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
108 .Ss STATEFUL IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
110 .Oo Cm set Ar N Oc Cm nat64lsn Ar name Cm create Ar create-options
112 .Oo Cm set Ar N Oc Cm nat64lsn Ar name Cm config Ar config-options
114 .Oo Cm set Ar N Oc Cm nat64lsn
119 .Oo Cm set Ar N Oc Cm nat64lsn
123 .Oo Cm set Ar N Oc Cm nat64lsn Ar name Cm stats Op Cm reset
124 .Ss STATELESS IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
126 .Oo Cm set Ar N Oc Cm nat64stl Ar name Cm create Ar create-options
128 .Oo Cm set Ar N Oc Cm nat64stl Ar name Cm config Ar config-options
130 .Oo Cm set Ar N Oc Cm nat64stl
134 .Oo Cm set Ar N Oc Cm nat64stl
138 .Oo Cm set Ar N Oc Cm nat64stl Ar name Cm stats Op Cm reset
139 .Ss XLAT464 CLAT IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
141 .Oo Cm set Ar N Oc Cm nat64clat Ar name Cm create Ar create-options
143 .Oo Cm set Ar N Oc Cm nat64clat Ar name Cm config Ar config-options
145 .Oo Cm set Ar N Oc Cm nat64clat
149 .Oo Cm set Ar N Oc Cm nat64clat
153 .Oo Cm set Ar N Oc Cm nat64clat Ar name Cm stats Op Cm reset
154 .Ss IPv6-to-IPv6 NETWORK PREFIX TRANSLATION
156 .Oo Cm set Ar N Oc Cm nptv6 Ar name Cm create Ar create-options
158 .Oo Cm set Ar N Oc Cm nptv6
162 .Oo Cm set Ar N Oc Cm nptv6
166 .Oo Cm set Ar N Oc Cm nptv6 Ar name Cm stats Op Cm reset
167 .Ss INTERNAL DIAGNOSTICS
174 .Ss LIST OF RULES AND PREPROCESSING
187 utility is the user interface for controlling the
191 traffic shaper/packet scheduler, and the
192 in-kernel NAT services.
194 A firewall configuration, or
198 numbered from 1 to 65535.
199 Packets are passed to the firewall
200 from a number of different places in the protocol stack
201 (depending on the source and destination of the packet,
202 it is possible for the firewall to be
203 invoked multiple times on the same packet).
204 The packet passed to the firewall is compared
205 against each of the rules in the
208 (multiple rules with the same number are permitted, in which case
209 they are processed in order of insertion).
210 When a match is found, the action corresponding to the
211 matching rule is performed.
213 Depending on the action and certain system settings, packets
214 can be reinjected into the firewall at some rule after the
215 matching one for further processing.
217 A ruleset always includes a
219 rule (numbered 65535) which cannot be modified or deleted,
220 and matches all packets.
221 The action associated with the
227 depending on how the kernel is configured.
229 If the ruleset includes one or more rules with the
236 the firewall will have a
238 behaviour, i.e., upon a match it will create
240 i.e., rules that match packets with the same 5-tuple
241 (protocol, source and destination addresses and ports)
242 as the packet which caused their creation.
243 Dynamic rules, which have a limited lifetime, are checked
244 at the first occurrence of a
249 rule, and are typically used to open the firewall on-demand to
250 legitimate traffic only.
257 for all packets (not only these matched by the rule) but
264 .Sx STATEFUL FIREWALL
267 Sections below for more information on the stateful behaviour of
270 All rules (including dynamic ones) have a few associated counters:
271 a packet count, a byte count, a log count and a timestamp
272 indicating the time of the last match.
273 Counters can be displayed or reset with
277 Each rule belongs to one of 32 different
281 commands to atomically manipulate sets, such as enable,
282 disable, swap sets, move all rules in a set to another
283 one, delete all rules in a set.
284 These can be useful to
285 install temporary configurations, or to test them.
288 for more information on
291 Rules can be added with the
293 command; deleted individually or in groups with the
295 command, and globally (except those in set 31) with the
297 command; displayed, optionally with the content of the
303 Finally, counters can be reset with the
310 The following general options are available when invoking
312 .Bl -tag -width indent
314 Show counter values when listing rules.
317 command implies this option.
319 Only show the action and the comment, not the body of a rule.
323 When entering or showing rules, print them in compact form,
324 i.e., omitting the "ip from any to any" string
325 when this does not carry any additional information.
327 When listing, show dynamic rules in addition to static ones.
329 When listing, show only dynamic states.
330 When deleting, delete only dynamic states.
332 Run without prompting for confirmation for commands that can cause problems if misused,
335 If there is no tty associated with the process, this is implied.
338 command with this flag ignores possible errors,
339 i.e., nonexistent rule number.
340 And for batched commands execution continues with the next command.
342 When listing a table (see the
344 section below for more information on lookup tables), format values
346 By default, values are shown as integers.
348 Only check syntax of the command strings, without actually passing
351 Try to resolve addresses and service names in output.
353 Be quiet when executing the
363 This is useful when updating rulesets by executing multiple
367 .Ql sh\ /etc/rc.firewall ) ,
368 or by processing a file with many
370 rules across a remote login session.
371 It also stops a table add or delete
372 from failing if the entry already exists or is not present.
374 The reason why this option may be important is that
375 for some of these actions,
377 may print a message; if the action results in blocking the
378 traffic to the remote client,
379 the remote login session will be closed
380 and the rest of the ruleset will not be processed.
381 Access to the console would then be required to recover.
383 When listing rules, show the
385 each rule belongs to.
386 If this flag is not specified, disabled rules will not be
389 When listing pipes, sort according to one of the four
390 counters (total or current packets or bytes).
392 When listing, show last match timestamp converted with ctime().
394 When listing, show last match timestamp as seconds from the epoch.
395 This form can be more convenient for postprocessing by scripts.
397 .Ss LIST OF RULES AND PREPROCESSING
398 To ease configuration, rules can be put into a file which is
401 as shown in the last synopsis line.
405 The file will be read line by line and applied as arguments to the
409 Optionally, a preprocessor can be specified using
413 is to be piped through.
414 Useful preprocessors include
420 does not start with a slash
422 as its first character, the usual
424 name search is performed.
425 Care should be taken with this in environments where not all
426 file systems are mounted (yet) by the time
428 is being run (e.g.\& when they are mounted over NFS).
431 has been specified, any additional arguments are passed on to the preprocessor
433 This allows for flexible configuration files (like conditionalizing
434 them on the local hostname) and the use of macros to centralize
435 frequently required arguments like IP addresses.
436 .Ss TRAFFIC SHAPER CONFIGURATION
442 commands are used to configure the traffic shaper and packet scheduler.
