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
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 .
1096 The search terminates.
1097 .It Cm unreach6 Ar code
1098 Discard packets that match this rule, and try to send an ICMPv6
1099 unreachable notice with code
1103 is a number from 0, 1, 3 or 4, or one of these aliases:
1104 .Cm no-route, admin-prohib, address
1107 The search terminates.
1108 .It Cm netgraph Ar cookie
1109 Divert packet into netgraph with given
1111 The search terminates.
1112 If packet is later returned from netgraph it is either
1113 accepted or continues with the next rule, depending on
1114 .Va net.inet.ip.fw.one_pass
1116 .It Cm ngtee Ar cookie
1117 A copy of packet is diverted into netgraph, original
1118 packet continues with the next rule.
1121 for more information on
1126 .It Cm setfib Ar fibnum | tablearg
1127 The packet is tagged so as to use the FIB (routing table)
1129 in any subsequent forwarding decisions.
1130 In the current implementation, this is limited to the values 0 through 15, see
1132 Processing continues at the next rule.
1133 It is possible to use the
1135 keyword with setfib.
1136 If the tablearg value is not within the compiled range of fibs,
1137 the packet's fib is set to 0.
1138 .It Cm setdscp Ar DSCP | number | tablearg
1139 Set specified DiffServ codepoint for an IPv4/IPv6 packet.
1140 Processing continues at the next rule.
1141 Supported values are:
1187 Additionally, DSCP value can be specified by number (0..63).
1188 It is also possible to use the
1190 keyword with setdscp.
1191 If the tablearg value is not within the 0..63 range, lower 6 bits of supplied
1193 .It Cm tcp-setmss Ar mss
1194 Set the Maximum Segment Size (MSS) in the TCP segment to value
1198 should be loaded or kernel should have
1199 .Cm options IPFIREWALL_PMOD
1200 to be able use this action.
1201 This command does not change a packet if original MSS value is lower than
1203 Both TCP over IPv4 and over IPv6 are supported.
1204 Regardless of matched a packet or not by the
1206 rule, the search continues with the next rule.
1208 Queue and reassemble IPv4 fragments.
1209 If the packet is not fragmented, counters are updated and
1210 processing continues with the next rule.
1211 If the packet is the last logical fragment, the packet is reassembled and, if
1212 .Va net.inet.ip.fw.one_pass
1213 is set to 0, processing continues with the next rule.
1214 Otherwise, the packet is allowed to pass and the search terminates.
1215 If the packet is a fragment in the middle of a logical group of fragments,
1217 processing stops immediately.
1219 Fragment handling can be tuned via
1220 .Va net.inet.ip.maxfragpackets
1222 .Va net.inet.ip.maxfragsperpacket
1223 which limit, respectively, the maximum number of processable
1224 fragments (default: 800) and
1225 the maximum number of fragments per packet (default: 16).
1227 NOTA BENE: since fragments do not contain port numbers,
1228 they should be avoided with the
1231 Alternatively, direction-based (like
1235 ) and source-based (like
1237 ) match patterns can be used to select fragments.
1239 Usually a simple rule like:
1240 .Bd -literal -offset indent
1241 # reassemble incoming fragments
1242 ipfw add reass all from any to any in
1245 is all you need at the beginning of your ruleset.
1247 Discard packets that match this rule, and if the packet is an SCTP packet,
1248 try to send an SCTP packet containing an ABORT chunk.
1249 The search terminates.
1251 Discard packets that match this rule, and if the packet is an SCTP packet,
1252 try to send an SCTP packet containing an ABORT chunk.
1253 The search terminates.
1256 The body of a rule contains zero or more patterns (such as
1257 specific source and destination addresses or ports,
1258 protocol options, incoming or outgoing interfaces, etc.)
1259 that the packet must match in order to be recognised.
1260 In general, the patterns are connected by (implicit)
1262 operators -- i.e., all must match in order for the
1264 Individual patterns can be prefixed by the
1266 operator to reverse the result of the match, as in
1268 .Dl "ipfw add 100 allow ip from not 1.2.3.4 to any"
1270 Additionally, sets of alternative match patterns
1272 can be constructed by putting the patterns in
1273 lists enclosed between parentheses ( ) or braces { }, and
1276 operator as follows:
1278 .Dl "ipfw add 100 allow ip from { x or not y or z } to any"
1280 Only one level of parentheses is allowed.
1281 Beware that most shells have special meanings for parentheses
1282 or braces, so it is advisable to put a backslash \\ in front of them
1283 to prevent such interpretations.
1285 The body of a rule must in general include a source and destination
1289 can be used in various places to specify that the content of
1290 a required field is irrelevant.
1292 The rule body has the following format:
1293 .Bd -ragged -offset indent
1294 .Op Ar proto Cm from Ar src Cm to Ar dst
1298 The first part (proto from src to dst) is for backward
1299 compatibility with earlier versions of
1303 any match pattern (including MAC headers, IP protocols,
1304 addresses and ports) can be specified in the
1308 Rule fields have the following meaning:
1309 .Bl -tag -width indent
1310 .It Ar proto : protocol | Cm { Ar protocol Cm or ... }
1311 .It Ar protocol : Oo Cm not Oc Ar protocol-name | protocol-number
1312 An IP protocol specified by number or name
1313 (for a complete list see
1314 .Pa /etc/protocols ) ,
1315 or one of the following keywords:
1316 .Bl -tag -width indent
1318 Matches IPv4 packets.
1320 Matches IPv6 packets.
1329 option will be treated as inner protocol.
1337 .Cm { Ar protocol Cm or ... }
1340 is provided for convenience only but its use is deprecated.
1341 .It Ar src No and Ar dst : Bro Cm addr | Cm { Ar addr Cm or ... } Brc Op Oo Cm not Oc Ar ports
1342 An address (or a list, see below)
1343 optionally followed by
1349 with multiple addresses) is provided for convenience only and
1350 its use is discouraged.
1351 .It Ar addr : Oo Cm not Oc Bro
1352 .Cm any | me | me6 |
1353 .Cm table Ns Pq Ar name Ns Op , Ns Ar value
1354 .Ar | addr-list | addr-set
1356 .Bl -tag -width indent
1358 Matches any IP address.
1360 Matches any IP address configured on an interface in the system.
1362 Matches any IPv6 address configured on an interface in the system.
1363 The address list is evaluated at the time the packet is
1365 .It Cm table Ns Pq Ar name Ns Op , Ns Ar value
1366 Matches any IPv4 or IPv6 address for which an entry exists in the lookup table
1368 If an optional 32-bit unsigned
1370 is also specified, an entry will match only if it has this value.
1373 section below for more information on lookup tables.
1375 .It Ar addr-list : ip-addr Ns Op Ns , Ns Ar addr-list
1377 A host or subnet address specified in one of the following ways:
1378 .Bl -tag -width indent
1379 .It Ar numeric-ip | hostname
1380 Matches a single IPv4 address, specified as dotted-quad or a hostname.
1381 Hostnames are resolved at the time the rule is added to the firewall list.
1382 .It Ar addr Ns / Ns Ar masklen
1383 Matches all addresses with base
1385 (specified as an IP address, a network number, or a hostname)
1389 As an example, 1.2.3.4/25 or 1.2.3.0/25 will match
1390 all IP numbers from 1.2.3.0 to 1.2.3.127 .
1391 .It Ar addr Ns : Ns Ar mask
1392 Matches all addresses with base
1394 (specified as an IP address, a network number, or a hostname)
1397 specified as a dotted quad.
1398 As an example, 1.2.3.4:255.0.255.0 or 1.0.3.0:255.0.255.0 will match
1400 This form is advised only for non-contiguous
1402 It is better to resort to the
1403 .Ar addr Ns / Ns Ar masklen
1404 format for contiguous masks, which is more compact and less
1407 .It Ar addr-set : addr Ns Oo Ns / Ns Ar masklen Oc Ns Cm { Ns Ar list Ns Cm }
1408 .It Ar list : Bro Ar num | num-num Brc Ns Op Ns , Ns Ar list
1409 Matches all addresses with base address
1411 (specified as an IP address, a network number, or a hostname)
1412 and whose last byte is in the list between braces { } .
1413 Note that there must be no spaces between braces and
1414 numbers (spaces after commas are allowed).
1415 Elements of the list can be specified as single entries
1419 field is used to limit the size of the set of addresses,
1420 and can have any value between 24 and 32.
1422 it will be assumed as 24.
1424 This format is particularly useful to handle sparse address sets
1425 within a single rule.
1426 Because the matching occurs using a
1427 bitmask, it takes constant time and dramatically reduces
1428 the complexity of rulesets.
1430 As an example, an address specified as 1.2.3.4/24{128,35-55,89}
1431 or 1.2.3.0/24{128,35-55,89}
1432 will match the following IP addresses:
1434 1.2.3.128, 1.2.3.35 to 1.2.3.55, 1.2.3.89 .
1435 .It Ar addr6-list : ip6-addr Ns Op Ns , Ns Ar addr6-list
1437 A host or subnet specified one of the following ways:
1438 .Bl -tag -width indent
1439 .It Ar numeric-ip | hostname
1440 Matches a single IPv6 address as allowed by
1443 Hostnames are resolved at the time the rule is added to the firewall
1445 .It Ar addr Ns / Ns Ar masklen
1446 Matches all IPv6 addresses with base
1448 (specified as allowed by
1454 .It Ar addr Ns / Ns Ar mask
1455 Matches all IPv6 addresses with base
1457 (specified as allowed by
1462 specified as allowed by
1464 As an example, fe::640:0:0/ffff::ffff:ffff:0:0 will match
1466 This form is advised only for non-contiguous
1468 It is better to resort to the
1469 .Ar addr Ns / Ns Ar masklen
1470 format for contiguous masks, which is more compact and less
1474 No support for sets of IPv6 addresses is provided because IPv6 addresses
1475 are typically random past the initial prefix.
1476 .It Ar ports : Bro Ar port | port Ns \&- Ns Ar port Ns Brc Ns Op , Ns Ar ports
1477 For protocols which support port numbers (such as SCTP, TCP and UDP), optional
1479 may be specified as one or more ports or port ranges, separated
1480 by commas but no spaces, and an optional
1485 notation specifies a range of ports (including boundaries).
1489 may be used instead of numeric port values.
1490 The length of the port list is limited to 30 ports or ranges,
1491 though one can specify larger ranges by using an
1495 section of the rule.
1499 can be used to escape the dash
1501 character in a service name (from a shell, the backslash must be
1502 typed twice to avoid the shell itself interpreting it as an escape
1505 .Dl "ipfw add count tcp from any ftp\e\e-data-ftp to any"
1507 Fragmented packets which have a non-zero offset (i.e., not the first
1508 fragment) will never match a rule which has one or more port
1512 option for details on matching fragmented packets.
1514 .Ss RULE OPTIONS (MATCH PATTERNS)
1515 Additional match patterns can be used within
1517 Zero or more of these so-called
1519 can be present in a rule, optionally prefixed by the
1521 operand, and possibly grouped into
1524 The following match patterns can be used (listed in alphabetical order):
1525 .Bl -tag -width indent
1526 .It Cm // this is a comment .
1527 Inserts the specified text as a comment in the rule.
1528 Everything following // is considered as a comment and stored in the rule.
1529 You can have comment-only rules, which are listed as having a
1531 action followed by the comment.
1535 .It Cm defer-immediate-action | defer-action
1536 A rule with this option will not perform normal action
1538 This option is intended to be used with
1542 as the dynamic rule, created but ignored on match, will work
1547 .Cm defer-immediate-action
1548 create a dynamic rule and continue with the next rule without actually
1549 performing the action part of this rule.
1550 When the rule is later activated via the state table, the action is
1553 Matches only packets generated by a divert socket.
1554 .It Cm diverted-loopback
1555 Matches only packets coming from a divert socket back into the IP stack
1557 .It Cm diverted-output
1558 Matches only packets going from a divert socket back outward to the IP
1559 stack output for delivery.
1560 .It Cm dst-ip Ar ip-address
1561 Matches IPv4 packets whose destination IP is one of the address(es)
1562 specified as argument.
1563 .It Bro Cm dst-ip6 | dst-ipv6 Brc Ar ip6-address
1564 Matches IPv6 packets whose destination IP is one of the address(es)
1565 specified as argument.
1566 .It Cm dst-port Ar ports
1567 Matches IP packets whose destination port is one of the port(s)
1568 specified as argument.
1570 Matches TCP packets that have the RST or ACK bits set.
1571 .It Cm ext6hdr Ar header
1572 Matches IPv6 packets containing the extended header given by
1574 Supported headers are:
1580 any type of Routing Header
1582 Source routing Routing Header Type 0
1584 Mobile IPv6 Routing Header Type 2
1588 IPSec authentication headers
1590 and IPsec encapsulated security payload headers
1592 .It Cm fib Ar fibnum
1593 Matches a packet that has been tagged to use
1594 the given FIB (routing table) number.
1595 .It Cm flow Ar table Ns Pq Ar name Ns Op , Ns Ar value
1596 Search for the flow entry in lookup table
1598 If not found, the match fails.
1599 Otherwise, the match succeeds and
1601 is set to the value extracted from the table.
1603 This option can be useful to quickly dispatch traffic based on
1604 certain packet fields.
1607 section below for more information on lookup tables.
