4174 List all table lookup algorithms currently available.
4177 There are far too many possible uses of
4179 so this Section will only give a small set of examples.
4180 .Ss BASIC PACKET FILTERING
4181 This command adds an entry which denies all tcp packets from
4182 .Em cracker.evil.org
4183 to the telnet port of
4185 from being forwarded by the host:
4187 .Dl "ipfw add deny tcp from cracker.evil.org to wolf.tambov.su telnet"
4189 This one disallows any connection from the entire cracker's
4192 .Dl "ipfw add deny ip from 123.45.67.0/24 to my.host.org"
4194 A first and efficient way to limit access (not using dynamic rules)
4195 is the use of the following rules:
4197 .Dl "ipfw add allow tcp from any to any established"
4198 .Dl "ipfw add allow tcp from net1 portlist1 to net2 portlist2 setup"
4199 .Dl "ipfw add allow tcp from net3 portlist3 to net3 portlist3 setup"
4201 .Dl "ipfw add deny tcp from any to any"
4203 The first rule will be a quick match for normal TCP packets,
4204 but it will not match the initial SYN packet, which will be
4207 rules only for selected source/destination pairs.
4208 All other SYN packets will be rejected by the final
4212 If you administer one or more subnets, you can take advantage
4213 of the address sets and or-blocks and write extremely
4214 compact rulesets which selectively enable services to blocks
4215 of clients, as below:
4217 .Dl "goodguys=\*q{ 10.1.2.0/24{20,35,66,18} or 10.2.3.0/28{6,3,11} }\*q"
4218 .Dl "badguys=\*q10.1.2.0/24{8,38,60}\*q"
4220 .Dl "ipfw add allow ip from ${goodguys} to any"
4221 .Dl "ipfw add deny ip from ${badguys} to any"
4222 .Dl "... normal policies ..."
4226 option could be used to do automated anti-spoofing by adding the
4227 following to the top of a ruleset:
4229 .Dl "ipfw add deny ip from any to any not verrevpath in"
4231 This rule drops all incoming packets that appear to be coming to the
4232 system on the wrong interface.
4233 For example, a packet with a source
4234 address belonging to a host on a protected internal network would be
4235 dropped if it tried to enter the system from an external interface.
4239 option could be used to do similar but more restricted anti-spoofing
4240 by adding the following to the top of a ruleset:
4242 .Dl "ipfw add deny ip from any to any not antispoof in"
4244 This rule drops all incoming packets that appear to be coming from another
4245 directly connected system but on the wrong interface.
4246 For example, a packet with a source address of
4247 .Li 192.168.0.0/24 ,
4256 option could be used to (re)mark user traffic,
4257 by adding the following to the appropriate place in ruleset:
4259 .Dl "ipfw add setdscp be ip from any to any dscp af11,af21"
4260 .Ss SELECTIVE MIRRORING
4261 If your network has network traffic analyzer
4262 connected to your host directly via dedicated interface
4263 or remotely via RSPAN vlan, you can selectively mirror
4264 some Ethernet layer2 frames to the analyzer.
4266 First, make sure your firewall is already configured and runs.
4267 Then, enable layer2 processing if not already enabled:
4269 .Dl "sysctl net.link.ether.ipfw=1"
4271 Next, load needed additional kernel modules:
4273 .Dl "kldload ng_ether ng_ipfw"
4275 Optionally, make system load these modules automatically
4278 .Dl sysrc kld_list+="ng_ether ng_ipfw"
4282 kernel module to transmit mirrored copies of layer2 frames
4283 out via vlan900 interface:
4285 .Dl "ngctl connect ipfw: vlan900: 1 lower"
4287 Think of "1" here as of "mirroring instance index" and vlan900 is its
4289 You can have arbitrary number of instances.
4294 At last, actually start mirroring of selected frames using "instance 1".
4295 For frames incoming from em0 interface:
4297 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 in recv em0"
4299 For frames outgoing to em0 interface:
4301 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 out xmit em0"
4303 For both incoming and outgoing frames while flowing through em0:
4305 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 via em0"
4307 Make sure you do not perform mirroring for already duplicated frames
4308 or kernel may hang as there is no safety net.