444 .Sx TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
445 Section below for details.
447 If the world and the kernel get out of sync the
449 ABI may break, preventing you from being able to add any rules.
450 This can adversely affect the booting process.
455 to temporarily disable the firewall to regain access to the network,
456 allowing you to fix the problem.
458 A packet is checked against the active ruleset in multiple places
459 in the protocol stack, under control of several sysctl variables.
460 These places and variables are shown below, and it is important to
461 have this picture in mind in order to design a correct ruleset.
462 .Bd -literal -offset indent
465 +----------->-----------+
467 [ip(6)_input] [ip(6)_output] net.inet(6).ip(6).fw.enable=1
470 [ether_demux] [ether_output_frame] net.link.ether.ipfw=1
472 +-->--[bdg_forward]-->--+ net.link.bridge.ipfw=1
478 times the same packet goes through the firewall can
479 vary between 0 and 4 depending on packet source and
480 destination, and system configuration.
482 Note that as packets flow through the stack, headers can be
483 stripped or added to it, and so they may or may not be available
485 E.g., incoming packets will include the MAC header when
489 but the same packets will have the MAC header stripped off when
496 Also note that each packet is always checked against the complete ruleset,
497 irrespective of the place where the check occurs, or the source of the packet.
498 If a rule contains some match patterns or actions which are not valid
499 for the place of invocation (e.g.\& trying to match a MAC header within
503 the match pattern will not match, but a
505 operator in front of such patterns
509 match on those packets.
510 It is thus the responsibility of
511 the programmer, if necessary, to write a suitable ruleset to
512 differentiate among the possible places.
514 rules can be useful here, as an example:
515 .Bd -literal -offset indent
516 # packets from ether_demux or bdg_forward
517 ipfw add 10 skipto 1000 all from any to any layer2 in
518 # packets from ip_input
519 ipfw add 10 skipto 2000 all from any to any not layer2 in
520 # packets from ip_output
521 ipfw add 10 skipto 3000 all from any to any not layer2 out
522 # packets from ether_output_frame
523 ipfw add 10 skipto 4000 all from any to any layer2 out
526 (yes, at the moment there is no way to differentiate between
527 ether_demux and bdg_forward).
529 Also note that only actions
538 frames and all other actions act as if they were
541 Full set of actions is supported for IP packets without
546 action does not divert
550 In general, each keyword or argument must be provided as
551 a separate command line argument, with no leading or trailing
553 Keywords are case-sensitive, whereas arguments may
554 or may not be case-sensitive depending on their nature
555 (e.g.\& uid's are, hostnames are not).
557 Some arguments (e.g., port or address lists) are comma-separated
559 In this case, spaces after commas ',' are allowed to make
560 the line more readable.
561 You can also put the entire
562 command (including flags) into a single argument.
563 E.g., the following forms are equivalent:
564 .Bd -literal -offset indent
565 ipfw -q add deny src-ip 10.0.0.0/24,127.0.0.1/8
566 ipfw -q add deny src-ip 10.0.0.0/24, 127.0.0.1/8
567 ipfw "-q add deny src-ip 10.0.0.0/24, 127.0.0.1/8"
570 The format of firewall rules is the following:
571 .Bd -ragged -offset indent
574 .Op Cm set Ar set_number
575 .Op Cm prob Ar match_probability
577 .Op Cm log Op Cm logamount Ar number
587 where the body of the rule specifies which information is used
588 for filtering packets, among the following:
590 .Bl -tag -width "Source and dest. addresses and ports" -offset XXX -compact
591 .It Layer-2 header fields
593 .It IPv4 and IPv6 Protocol
594 SCTP, TCP, UDP, ICMP, etc.
595 .It Source and dest. addresses and ports
599 .It Transmit and receive interface
601 .It Misc. IP header fields
602 Version, type of service, datagram length, identification,
603 fragment flag (non-zero IP offset),
606 .It IPv6 Extension headers
607 Fragmentation, Hop-by-Hop options,
608 Routing Headers, Source routing rthdr0, Mobile IPv6 rthdr2, IPSec options.
610 .It Misc. TCP header fields
611 TCP flags (SYN, FIN, ACK, RST, etc.),
612 sequence number, acknowledgment number,
620 When the packet can be associated with a local socket.
622 Whether a packet came from a divert socket (e.g.,
624 .It Fib annotation state
625 Whether a packet has been tagged for using a specific FIB (routing table)
626 in future forwarding decisions.
629 Note that some of the above information, e.g.\& source MAC or IP addresses and
630 TCP/UDP ports, can be easily spoofed, so filtering on those fields
631 alone might not guarantee the desired results.
632 .Bl -tag -width indent
634 Each rule is associated with a
636 in the range 1..65535, with the latter reserved for the
639 Rules are checked sequentially by rule number.
640 Multiple rules can have the same number, in which case they are
641 checked (and listed) according to the order in which they have
643 If a rule is entered without specifying a number, the kernel will
644 assign one in such a way that the rule becomes the last one
648 Automatic rule numbers are assigned by incrementing the last
649 non-default rule number by the value of the sysctl variable
650 .Ar net.inet.ip.fw.autoinc_step
651 which defaults to 100.
652 If this is not possible (e.g.\& because we would go beyond the
653 maximum allowed rule number), the number of the last
654 non-default value is used instead.
655 .It Cm set Ar set_number
656 Each rule is associated with a
659 Sets can be individually disabled and enabled, so this parameter
660 is of fundamental importance for atomic ruleset manipulation.
661 It can be also used to simplify deletion of groups of rules.
662 If a rule is entered without specifying a set number,
665 Set 31 is special in that it cannot be disabled,
666 and rules in set 31 are not deleted by the
668 command (but you can delete them with the
669 .Nm ipfw delete set 31
671 Set 31 is also used for the
674 .It Cm prob Ar match_probability
675 A match is only declared with the specified probability
676 (floating point number between 0 and 1).
677 This can be useful for a number of applications such as
678 random packet drop or
681 to simulate the effect of multiple paths leading to out-of-order
684 Note: this condition is checked before any other condition, including
691 .It Cm log Op Cm logamount Ar number
692 Packets matching a rule with the
694 keyword will be made available for logging in two ways:
695 if the sysctl variable
696 .Va net.inet.ip.fw.verbose
697 is set to 0 (default), one can use
702 This pseudo interface can be created manually after a system
703 boot by using the following command:
704 .Bd -literal -offset indent
705 # ifconfig ipfw0 create
708 Or, automatically at boot time by adding the following
712 .Bd -literal -offset indent
716 There is zero overhead when no
718 is attached to the pseudo interface.
721 .Va net.inet.ip.fw.verbose
722 is set to 1, packets will be logged to
726 facility up to a maximum of
731 is specified, the limit is taken from the sysctl variable
732 .Va net.inet.ip.fw.verbose_limit .