1608 .It Cm flow-id Ar labels
1609 Matches IPv6 packets containing any of the flow labels given in
1612 is a comma separated list of numeric flow labels.
1613 .It Cm dst-mac Ar table Ns Pq Ar name Ns Op , Ns Ar value
1614 Search for the destination MAC address entry in lookup table
1616 If not found, the match fails.
1617 Otherwise, the match succeeds and
1619 is set to the value extracted from the table.
1620 .It Cm src-mac Ar table Ns Pq Ar name Ns Op , Ns Ar value
1621 Search for the source MAC address entry in lookup table
1623 If not found, the match fails.
1624 Otherwise, the match succeeds and
1626 is set to the value extracted from the table.
1628 Matches IPv4 packets whose
1630 field contains the comma separated list of IPv4 fragmentation
1631 options specified in
1633 The recognized options are:
1635 .Pq Dv don't fragment ,
1637 .Pq Dv more fragments ,
1639 .Pq Dv reserved fragment bit
1641 .Pq Dv non-zero fragment offset .
1642 The absence of a particular options may be denoted
1646 Empty list of options defaults to matching on non-zero fragment offset.
1647 Such rule would match all not the first fragment datagrams,
1649 This is a backward compatibility with older rulesets.
1651 Matches all TCP or UDP packets sent by or received for a
1655 may be specified by name or number.
1657 Matches all TCP or UDP packets sent by or received for the
1658 jail whose ID or name is
1660 .It Cm icmptypes Ar types
1661 Matches ICMP packets whose ICMP type is in the list
1663 The list may be specified as any combination of
1664 individual types (numeric) separated by commas.
1665 .Em Ranges are not allowed .
1666 The supported ICMP types are:
1670 destination unreachable
1678 router advertisement
1682 time-to-live exceeded
1694 address mask request
1696 and address mask reply
1698 .It Cm icmp6types Ar types
1699 Matches ICMP6 packets whose ICMP6 type is in the list of
1701 The list may be specified as any combination of
1702 individual types (numeric) separated by commas.
1703 .Em Ranges are not allowed .
1705 Matches incoming or outgoing packets, respectively.
1709 are mutually exclusive (in fact,
1713 .It Cm ipid Ar id-list
1714 Matches IPv4 packets whose
1716 field has value included in
1718 which is either a single value or a list of values or ranges
1719 specified in the same way as
1721 .It Cm iplen Ar len-list
1722 Matches IP packets whose total length, including header and data, is
1725 which is either a single value or a list of values or ranges
1726 specified in the same way as
1728 .It Cm ipoptions Ar spec
1729 Matches packets whose IPv4 header contains the comma separated list of
1730 options specified in
1732 The supported IP options are:
1735 (strict source route),
1737 (loose source route),
1739 (record packet route) and
1742 The absence of a particular option may be denoted
1745 .It Cm ipprecedence Ar precedence
1746 Matches IPv4 packets whose precedence field is equal to
1749 Matches packets that have IPSEC history associated with them
1750 (i.e., the packet comes encapsulated in IPSEC, the kernel
1751 has IPSEC support, and can correctly decapsulate it).
1753 Note that specifying
1755 is different from specifying
1757 as the latter will only look at the specific IP protocol field,
1758 irrespective of IPSEC kernel support and the validity of the IPSEC data.
1760 Further note that this flag is silently ignored in kernels without
1762 It does not affect rule processing when given and the
1763 rules are handled as if with no
1766 .It Cm iptos Ar spec
1767 Matches IPv4 packets whose
1769 field contains the comma separated list of
1770 service types specified in
1772 The supported IP types of service are:
1775 .Pq Dv IPTOS_LOWDELAY ,
1777 .Pq Dv IPTOS_THROUGHPUT ,
1779 .Pq Dv IPTOS_RELIABILITY ,
1781 .Pq Dv IPTOS_MINCOST ,
1783 .Pq Dv IPTOS_ECN_CE .
1784 The absence of a particular type may be denoted
1787 .It Cm dscp spec Ns Op , Ns Ar spec
1788 Matches IPv4/IPv6 packets whose
1790 field value is contained in
1793 Multiple values can be specified via
1794 the comma separated list.
1795 Value can be one of keywords used in
1797 action or exact number.
1798 .It Cm ipttl Ar ttl-list
1799 Matches IPv4 packets whose time to live is included in
1801 which is either a single value or a list of values or ranges
1802 specified in the same way as
1804 .It Cm ipversion Ar ver
1805 Matches IP packets whose IP version field is
1807 .It Cm keep-state Op Ar :flowname
1808 Upon a match, the firewall will create a dynamic rule, whose
1809 default behaviour is to match bidirectional traffic between
1810 source and destination IP/port using the same protocol.
1811 The rule has a limited lifetime (controlled by a set of
1813 variables), and the lifetime is refreshed every time a matching
1817 is used to assign additional to addresses, ports and protocol parameter
1819 It can be used for more accurate matching by
1824 keyword is special name used for compatibility with old rulesets.
1826 Matches only layer2 packets, i.e., those passed to
1831 .Fn ether_output_frame .
1832 .It Cm limit Bro Cm src-addr | src-port | dst-addr | dst-port Brc Ar N Op Ar :flowname
1833 The firewall will only allow
1835 connections with the same
1836 set of parameters as specified in the rule.
1838 of source and destination addresses and ports can be
1840 .It Cm lookup Bro Cm dst-ip | dst-port | dst-mac | src-ip | src-port | src-mac | uid | jail Brc Ar name
1841 Search an entry in lookup table
1843 that matches the field specified as argument.
1844 If not found, the match fails.
1845 Otherwise, the match succeeds and
1847 is set to the value extracted from the table.
1849 This option can be useful to quickly dispatch traffic based on
1850 certain packet fields.
1853 section below for more information on lookup tables.
1854 .It Cm { MAC | mac } Ar dst-mac src-mac
1855 Match packets with a given
1859 addresses, specified as the
1861 keyword (matching any MAC address), or six groups of hex digits
1862 separated by colons,
1863 and optionally followed by a mask indicating the significant bits.
1864 The mask may be specified using either of the following methods:
1865 .Bl -enum -width indent
1869 followed by the number of significant bits.
1870 For example, an address with 33 significant bits could be specified as:
1872 .Dl "MAC 10:20:30:40:50:60/33 any"
1876 followed by a bitmask specified as six groups of hex digits separated
1878 For example, an address in which the last 16 bits are significant could
1881 .Dl "MAC 10:20:30:40:50:60&00:00:00:00:ff:ff any"
1883 Note that the ampersand character has a special meaning in many shells
1884 and should generally be escaped.
1886 Note that the order of MAC addresses (destination first,
1888 the same as on the wire, but the opposite of the one used for
1890 .It Cm mac-type Ar mac-type
1891 Matches packets whose Ethernet Type field
1892 corresponds to one of those specified as argument.
1894 is specified in the same way as
1896 (i.e., one or more comma-separated single values or ranges).
1897 You can use symbolic names for known values such as
1898 .Em vlan , ipv4, ipv6 .
1899 Values can be entered as decimal or hexadecimal (if prefixed by 0x),
1900 and they are always printed as hexadecimal (unless the
1902 option is used, in which case symbolic resolution will be attempted).
1903 .It Cm proto Ar protocol
1904 Matches packets with the corresponding IP protocol.
1906 Upon a match, the firewall will create a dynamic rule as if
1909 However, this option doesn't imply an implicit
1913 .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
1914 Matches packets received, transmitted or going through,
1915 respectively, the interface specified by exact name
1919 by IP address, or through some interface.
1922 may be used to match interface by its kernel ifindex.
1925 section below for more information on lookup tables.
1929 keyword causes the interface to always be checked.
1936 then only the receive or transmit interface (respectively)
1938 By specifying both, it is possible to match packets based on
1939 both receive and transmit interface, e.g.:
1941 .Dl "ipfw add deny ip from any to any out recv ed0 xmit ed1"
1945 interface can be tested on either incoming or outgoing packets,
1948 interface can only be tested on outgoing packets.
1953 is invalid) whenever
1957 A packet might not have a receive or transmit interface: packets
1958 originating from the local host have no receive interface,
1959 while packets destined for the local host have no transmit
1961 .It Cm set-limit Bro Cm src-addr | src-port | dst-addr | dst-port Brc Ar N
1964 but does not have an implicit
1968 Matches TCP packets that have the SYN bit set but no ACK bit.
1969 This is the short form of
1970 .Dq Li tcpflags\ syn,!ack .
1972 Matches packets that are associated to a local socket and
1973 for which the SO_USER_COOKIE socket option has been set
1974 to a non-zero value.
1975 As a side effect, the value of the
1976 option is made available as
1978 value, which in turn can be used as
1983 .It Cm src-ip Ar ip-address
1984 Matches IPv4 packets whose source IP is one of the address(es)
1985 specified as an argument.
1986 .It Cm src-ip6 Ar ip6-address
1987 Matches IPv6 packets whose source IP is one of the address(es)
1988 specified as an argument.
1989 .It Cm src-port Ar ports
1990 Matches IP packets whose source port is one of the port(s)
1991 specified as argument.
1992 .It Cm tagged Ar tag-list
1993 Matches packets whose tags are included in
1995 which is either a single value or a list of values or ranges
1996 specified in the same way as
1998 Tags can be applied to the packet using
2000 rule action parameter (see it's description for details on tags).
2001 .It Cm tcpack Ar ack
2003 Match if the TCP header acknowledgment number field is set to
2005 .It Cm tcpdatalen Ar tcpdatalen-list
2006 Matches TCP packets whose length of TCP data is
2007 .Ar tcpdatalen-list ,
2008 which is either a single value or a list of values or ranges
2009 specified in the same way as
2011 .It Cm tcpflags Ar spec
2013 Match if the TCP header contains the comma separated list of
2016 The supported TCP flags are:
2025 The absence of a particular flag may be denoted
2028 A rule which contains a
2030 specification can never match a fragmented packet which has
2034 option for details on matching fragmented packets.
2035 .It Cm tcpmss Ar tcpmss-list
2036 Matches TCP packets whose MSS (maximum segment size) value is set to
2038 which is either a single value or a list of values or ranges
2039 specified in the same way as
2041 .It Cm tcpseq Ar seq
2043 Match if the TCP header sequence number field is set to
2045 .It Cm tcpwin Ar tcpwin-list
2046 Matches TCP packets whose header window field is set to
2048 which is either a single value or a list of values or ranges
2049 specified in the same way as
2051 .It Cm tcpoptions Ar spec
2053 Match if the TCP header contains the comma separated list of
2054 options specified in
2056 The supported TCP options are:
2059 (maximum segment size),
2061 (tcp window advertisement),
2065 (rfc1323 timestamp) and
2067 (rfc1644 t/tcp connection count).
2068 The absence of a particular option may be denoted
2072 Match all TCP or UDP packets sent by or received for a
2076 may be matched by name or identification number.
2078 For incoming packets,
2079 a routing table lookup is done on the packet's source address.
2080 If the interface on which the packet entered the system matches the
2081 outgoing interface for the route,
2083 If the interfaces do not match up,
2084 the packet does not match.
2085 All outgoing packets or packets with no incoming interface match.
2087 The name and functionality of the option is intentionally similar to
2088 the Cisco IOS command:
2090 .Dl ip verify unicast reverse-path
2092 This option can be used to make anti-spoofing rules to reject all
2093 packets with source addresses not from this interface.
2097 For incoming packets,
2098 a routing table lookup is done on the packet's source address.
2099 If a route to the source address exists, but not the default route
2100 or a blackhole/reject route, the packet matches.
2101 Otherwise, the packet does not match.
2102 All outgoing packets match.
2104 The name and functionality of the option is intentionally similar to
2105 the Cisco IOS command:
2107 .Dl ip verify unicast source reachable-via any
2109 This option can be used to make anti-spoofing rules to reject all
2110 packets whose source address is unreachable.
2112 For incoming packets, the packet's source address is checked if it
2113 belongs to a directly connected network.
2114 If the network is directly connected, then the interface the packet
2115 came on in is compared to the interface the network is connected to.
2116 When incoming interface and directly connected interface are not the
2117 same, the packet does not match.
2118 Otherwise, the packet does match.
2119 All outgoing packets match.
2121 This option can be used to make anti-spoofing rules to reject all
2122 packets that pretend to be from a directly connected network but do
2123 not come in through that interface.
2124 This option is similar to but more restricted than
2126 because it engages only on packets with source addresses of directly
2127 connected networks instead of all source addresses.
2130 Lookup tables are useful to handle large sparse sets of
2131 addresses or other search keys (e.g., ports, jail IDs, interface names).
2132 In the rest of this section we will use the term ``key''.
2133 Table name needs to match the following spec:
2135 Tables with the same name can be created in different
2137 However, rule links to the tables in
2140 This behavior can be controlled by
2141 .Va net.inet.ip.fw.tables_sets
2145 section for more information.
2146 There may be up to 65535 different lookup tables.
2148 The following table types are supported:
2149 .Bl -tag -width indent
2150 .It Ar table-type : Ar addr | iface | number | flow | mac
2151 .It Ar table-key : Ar addr Ns Oo / Ns Ar masklen Oc | iface-name | number | flow-spec
2152 .It Ar flow-spec : Ar flow-field Ns Op , Ns Ar flow-spec
2153 .It Ar flow-field : src-ip | proto | src-port | dst-ip | dst-port
2155 Matches IPv4 or IPv6 address.
2156 Each entry is represented by an
2157 .Ar addr Ns Op / Ns Ar masklen
2158 and will match all addresses with base
2160 (specified as an IPv4/IPv6 address, or a hostname) and mask width of
2165 is not specified, it defaults to 32 for IPv4 and 128 for IPv6.