4310 In order to protect a site from flood attacks involving fake
4311 TCP packets, it is safer to use dynamic rules:
4313 .Dl "ipfw add check-state"
4314 .Dl "ipfw add deny tcp from any to any established"
4315 .Dl "ipfw add allow tcp from my-net to any setup keep-state"
4317 This will let the firewall install dynamic rules only for
4318 those connection which start with a regular SYN packet coming
4319 from the inside of our network.
4320 Dynamic rules are checked when encountering the first
4329 rule should usually be placed near the beginning of the
4330 ruleset to minimize the amount of work scanning the ruleset.
4331 Your mileage may vary.
4333 For more complex scenarios with dynamic rules
4337 can be used to precisely control creation and checking of dynamic rules.
4338 Example of usage of these options are provided in
4339 .Sx NETWORK ADDRESS TRANSLATION (NAT)
4342 To limit the number of connections a user can open
4343 you can use the following type of rules:
4345 .Dl "ipfw add allow tcp from my-net/24 to any setup limit src-addr 10"
4346 .Dl "ipfw add allow tcp from any to me setup limit src-addr 4"
4348 The former (assuming it runs on a gateway) will allow each host
4349 on a /24 network to open at most 10 TCP connections.
4350 The latter can be placed on a server to make sure that a single
4351 client does not use more than 4 simultaneous connections.
4354 stateful rules can be subject to denial-of-service attacks
4355 by a SYN-flood which opens a huge number of dynamic rules.
4356 The effects of such attacks can be partially limited by
4359 variables which control the operation of the firewall.
4361 Here is a good usage of the
4363 command to see accounting records and timestamp information:
4367 or in short form without timestamps:
4371 which is equivalent to:
4375 Next rule diverts all incoming packets from 192.168.2.0/24
4376 to divert port 5000:
4378 .Dl ipfw divert 5000 ip from 192.168.2.0/24 to any in
4380 The following rules show some of the applications of
4384 for simulations and the like.
4386 This rule drops random incoming packets with a probability
4389 .Dl "ipfw add prob 0.05 deny ip from any to any in"
4391 A similar effect can be achieved making use of
4395 .Dl "dnctl add pipe 10 ip from any to any"
4396 .Dl "dnctl pipe 10 config plr 0.05"
4398 We can use pipes to artificially limit bandwidth, e.g.\& on a
4399 machine acting as a router, if we want to limit traffic from
4400 local clients on 192.168.2.0/24 we do:
4402 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4403 .Dl "dnctl pipe 1 config bw 300Kbit/s queue 50KBytes"
4405 note that we use the
4407 modifier so that the rule is not used twice.
4408 Remember in fact that
4410 rules are checked both on incoming and outgoing packets.
4412 Should we want to simulate a bidirectional link with bandwidth
4413 limitations, the correct way is the following:
4415 .Dl "ipfw add pipe 1 ip from any to any out"
4416 .Dl "ipfw add pipe 2 ip from any to any in"
4417 .Dl "dnctl pipe 1 config bw 64Kbit/s queue 10Kbytes"
4418 .Dl "dnctl pipe 2 config bw 64Kbit/s queue 10Kbytes"
4420 The above can be very useful, e.g.\& if you want to see how
4421 your fancy Web page will look for a residential user who
4422 is connected only through a slow link.
4423 You should not use only one pipe for both directions, unless
4424 you want to simulate a half-duplex medium (e.g.\& AppleTalk,
4426 It is not necessary that both pipes have the same configuration,
4427 so we can also simulate asymmetric links.
4429 Should we want to verify network performance with the RED queue
4430 management algorithm:
4432 .Dl "ipfw add pipe 1 ip from any to any"
4433 .Dl "dnctl pipe 1 config bw 500Kbit/s queue 100 red 0.002/30/80/0.1"
4435 Another typical application of the traffic shaper is to
4436 introduce some delay in the communication.
4437 This can significantly affect applications which do a lot of Remote
4438 Procedure Calls, and where the round-trip-time of the
4439 connection often becomes a limiting factor much more than
4442 .Dl "ipfw add pipe 1 ip from any to any out"
4443 .Dl "ipfw add pipe 2 ip from any to any in"
4444 .Dl "dnctl pipe 1 config delay 250ms bw 1Mbit/s"
4445 .Dl "dnctl pipe 2 config delay 250ms bw 1Mbit/s"
4447 Per-flow queueing can be useful for a variety of purposes.
4448 A very simple one is counting traffic:
4450 .Dl "ipfw add pipe 1 tcp from any to any"
4451 .Dl "ipfw add pipe 1 udp from any to any"
4452 .Dl "ipfw add pipe 1 ip from any to any"
4453 .Dl "dnctl pipe 1 config mask all"
4455 The above set of rules will create queues (and collect
4456 statistics) for all traffic.