733 In both cases, a value of 0 means unlimited logging.
735 Once the limit is reached, logging can be re-enabled by
736 clearing the logging counter or the packet counter for that entry, see the
740 Note: logging is done after all other packet matching conditions
741 have been successfully verified, and before performing the final
742 action (accept, deny, etc.) on the packet.
744 When a packet matches a rule with the
746 keyword, the numeric tag for the given
748 in the range 1..65534 will be attached to the packet.
749 The tag acts as an internal marker (it is not sent out over
750 the wire) that can be used to identify these packets later on.
751 This can be used, for example, to provide trust between interfaces
752 and to start doing policy-based filtering.
753 A packet can have multiple tags at the same time.
754 Tags are "sticky", meaning once a tag is applied to a packet by a
755 matching rule it exists until explicit removal.
756 Tags are kept with the packet everywhere within the kernel, but are
757 lost when packet leaves the kernel, for example, on transmitting
758 packet out to the network or sending packet to a
762 To check for previously applied tags, use the
765 To delete previously applied tag, use the
769 Note: since tags are kept with the packet everywhere in kernelspace,
770 they can be set and unset anywhere in the kernel network subsystem
773 facility), not only by means of the
779 For example, there can be a specialized
781 node doing traffic analyzing and tagging for later inspecting
783 .It Cm untag Ar number
784 When a packet matches a rule with the
786 keyword, the tag with the number
788 is searched among the tags attached to this packet and,
789 if found, removed from it.
790 Other tags bound to packet, if present, are left untouched.
792 When a packet matches a rule with the
794 keyword, the ALTQ identifier for the given
799 Note that this ALTQ tag is only meaningful for packets going "out" of IPFW,
800 and not being rejected or going to divert sockets.
801 Note that if there is insufficient memory at the time the packet is
802 processed, it will not be tagged, so it is wise to make your ALTQ
803 "default" queue policy account for this.
806 rules match a single packet, only the first one adds the ALTQ classification
808 In doing so, traffic may be shaped by using
809 .Cm count Cm altq Ar queue
810 rules for classification early in the ruleset, then later applying
811 the filtering decision.
816 rules may come later and provide the actual filtering decisions in
817 addition to the fallback ALTQ tag.
821 to set up the queues before IPFW will be able to look them up by name,
822 and if the ALTQ disciplines are rearranged, the rules in containing the
823 queue identifiers in the kernel will likely have gone stale and need
825 Stale queue identifiers will probably result in misclassification.
827 All system ALTQ processing can be turned on or off via
832 .Cm disable Ar altq .
834 .Va net.inet.ip.fw.one_pass
835 is irrelevant to ALTQ traffic shaping, as the actual rule action is followed
836 always after adding an ALTQ tag.
839 A rule can be associated with one of the following actions, which
840 will be executed when the packet matches the body of the rule.
841 .Bl -tag -width indent
842 .It Cm allow | accept | pass | permit
843 Allow packets that match rule.
844 The search terminates.
845 .It Cm check-state Op Ar :flowname | Cm :any
846 Checks the packet against the dynamic ruleset.
847 If a match is found, execute the action associated with
848 the rule which generated this dynamic rule, otherwise
849 move to the next rule.
852 rules do not have a body.
855 rule is found, the dynamic ruleset is checked at the first
862 is symbolic name assigned to dynamic rule by
867 can be used to ignore states flowname when matching.
870 keyword is special name used for compatibility with old rulesets.
872 Update counters for all packets that match rule.
873 The search continues with the next rule.
875 Discard packets that match this rule.
876 The search terminates.
877 .It Cm divert Ar port
878 Divert packets that match this rule to the
882 The search terminates.
883 .It Cm fwd | forward Ar ipaddr | tablearg Ns Op , Ns Ar port
884 Change the next-hop on matching packets to
886 which can be an IP address or a host name.
887 The next hop can also be supplied by the last table
888 looked up for the packet by using the
890 keyword instead of an explicit address.
891 The search terminates if this rule matches.
895 is a local address, then matching packets will be forwarded to
897 (or the port number in the packet if one is not specified in the rule)
898 on the local machine.
902 is not a local address, then the port number
903 (if specified) is ignored, and the packet will be
904 forwarded to the remote address, using the route as found in
905 the local routing table for that IP.
909 rule will not match layer-2 packets (those received
910 on ether_input, ether_output, or bridged).
914 action does not change the contents of the packet at all.
915 In particular, the destination address remains unmodified, so
916 packets forwarded to another system will usually be rejected by that system
917 unless there is a matching rule on that system to capture them.
918 For packets forwarded locally,
919 the local address of the socket will be
920 set to the original destination address of the packet.
923 entry look rather weird but is intended for
924 use with transparent proxy servers.
925 .It Cm nat Ar nat_nr | tablearg
928 (for network address translation, address redirect, etc.):
930 .Sx NETWORK ADDRESS TRANSLATION (NAT)
931 Section for further information.
932 .It Cm nat64lsn Ar name
933 Pass packet to a stateful NAT64 instance (for IPv6/IPv4 network address and
934 protocol translation): see the
935 .Sx IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
936 Section for further information.
937 .It Cm nat64stl Ar name
938 Pass packet to a stateless 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 nat64clat Ar name
943 Pass packet to a CLAT NAT64 instance (for client-side IPv6/IPv4 network address and
944 protocol translation): see the
945 .Sx IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
946 Section for further information.
948 Pass packet to a NPTv6 instance (for IPv6-to-IPv6 network prefix translation):
950 .Sx IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
951 Section for further information.
952 .It Cm pipe Ar pipe_nr
956 (for bandwidth limitation, delay, etc.).
958 .Sx TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
959 Section for further information.
960 The search terminates; however, on exit from the pipe and if
964 .Va net.inet.ip.fw.one_pass
965 is not set, the packet is passed again to the firewall code
966 starting from the next rule.
967 .It Cm queue Ar queue_nr
971 (for bandwidth limitation using WF2Q+).
977 Discard packets that match this rule, and if the
978 packet is a TCP packet, try to send a TCP reset (RST) notice.
979 The search terminates.
981 Discard packets that match this rule, and if the
982 packet is a TCP packet, try to send a TCP reset (RST) notice.
983 The search terminates.
984 .It Cm skipto Ar number | tablearg
985 Skip all subsequent rules numbered less than
987 The search continues with the first rule numbered
990 It is possible to use the
992 keyword with a skipto for a
994 skipto. Skipto may work either in O(log(N)) or in O(1) depending
995 on amount of memory and/or sysctl variables.
998 section for more details.
999 .It Cm call Ar number | tablearg
1000 The current rule number is saved in the internal stack and
1001 ruleset processing continues with the first rule numbered
1004 If later a rule with the
1006 action is encountered, the processing returns to the first rule
1009 rule plus one or higher
1010 (the same behaviour as with packets returning from
1015 This could be used to make somewhat like an assembly language
1017 calls to rules with common checks for different interfaces, etc.