2166 When looking up an IP address in a table, the most specific
2169 Matches interface names.
2170 Each entry is represented by string treated as interface name.
2171 Wildcards are not supported.
2173 Matches protocol ports, uids/gids or jail IDs.
2174 Each entry is represented by 32-bit unsigned integer.
2175 Ranges are not supported.
2177 Matches packet fields specified by
2179 type suboptions with table entries.
2181 Matches MAC address.
2182 Each entry is represented by an
2183 .Ar addr Ns Op / Ns Ar masklen
2184 and will match all addresses with base
2191 is not specified, it defaults to 48.
2192 When looking up an MAC address in a table, the most specific
2196 Tables require explicit creation via
2200 The following creation options are supported:
2201 .Bl -tag -width indent
2202 .It Ar create-options : Ar create-option | create-options
2203 .It Ar create-option : Cm type Ar table-type | Cm valtype Ar value-mask | Cm algo Ar algo-desc |
2204 .Cm limit Ar number | Cm locked | Cm missing | Cm or-flush
2210 Table algorithm to use (see below).
2212 Maximum number of items that may be inserted into table.
2214 Restrict any table modifications.
2216 Do not fail if table already exists and has exactly same options as new one.
2218 Flush existing table with same name instead of returning error.
2221 so existing table must be compatible with new one.
2224 Some of these options may be modified later via
2227 The following options can be changed:
2228 .Bl -tag -width indent
2229 .It Ar modify-options : Ar modify-option | modify-options
2230 .It Ar modify-option : Cm limit Ar number
2232 Alter maximum number of items that may be inserted into table.
2235 Additionally, table can be locked or unlocked using
2243 can be swapped with each other using
2246 Swap may fail if tables limits are set and data exchange
2247 would result in limits hit.
2248 Operation is performed atomically.
2250 One or more entries can be added to a table at once using
2253 Addition of all items are performed atomically.
2254 By default, error in addition of one entry does not influence
2255 addition of other entries.
2256 However, non-zero error code is returned in that case.
2259 keyword may be specified before
2261 to indicate all-or-none add request.
2263 One or more entries can be removed from a table at once using
2266 By default, error in removal of one entry does not influence
2267 removing of other entries.
2268 However, non-zero error code is returned in that case.
2270 It may be possible to check what entry will be found on particular
2276 This functionality is optional and may be unsupported in some algorithms.
2278 The following operations can be performed on
2283 .Bl -tag -width indent
2287 Removes all entries.
2289 Shows generic table information.
2291 Shows generic table information and algo-specific data.
2294 The following lookup algorithms are supported:
2295 .Bl -tag -width indent
2296 .It Ar algo-desc : algo-name | "algo-name algo-data"
2297 .It Ar algo-name : Ar addr: radix | addr: hash | iface: array | number: array | flow: hash | mac: radix
2299 Separate Radix trees for IPv4 and IPv6, the same way as the routing table (see
2305 Separate auto-growing hashes for IPv4 and IPv6.
2306 Accepts entries with the same mask length specified initially via
2307 .Cm "addr:hash masks=/v4,/v6"
2308 algorithm creation options.
2309 Assume /32 and /128 masks by default.
2310 Search removes host bits (according to mask) from supplied address and checks
2311 resulting key in appropriate hash.
2312 Mostly optimized for /64 and byte-ranged IPv6 masks.
2314 Array storing sorted indexes for entries which are presented in the system.
2315 Optimized for very fast lookup.
2317 Array storing sorted u32 numbers.
2319 Auto-growing hash storing flow entries.
2320 Search calculates hash on required packet fields and searches for matching
2321 entries in selected bucket.
2323 Radix tree for MAC address
2328 feature provides the ability to use a value, looked up in the table, as
2329 the argument for a rule action, action parameter or rule option.
2330 This can significantly reduce number of rules in some configurations.
2331 If two tables are used in a rule, the result of the second (destination)
2334 Each record may hold one or more values according to
2336 This mask is set on table creation via
2339 The following value types are supported:
2340 .Bl -tag -width indent
2341 .It Ar value-mask : Ar value-type Ns Op , Ns Ar value-mask
2342 .It Ar value-type : Ar skipto | pipe | fib | nat | dscp | tag | divert |
2343 .Ar netgraph | limit | ipv4
2345 rule number to jump to.
2349 fib number to match/set.
2351 nat number to jump to.
2353 dscp value to match/set.
2355 tag number to match/set.
2357 port number to divert traffic to.
2359 hook number to move packet to.
2361 maximum number of connections.
2363 IPv4 nexthop to fwd packets to.
2365 IPv6 nexthop to fwd packets to.
2370 argument can be used with the following actions:
2371 .Cm nat, pipe, queue, divert, tee, netgraph, ngtee, fwd, skipto, setfib ,
2379 action, the user should be aware that the code will walk the ruleset
2380 up to a rule equal to, or past, the given number.
2384 Section for example usage of tables and the tablearg keyword.
2386 Each rule or table belongs to one of 32 different
2389 Set 31 is reserved for the default rule.
2391 By default, rules or tables are put in set 0, unless you use the
2393 attribute when adding a new rule or table.
2394 Sets can be individually and atomically enabled or disabled,
2395 so this mechanism permits an easy way to store multiple configurations
2396 of the firewall and quickly (and atomically) switch between them.
2398 By default, tables from set 0 are referenced when adding rule with
2399 table opcodes regardless of rule set.
2400 This behavior can be changed by setting
2401 .Va net.inet.ip.fw.tables_sets
2403 Rule's set will then be used for table references.
2405 The command to enable/disable sets is
2406 .Bd -ragged -offset indent
2408 .Cm set Oo Cm disable Ar number ... Oc Op Cm enable Ar number ...
2415 sections can be specified.
2416 Command execution is atomic on all the sets specified in the command.
2417 By default, all sets are enabled.
2419 When you disable a set, its rules behave as if they do not exist
2420 in the firewall configuration, with only one exception:
2421 .Bd -ragged -offset indent
2422 dynamic rules created from a rule before it had been disabled
2423 will still be active until they expire.
2425 dynamic rules you have to explicitly delete the parent rule
2426 which generated them.
2429 The set number of rules can be changed with the command
2430 .Bd -ragged -offset indent
2433 .Brq Cm rule Ar rule-number | old-set
2437 Also, you can atomically swap two rulesets with the command
2438 .Bd -ragged -offset indent
2440 .Cm set swap Ar first-set second-set
2445 Section on some possible uses of sets of rules.
2446 .Sh STATEFUL FIREWALL
2447 Stateful operation is a way for the firewall to dynamically
2448 create rules for specific flows when packets that
2449 match a given pattern are detected.
2450 Support for stateful
2451 operation comes through the
2452 .Cm check-state , keep-state , record-state , limit
2458 Dynamic rules are created when a packet matches a
2464 rule, causing the creation of a
2466 rule which will match all and only packets with
2470 .Em src-ip/src-port dst-ip/dst-port
2475 are used here only to denote the initial match addresses, but they
2476 are completely equivalent afterwards).
2482 This name is used in matching together with addresses, ports and protocol.
2483 Dynamic rules will be checked at the first
2484 .Cm check-state, keep-state
2487 occurrence, and the action performed upon a match will be the same
2488 as in the parent rule.
2490 Note that no additional attributes other than protocol and IP addresses
2491 and ports and :flowname are checked on dynamic rules.
2493 The typical use of dynamic rules is to keep a closed firewall configuration,
2494 but let the first TCP SYN packet from the inside network install a
2495 dynamic rule for the flow so that packets belonging to that session
2496 will be allowed through the firewall:
2498 .Dl "ipfw add check-state :OUTBOUND"
2499 .Dl "ipfw add allow tcp from my-subnet to any setup keep-state :OUTBOUND"
2500 .Dl "ipfw add deny tcp from any to any"
2502 A similar approach can be used for UDP, where an UDP packet coming
2503 from the inside will install a dynamic rule to let the response through
2506 .Dl "ipfw add check-state :OUTBOUND"
2507 .Dl "ipfw add allow udp from my-subnet to any keep-state :OUTBOUND"
2508 .Dl "ipfw add deny udp from any to any"
2510 Dynamic rules expire after some time, which depends on the status
2511 of the flow and the setting of some
2515 .Sx SYSCTL VARIABLES
2517 For TCP sessions, dynamic rules can be instructed to periodically
2518 send keepalive packets to refresh the state of the rule when it is
2523 for more examples on how to use dynamic rules.
2524 .Sh TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
2526 is also the user interface for the
2528 traffic shaper, packet scheduler and network emulator, a subsystem that
2529 can artificially queue, delay or drop packets
2530 emulating the behaviour of certain network links
2531 or queueing systems.
2534 operates by first using the firewall to select packets
2535 using any match pattern that can be used in
2538 Matching packets are then passed to either of two
2539 different objects, which implement the traffic regulation:
2540 .Bl -hang -offset XXXX
2546 with given bandwidth and propagation delay,
2547 driven by a FIFO scheduler and a single queue with programmable
2548 queue size and packet loss rate.
2549 Packets are appended to the queue as they come out from
2551 and then transferred in FIFO order to the link at the desired rate.
2555 is an abstraction used to implement packet scheduling
2556 using one of several packet scheduling algorithms.
2559 are first grouped into flows according to a mask on the 5-tuple.
2560 Flows are then passed to the scheduler associated to the
2562 and each flow uses scheduling parameters (weight and others)
2563 as configured in the
2566 A scheduler in turn is connected to an emulated link,
2567 and arbitrates the link's bandwidth among backlogged flows according to
2568 weights and to the features of the scheduling algorithm in use.
2573 can be used to set hard limits to the bandwidth that a flow can use, whereas
2575 can be used to determine how different flows share the available bandwidth.
2577 A graphical representation of the binding of queues,
2578 flows, schedulers and links is below.
2579 .Bd -literal -offset indent
2580 (flow_mask|sched_mask) sched_mask
2581 +---------+ weight Wx +-------------+
2582 | |->-[flow]-->--| |-+
2583 -->--| QUEUE x | ... | | |
2584 | |->-[flow]-->--| SCHEDuler N | |
2586 ... | +--[LINK N]-->--
2587 +---------+ weight Wy | | +--[LINK N]-->--
2588 | |->-[flow]-->--| | |
2589 -->--| QUEUE y | ... | | |
2590 | |->-[flow]-->--| | |
2591 +---------+ +-------------+ |
2594 It is important to understand the role of the SCHED_MASK
2595 and FLOW_MASK, which are configured through the commands
2596 .Dl "ipfw sched N config mask SCHED_MASK ..."
2598 .Dl "ipfw queue X config mask FLOW_MASK ..." .
2600 The SCHED_MASK is used to assign flows to one or more
2601 scheduler instances, one for each
2602 value of the packet's 5-tuple after applying SCHED_MASK.
2603 As an example, using ``src-ip 0xffffff00'' creates one instance
2604 for each /24 destination subnet.
2606 The FLOW_MASK, together with the SCHED_MASK, is used to split
2608 As an example, using
2609 ``src-ip 0x000000ff''
2610 together with the previous SCHED_MASK makes a flow for
2611 each individual source address.
2612 In turn, flows for each /24
2613 subnet will be sent to the same scheduler instance.
2615 The above diagram holds even for the
2617 case, with the only restriction that a
2619 only supports a SCHED_MASK, and forces the use of a FIFO
2620 scheduler (these are for backward compatibility reasons;
2621 in fact, internally, a
2623 pipe is implemented exactly as above).
2625 There are two modes of
2633 mode tries to emulate a real link: the
2635 scheduler ensures that the packet will not leave the pipe faster than it
2636 would on the real link with a given bandwidth.
2639 mode allows certain packets to bypass the
2641 scheduler (if packet flow does not exceed pipe's bandwidth).
2642 This is the reason why the
2644 mode requires less CPU cycles per packet (on average) and packet latency
2645 can be significantly lower in comparison to a real link with the same
2651 mode can be enabled by setting the
2652 .Va net.inet.ip.dummynet.io_fast
2654 variable to a non-zero value.
2655 .Ss PIPE, QUEUE AND SCHEDULER CONFIGURATION
2661 configuration commands are the following:
2662 .Bd -ragged -offset indent
2663 .Cm pipe Ar number Cm config Ar pipe-configuration
2665 .Cm queue Ar number Cm config Ar queue-configuration
2667 .Cm sched Ar number Cm config Ar sched-configuration
2670 The following parameters can be configured for a pipe:
2672 .Bl -tag -width indent -compact
2673 .It Cm bw Ar bandwidth | device
2674 Bandwidth, measured in
2677 .Brq Cm bit/s | Byte/s .
2680 A value of 0 (default) means unlimited bandwidth.
2681 The unit must immediately follow the number, as in
2683 .Dl "dnctl pipe 1 config bw 300Kbit/s"
2685 If a device name is specified instead of a numeric value, as in
2687 .Dl "dnctl pipe 1 config bw tun0"
2689 then the transmit clock is supplied by the specified device.