4457 Because the pipes have no limitations, the only effect is
4458 collecting statistics.
4459 Note that we need 3 rules, not just the last one, because
4462 tries to match IP packets it will not consider ports, so we
4463 would not see connections on separate ports as different
4466 A more sophisticated example is limiting the outbound traffic
4467 on a net with per-host limits, rather than per-network limits:
4469 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4470 .Dl "ipfw add pipe 2 ip from any to 192.168.2.0/24 in"
4471 .Dl "dnctl pipe 1 config mask src-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4472 .Dl "dnctl pipe 2 config mask dst-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4474 In the following example, we need to create several traffic bandwidth
4475 classes and we need different hosts/networks to fall into different classes.
4476 We create one pipe for each class and configure them accordingly.
4477 Then we create a single table and fill it with IP subnets and addresses.
4478 For each subnet/host we set the argument equal to the number of the pipe
4480 Then we classify traffic using a single rule:
4482 .Dl "dnctl pipe 1 config bw 1000Kbyte/s"
4483 .Dl "dnctl pipe 4 config bw 4000Kbyte/s"
4485 .Dl "ipfw table T1 create type addr"
4486 .Dl "ipfw table T1 add 192.168.2.0/24 1"
4487 .Dl "ipfw table T1 add 192.168.0.0/27 4"
4488 .Dl "ipfw table T1 add 192.168.0.2 1"
4490 .Dl "ipfw add pipe tablearg ip from 'table(T1)' to any"
4494 action, the table entries may include hostnames and IP addresses.
4496 .Dl "ipfw table T2 create type addr valtype ipv4"
4497 .Dl "ipfw table T2 add 192.168.2.0/24 10.23.2.1"
4498 .Dl "ipfw table T2 add 192.168.0.0/27 router1.dmz"
4500 .Dl "ipfw add 100 fwd tablearg ip from any to 'table(T2)'"
4502 In the following example per-interface firewall is created:
4504 .Dl "ipfw table IN create type iface valtype skipto,fib"
4505 .Dl "ipfw table IN add vlan20 12000,12"
4506 .Dl "ipfw table IN add vlan30 13000,13"
4507 .Dl "ipfw table OUT create type iface valtype skipto"
4508 .Dl "ipfw table OUT add vlan20 22000"
4509 .Dl "ipfw table OUT add vlan30 23000"
4511 .Dl "ipfw add 100 setfib tablearg ip from any to any recv 'table(IN)' in"
4512 .Dl "ipfw add 200 skipto tablearg ip from any to any recv 'table(IN)' in"
4513 .Dl "ipfw add 300 skipto tablearg ip from any to any xmit 'table(OUT)' out"
4515 The following example illustrate usage of flow tables:
4517 .Dl "ipfw table fl create type flow:src-ip,proto,dst-ip,dst-port"
4518 .Dl "ipfw table fl add 2a02:6b8:77::88,tcp,2a02:6b8:77::99,80 11"
4519 .Dl "ipfw table fl add 10.0.0.1,udp,10.0.0.2,53 12"
4521 .Dl "ipfw add 100 allow ip from any to any flow 'table(fl,11)' recv ix0"
4523 To add a set of rules atomically, e.g.\& set 18:
4525 .Dl "ipfw set disable 18"
4526 .Dl "ipfw add NN set 18 ... # repeat as needed"
4527 .Dl "ipfw set enable 18"
4529 To delete a set of rules atomically the command is simply:
4531 .Dl "ipfw delete set 18"
4533 To test a ruleset and disable it and regain control if something goes wrong:
4535 .Dl "ipfw set disable 18"
4536 .Dl "ipfw add NN set 18 ... # repeat as needed"
4537 .Dl "ipfw set enable 18; echo done; sleep 30 && ipfw set disable 18"
4539 Here if everything goes well, you press control-C before the "sleep"
4540 terminates, and your ruleset will be left active.
4541 Otherwise, e.g.\& if
4542 you cannot access your box, the ruleset will be disabled after
4543 the sleep terminates thus restoring the previous situation.