1019 Rule with any number could be called, not just forward jumps as with
1021 So, to prevent endless loops in case of mistakes, both
1025 actions don't do any jumps and simply go to the next rule if memory
1026 cannot be allocated or stack overflowed/underflowed.
1028 Internally stack for rule numbers is implemented using
1030 facility and currently has size of 16 entries.
1031 As mbuf tags are lost when packet leaves the kernel,
1033 should not be used in subroutines to avoid endless loops
1034 and other undesired effects.
1036 Takes rule number saved to internal stack by the last
1038 action and returns ruleset processing to the first rule
1039 with number greater than number of corresponding
1042 See description of the
1044 action for more details.
1050 and thus are unconditional, but
1052 command-line utility currently requires every action except
1055 While it is sometimes useful to return only on some packets,
1056 usually you want to print just
1059 A workaround for this is to use new syntax and
1062 .Bd -literal -offset indent
1063 # Add a rule without actual body
1064 ipfw add 2999 return via any
1066 # List rules without "from any to any" part
1070 This cosmetic annoyance may be fixed in future releases.
1072 Send a copy of packets matching this rule to the
1074 socket bound to port
1076 The search continues with the next rule.
1077 .It Cm unreach Ar code
1078 Discard packets that match this rule, and try to send an ICMP
1079 unreachable notice with code
1083 is a number from 0 to 255, or one of these aliases:
1084 .Cm net , host , protocol , port ,
1085 .Cm needfrag , srcfail , net-unknown , host-unknown ,
1086 .Cm isolated , net-prohib , host-prohib , tosnet ,
1087 .Cm toshost , filter-prohib , host-precedence
1089 .Cm precedence-cutoff .
1090 The search terminates.
1091 .It Cm unreach6 Ar code
1092 Discard packets that match this rule, and try to send an ICMPv6
1093 unreachable notice with code
1097 is a number from 0, 1, 3 or 4, or one of these aliases:
1098 .Cm no-route, admin-prohib, address
1101 The search terminates.
1102 .It Cm netgraph Ar cookie
1103 Divert packet into netgraph with given
1105 The search terminates.
1106 If packet is later returned from netgraph it is either
1107 accepted or continues with the next rule, depending on
1108 .Va net.inet.ip.fw.one_pass
1110 .It Cm ngtee Ar cookie
1111 A copy of packet is diverted into netgraph, original
1112 packet continues with the next rule.
1115 for more information on
1120 .It Cm setfib Ar fibnum | tablearg
1121 The packet is tagged so as to use the FIB (routing table)
1123 in any subsequent forwarding decisions.
1124 In the current implementation, this is limited to the values 0 through 15, see
1126 Processing continues at the next rule.
1127 It is possible to use the
1129 keyword with setfib.
1130 If the tablearg value is not within the compiled range of fibs,
1131 the packet's fib is set to 0.
1132 .It Cm setdscp Ar DSCP | number | tablearg
1133 Set specified DiffServ codepoint for an IPv4/IPv6 packet.
1134 Processing continues at the next rule.
1135 Supported values are:
1181 Additionally, DSCP value can be specified by number (0..63).
1182 It is also possible to use the
1184 keyword with setdscp.
1185 If the tablearg value is not within the 0..63 range, lower 6 bits of supplied
1187 .It Cm tcp-setmss Ar mss
1188 Set the Maximum Segment Size (MSS) in the TCP segment to value
1192 should be loaded or kernel should have
1193 .Cm options IPFIREWALL_PMOD
1194 to be able use this action.
1195 This command does not change a packet if original MSS value is lower than
1197 Both TCP over IPv4 and over IPv6 are supported.
1198 Regardless of matched a packet or not by the
1200 rule, the search continues with the next rule.
1202 Queue and reassemble IPv4 fragments.
1203 If the packet is not fragmented, counters are updated and
1204 processing continues with the next rule.
1205 If the packet is the last logical fragment, the packet is reassembled and, if
1206 .Va net.inet.ip.fw.one_pass
1207 is set to 0, processing continues with the next rule.
1208 Otherwise, the packet is allowed to pass and the search terminates.
1209 If the packet is a fragment in the middle of a logical group of fragments,
1211 processing stops immediately.
1213 Fragment handling can be tuned via
1214 .Va net.inet.ip.maxfragpackets
1216 .Va net.inet.ip.maxfragsperpacket
1217 which limit, respectively, the maximum number of processable
1218 fragments (default: 800) and
1219 the maximum number of fragments per packet (default: 16).
1221 NOTA BENE: since fragments do not contain port numbers,
1222 they should be avoided with the
1225 Alternatively, direction-based (like
1229 ) and source-based (like
1231 ) match patterns can be used to select fragments.
1233 Usually a simple rule like:
1234 .Bd -literal -offset indent
1235 # reassemble incoming fragments
1236 ipfw add reass all from any to any in
1239 is all you need at the beginning of your ruleset.
1241 Discard packets that match this rule, and if the packet is an SCTP packet,
1242 try to send an SCTP packet containing an ABORT chunk.
1243 The search terminates.
1245 Discard packets that match this rule, and if the packet is an SCTP packet,
1246 try to send an SCTP packet containing an ABORT chunk.
1247 The search terminates.
1250 The body of a rule contains zero or more patterns (such as
1251 specific source and destination addresses or ports,
1252 protocol options, incoming or outgoing interfaces, etc.)
1253 that the packet must match in order to be recognised.
1254 In general, the patterns are connected by (implicit)
1256 operators -- i.e., all must match in order for the
1258 Individual patterns can be prefixed by the
1260 operator to reverse the result of the match, as in
1262 .Dl "ipfw add 100 allow ip from not 1.2.3.4 to any"
1264 Additionally, sets of alternative match patterns
1266 can be constructed by putting the patterns in
1267 lists enclosed between parentheses ( ) or braces { }, and
1270 operator as follows:
1272 .Dl "ipfw add 100 allow ip from { x or not y or z } to any"
1274 Only one level of parentheses is allowed.
1275 Beware that most shells have special meanings for parentheses
1276 or braces, so it is advisable to put a backslash \\ in front of them
1277 to prevent such interpretations.
1279 The body of a rule must in general include a source and destination
1283 can be used in various places to specify that the content of
1284 a required field is irrelevant.
1286 The rule body has the following format:
1287 .Bd -ragged -offset indent
1288 .Op Ar proto Cm from Ar src Cm to Ar dst
1292 The first part (proto from src to dst) is for backward
1293 compatibility with earlier versions of
1297 any match pattern (including MAC headers, IP protocols,
1298 addresses and ports) can be specified in the
1302 Rule fields have the following meaning:
1303 .Bl -tag -width indent
1304 .It Ar proto : protocol | Cm { Ar protocol Cm or ... }
1305 .It Ar protocol : Oo Cm not Oc Ar protocol-name | protocol-number
1306 An IP protocol specified by number or name
1307 (for a complete list see
1308 .Pa /etc/protocols ) ,
1309 or one of the following keywords:
1310 .Bl -tag -width indent
1312 Matches IPv4 packets.
1314 Matches IPv6 packets.
1323 option will be treated as inner protocol.