2690 At the moment only the
2692 device supports this
2693 functionality, for use in conjunction with
2696 .It Cm delay Ar ms-delay
2697 Propagation delay, measured in milliseconds.
2698 The value is rounded to the next multiple of the clock tick
2699 (typically 10ms, but it is a good practice to run kernels
2701 .Dq "options HZ=1000"
2703 the granularity to 1ms or less).
2704 The default value is 0, meaning no delay.
2706 .It Cm burst Ar size
2707 If the data to be sent exceeds the pipe's bandwidth limit
2708 (and the pipe was previously idle), up to
2710 bytes of data are allowed to bypass the
2712 scheduler, and will be sent as fast as the physical link allows.
2713 Any additional data will be transmitted at the rate specified
2717 The burst size depends on how long the pipe has been idle;
2718 the effective burst size is calculated as follows:
2725 .It Cm profile Ar filename
2726 A file specifying the additional overhead incurred in the transmission
2727 of a packet on the link.
2729 Some link types introduce extra delays in the transmission
2730 of a packet, e.g., because of MAC level framing, contention on
2731 the use of the channel, MAC level retransmissions and so on.
2732 From our point of view, the channel is effectively unavailable
2733 for this extra time, which is constant or variable depending
2735 Additionally, packets may be dropped after this
2736 time (e.g., on a wireless link after too many retransmissions).
2737 We can model the additional delay with an empirical curve
2738 that represents its distribution.
2739 .Bd -literal -offset indent
2740 cumulative probability
2750 +-------*------------------->
2753 The empirical curve may have both vertical and horizontal lines.
2754 Vertical lines represent constant delay for a range of
2756 Horizontal lines correspond to a discontinuity in the delay
2757 distribution: the pipe will use the largest delay for a
2760 The file format is the following, with whitespace acting as
2761 a separator and '#' indicating the beginning a comment:
2762 .Bl -tag -width indent
2763 .It Cm name Ar identifier
2764 optional name (listed by "dnctl pipe show")
2765 to identify the delay distribution;
2767 the bandwidth used for the pipe.
2768 If not specified here, it must be present
2769 explicitly as a configuration parameter for the pipe;
2770 .It Cm loss-level Ar L
2771 the probability above which packets are lost.
2772 (0.0 <= L <= 1.0, default 1.0 i.e., no loss);
2774 the number of samples used in the internal
2775 representation of the curve (2..1024; default 100);
2776 .It Cm "delay prob" | "prob delay"
2777 One of these two lines is mandatory and defines
2778 the format of the following lines with data points.
2780 2 or more lines representing points in the curve,
2781 with either delay or probability first, according
2782 to the chosen format.
2783 The unit for delay is milliseconds.
2784 Data points do not need to be sorted.
2785 Also, the number of actual lines can be different
2786 from the value of the "samples" parameter:
2788 utility will sort and interpolate
2789 the curve as needed.
2792 Example of a profile file:
2793 .Bd -literal -offset indent
2798 0 200 # minimum overhead is 200ms
2804 #configuration file end
2808 The following parameters can be configured for a queue:
2810 .Bl -tag -width indent -compact
2811 .It Cm pipe Ar pipe_nr
2812 Connects a queue to the specified pipe.
2813 Multiple queues (with the same or different weights) can be connected to
2814 the same pipe, which specifies the aggregate rate for the set of queues.
2816 .It Cm weight Ar weight
2817 Specifies the weight to be used for flows matching this queue.
2818 The weight must be in the range 1..100, and defaults to 1.
2821 The following case-insensitive parameters can be configured for a
2824 .Bl -tag -width indent -compact
2825 .It Cm type Ar {fifo | wf2q+ | rr | qfq | fq_codel | fq_pie}
2826 specifies the scheduling algorithm to use.
2827 .Bl -tag -width indent -compact
2829 is just a FIFO scheduler (which means that all packets
2830 are stored in the same queue as they arrive to the scheduler).
2831 FIFO has O(1) per-packet time complexity, with very low
2832 constants (estimate 60-80ns on a 2GHz desktop machine)
2833 but gives no service guarantees.
2835 implements the WF2Q+ algorithm, which is a Weighted Fair Queueing
2836 algorithm which permits flows to share bandwidth according to
2838 Note that weights are not priorities; even a flow
2839 with a minuscule weight will never starve.
2840 WF2Q+ has O(log N) per-packet processing cost, where N is the number
2841 of flows, and is the default algorithm used by previous versions
2844 implements the Deficit Round Robin algorithm, which has O(1) processing
2845 costs (roughly, 100-150ns per packet)
2846 and permits bandwidth allocation according to weights, but
2847 with poor service guarantees.
2849 implements the QFQ algorithm, which is a very fast variant of
2850 WF2Q+, with similar service guarantees and O(1) processing
2851 costs (roughly, 200-250ns per packet).
2853 implements the FQ-CoDel (FlowQueue-CoDel) scheduler/AQM algorithm, which
2854 uses a modified Deficit Round Robin scheduler to manage two lists of sub-queues
2855 (old sub-queues and new sub-queues) for providing brief periods of priority to
2856 lightweight or short burst flows.
2857 By default, the total number of sub-queues is 1024.
2858 FQ-CoDel's internal, dynamically
2859 created sub-queues are controlled by separate instances of CoDel AQM.
2861 implements the FQ-PIE (FlowQueue-PIE) scheduler/AQM algorithm, which similar to
2863 but uses per sub-queue PIE AQM instance to control the queue delay.
2867 inherits AQM parameters and options from
2871 inherits AQM parameters and options from
2874 Additionally, both of
2878 have shared scheduler parameters which are:
2879 .Bl -tag -width indent
2882 specifies the quantum (credit) of the scheduler.
2884 is the number of bytes a queue can serve before being moved to the tail
2886 The default is 1514 bytes, and the maximum acceptable value
2890 specifies the hard size limit (in unit of packets) of all queues managed by an
2891 instance of the scheduler.
2892 The default value of
2894 is 10240 packets, and the maximum acceptable value is 20480 packets.
2897 specifies the total number of flow queues (sub-queues) that fq_*
2898 creates and manages.
2899 By default, 1024 sub-queues are created when an instance
2900 of the fq_{codel/pie} scheduler is created.
2901 The maximum acceptable value is
2905 Note that any token after
2909 is considered a parameter for fq_{codel/pie}.
2910 So, ensure all scheduler
2911 configuration options not related to fq_{codel/pie} are written before
2916 In addition to the type, all parameters allowed for a pipe can also
2917 be specified for a scheduler.
2919 Finally, the following parameters can be configured for both
2922 .Bl -tag -width XXXX -compact
2923 .It Cm buckets Ar hash-table-size
2924 Specifies the size of the hash table used for storing the
2926 Default value is 64 controlled by the
2929 .Va net.inet.ip.dummynet.hash_size ,
2930 allowed range is 16 to 65536.
2932 .It Cm mask Ar mask-specifier
2933 Packets sent to a given pipe or queue by an
2935 rule can be further classified into multiple flows, each of which is then
2939 A flow identifier is constructed by masking the IP addresses,
2940 ports and protocol types as specified with the
2942 options in the configuration of the pipe or queue.
2943 For each different flow identifier, a new pipe or queue is created
2944 with the same parameters as the original object, and matching packets
2949 are used, each flow will get the same bandwidth as defined by the pipe,
2952 are used, each flow will share the parent's pipe bandwidth evenly
2953 with other flows generated by the same queue (note that other queues
2954 with different weights might be connected to the same pipe).
2956 Available mask specifiers are a combination of one or more of the following:
2958 .Cm dst-ip Ar mask ,
2959 .Cm dst-ip6 Ar mask ,
2960 .Cm src-ip Ar mask ,
2961 .Cm src-ip6 Ar mask ,
2962 .Cm dst-port Ar mask ,
2963 .Cm src-port Ar mask ,
2964 .Cm flow-id Ar mask ,
2969 where the latter means all bits in all fields are significant.
2972 When a packet is dropped by a
2974 queue or pipe, the error
2975 is normally reported to the caller routine in the kernel, in the
2976 same way as it happens when a device queue fills up.
2978 option reports the packet as successfully delivered, which can be
2979 needed for some experimental setups where you want to simulate
2980 loss or congestion at a remote router.
2982 .It Cm plr Ar packet-loss-rate
2985 .Ar packet-loss-rate
2986 is a floating-point number between 0 and 1, with 0 meaning no
2987 loss, 1 meaning 100% loss.
2988 The loss rate is internally represented on 31 bits.
2990 .It Cm queue Brq Ar slots | size Ns Cm Kbytes
2995 Default value is 50 slots, which
2996 is the typical queue size for Ethernet devices.
2997 Note that for slow speed links you should keep the queue
2998 size short or your traffic might be affected by a significant
3000 E.g., 50 max-sized Ethernet packets (1500 bytes) mean 600Kbit
3001 or 20s of queue on a 30Kbit/s pipe.
3002 Even worse effects can result if you get packets from an
3003 interface with a much larger MTU, e.g.\& the loopback interface
3004 with its 16KB packets.
3008 .Em net.inet.ip.dummynet.pipe_byte_limit
3010 .Em net.inet.ip.dummynet.pipe_slot_limit
3011 control the maximum lengths that can be specified.
3013 .It Cm red | gred Ar w_q Ns / Ns Ar min_th Ns / Ns Ar max_th Ns / Ns Ar max_p
3015 Make use of the RED (Random Early Detection) queue management algorithm.
3020 point numbers between 0 and 1 (inclusive), while
3024 are integer numbers specifying thresholds for queue management
3025 (thresholds are computed in bytes if the queue has been defined
3026 in bytes, in slots otherwise).
3027 The two parameters can also be of the same value if needed.
3030 also supports the gentle RED variant (gred) and ECN (Explicit Congestion
3031 Notification) as optional.
3034 variables can be used to control the RED behaviour:
3035 .Bl -tag -width indent
3036 .It Va net.inet.ip.dummynet.red_lookup_depth
3037 specifies the accuracy in computing the average queue
3038 when the link is idle (defaults to 256, must be greater than zero)
3039 .It Va net.inet.ip.dummynet.red_avg_pkt_size
3040 specifies the expected average packet size (defaults to 512, must be
3042 .It Va net.inet.ip.dummynet.red_max_pkt_size
3043 specifies the expected maximum packet size, only used when queue
3044 thresholds are in bytes (defaults to 1500, must be greater than zero).
3047 .It Cm codel Oo Cm target Ar time Oc Oo Cm interval Ar time Oc Oo Cm ecn |
3049 Make use of the CoDel (Controlled-Delay) queue management algorithm.
3051 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
3052 microseconds (us) can be specified instead.
3053 CoDel drops or marks (ECN) packets
3054 depending on packet sojourn time in the queue.
3057 (5ms by default) is the minimum acceptable persistent queue delay that CoDel
3059 CoDel does not drop packets directly after packets sojourn time becomes
3066 (100ms default) before dropping.
3069 should be set to maximum RTT for all expected connections.
3071 enables (disabled by default) packet marking (instead of dropping) for
3072 ECN-enabled TCP flows when queue delay becomes high.
3074 Note that any token after
3076 is considered a parameter for CoDel.
3077 So, ensure all pipe/queue
3078 configuration options are written before
3085 .Va net.inet.ip.dummynet.codel.target
3087 .Va net.inet.ip.dummynet.codel.interval
3088 can be used to set CoDel default parameters.
3090 .It Cm pie Oo Cm target Ar time Oc Oo Cm tupdate Ar time Oc Oo
3091 .Cm alpha Ar n Oc Oo Cm beta Ar n Oc Oo Cm max_burst Ar time Oc Oo
3092 .Cm max_ecnth Ar n Oc Oo Cm ecn | Cm noecn Oc Oo Cm capdrop |
3093 .Cm nocapdrop Oc Oo Cm drand | Cm nodrand Oc Oo Cm onoff
3094 .Oc Oo Cm dre | Cm ts Oc
3095 Make use of the PIE (Proportional Integral controller Enhanced) queue management
3097 PIE drops or marks packets depending on a calculated drop probability during
3098 en-queue process, with the aim of achieving high throughput while keeping queue
3100 At regular time intervals of
3103 (15ms by default) a background process (re)calculates the probability based on queue delay
3107 (15ms by default) and queue delay trends.
3108 PIE approximates current queue
3109 delay by using a departure rate estimation method, or (optionally) by using a
3110 packet timestamp method similar to CoDel.
3112 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
3113 microseconds (us) can be specified instead.
3114 The other PIE parameters and options are as follows:
3115 .Bl -tag -width indent
3118 is a floating point number between 0 and 7 which specifies the weight of queue
3119 delay deviations that is used in drop probability calculation.
3120 0.125 is the default.
3123 is a floating point number between 0 and 7 which specifies is the weight of queue
3124 delay trend that is used in drop probability calculation.
3125 1.25 is the default.
3126 .It Cm max_burst Ar time
3127 The maximum period of time that PIE does not drop/mark packets.
3129 default and 10s is the maximum value.
3130 .It Cm max_ecnth Ar n
3131 Even when ECN is enabled, PIE drops packets instead of marking them when drop
3132 probability becomes higher than ECN probability threshold
3134 , the default is 0.1 (i.e 10%) and 1 is the maximum value.
3136 enable or disable ECN marking for ECN-enabled TCP flows.