4545 To show rules of the specific set:
4547 .Dl "ipfw set 18 show"
4549 To show rules of the disabled set:
4551 .Dl "ipfw -S set 18 show"
4553 To clear a specific rule counters of the specific set:
4555 .Dl "ipfw set 18 zero NN"
4557 To delete a specific rule of the specific set:
4559 .Dl "ipfw set 18 delete NN"
4560 .Ss NAT, REDIRECT AND LSNAT
4561 First redirect all the traffic to nat instance 123:
4563 .Dl "ipfw add nat 123 all from any to any"
4565 Then to configure nat instance 123 to alias all the outgoing traffic with ip
4566 192.168.0.123, blocking all incoming connections, trying to keep
4567 same ports on both sides, clearing aliasing table on address change
4568 and keeping a log of traffic/link statistics:
4570 .Dl "ipfw nat 123 config ip 192.168.0.123 log deny_in reset same_ports"
4572 Or to change address of instance 123, aliasing table will be cleared (see
4575 .Dl "ipfw nat 123 config ip 10.0.0.1"
4577 To see configuration of nat instance 123:
4579 .Dl "ipfw nat 123 show config"
4581 To show logs of all instances:
4583 .Dl "ipfw nat show log"
4585 To see configurations of all instances:
4587 .Dl "ipfw nat show config"
4589 Or a redirect rule with mixed modes could looks like:
4590 .Bd -literal -offset 2n
4591 ipfw nat 123 config redirect_addr 10.0.0.1 10.0.0.66
4592 redirect_port tcp 192.168.0.1:80 500
4593 redirect_proto udp 192.168.1.43 192.168.1.1
4594 redirect_addr 192.168.0.10,192.168.0.11
4596 redirect_port tcp 192.168.0.1:80,192.168.0.10:22
4600 or it could be split in:
4601 .Bd -literal -offset 2n
4602 ipfw nat 1 config redirect_addr 10.0.0.1 10.0.0.66
4603 ipfw nat 2 config redirect_port tcp 192.168.0.1:80 500
4604 ipfw nat 3 config redirect_proto udp 192.168.1.43 192.168.1.1
4605 ipfw nat 4 config redirect_addr 192.168.0.10,192.168.0.11,192.168.0.12
4607 ipfw nat 5 config redirect_port tcp
4608 192.168.0.1:80,192.168.0.10:22,192.168.0.20:25 500
4611 Sometimes you may want to mix NAT and dynamic rules.
4612 It could be achieved with
4617 Problem is, you need to create dynamic rule before NAT and check it
4618 after NAT actions (or vice versa) to have consistent addresses and ports.
4621 option will trigger activation of existing dynamic state, and action of such
4622 rule will be performed as soon as rule is matched.
4625 rule packet need to be passed to NAT, not allowed as soon is possible.
4627 There is example of set of rules to achieve this.
4628 Bear in mind that this is example only and it is not very useful by itself.
4630 On way out, after all checks place this rules:
4632 .Dl "ipfw add allow record-state skip-action"
4633 .Dl "ipfw add nat 1"
4635 And on way in there should be something like this:
4637 .Dl "ipfw add nat 1"
4638 .Dl "ipfw add check-state"
4640 Please note, that first rule on way out doesn't allow packet and doesn't
4641 execute existing dynamic rules.
4642 All it does, create new dynamic rule with
4644 action, if it is not created yet.
4645 Later, this dynamic rule is used on way in by
4648 .Ss CONFIGURING CODEL, PIE, FQ-CODEL and FQ-PIE AQM
4652 AQM can be configured for
4662 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4665 .Dl "dnctl pipe 1 config bw 1mbits/s codel"
4666 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4672 AQM using different configurations parameters for traffic from
4673 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4675 .Dl "dnctl pipe 1 config bw 1mbits/s"
4676 .Dl "dnctl queue 1 config pipe 1 codel target 8ms interval 160ms ecn"
4677 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4683 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4686 .Dl "dnctl pipe 1 config bw 1mbits/s pie"
4687 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4693 AQM using different configuration parameters for traffic from
4694 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4696 .Dl "dnctl pipe 1 config bw 1mbits/s"
4697 .Dl "dnctl queue 1 config pipe 1 pie target 20ms tupdate 30ms ecn"
4698 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4703 AQM can be configured for
4709 scheduler using different configurations parameters for traffic from
4710 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4712 .Dl "dnctl pipe 1 config bw 1mbits/s"
4713 .Dl "dnctl sched 1 config pipe 1 type fq_codel"
4714 .Dl "dnctl queue 1 config sched 1"
4715 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4719 default configuration for a
4721 such as disable ECN and change the
4725 .Dl "dnctl sched 1 config pipe 1 type fq_codel target 10ms noecn"
4731 scheduler using different configurations parameters for traffic from
4732 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4734 .Dl "dnctl pipe 1 config bw 1mbits/s"
4735 .Dl "dnctl sched 1 config pipe 1 type fq_pie"
4736 .Dl "dnctl queue 1 config sched 1"
4737 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4739 The configurations of
4742 can be changed in a similar way as for
4766 utility first appeared in
4771 Stateful extensions were introduced in
4774 was introduced in Summer 2002.