1331 .Cm { Ar protocol Cm or ... }
1334 is provided for convenience only but its use is deprecated.
1335 .It Ar src No and Ar dst : Bro Cm addr | Cm { Ar addr Cm or ... } Brc Op Oo Cm not Oc Ar ports
1336 An address (or a list, see below)
1337 optionally followed by
1343 with multiple addresses) is provided for convenience only and
1344 its use is discouraged.
1345 .It Ar addr : Oo Cm not Oc Bro
1346 .Cm any | me | me6 |
1347 .Cm table Ns Pq Ar name Ns Op , Ns Ar value
1348 .Ar | addr-list | addr-set
1350 .Bl -tag -width indent
1352 Matches any IP address.
1354 Matches any IP address configured on an interface in the system.
1356 Matches any IPv6 address configured on an interface in the system.
1357 The address list is evaluated at the time the packet is
1359 .It Cm table Ns Pq Ar name Ns Op , Ns Ar value
1360 Matches any IPv4 or IPv6 address for which an entry exists in the lookup table
1362 If an optional 32-bit unsigned
1364 is also specified, an entry will match only if it has this value.
1367 section below for more information on lookup tables.
1369 .It Ar addr-list : ip-addr Ns Op Ns , Ns Ar addr-list
1371 A host or subnet address specified in one of the following ways:
1372 .Bl -tag -width indent
1373 .It Ar numeric-ip | hostname
1374 Matches a single IPv4 address, specified as dotted-quad or a hostname.
1375 Hostnames are resolved at the time the rule is added to the firewall list.
1376 .It Ar addr Ns / Ns Ar masklen
1377 Matches all addresses with base
1379 (specified as an IP address, a network number, or a hostname)
1383 As an example, 1.2.3.4/25 or 1.2.3.0/25 will match
1384 all IP numbers from 1.2.3.0 to 1.2.3.127 .
1385 .It Ar addr Ns : Ns Ar mask
1386 Matches all addresses with base
1388 (specified as an IP address, a network number, or a hostname)
1391 specified as a dotted quad.
1392 As an example, 1.2.3.4:255.0.255.0 or 1.0.3.0:255.0.255.0 will match
1394 This form is advised only for non-contiguous
1396 It is better to resort to the
1397 .Ar addr Ns / Ns Ar masklen
1398 format for contiguous masks, which is more compact and less
1401 .It Ar addr-set : addr Ns Oo Ns / Ns Ar masklen Oc Ns Cm { Ns Ar list Ns Cm }
1402 .It Ar list : Bro Ar num | num-num Brc Ns Op Ns , Ns Ar list
1403 Matches all addresses with base address
1405 (specified as an IP address, a network number, or a hostname)
1406 and whose last byte is in the list between braces { } .
1407 Note that there must be no spaces between braces and
1408 numbers (spaces after commas are allowed).
1409 Elements of the list can be specified as single entries
1413 field is used to limit the size of the set of addresses,
1414 and can have any value between 24 and 32.
1416 it will be assumed as 24.
1418 This format is particularly useful to handle sparse address sets
1419 within a single rule.
1420 Because the matching occurs using a
1421 bitmask, it takes constant time and dramatically reduces
1422 the complexity of rulesets.
1424 As an example, an address specified as 1.2.3.4/24{128,35-55,89}
1425 or 1.2.3.0/24{128,35-55,89}
1426 will match the following IP addresses:
1428 1.2.3.128, 1.2.3.35 to 1.2.3.55, 1.2.3.89 .
1429 .It Ar addr6-list : ip6-addr Ns Op Ns , Ns Ar addr6-list
1431 A host or subnet specified one of the following ways:
1432 .Bl -tag -width indent
1433 .It Ar numeric-ip | hostname
1434 Matches a single IPv6 address as allowed by
1437 Hostnames are resolved at the time the rule is added to the firewall
1439 .It Ar addr Ns / Ns Ar masklen
1440 Matches all IPv6 addresses with base
1442 (specified as allowed by
1448 .It Ar addr Ns / Ns Ar mask
1449 Matches all IPv6 addresses with base
1451 (specified as allowed by
1456 specified as allowed by
1458 As an example, fe::640:0:0/ffff::ffff:ffff:0:0 will match
1460 This form is advised only for non-contiguous
1462 It is better to resort to the
1463 .Ar addr Ns / Ns Ar masklen
1464 format for contiguous masks, which is more compact and less
1468 No support for sets of IPv6 addresses is provided because IPv6 addresses
1469 are typically random past the initial prefix.
1470 .It Ar ports : Bro Ar port | port Ns \&- Ns Ar port Ns Brc Ns Op , Ns Ar ports
1471 For protocols which support port numbers (such as SCTP, TCP and UDP), optional
1473 may be specified as one or more ports or port ranges, separated
1474 by commas but no spaces, and an optional
1479 notation specifies a range of ports (including boundaries).
1483 may be used instead of numeric port values.
1484 The length of the port list is limited to 30 ports or ranges,
1485 though one can specify larger ranges by using an
1489 section of the rule.
1493 can be used to escape the dash
1495 character in a service name (from a shell, the backslash must be
1496 typed twice to avoid the shell itself interpreting it as an escape
1499 .Dl "ipfw add count tcp from any ftp\e\e-data-ftp to any"
1501 Fragmented packets which have a non-zero offset (i.e., not the first
1502 fragment) will never match a rule which has one or more port
1506 option for details on matching fragmented packets.
1508 .Ss RULE OPTIONS (MATCH PATTERNS)
1509 Additional match patterns can be used within
1511 Zero or more of these so-called
1513 can be present in a rule, optionally prefixed by the
1515 operand, and possibly grouped into
1518 The following match patterns can be used (listed in alphabetical order):
1519 .Bl -tag -width indent
1520 .It Cm // this is a comment.
1521 Inserts the specified text as a comment in the rule.
1522 Everything following // is considered as a comment and stored in the rule.
1523 You can have comment-only rules, which are listed as having a
1525 action followed by the comment.
1529 .It Cm defer-immediate-action | defer-action
1530 A rule with this option will not perform normal action
1531 upon a match. This option is intended to be used with
1535 as the dynamic rule, created but ignored on match, will work
1540 .Cm defer-immediate-action
1541 create a dynamic rule and continue with the next rule without actually
1542 performing the action part of this rule. When the rule is later activated
1543 via the state table, the action is performed as usual.