3137 Disabled by default.
3138 .It Cm capdrop | nocapdrop
3139 enable or disable cap drop adjustment.
3140 Cap drop adjustment is enabled by default.
3141 .It Cm drand | nodrand
3142 enable or disable drop probability de-randomisation.
3143 De-randomisation eliminates
3144 the problem of dropping packets too close or too far.
3145 De-randomisation is enabled by default.
3147 enable turning PIE on and off depending on queue load.
3148 If this option is enabled,
3149 PIE turns on when over 1/3 of queue becomes full.
3150 This option is disabled by
3153 Calculate queue delay using departure rate estimation
3161 Note that any token after
3163 is considered a parameter for PIE.
3164 So ensure all pipe/queue
3165 the configuration options are written before
3169 variables can be used to control the
3173 .Sx SYSCTL VARIABLES
3174 section for more details.
3177 When used with IPv6 data,
3179 currently has several limitations.
3180 Information necessary to route link-local packets to an
3181 interface is not available after processing by
3183 so those packets are dropped in the output path.
3184 Care should be taken to ensure that link-local packets are not passed to
3187 Here are some important points to consider when designing your
3191 Remember that you filter both packets going
3195 Most connections need packets going in both directions.
3197 Remember to test very carefully.
3198 It is a good idea to be near the console when doing this.
3199 If you cannot be near the console,
3200 use an auto-recovery script such as the one in
3201 .Pa /usr/share/examples/ipfw/change_rules.sh .
3203 Do not forget the loopback interface.
3208 There are circumstances where fragmented datagrams are unconditionally
3210 TCP packets are dropped if they do not contain at least 20 bytes of
3211 TCP header, UDP packets are dropped if they do not contain a full 8
3212 byte UDP header, and ICMP packets are dropped if they do not contain
3213 4 bytes of ICMP header, enough to specify the ICMP type, code, and
3215 These packets are simply logged as
3217 since there may not be enough good data in the packet to produce a
3218 meaningful log entry.
3220 Another type of packet is unconditionally dropped, a TCP packet with a
3221 fragment offset of one.
3222 This is a valid packet, but it only has one use, to try
3223 to circumvent firewalls.
3224 When logging is enabled, these packets are
3225 reported as being dropped by rule -1.
3227 If you are logged in over a network, loading the
3231 is probably not as straightforward as you would think.
3232 The following command line is recommended:
3233 .Bd -literal -offset indent
3235 ipfw add 32000 allow ip from any to any
3238 Along the same lines, doing an
3239 .Bd -literal -offset indent
3243 in similar surroundings is also a bad idea.
3247 filter list may not be modified if the system security level
3248 is set to 3 or higher
3251 for information on system security levels).
3253 .Sh PACKET DIVERSION
3256 socket bound to the specified port will receive all packets
3257 diverted to that port.
3258 If no socket is bound to the destination port, or if the divert module is
3259 not loaded, or if the kernel was not compiled with divert socket support,
3260 the packets are dropped.
3261 .Sh NETWORK ADDRESS TRANSLATION (NAT)
3263 support in-kernel NAT using the kernel version of
3267 should be loaded or kernel should have
3268 .Cm options IPFIREWALL_NAT
3271 The nat configuration command is the following:
3272 .Bd -ragged -offset indent
3277 .Ar nat-configuration
3281 The following parameters can be configured:
3282 .Bl -tag -width indent
3283 .It Cm ip Ar ip_address
3284 Define an ip address to use for aliasing.
3286 Use ip address of NIC for aliasing, dynamically changing
3287 it if NIC's ip address changes.
3289 Enable logging on this nat instance.
3291 Deny any incoming connection from outside world.
3293 Try to leave the alias port numbers unchanged from
3294 the actual local port numbers.
3296 Traffic on the local network not originating from a RFC 1918
3297 unregistered address spaces will be ignored.
3299 Like unreg_only, but includes the RFC 6598 (Carrier Grade NAT)
3302 Reset table of the packet aliasing engine on address change.
3304 Reverse the way libalias handles aliasing.
3306 Obey transparent proxy rules only, packet aliasing is not performed.
3308 Skip instance in case of global state lookup (see below).
3309 .It Cm port_range Ar lower-upper
3310 Set the aliasing ports between the ranges given. Upper port has to be greater
3314 Some special values can be supplied instead of
3316 in nat rule actions:
3317 .Bl -tag -width indent
3319 Looks up translation state in all configured nat instances.
3320 If an entry is found, packet is aliased according to that entry.
3321 If no entry was found in any of the instances, packet is passed unchanged,
3322 and no new entry will be created.
3324 .Sx MULTIPLE INSTANCES
3327 for more information.
3329 Uses argument supplied in lookup table.
3332 section below for more information on lookup tables.
3335 To let the packet continue after being (de)aliased, set the sysctl variable
3336 .Va net.inet.ip.fw.one_pass
3338 For more information about aliasing modes, refer to
3342 for some examples of nat usage.
3343 .Ss REDIRECT AND LSNAT SUPPORT IN IPFW
3344 Redirect and LSNAT support follow closely the syntax used in
3348 for some examples on how to do redirect and lsnat.
3349 .Ss SCTP NAT SUPPORT
3350 SCTP nat can be configured in a similar manner to TCP through the
3353 The main difference is that
3355 does not do port translation.
3356 Since the local and global side ports will be the same,
3357 there is no need to specify both.
3358 Ports are redirected as follows:
3359 .Bd -ragged -offset indent
3365 .Cm redirect_port sctp
3366 .Ar ip_address [,addr_list] {[port | port-port] [,ports]}
3372 configuration can be done in real-time through the
3375 All may be changed dynamically, though the hash_table size will only
3380 .Sx SYSCTL VARIABLES
3382 .Sh IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
3383 .Ss Stateful translation
3385 supports in-kernel IPv6/IPv4 network address and protocol translation.
3386 Stateful NAT64 translation allows IPv6-only clients to contact IPv4 servers
3387 using unicast TCP, UDP or ICMP protocols.
3388 One or more IPv4 addresses assigned to a stateful NAT64 translator are shared
3389 among several IPv6-only clients.
3390 When stateful NAT64 is used in conjunction with DNS64, no changes are usually
3391 required in the IPv6 client or the IPv4 server.
3394 should be loaded or kernel should have
3395 .Cm options IPFIREWALL_NAT64
3396 to be able use stateful NAT64 translator.
3398 Stateful NAT64 uses a bunch of memory for several types of objects.
3399 When IPv6 client initiates connection, NAT64 translator creates a host entry
3400 in the states table.
3401 Each host entry uses preallocated IPv4 alias entry.
3402 Each alias entry has a number of ports group entries allocated on demand.
3403 Ports group entries contains connection state entries.
3404 There are several options to control limits and lifetime for these objects.
3406 NAT64 translator follows RFC7915 when does ICMPv6/ICMP translation,
3407 unsupported message types will be silently dropped.
3408 IPv6 needs several ICMPv6 message types to be explicitly allowed for correct
3410 Make sure that ND6 neighbor solicitation (ICMPv6 type 135) and neighbor
3411 advertisement (ICMPv6 type 136) messages will not be handled by translation
3414 After translation NAT64 translator by default sends packets through
3415 corresponding netisr queue.
3416 Thus translator host should be configured as IPv4 and IPv6 router.
3417 Also this means, that a packet is handled by firewall twice.
3418 First time an original packet is handled and consumed by translator,
3419 and then it is handled again as translated packet.
3420 This behavior can be changed by sysctl variable
3421 .Va net.inet.ip.fw.nat64_direct_output .
3422 Also translated packet can be tagged using
3424 rule action, and then matched by
3426 opcode to avoid loops and extra overhead.
3428 The stateful NAT64 configuration command is the following:
3429 .Bd -ragged -offset indent
3438 The following parameters can be configured:
3439 .Bl -tag -width indent
3440 .It Cm prefix4 Ar ipv4_prefix/plen
3441 The IPv4 prefix with mask defines the pool of IPv4 addresses used as
3442 source address after translation.
3443 Stateful NAT64 module translates IPv6 source address of client to one
3444 IPv4 address from this pool.
3445 Note that incoming IPv4 packets that don't have corresponding state entry
3446 in the states table will be dropped by translator.
3447 Make sure that translation rules handle packets, destined to configured prefix.
3448 .It Cm prefix6 Ar ipv6_prefix/length
3449 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3450 to represent IPv4 addresses.
3451 This IPv6 prefix should be configured in DNS64.
3452 The translator implementation follows RFC6052, that restricts the length of
3453 prefixes to one of following: 32, 40, 48, 56, 64, or 96.
3454 The Well-Known IPv6 Prefix 64:ff9b:: must be 96 bits long.
3457 prefix can be used to handle several IPv6 prefixes with one NAT64 instance.
3458 The NAT64 instance will determine a destination IPv4 address from prefix
3460 .It Cm states_chunks Ar number
3461 The number of states chunks in single ports group.
3462 Each ports group by default can keep 64 state entries in single chunk.
3463 The above value affects the maximum number of states that can be associated with single IPv4 alias address and port.
3464 The value must be power of 2, and up to 128.
3465 .It Cm host_del_age Ar seconds
3466 The number of seconds until the host entry for a IPv6 client will be deleted
3467 and all its resources will be released due to inactivity.
3470 .It Cm pg_del_age Ar seconds
3471 The number of seconds until a ports group with unused state entries will
3475 .It Cm tcp_syn_age Ar seconds
3476 The number of seconds while a state entry for TCP connection with only SYN
3478 If TCP connection establishing will not be finished,
3479 state entry will be deleted.
3482 .It Cm tcp_est_age Ar seconds
3483 The number of seconds while a state entry for established TCP connection
3487 .It Cm tcp_close_age Ar seconds
3488 The number of seconds while a state entry for closed TCP connection
3490 Keeping state entries for closed connections is needed, because IPv4 servers
3491 typically keep closed connections in a TIME_WAIT state for a several minutes.
3492 Since translator's IPv4 addresses are shared among all IPv6 clients,
3493 new connections from the same addresses and ports may be rejected by server,
3494 because these connections are still in a TIME_WAIT state.
3495 Keeping them in translator's state table protects from such rejects.
3498 .It Cm udp_age Ar seconds
3499 The number of seconds while translator keeps state entry in a waiting for
3500 reply to the sent UDP datagram.
3503 .It Cm icmp_age Ar seconds
3504 The number of seconds while translator keeps state entry in a waiting for
3505 reply to the sent ICMP message.
3509 Turn on logging of all handled packets via BPF through
3513 is a pseudo interface and can be created after a boot manually with
3516 Note that it has different purpose than
3519 Translators sends to BPF an additional information with each packet.
3522 you are able to see each handled packet before and after translation.
3524 Turn off logging of all handled packets via BPF.
3525 .It Cm allow_private
3526 Turn on processing private IPv4 addresses.
3527 By default IPv6 packets with destinations mapped to private address ranges
3528 defined by RFC1918 are not processed.
3529 .It Cm -allow_private
3530 Turn off private address handling in
3535 To inspect a states table of stateful NAT64 the following command can be used:
3536 .Bd -ragged -offset indent
3544 Stateless NAT64 translator doesn't use a states table for translation
3545 and converts IPv4 addresses to IPv6 and vice versa solely based on the
3546 mappings taken from configured lookup tables.
3547 Since a states table doesn't used by stateless translator,
3548 it can be configured to pass IPv4 clients to IPv6-only servers.
3550 The stateless NAT64 configuration command is the following:
3551 .Bd -ragged -offset indent
3560 The following parameters can be configured:
3561 .Bl -tag -width indent
3562 .It Cm prefix6 Ar ipv6_prefix/length
3563 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3564 to represent IPv4 addresses.
3565 This IPv6 prefix should be configured in DNS64.
3566 .It Cm table4 Ar table46
3569 contains mapping how IPv4 addresses should be translated to IPv6 addresses.
3570 .It Cm table6 Ar table64
3573 contains mapping how IPv6 addresses should be translated to IPv4 addresses.
3575 Turn on logging of all handled packets via BPF through
3579 Turn off logging of all handled packets via BPF.
3580 .It Cm allow_private
3581 Turn on processing private IPv4 addresses.
3582 By default IPv6 packets with destinations mapped to private address ranges
3583 defined by RFC1918 are not processed.
3584 .It Cm -allow_private
3585 Turn off private address handling in
3590 Note that the behavior of stateless translator with respect to not matched
3591 packets differs from stateful translator.
3592 If corresponding addresses was not found in the lookup tables, the packet
3593 will not be dropped and the search continues.
3594 .Ss XLAT464 CLAT translation
3595 XLAT464 CLAT NAT64 translator implements client-side stateless translation as
3596 defined in RFC6877 and is very similar to statless NAT64 translator
3598 Instead of lookup tables it uses one-to-one mapping between IPv4 and IPv6
3599 addresses using configured prefixes.
3600 This mode can be used as a replacement of DNS64 service for applications
3601 that are not using it (e.g. VoIP) allowing them to access IPv4-only Internet
3602 over IPv6-only networks with help of remote NAT64 translator.
3604 The CLAT NAT64 configuration command is the following:
3605 .Bd -ragged -offset indent
3614 The following parameters can be configured:
3615 .Bl -tag -width indent
3616 .It Cm clat_prefix Ar ipv6_prefix/length
3617 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3618 to represent source IPv4 addresses.