4776 .An Ugen J. S. Antsilevich ,
4777 .An Poul-Henning Kamp ,
4781 .An Rasool Al-Saadi .
4784 API based upon code written by
4788 Dummynet has been introduced by Luigi Rizzo in 1997-1998.
4790 Some early work (1999-2000) on the
4792 traffic shaper supported by Akamba Corp.
4794 The ipfw core (ipfw2) has been completely redesigned and
4795 reimplemented by Luigi Rizzo in summer 2002.
4798 options have been added by various developers over the years.
4801 In-kernel NAT support written by
4802 .An Paolo Pisati Aq Mt piso@FreeBSD.org
4803 as part of a Summer of Code 2005 project.
4807 support has been developed by
4808 .An The Centre for Advanced Internet Architectures (CAIA) Aq http://www.caia.swin.edu.au .
4809 The primary developers and maintainers are David Hayes and Jason But.
4810 For further information visit:
4811 .Aq http://www.caia.swin.edu.au/urp/SONATA
4813 Delay profiles have been developed by Alessandro Cerri and
4814 Luigi Rizzo, supported by the
4815 European Commission within Projects Onelab and Onelab2.
4817 CoDel, PIE, FQ-CoDel and FQ-PIE AQM for Dummynet have been implemented by
4818 .An The Centre for Advanced Internet Architectures (CAIA)
4819 in 2016, supported by The Comcast Innovation Fund.
4820 The primary developer is
4823 The syntax has grown over the years and sometimes it might be confusing.
4824 Unfortunately, backward compatibility prevents cleaning up mistakes
4825 made in the definition of the syntax.
4829 Misconfiguring the firewall can put your computer in an unusable state,
4830 possibly shutting down network services and requiring console access to
4831 regain control of it.
4833 Incoming packet fragments diverted by
4835 are reassembled before delivery to the socket.
4836 The action used on those packet is the one from the
4837 rule which matches the first fragment of the packet.
4839 Packets diverted to userland, and then reinserted by a userland process
4840 may lose various packet attributes.
4841 The packet source interface name
4842 will be preserved if it is shorter than 8 bytes and the userland process
4843 saves and reuses the sockaddr_in
4846 otherwise, it may be lost.
4847 If a packet is reinserted in this manner, later rules may be incorrectly
4848 applied, making the order of
4850 rules in the rule sequence very important.
4852 Dummynet drops all packets with IPv6 link-local addresses.
4858 may not behave as expected.
4859 In particular, incoming SYN packets may
4860 have no uid or gid associated with them since they do not yet belong
4861 to a TCP connection, and the uid/gid associated with a packet may not
4862 be as expected if the associated process calls
4864 or similar system calls.
4866 Rule syntax is subject to the command line environment and some patterns
4867 may need to be escaped with the backslash character
4868 or quoted appropriately.
4870 Due to the architecture of
4872 ipfw nat is not compatible with the TCP segmentation offloading (TSO).
4873 Thus, to reliably nat your network traffic, please disable TSO
4877 ICMP error messages are not implicitly matched by dynamic rules
4878 for the respective conversations.
4879 To avoid failures of network error detection and path MTU discovery,
4880 ICMP error messages may need to be allowed explicitly through static
4887 actions may lead to confusing behaviour if ruleset has mistakes,
4888 and/or interaction with other subsystems (netgraph, dummynet, etc.) is used.
4889 One possible case for this is packet leaving
4891 in subroutine on the input pass, while later on output encountering unpaired
4894 As the call stack is kept intact after input pass, packet will suddenly
4895 return to the rule number used on input pass, not on output one.
4896 Order of processing should be checked carefully to avoid such mistakes.
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