1545 Matches only packets generated by a divert socket.
1546 .It Cm diverted-loopback
1547 Matches only packets coming from a divert socket back into the IP stack
1549 .It Cm diverted-output
1550 Matches only packets going from a divert socket back outward to the IP
1551 stack output for delivery.
1552 .It Cm dst-ip Ar ip-address
1553 Matches IPv4 packets whose destination IP is one of the address(es)
1554 specified as argument.
1555 .It Bro Cm dst-ip6 | dst-ipv6 Brc Ar ip6-address
1556 Matches IPv6 packets whose destination IP is one of the address(es)
1557 specified as argument.
1558 .It Cm dst-port Ar ports
1559 Matches IP packets whose destination port is one of the port(s)
1560 specified as argument.
1562 Matches TCP packets that have the RST or ACK bits set.
1563 .It Cm ext6hdr Ar header
1564 Matches IPv6 packets containing the extended header given by
1566 Supported headers are:
1572 any type of Routing Header
1574 Source routing Routing Header Type 0
1576 Mobile IPv6 Routing Header Type 2
1580 IPSec authentication headers
1582 and IPsec encapsulated security payload headers
1584 .It Cm fib Ar fibnum
1585 Matches a packet that has been tagged to use
1586 the given FIB (routing table) number.
1587 .It Cm flow Ar table Ns Pq Ar name Ns Op , Ns Ar value
1588 Search for the flow entry in lookup table
1590 If not found, the match fails.
1591 Otherwise, the match succeeds and
1593 is set to the value extracted from the table.
1595 This option can be useful to quickly dispatch traffic based on
1596 certain packet fields.
1599 section below for more information on lookup tables.
1600 .It Cm flow-id Ar labels
1601 Matches IPv6 packets containing any of the flow labels given in
1604 is a comma separated list of numeric flow labels.
1606 Matches packets that are fragments and not the first
1607 fragment of an IP datagram.
1608 Note that these packets will not have
1609 the next protocol header (e.g.\& TCP, UDP) so options that look into
1610 these headers cannot match.
1612 Matches all TCP or UDP packets sent by or received for a
1616 may be specified by name or number.
1618 Matches all TCP or UDP packets sent by or received for the
1619 jail whose ID or name is
1621 .It Cm icmptypes Ar types
1622 Matches ICMP packets whose ICMP type is in the list
1624 The list may be specified as any combination of
1625 individual types (numeric) separated by commas.
1626 .Em Ranges are not allowed .
1627 The supported ICMP types are:
1631 destination unreachable
1639 router advertisement
1643 time-to-live exceeded
1655 address mask request
1657 and address mask reply
1659 .It Cm icmp6types Ar types
1660 Matches ICMP6 packets whose ICMP6 type is in the list of
1662 The list may be specified as any combination of
1663 individual types (numeric) separated by commas.
1664 .Em Ranges are not allowed .
1666 Matches incoming or outgoing packets, respectively.
1670 are mutually exclusive (in fact,
1674 .It Cm ipid Ar id-list
1675 Matches IPv4 packets whose
1677 field has value included in
1679 which is either a single value or a list of values or ranges
1680 specified in the same way as
1682 .It Cm iplen Ar len-list
1683 Matches IP packets whose total length, including header and data, is
1686 which is either a single value or a list of values or ranges
1687 specified in the same way as
1689 .It Cm ipoptions Ar spec
1690 Matches packets whose IPv4 header contains the comma separated list of
1691 options specified in
1693 The supported IP options are:
1696 (strict source route),
1698 (loose source route),
1700 (record packet route) and
1703 The absence of a particular option may be denoted
1706 .It Cm ipprecedence Ar precedence
1707 Matches IPv4 packets whose precedence field is equal to
1710 Matches packets that have IPSEC history associated with them
1711 (i.e., the packet comes encapsulated in IPSEC, the kernel
1712 has IPSEC support, and can correctly decapsulate it).
1714 Note that specifying
1716 is different from specifying
1718 as the latter will only look at the specific IP protocol field,
1719 irrespective of IPSEC kernel support and the validity of the IPSEC data.
1721 Further note that this flag is silently ignored in kernels without
1723 It does not affect rule processing when given and the
1724 rules are handled as if with no
1727 .It Cm iptos Ar spec
1728 Matches IPv4 packets whose
1730 field contains the comma separated list of
1731 service types specified in
1733 The supported IP types of service are:
1736 .Pq Dv IPTOS_LOWDELAY ,
1738 .Pq Dv IPTOS_THROUGHPUT ,
1740 .Pq Dv IPTOS_RELIABILITY ,
1742 .Pq Dv IPTOS_MINCOST ,
1744 .Pq Dv IPTOS_ECN_CE .
1745 The absence of a particular type may be denoted
1748 .It Cm dscp spec Ns Op , Ns Ar spec
1749 Matches IPv4/IPv6 packets whose
1751 field value is contained in
1754 Multiple values can be specified via
1755 the comma separated list.
1756 Value can be one of keywords used in
1758 action or exact number.
1759 .It Cm ipttl Ar ttl-list
1760 Matches IPv4 packets whose time to live is included in
1762 which is either a single value or a list of values or ranges
1763 specified in the same way as
1765 .It Cm ipversion Ar ver
1766 Matches IP packets whose IP version field is
1768 .It Cm keep-state Op Ar :flowname
1769 Upon a match, the firewall will create a dynamic rule, whose
1770 default behaviour is to match bidirectional traffic between
1771 source and destination IP/port using the same protocol.
1772 The rule has a limited lifetime (controlled by a set of
1774 variables), and the lifetime is refreshed every time a matching
1778 is used to assign additional to addresses, ports and protocol parameter
1779 to dynamic rule. It can be used for more accurate matching by
1784 keyword is special name used for compatibility with old rulesets.
1786 Matches only layer2 packets, i.e., those passed to
1788 from ether_demux() and ether_output_frame().
1789 .It Cm limit Bro Cm src-addr | src-port | dst-addr | dst-port Brc Ar N Op Ar :flowname
1790 The firewall will only allow
1792 connections with the same
1793 set of parameters as specified in the rule.
1795 of source and destination addresses and ports can be
1797 .It Cm lookup Bro Cm dst-ip | dst-port | src-ip | src-port | uid | jail Brc Ar name
1798 Search an entry in lookup table
1800 that matches the field specified as argument.
1801 If not found, the match fails.
1802 Otherwise, the match succeeds and
1804 is set to the value extracted from the table.
1806 This option can be useful to quickly dispatch traffic based on
1807 certain packet fields.
1810 section below for more information on lookup tables.
1811 .It Cm { MAC | mac } Ar dst-mac src-mac
1812 Match packets with a given
1816 addresses, specified as the
1818 keyword (matching any MAC address), or six groups of hex digits
1819 separated by colons,
1820 and optionally followed by a mask indicating the significant bits.