3619 .It Cm plat_prefix Ar ipv6_prefix/length
3620 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3621 to represent destination IPv4 addresses.
3622 This IPv6 prefix should be configured on a remote NAT64 translator.
3624 Turn on logging of all handled packets via BPF through
3628 Turn off logging of all handled packets via BPF.
3629 .It Cm allow_private
3630 Turn on processing private IPv4 addresses.
3633 instance will not process IPv4 packets with destination address from private
3634 ranges as defined in RFC1918.
3635 .It Cm -allow_private
3636 Turn off private address handling in
3641 Note that the behavior of CLAT translator with respect to not matched
3642 packets differs from stateful translator.
3643 If corresponding addresses were not matched against prefixes configured,
3644 the packet will not be dropped and the search continues.
3645 .Sh IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
3647 supports in-kernel IPv6-to-IPv6 network prefix translation as described
3651 should be loaded or kernel should has
3652 .Cm options IPFIREWALL_NPTV6
3653 to be able use NPTv6 translator.
3655 The NPTv6 configuration command is the following:
3656 .Bd -ragged -offset indent
3665 The following parameters can be configured:
3666 .Bl -tag -width indent
3667 .It Cm int_prefix Ar ipv6_prefix
3668 IPv6 prefix used in internal network.
3669 NPTv6 module translates source address when it matches this prefix.
3670 .It Cm ext_prefix Ar ipv6_prefix
3671 IPv6 prefix used in external network.
3672 NPTv6 module translates destination address when it matches this prefix.
3673 .It Cm ext_if Ar nic
3674 The NPTv6 module will use first global IPv6 address from interface
3677 It can be useful when IPv6 prefix of external network is dynamically obtained.
3681 options are mutually exclusive.
3682 .It Cm prefixlen Ar length
3683 The length of specified IPv6 prefixes.
3684 It must be in range from 8 to 64.
3687 Note that the prefix translation rules are silently ignored when IPv6 packet
3688 forwarding is disabled.
3689 To enable the packet forwarding, set the sysctl variable
3690 .Va net.inet6.ip6.forwarding
3693 To let the packet continue after being translated, set the sysctl variable
3694 .Va net.inet.ip.fw.one_pass
3697 Tunables can be set in
3703 before ipfw module gets loaded.
3704 .Bl -tag -width indent
3705 .It Va net.inet.ip.fw.default_to_accept : No 0
3706 Defines ipfw last rule behavior.
3707 This value overrides
3708 .Cd "options IPFW_DEFAULT_TO_(ACCEPT|DENY)"
3709 from kernel configuration file.
3710 .It Va net.inet.ip.fw.tables_max : No 128
3711 Defines number of tables available in ipfw.
3712 Number cannot exceed 65534.
3714 .Sh SYSCTL VARIABLES
3717 variables controls the behaviour of the firewall and
3719 .Pq Nm dummynet , bridge , sctp nat .
3720 These are shown below together with their default value
3721 (but always check with the
3723 command what value is actually in use) and meaning:
3724 .Bl -tag -width indent
3725 .It Va net.inet.ip.alias.sctp.accept_global_ootb_addip : No 0
3728 responds to receipt of global OOTB ASCONF-AddIP:
3729 .Bl -tag -width indent
3731 No response (unless a partially matching association exists -
3732 ports and vtags match but global address does not)
3735 will accept and process all OOTB global AddIP messages.
3738 Option 1 should never be selected as this forms a security risk.
3740 establish multiple fake associations by sending AddIP messages.
3741 .It Va net.inet.ip.alias.sctp.chunk_proc_limit : No 5
3742 Defines the maximum number of chunks in an SCTP packet that will be
3744 packet that matches an existing association.
3745 This value is enforced to be greater or equal than
3746 .Cm net.inet.ip.alias.sctp.initialising_chunk_proc_limit .
3748 a DoS risk yet setting too low a value may result in
3749 important control chunks in
3750 the packet not being located and parsed.
3751 .It Va net.inet.ip.alias.sctp.error_on_ootb : No 1
3754 responds to any Out-of-the-Blue (OOTB) packets with ErrorM packets.
3755 An OOTB packet is a packet that arrives with no existing association
3758 and is not an INIT or ASCONF-AddIP packet:
3759 .Bl -tag -width indent
3761 ErrorM is never sent in response to OOTB packets.
3763 ErrorM is only sent to OOTB packets received on the local side.
3765 ErrorM is sent to the local side and on the global side ONLY if there is a
3766 partial match (ports and vtags match but the source global IP does not).
3767 This value is only useful if the
3769 is tracking global IP addresses.
3771 ErrorM is sent in response to all OOTB packets on both
3772 the local and global side
3776 At the moment the default is 0, since the ErrorM packet is not yet
3777 supported by most SCTP stacks.
3778 When it is supported, and if not tracking
3779 global addresses, we recommend setting this value to 1 to allow
3780 multi-homed local hosts to function with the
3782 To track global addresses, we recommend setting this value to 2 to
3783 allow global hosts to be informed when they need to (re)send an
3785 Value 3 should never be chosen (except for debugging) as the
3787 will respond to all OOTB global packets (a DoS risk).
3788 .It Va net.inet.ip.alias.sctp.hashtable_size : No 2003
3789 Size of hash tables used for
3791 lookups (100 < prime_number > 1000001).
3794 size for any future created
3796 instance and therefore must be set prior to creating a
3799 The table sizes may be changed to suit specific needs.
3800 If there will be few
3801 concurrent associations, and memory is scarce, you may make these smaller.
3802 If there will be many thousands (or millions) of concurrent associations, you
3803 should make these larger.
3804 A prime number is best for the table size.
3806 update function will adjust your input value to the next highest prime number.
3807 .It Va net.inet.ip.alias.sctp.holddown_time : No 0
3808 Hold association in table for this many seconds after receiving a
3810 This allows endpoints to correct shutdown gracefully if a
3811 shutdown_complete is lost and retransmissions are required.
3812 .It Va net.inet.ip.alias.sctp.init_timer : No 15
3813 Timeout value while waiting for (INIT-ACK|AddIP-ACK).
3814 This value cannot be 0.
3815 .It Va net.inet.ip.alias.sctp.initialising_chunk_proc_limit : No 2
3816 Defines the maximum number of chunks in an SCTP packet that will be parsed when
3817 no existing association exists that matches that packet.
3819 will only be an INIT or ASCONF-AddIP packet.
3820 A higher value may become a DoS
3821 risk as malformed packets can consume processing resources.
3822 .It Va net.inet.ip.alias.sctp.param_proc_limit : No 25
3823 Defines the maximum number of parameters within a chunk that will be
3826 As for other similar sysctl variables, larger values pose a DoS risk.
3827 .It Va net.inet.ip.alias.sctp.log_level : No 0
3828 Level of detail in the system log messages (0 \- minimal, 1 \- event,
3829 2 \- info, 3 \- detail, 4 \- debug, 5 \- max debug).
3831 option in high loss environments.
3832 .It Va net.inet.ip.alias.sctp.shutdown_time : No 15
3833 Timeout value while waiting for SHUTDOWN-COMPLETE.
3834 This value cannot be 0.
3835 .It Va net.inet.ip.alias.sctp.track_global_addresses : No 0
3836 Enables/disables global IP address tracking within the
3839 upper limit on the number of addresses tracked for each association:
3840 .Bl -tag -width indent
3842 Global tracking is disabled
3844 Enables tracking, the maximum number of addresses tracked for each
3845 association is limited to this value
3848 This variable is fully dynamic, the new value will be adopted for all newly
3849 arriving associations, existing associations are treated
3850 as they were previously.
3851 Global tracking will decrease the number of collisions within the
3854 of increased processing load, memory usage, complexity, and possible
3857 problems in complex networks with multiple
3859 We recommend not tracking
3860 global IP addresses, this will still result in a fully functional
3862 .It Va net.inet.ip.alias.sctp.up_timer : No 300
3863 Timeout value to keep an association up with no traffic.
3864 This value cannot be 0.
3865 .It Va net.inet.ip.dummynet.codel.interval : No 100000
3868 AQM interval in microseconds.
3869 The value must be in the range 1..5000000.
3870 .It Va net.inet.ip.dummynet.codel.target : No 5000
3873 AQM target delay time in microseconds (the minimum acceptable persistent queue
3875 The value must be in the range 1..5000000.
3876 .It Va net.inet.ip.dummynet.expire : No 1
3877 Lazily delete dynamic pipes/queue once they have no pending traffic.
3878 You can disable this by setting the variable to 0, in which case
3879 the pipes/queues will only be deleted when the threshold is reached.
3880 .It Va net.inet.ip.dummynet.fqcodel.flows : No 1024
3881 Defines the default total number of flow queues (sub-queues) that
3883 creates and manages.
3884 The value must be in the range 1..65536.
3885 .It Va net.inet.ip.dummynet.fqcodel.interval : No 100000
3888 scheduler/AQM interval in microseconds.
3889 The value must be in the range 1..5000000.
3890 .It Va net.inet.ip.dummynet.fqcodel.limit : No 10240
3891 The default hard size limit (in unit of packet) of all queues managed by an
3895 The value must be in the range 1..20480.
3896 .It Va net.inet.ip.dummynet.fqcodel.quantum : No 1514
3897 The default quantum (credit) of the
3900 The value must be in the range 1..9000.
3901 .It Va net.inet.ip.dummynet.fqcodel.target : No 5000
3904 scheduler/AQM target delay time in microseconds (the minimum acceptable
3905 persistent queue delay).
3906 The value must be in the range 1..5000000.
3907 .It Va net.inet.ip.dummynet.fqpie.alpha : No 125
3910 parameter (scaled by 1000) for
3913 The value must be in the range 1..7000.
3914 .It Va net.inet.ip.dummynet.fqpie.beta : No 1250
3917 parameter (scaled by 1000) for
3920 The value must be in the range 1..7000.
3921 .It Va net.inet.ip.dummynet.fqpie.flows : No 1024
3922 Defines the default total number of flow queues (sub-queues) that
3924 creates and manages.
3925 The value must be in the range 1..65536.
3926 .It Va net.inet.ip.dummynet.fqpie.limit : No 10240
3927 The default hard size limit (in unit of packet) of all queues managed by an
3931 The value must be in the range 1..20480.
3932 .It Va net.inet.ip.dummynet.fqpie.max_burst : No 150000
3933 The default maximum period of microseconds that
3935 scheduler/AQM does not drop/mark packets.
3936 The value must be in the range 1..10000000.
3937 .It Va net.inet.ip.dummynet.fqpie.max_ecnth : No 99
3938 The default maximum ECN probability threshold (scaled by 1000) for
3941 The value must be in the range 1..7000.
3942 .It Va net.inet.ip.dummynet.fqpie.quantum : No 1514
3943 The default quantum (credit) of the
3946 The value must be in the range 1..9000.
3947 .It Va net.inet.ip.dummynet.fqpie.target : No 15000
3952 in unit of microsecond.
3953 The value must be in the range 1..5000000.
3954 .It Va net.inet.ip.dummynet.fqpie.tupdate : No 15000
3959 in unit of microsecond.
3960 The value must be in the range 1..5000000.
3961 .It Va net.inet.ip.dummynet.hash_size : No 64
3962 Default size of the hash table used for dynamic pipes/queues.
3963 This value is used when no
3965 option is specified when configuring a pipe/queue.
3966 .It Va net.inet.ip.dummynet.io_fast : No 0
3967 If set to a non-zero value,
3972 operation (see above) is enabled.
3973 .It Va net.inet.ip.dummynet.io_pkt
3974 Number of packets passed to
3976 .It Va net.inet.ip.dummynet.io_pkt_drop
3977 Number of packets dropped by
3979 .It Va net.inet.ip.dummynet.io_pkt_fast
3980 Number of packets bypassed by the
3983 .It Va net.inet.ip.dummynet.max_chain_len : No 16
3984 Target value for the maximum number of pipes/queues in a hash bucket.
3986 .Cm max_chain_len*hash_size
3987 is used to determine the threshold over which empty pipes/queues
3988 will be expired even when
3989 .Cm net.inet.ip.dummynet.expire=0 .
3990 .It Va net.inet.ip.dummynet.red_lookup_depth : No 256
3991 .It Va net.inet.ip.dummynet.red_avg_pkt_size : No 512
3992 .It Va net.inet.ip.dummynet.red_max_pkt_size : No 1500
3993 Parameters used in the computations of the drop probability
3994 for the RED algorithm.
3995 .It Va net.inet.ip.dummynet.pie.alpha : No 125
3998 parameter (scaled by 1000) for
4001 The value must be in the range 1..7000.
4002 .It Va net.inet.ip.dummynet.pie.beta : No 1250
4005 parameter (scaled by 1000) for
4008 The value must be in the range 1..7000.
4009 .It Va net.inet.ip.dummynet.pie.max_burst : No 150000
4010 The default maximum period of microseconds that
4012 AQM does not drop/mark packets.
4013 The value must be in the range 1..10000000.
4014 .It Va net.inet.ip.dummynet.pie.max_ecnth : No 99
4015 The default maximum ECN probability threshold (scaled by 1000) for
4018 The value must be in the range 1..7000.
4019 .It Va net.inet.ip.dummynet.pie.target : No 15000
4024 AQM in unit of microsecond.
4025 The value must be in the range 1..5000000.
4026 .It Va net.inet.ip.dummynet.pie.tupdate : No 15000
4031 AQM in unit of microsecond.
4032 The value must be in the range 1..5000000.
4033 .It Va net.inet.ip.dummynet.pipe_byte_limit : No 1048576
4034 .It Va net.inet.ip.dummynet.pipe_slot_limit : No 100
4035 The maximum queue size that can be specified in bytes or packets.
4036 These limits prevent accidental exhaustion of resources such as mbufs.
4037 If you raise these limits,
4038 you should make sure the system is configured so that sufficient resources
4040 .It Va net.inet.ip.fw.autoinc_step : No 100
4041 Delta between rule numbers when auto-generating them.
4042 The value must be in the range 1..1000.
4043 .It Va net.inet.ip.fw.curr_dyn_buckets : Va net.inet.ip.fw.dyn_buckets
4044 The current number of buckets in the hash table for dynamic rules
4046 .It Va net.inet.ip.fw.debug : No 1
4047 Controls debugging messages produced by
4049 .It Va net.inet.ip.fw.default_rule : No 65535
4050 The default rule number (read-only).
4052 .Nm , the default rule is the last one, so its number
4053 can also serve as the highest number allowed for a rule.
4054 .It Va net.inet.ip.fw.dyn_buckets : No 256
4055 The number of buckets in the hash table for dynamic rules.
4056 Must be a power of 2, up to 65536.
4057 It only takes effect when all dynamic rules have expired, so you
4058 are advised to use a
4060 command to make sure that the hash table is resized.
4061 .It Va net.inet.ip.fw.dyn_count : No 3
4062 Current number of dynamic rules
4064 .It Va net.inet.ip.fw.dyn_keepalive : No 1
4065 Enables generation of keepalive packets for
4067 rules on TCP sessions.
4068 A keepalive is generated to both
4069 sides of the connection every 5 seconds for the last 20
4070 seconds of the lifetime of the rule.
4071 .It Va net.inet.ip.fw.dyn_max : No 8192
4072 Maximum number of dynamic rules.
4073 When you hit this limit, no more dynamic rules can be
4074 installed until old ones expire.
4075 .It Va net.inet.ip.fw.dyn_ack_lifetime : No 300
4076 .It Va net.inet.ip.fw.dyn_syn_lifetime : No 20
4077 .It Va net.inet.ip.fw.dyn_fin_lifetime : No 1
4078 .It Va net.inet.ip.fw.dyn_rst_lifetime : No 1
4079 .It Va net.inet.ip.fw.dyn_udp_lifetime : No 5
4080 .It Va net.inet.ip.fw.dyn_short_lifetime : No 30
4081 These variables control the lifetime, in seconds, of dynamic
4083 Upon the initial SYN exchange the lifetime is kept short,
4084 then increased after both SYN have been seen, then decreased
4085 again during the final FIN exchange or when a RST is received.
4087 .Em dyn_fin_lifetime
4089 .Em dyn_rst_lifetime
4090 must be strictly lower than 5 seconds, the period of
4091 repetition of keepalives.
4092 The firewall enforces that.
4093 .It Va net.inet.ip.fw.dyn_keep_states : No 0
4094 Keep dynamic states on rule/set deletion.
4095 States are relinked to default rule (65535).
4096 This can be handly for ruleset reload.
4097 Turned off by default.
4098 .It Va net.inet.ip.fw.enable : No 1
4099 Enables the firewall.
4100 Setting this variable to 0 lets you run your machine without
4101 firewall even if compiled in.
4102 .It Va net.inet6.ip6.fw.enable : No 1
4103 provides the same functionality as above for the IPv6 case.
4104 .It Va net.inet.ip.fw.one_pass : No 1
4105 When set, the packet exiting from the
4109 node is not passed though the firewall again.
4110 Otherwise, after an action, the packet is
4111 reinjected into the firewall at the next rule.
4112 .It Va net.inet.ip.fw.tables_max : No 128
4113 Maximum number of tables.
4114 .It Va net.inet.ip.fw.verbose : No 1
4115 Enables verbose messages.
4116 .It Va net.inet.ip.fw.verbose_limit : No 0
4117 Limits the number of messages produced by a verbose firewall.
4118 .It Va net.inet6.ip6.fw.deny_unknown_exthdrs : No 1
4119 If enabled packets with unknown IPv6 Extension Headers will be denied.
4120 .It Va net.link.ether.ipfw : No 0
4121 Controls whether layer2 packets are passed to
4124 .It Va net.link.bridge.ipfw : No 0
4125 Controls whether bridged packets are passed to
4128 .It Va net.inet.ip.fw.nat64_debug : No 0
4129 Controls debugging messages produced by
4132 .It Va net.inet.ip.fw.nat64_direct_output : No 0
4133 Controls the output method used by
4136 .Bl -tag -width indent
4138 A packet is handled by
4141 First time an original packet is handled by
4146 Then translated packet is queued via netisr to input processing again.
4148 A packet is handled by
4150 only once, and after translation it will be pushed directly to outgoing
4154 .Sh INTERNAL DIAGNOSTICS
4155 There are some commands that may be useful to understand current state
4156 of certain subsystems inside kernel module.
4157 These commands provide debugging output which may change without notice.
4159 Currently the following commands are available as
4162 .Bl -tag -width indent
4164 Lists all interface which are currently tracked by
4166 with their in-kernel status.
4168 List all table lookup algorithms currently available.
4171 There are far too many possible uses of
4173 so this Section will only give a small set of examples.
4174 .Ss BASIC PACKET FILTERING
4175 This command adds an entry which denies all tcp packets from
4176 .Em cracker.evil.org
4177 to the telnet port of
4179 from being forwarded by the host:
4181 .Dl "ipfw add deny tcp from cracker.evil.org to wolf.tambov.su telnet"
4183 This one disallows any connection from the entire cracker's
4186 .Dl "ipfw add deny ip from 123.45.67.0/24 to my.host.org"
4188 A first and efficient way to limit access (not using dynamic rules)
4189 is the use of the following rules:
4191 .Dl "ipfw add allow tcp from any to any established"
4192 .Dl "ipfw add allow tcp from net1 portlist1 to net2 portlist2 setup"
4193 .Dl "ipfw add allow tcp from net3 portlist3 to net3 portlist3 setup"
4195 .Dl "ipfw add deny tcp from any to any"
4197 The first rule will be a quick match for normal TCP packets,
4198 but it will not match the initial SYN packet, which will be
4201 rules only for selected source/destination pairs.
4202 All other SYN packets will be rejected by the final
4206 If you administer one or more subnets, you can take advantage
4207 of the address sets and or-blocks and write extremely
4208 compact rulesets which selectively enable services to blocks
4209 of clients, as below:
4211 .Dl "goodguys=\*q{ 10.1.2.0/24{20,35,66,18} or 10.2.3.0/28{6,3,11} }\*q"
4212 .Dl "badguys=\*q10.1.2.0/24{8,38,60}\*q"
4214 .Dl "ipfw add allow ip from ${goodguys} to any"
4215 .Dl "ipfw add deny ip from ${badguys} to any"
4216 .Dl "... normal policies ..."
4220 option could be used to do automated anti-spoofing by adding the
4221 following to the top of a ruleset:
4223 .Dl "ipfw add deny ip from any to any not verrevpath in"
4225 This rule drops all incoming packets that appear to be coming to the
4226 system on the wrong interface.
4227 For example, a packet with a source
4228 address belonging to a host on a protected internal network would be
4229 dropped if it tried to enter the system from an external interface.
4233 option could be used to do similar but more restricted anti-spoofing
4234 by adding the following to the top of a ruleset:
4236 .Dl "ipfw add deny ip from any to any not antispoof in"
4238 This rule drops all incoming packets that appear to be coming from another
4239 directly connected system but on the wrong interface.
4240 For example, a packet with a source address of
4241 .Li 192.168.0.0/24 ,
4250 option could be used to (re)mark user traffic,
4251 by adding the following to the appropriate place in ruleset:
4253 .Dl "ipfw add setdscp be ip from any to any dscp af11,af21"
4254 .Ss SELECTIVE MIRRORING
4255 If your network has network traffic analyzer
4256 connected to your host directly via dedicated interface
4257 or remotely via RSPAN vlan, you can selectively mirror
4258 some Ethernet layer2 frames to the analyzer.
4260 First, make sure your firewall is already configured and runs.
4261 Then, enable layer2 processing if not already enabled:
4263 .Dl "sysctl net.link.ether.ipfw=1"
4265 Next, load needed additional kernel modules:
4267 .Dl "kldload ng_ether ng_ipfw"
4269 Optionally, make system load these modules automatically
4272 .Dl sysrc kld_list+="ng_ether ng_ipfw"
4276 kernel module to transmit mirrored copies of layer2 frames
4277 out via vlan900 interface:
4279 .Dl "ngctl connect ipfw: vlan900: 1 lower"
4281 Think of "1" here as of "mirroring instance index" and vlan900 is its
4283 You can have arbitrary number of instances.
4288 At last, actually start mirroring of selected frames using "instance 1".
4289 For frames incoming from em0 interface:
4291 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 in recv em0"
4293 For frames outgoing to em0 interface:
4295 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 out xmit em0"
4297 For both incoming and outgoing frames while flowing through em0:
4299 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 via em0"
4301 Make sure you do not perform mirroring for already duplicated frames
4302 or kernel may hang as there is no safety net.
4304 In order to protect a site from flood attacks involving fake
4305 TCP packets, it is safer to use dynamic rules:
4307 .Dl "ipfw add check-state"
4308 .Dl "ipfw add deny tcp from any to any established"
4309 .Dl "ipfw add allow tcp from my-net to any setup keep-state"
4311 This will let the firewall install dynamic rules only for
4312 those connection which start with a regular SYN packet coming
4313 from the inside of our network.
4314 Dynamic rules are checked when encountering the first
4323 rule should usually be placed near the beginning of the
4324 ruleset to minimize the amount of work scanning the ruleset.
4325 Your mileage may vary.
4327 For more complex scenarios with dynamic rules
4331 can be used to precisely control creation and checking of dynamic rules.
4332 Example of usage of these options are provided in
4333 .Sx NETWORK ADDRESS TRANSLATION (NAT)
4336 To limit the number of connections a user can open
4337 you can use the following type of rules:
4339 .Dl "ipfw add allow tcp from my-net/24 to any setup limit src-addr 10"
4340 .Dl "ipfw add allow tcp from any to me setup limit src-addr 4"
4342 The former (assuming it runs on a gateway) will allow each host
4343 on a /24 network to open at most 10 TCP connections.
4344 The latter can be placed on a server to make sure that a single
4345 client does not use more than 4 simultaneous connections.
4348 stateful rules can be subject to denial-of-service attacks
4349 by a SYN-flood which opens a huge number of dynamic rules.
4350 The effects of such attacks can be partially limited by
4353 variables which control the operation of the firewall.
4355 Here is a good usage of the
4357 command to see accounting records and timestamp information:
4361 or in short form without timestamps:
4365 which is equivalent to:
4369 Next rule diverts all incoming packets from 192.168.2.0/24
4370 to divert port 5000:
4372 .Dl ipfw divert 5000 ip from 192.168.2.0/24 to any in
4374 The following rules show some of the applications of
4378 for simulations and the like.
4380 This rule drops random incoming packets with a probability
4383 .Dl "ipfw add prob 0.05 deny ip from any to any in"
4385 A similar effect can be achieved making use of
4389 .Dl "dnctl add pipe 10 ip from any to any"
4390 .Dl "dnctl pipe 10 config plr 0.05"
4392 We can use pipes to artificially limit bandwidth, e.g.\& on a
4393 machine acting as a router, if we want to limit traffic from
4394 local clients on 192.168.2.0/24 we do:
4396 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4397 .Dl "dnctl pipe 1 config bw 300Kbit/s queue 50KBytes"
4399 note that we use the
4401 modifier so that the rule is not used twice.
4402 Remember in fact that
4404 rules are checked both on incoming and outgoing packets.
4406 Should we want to simulate a bidirectional link with bandwidth
4407 limitations, the correct way is the following:
4409 .Dl "ipfw add pipe 1 ip from any to any out"
4410 .Dl "ipfw add pipe 2 ip from any to any in"
4411 .Dl "dnctl pipe 1 config bw 64Kbit/s queue 10Kbytes"
4412 .Dl "dnctl pipe 2 config bw 64Kbit/s queue 10Kbytes"
4414 The above can be very useful, e.g.\& if you want to see how
4415 your fancy Web page will look for a residential user who
4416 is connected only through a slow link.
4417 You should not use only one pipe for both directions, unless
4418 you want to simulate a half-duplex medium (e.g.\& AppleTalk,
4420 It is not necessary that both pipes have the same configuration,
4421 so we can also simulate asymmetric links.
4423 Should we want to verify network performance with the RED queue
4424 management algorithm:
4426 .Dl "ipfw add pipe 1 ip from any to any"
4427 .Dl "dnctl pipe 1 config bw 500Kbit/s queue 100 red 0.002/30/80/0.1"
4429 Another typical application of the traffic shaper is to
4430 introduce some delay in the communication.