1821 The mask may be specified using either of the following methods:
1822 .Bl -enum -width indent
1826 followed by the number of significant bits.
1827 For example, an address with 33 significant bits could be specified as:
1829 .Dl "MAC 10:20:30:40:50:60/33 any"
1833 followed by a bitmask specified as six groups of hex digits separated
1835 For example, an address in which the last 16 bits are significant could
1838 .Dl "MAC 10:20:30:40:50:60&00:00:00:00:ff:ff any"
1840 Note that the ampersand character has a special meaning in many shells
1841 and should generally be escaped.
1843 Note that the order of MAC addresses (destination first,
1845 the same as on the wire, but the opposite of the one used for
1847 .It Cm mac-type Ar mac-type
1848 Matches packets whose Ethernet Type field
1849 corresponds to one of those specified as argument.
1851 is specified in the same way as
1853 (i.e., one or more comma-separated single values or ranges).
1854 You can use symbolic names for known values such as
1855 .Em vlan , ipv4, ipv6 .
1856 Values can be entered as decimal or hexadecimal (if prefixed by 0x),
1857 and they are always printed as hexadecimal (unless the
1859 option is used, in which case symbolic resolution will be attempted).
1860 .It Cm proto Ar protocol
1861 Matches packets with the corresponding IP protocol.
1863 Upon a match, the firewall will create a dynamic rule as if
1866 However, this option doesn't imply an implicit
1870 .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
1871 Matches packets received, transmitted or going through,
1872 respectively, the interface specified by exact name
1876 by IP address, or through some interface.
1879 may be used to match interface by its kernel ifindex.
1882 section below for more information on lookup tables.
1886 keyword causes the interface to always be checked.
1893 then only the receive or transmit interface (respectively)
1895 By specifying both, it is possible to match packets based on
1896 both receive and transmit interface, e.g.:
1898 .Dl "ipfw add deny ip from any to any out recv ed0 xmit ed1"
1902 interface can be tested on either incoming or outgoing packets,
1905 interface can only be tested on outgoing packets.
1910 is invalid) whenever
1914 A packet might not have a receive or transmit interface: packets
1915 originating from the local host have no receive interface,
1916 while packets destined for the local host have no transmit
1918 .It Cm set-limit Bro Cm src-addr | src-port | dst-addr | dst-port Brc Ar N
1921 but does not have an implicit
1925 Matches TCP packets that have the SYN bit set but no ACK bit.
1926 This is the short form of
1927 .Dq Li tcpflags\ syn,!ack .
1929 Matches packets that are associated to a local socket and
1930 for which the SO_USER_COOKIE socket option has been set
1931 to a non-zero value.
1932 As a side effect, the value of the
1933 option is made available as
1935 value, which in turn can be used as
1940 .It Cm src-ip Ar ip-address
1941 Matches IPv4 packets whose source IP is one of the address(es)
1942 specified as an argument.
1943 .It Cm src-ip6 Ar ip6-address
1944 Matches IPv6 packets whose source IP is one of the address(es)
1945 specified as an argument.
1946 .It Cm src-port Ar ports
1947 Matches IP packets whose source port is one of the port(s)
1948 specified as argument.
1949 .It Cm tagged Ar tag-list
1950 Matches packets whose tags are included in
1952 which is either a single value or a list of values or ranges
1953 specified in the same way as
1955 Tags can be applied to the packet using
1957 rule action parameter (see it's description for details on tags).
1958 .It Cm tcpack Ar ack
1960 Match if the TCP header acknowledgment number field is set to
1962 .It Cm tcpdatalen Ar tcpdatalen-list
1963 Matches TCP packets whose length of TCP data is
1964 .Ar tcpdatalen-list ,
1965 which is either a single value or a list of values or ranges
1966 specified in the same way as
1968 .It Cm tcpflags Ar spec
1970 Match if the TCP header contains the comma separated list of
1973 The supported TCP flags are:
1982 The absence of a particular flag may be denoted
1985 A rule which contains a
1987 specification can never match a fragmented packet which has
1991 option for details on matching fragmented packets.
1992 .It Cm tcpmss Ar tcpmss-list
1993 Matches TCP packets whose MSS (maximum segment size) value is set to
1995 which is either a single value or a list of values or ranges
1996 specified in the same way as
1998 .It Cm tcpseq Ar seq
2000 Match if the TCP header sequence number field is set to
2002 .It Cm tcpwin Ar tcpwin-list
2003 Matches TCP packets whose header window field is set to
2005 which is either a single value or a list of values or ranges
2006 specified in the same way as
2008 .It Cm tcpoptions Ar spec
2010 Match if the TCP header contains the comma separated list of
2011 options specified in
2013 The supported TCP options are:
2016 (maximum segment size),
2018 (tcp window advertisement),
2022 (rfc1323 timestamp) and
2024 (rfc1644 t/tcp connection count).
2025 The absence of a particular option may be denoted
2029 Match all TCP or UDP packets sent by or received for a
2033 may be matched by name or identification number.
2035 For incoming packets,
2036 a routing table lookup is done on the packet's source address.
2037 If the interface on which the packet entered the system matches the
2038 outgoing interface for the route,
2040 If the interfaces do not match up,
2041 the packet does not match.
2042 All outgoing packets or packets with no incoming interface match.
2044 The name and functionality of the option is intentionally similar to
2045 the Cisco IOS command:
2047 .Dl ip verify unicast reverse-path
2049 This option can be used to make anti-spoofing rules to reject all
2050 packets with source addresses not from this interface.
2054 For incoming packets,
2055 a routing table lookup is done on the packet's source address.
2056 If a route to the source address exists, but not the default route
2057 or a blackhole/reject route, the packet matches.
2058 Otherwise, the packet does not match.
2059 All outgoing packets match.
2061 The name and functionality of the option is intentionally similar to
2062 the Cisco IOS command:
2064 .Dl ip verify unicast source reachable-via any
2066 This option can be used to make anti-spoofing rules to reject all
2067 packets whose source address is unreachable.
2069 For incoming packets, the packet's source address is checked if it
2070 belongs to a directly connected network.
2071 If the network is directly connected, then the interface the packet
2072 came on in is compared to the interface the network is connected to.
2073 When incoming interface and directly connected interface are not the
2074 same, the packet does not match.
2075 Otherwise, the packet does match.
2076 All outgoing packets match.
2078 This option can be used to make anti-spoofing rules to reject all
2079 packets that pretend to be from a directly connected network but do
2080 not come in through that interface.
2081 This option is similar to but more restricted than
2083 because it engages only on packets with source addresses of directly
2084 connected networks instead of all source addresses.
2087 Lookup tables are useful to handle large sparse sets of
2088 addresses or other search keys (e.g., ports, jail IDs, interface names).