4431 This can significantly affect applications which do a lot of Remote
4432 Procedure Calls, and where the round-trip-time of the
4433 connection often becomes a limiting factor much more than
4436 .Dl "ipfw add pipe 1 ip from any to any out"
4437 .Dl "ipfw add pipe 2 ip from any to any in"
4438 .Dl "dnctl pipe 1 config delay 250ms bw 1Mbit/s"
4439 .Dl "dnctl pipe 2 config delay 250ms bw 1Mbit/s"
4441 Per-flow queueing can be useful for a variety of purposes.
4442 A very simple one is counting traffic:
4444 .Dl "ipfw add pipe 1 tcp from any to any"
4445 .Dl "ipfw add pipe 1 udp from any to any"
4446 .Dl "ipfw add pipe 1 ip from any to any"
4447 .Dl "dnctl pipe 1 config mask all"
4449 The above set of rules will create queues (and collect
4450 statistics) for all traffic.
4451 Because the pipes have no limitations, the only effect is
4452 collecting statistics.
4453 Note that we need 3 rules, not just the last one, because
4456 tries to match IP packets it will not consider ports, so we
4457 would not see connections on separate ports as different
4460 A more sophisticated example is limiting the outbound traffic
4461 on a net with per-host limits, rather than per-network limits:
4463 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4464 .Dl "ipfw add pipe 2 ip from any to 192.168.2.0/24 in"
4465 .Dl "dnctl pipe 1 config mask src-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4466 .Dl "dnctl pipe 2 config mask dst-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4468 In the following example, we need to create several traffic bandwidth
4469 classes and we need different hosts/networks to fall into different classes.
4470 We create one pipe for each class and configure them accordingly.
4471 Then we create a single table and fill it with IP subnets and addresses.
4472 For each subnet/host we set the argument equal to the number of the pipe
4474 Then we classify traffic using a single rule:
4476 .Dl "dnctl pipe 1 config bw 1000Kbyte/s"
4477 .Dl "dnctl pipe 4 config bw 4000Kbyte/s"
4479 .Dl "ipfw table T1 create type addr"
4480 .Dl "ipfw table T1 add 192.168.2.0/24 1"
4481 .Dl "ipfw table T1 add 192.168.0.0/27 4"
4482 .Dl "ipfw table T1 add 192.168.0.2 1"
4484 .Dl "ipfw add pipe tablearg ip from 'table(T1)' to any"
4488 action, the table entries may include hostnames and IP addresses.
4490 .Dl "ipfw table T2 create type addr valtype ipv4"
4491 .Dl "ipfw table T2 add 192.168.2.0/24 10.23.2.1"
4492 .Dl "ipfw table T2 add 192.168.0.0/27 router1.dmz"
4494 .Dl "ipfw add 100 fwd tablearg ip from any to 'table(T2)'"
4496 In the following example per-interface firewall is created:
4498 .Dl "ipfw table IN create type iface valtype skipto,fib"
4499 .Dl "ipfw table IN add vlan20 12000,12"
4500 .Dl "ipfw table IN add vlan30 13000,13"
4501 .Dl "ipfw table OUT create type iface valtype skipto"
4502 .Dl "ipfw table OUT add vlan20 22000"
4503 .Dl "ipfw table OUT add vlan30 23000"
4505 .Dl "ipfw add 100 setfib tablearg ip from any to any recv 'table(IN)' in"
4506 .Dl "ipfw add 200 skipto tablearg ip from any to any recv 'table(IN)' in"
4507 .Dl "ipfw add 300 skipto tablearg ip from any to any xmit 'table(OUT)' out"
4509 The following example illustrate usage of flow tables:
4511 .Dl "ipfw table fl create type flow:src-ip,proto,dst-ip,dst-port"
4512 .Dl "ipfw table fl add 2a02:6b8:77::88,tcp,2a02:6b8:77::99,80 11"
4513 .Dl "ipfw table fl add 10.0.0.1,udp,10.0.0.2,53 12"
4515 .Dl "ipfw add 100 allow ip from any to any flow 'table(fl,11)' recv ix0"
4517 To add a set of rules atomically, e.g.\& set 18:
4519 .Dl "ipfw set disable 18"
4520 .Dl "ipfw add NN set 18 ... # repeat as needed"
4521 .Dl "ipfw set enable 18"
4523 To delete a set of rules atomically the command is simply:
4525 .Dl "ipfw delete set 18"
4527 To test a ruleset and disable it and regain control if something goes wrong:
4529 .Dl "ipfw set disable 18"
4530 .Dl "ipfw add NN set 18 ... # repeat as needed"
4531 .Dl "ipfw set enable 18; echo done; sleep 30 && ipfw set disable 18"
4533 Here if everything goes well, you press control-C before the "sleep"
4534 terminates, and your ruleset will be left active.
4535 Otherwise, e.g.\& if
4536 you cannot access your box, the ruleset will be disabled after
4537 the sleep terminates thus restoring the previous situation.
4539 To show rules of the specific set:
4541 .Dl "ipfw set 18 show"
4543 To show rules of the disabled set:
4545 .Dl "ipfw -S set 18 show"
4547 To clear a specific rule counters of the specific set:
4549 .Dl "ipfw set 18 zero NN"
4551 To delete a specific rule of the specific set:
4553 .Dl "ipfw set 18 delete NN"
4554 .Ss NAT, REDIRECT AND LSNAT
4555 First redirect all the traffic to nat instance 123:
4557 .Dl "ipfw add nat 123 all from any to any"
4559 Then to configure nat instance 123 to alias all the outgoing traffic with ip
4560 192.168.0.123, blocking all incoming connections, trying to keep
4561 same ports on both sides, clearing aliasing table on address change
4562 and keeping a log of traffic/link statistics:
4564 .Dl "ipfw nat 123 config ip 192.168.0.123 log deny_in reset same_ports"
4566 Or to change address of instance 123, aliasing table will be cleared (see
4569 .Dl "ipfw nat 123 config ip 10.0.0.1"
4571 To see configuration of nat instance 123:
4573 .Dl "ipfw nat 123 show config"
4575 To show logs of all instances:
4577 .Dl "ipfw nat show log"
4579 To see configurations of all instances:
4581 .Dl "ipfw nat show config"
4583 Or a redirect rule with mixed modes could looks like:
4584 .Bd -literal -offset 2n
4585 ipfw nat 123 config redirect_addr 10.0.0.1 10.0.0.66
4586 redirect_port tcp 192.168.0.1:80 500
4587 redirect_proto udp 192.168.1.43 192.168.1.1
4588 redirect_addr 192.168.0.10,192.168.0.11
4590 redirect_port tcp 192.168.0.1:80,192.168.0.10:22
4594 or it could be split in:
4595 .Bd -literal -offset 2n
4596 ipfw nat 1 config redirect_addr 10.0.0.1 10.0.0.66
4597 ipfw nat 2 config redirect_port tcp 192.168.0.1:80 500
4598 ipfw nat 3 config redirect_proto udp 192.168.1.43 192.168.1.1
4599 ipfw nat 4 config redirect_addr 192.168.0.10,192.168.0.11,192.168.0.12
4601 ipfw nat 5 config redirect_port tcp
4602 192.168.0.1:80,192.168.0.10:22,192.168.0.20:25 500
4605 Sometimes you may want to mix NAT and dynamic rules.
4606 It could be achieved with
4611 Problem is, you need to create dynamic rule before NAT and check it
4612 after NAT actions (or vice versa) to have consistent addresses and ports.
4615 option will trigger activation of existing dynamic state, and action of such
4616 rule will be performed as soon as rule is matched.
4619 rule packet need to be passed to NAT, not allowed as soon is possible.
4621 There is example of set of rules to achieve this.
4622 Bear in mind that this is example only and it is not very useful by itself.
4624 On way out, after all checks place this rules:
4626 .Dl "ipfw add allow record-state skip-action"
4627 .Dl "ipfw add nat 1"
4629 And on way in there should be something like this:
4631 .Dl "ipfw add nat 1"
4632 .Dl "ipfw add check-state"
4634 Please note, that first rule on way out doesn't allow packet and doesn't
4635 execute existing dynamic rules.
4636 All it does, create new dynamic rule with
4638 action, if it is not created yet.
4639 Later, this dynamic rule is used on way in by
4642 .Ss CONFIGURING CODEL, PIE, FQ-CODEL and FQ-PIE AQM
4646 AQM can be configured for
4656 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4659 .Dl "dnctl pipe 1 config bw 1mbits/s codel"
4660 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4666 AQM using different configurations parameters for traffic from
4667 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4669 .Dl "dnctl pipe 1 config bw 1mbits/s"
4670 .Dl "dnctl queue 1 config pipe 1 codel target 8ms interval 160ms ecn"
4671 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4677 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4680 .Dl "dnctl pipe 1 config bw 1mbits/s pie"
4681 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4687 AQM using different configuration parameters for traffic from
4688 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4690 .Dl "dnctl pipe 1 config bw 1mbits/s"
4691 .Dl "dnctl queue 1 config pipe 1 pie target 20ms tupdate 30ms ecn"
4692 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4697 AQM can be configured for
4703 scheduler using different configurations parameters for traffic from
4704 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4706 .Dl "dnctl pipe 1 config bw 1mbits/s"
4707 .Dl "dnctl sched 1 config pipe 1 type fq_codel"
4708 .Dl "dnctl queue 1 config sched 1"
4709 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4713 default configuration for a
4715 such as disable ECN and change the
4719 .Dl "dnctl sched 1 config pipe 1 type fq_codel target 10ms noecn"
4725 scheduler using different configurations parameters for traffic from
4726 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4728 .Dl "dnctl pipe 1 config bw 1mbits/s"
4729 .Dl "dnctl sched 1 config pipe 1 type fq_pie"
4730 .Dl "dnctl queue 1 config sched 1"
4731 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4733 The configurations of
4736 can be changed in a similar way as for
4760 utility first appeared in
4765 Stateful extensions were introduced in
4768 was introduced in Summer 2002.
4770 .An Ugen J. S. Antsilevich ,
4771 .An Poul-Henning Kamp ,
4775 .An Rasool Al-Saadi .
4778 API based upon code written by
4782 Dummynet has been introduced by Luigi Rizzo in 1997-1998.
4784 Some early work (1999-2000) on the
4786 traffic shaper supported by Akamba Corp.
4788 The ipfw core (ipfw2) has been completely redesigned and
4789 reimplemented by Luigi Rizzo in summer 2002.
4792 options have been added by various developers over the years.
4795 In-kernel NAT support written by
4796 .An Paolo Pisati Aq Mt piso@FreeBSD.org
4797 as part of a Summer of Code 2005 project.
4801 support has been developed by
4802 .An The Centre for Advanced Internet Architectures (CAIA) Aq http://www.caia.swin.edu.au .
4803 The primary developers and maintainers are David Hayes and Jason But.
4804 For further information visit:
4805 .Aq http://www.caia.swin.edu.au/urp/SONATA
4807 Delay profiles have been developed by Alessandro Cerri and
4808 Luigi Rizzo, supported by the
4809 European Commission within Projects Onelab and Onelab2.
4811 CoDel, PIE, FQ-CoDel and FQ-PIE AQM for Dummynet have been implemented by
4812 .An The Centre for Advanced Internet Architectures (CAIA)
4813 in 2016, supported by The Comcast Innovation Fund.
4814 The primary developer is
4817 The syntax has grown over the years and sometimes it might be confusing.
4818 Unfortunately, backward compatibility prevents cleaning up mistakes
4819 made in the definition of the syntax.
4823 Misconfiguring the firewall can put your computer in an unusable state,
4824 possibly shutting down network services and requiring console access to
4825 regain control of it.
4827 Incoming packet fragments diverted by
4829 are reassembled before delivery to the socket.
4830 The action used on those packet is the one from the
4831 rule which matches the first fragment of the packet.
4833 Packets diverted to userland, and then reinserted by a userland process
4834 may lose various packet attributes.
4835 The packet source interface name
4836 will be preserved if it is shorter than 8 bytes and the userland process
4837 saves and reuses the sockaddr_in
4840 otherwise, it may be lost.
4841 If a packet is reinserted in this manner, later rules may be incorrectly
4842 applied, making the order of
4844 rules in the rule sequence very important.
4846 Dummynet drops all packets with IPv6 link-local addresses.
4852 may not behave as expected.
4853 In particular, incoming SYN packets may
4854 have no uid or gid associated with them since they do not yet belong
4855 to a TCP connection, and the uid/gid associated with a packet may not
4856 be as expected if the associated process calls
4858 or similar system calls.
4860 Rule syntax is subject to the command line environment and some patterns
4861 may need to be escaped with the backslash character
4862 or quoted appropriately.
4864 Due to the architecture of
4866 ipfw nat is not compatible with the TCP segmentation offloading (TSO).
4867 Thus, to reliably nat your network traffic, please disable TSO
4871 ICMP error messages are not implicitly matched by dynamic rules
4872 for the respective conversations.
4873 To avoid failures of network error detection and path MTU discovery,
4874 ICMP error messages may need to be allowed explicitly through static
4881 actions may lead to confusing behaviour if ruleset has mistakes,
4882 and/or interaction with other subsystems (netgraph, dummynet, etc.) is used.
4883 One possible case for this is packet leaving
4885 in subroutine on the input pass, while later on output encountering unpaired
4888 As the call stack is kept intact after input pass, packet will suddenly
4889 return to the rule number used on input pass, not on output one.
4890 Order of processing should be checked carefully to avoid such mistakes.
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