2089 In the rest of this section we will use the term ``key''.
2090 Table name needs to match the following spec:
2092 Tables with the same name can be created in different
2094 However, rule links to the tables in
2097 This behavior can be controlled by
2098 .Va net.inet.ip.fw.tables_sets
2102 section for more information.
2103 There may be up to 65535 different lookup tables.
2105 The following table types are supported:
2106 .Bl -tag -width indent
2107 .It Ar table-type : Ar addr | iface | number | flow
2108 .It Ar table-key : Ar addr Ns Oo / Ns Ar masklen Oc | iface-name | number | flow-spec
2109 .It Ar flow-spec : Ar flow-field Ns Op , Ns Ar flow-spec
2110 .It Ar flow-field : src-ip | proto | src-port | dst-ip | dst-port
2112 Matches IPv4 or IPv6 address.
2113 Each entry is represented by an
2114 .Ar addr Ns Op / Ns Ar masklen
2115 and will match all addresses with base
2117 (specified as an IPv4/IPv6 address, or a hostname) and mask width of
2122 is not specified, it defaults to 32 for IPv4 and 128 for IPv6.
2123 When looking up an IP address in a table, the most specific
2126 Matches interface names.
2127 Each entry is represented by string treated as interface name.
2128 Wildcards are not supported.
2130 Matches protocol ports, uids/gids or jail IDs.
2131 Each entry is represented by 32-bit unsigned integer.
2132 Ranges are not supported.
2134 Matches packet fields specified by
2136 type suboptions with table entries.
2139 Tables require explicit creation via
2143 The following creation options are supported:
2144 .Bl -tag -width indent
2145 .It Ar create-options : Ar create-option | create-options
2146 .It Ar create-option : Cm type Ar table-type | Cm valtype Ar value-mask | Cm algo Ar algo-desc |
2147 .Cm limit Ar number | Cm locked | Cm missing | Cm or-flush
2153 Table algorithm to use (see below).
2155 Maximum number of items that may be inserted into table.
2157 Restrict any table modifications.
2159 Do not fail if table already exists and has exactly same options as new one.
2161 Flush existing table with same name instead of returning error.
2164 so existing table must be compatible with new one.
2167 Some of these options may be modified later via
2170 The following options can be changed:
2171 .Bl -tag -width indent
2172 .It Ar modify-options : Ar modify-option | modify-options
2173 .It Ar modify-option : Cm limit Ar number
2175 Alter maximum number of items that may be inserted into table.
2178 Additionally, table can be locked or unlocked using
2186 can be swapped with each other using
2189 Swap may fail if tables limits are set and data exchange
2190 would result in limits hit.
2191 Operation is performed atomically.
2193 One or more entries can be added to a table at once using
2196 Addition of all items are performed atomically.
2197 By default, error in addition of one entry does not influence
2198 addition of other entries. However, non-zero error code is returned
2202 keyword may be specified before
2204 to indicate all-or-none add request.
2206 One or more entries can be removed from a table at once using
2209 By default, error in removal of one entry does not influence
2210 removing of other entries. However, non-zero error code is returned
2213 It may be possible to check what entry will be found on particular
2219 This functionality is optional and may be unsupported in some algorithms.
2221 The following operations can be performed on
2226 .Bl -tag -width indent
2230 Removes all entries.
2232 Shows generic table information.
2234 Shows generic table information and algo-specific data.
2237 The following lookup algorithms are supported:
2238 .Bl -tag -width indent
2239 .It Ar algo-desc : algo-name | "algo-name algo-data"
2240 .It Ar algo-name: Ar addr:radix | addr:hash | iface:array | number:array | flow:hash
2242 Separate Radix trees for IPv4 and IPv6, the same way as the routing table (see
2248 Separate auto-growing hashes for IPv4 and IPv6.
2249 Accepts entries with the same mask length specified initially via
2250 .Cm "addr:hash masks=/v4,/v6"
2251 algorithm creation options.
2252 Assume /32 and /128 masks by default.
2253 Search removes host bits (according to mask) from supplied address and checks
2254 resulting key in appropriate hash.
2255 Mostly optimized for /64 and byte-ranged IPv6 masks.
2257 Array storing sorted indexes for entries which are presented in the system.
2258 Optimized for very fast lookup.
2260 Array storing sorted u32 numbers.
2262 Auto-growing hash storing flow entries.
2263 Search calculates hash on required packet fields and searches for matching
2264 entries in selected bucket.
2269 feature provides the ability to use a value, looked up in the table, as
2270 the argument for a rule action, action parameter or rule option.
2271 This can significantly reduce number of rules in some configurations.
2272 If two tables are used in a rule, the result of the second (destination)
2275 Each record may hold one or more values according to
2277 This mask is set on table creation via
2280 The following value types are supported:
2281 .Bl -tag -width indent
2282 .It Ar value-mask : Ar value-type Ns Op , Ns Ar value-mask
2283 .It Ar value-type : Ar skipto | pipe | fib | nat | dscp | tag | divert |
2284 .Ar netgraph | limit | ipv4
2286 rule number to jump to.
2290 fib number to match/set.
2292 nat number to jump to.
2294 dscp value to match/set.
2296 tag number to match/set.
2298 port number to divert traffic to.
2300 hook number to move packet to.
2302 maximum number of connections.
2304 IPv4 nexthop to fwd packets to.
2306 IPv6 nexthop to fwd packets to.
2311 argument can be used with the following actions:
2312 .Cm nat, pipe , queue, divert, tee, netgraph, ngtee, fwd, skipto, setfib,
2320 action, the user should be aware that the code will walk the ruleset
2321 up to a rule equal to, or past, the given number.
2325 Section for example usage of tables and the tablearg keyword.
2327 Each rule or table belongs to one of 32 different
2330 Set 31 is reserved for the default rule.
2332 By default, rules or tables are put in set 0, unless you use the
2334 attribute when adding a new rule or table.
2335 Sets can be individually and atomically enabled or disabled,
2336 so this mechanism permits an easy way to store multiple configurations
2337 of the firewall and quickly (and atomically) switch between them.
2339 By default, tables from set 0 are referenced when adding rule with
2340 table opcodes regardless of rule set.
2341 This behavior can be changed by setting
2342 .Va net.inet.ip.fw.tables_sets
2344 Rule's set will then be used for table references.
2346 The command to enable/disable sets is
2347 .Bd -ragged -offset indent
2349 .Cm set Oo Cm disable Ar number ... Oc Op Cm enable Ar number ...
2356 sections can be specified.
2357 Command execution is atomic on all the sets specified in the command.
2358 By default, all sets are enabled.
2360 When you disable a set, its rules behave as if they do not exist
2361 in the firewall configuration, with only one exception:
2362 .Bd -ragged -offset indent
2363 dynamic rules created from a rule before it had been disabled
2364 will still be active until they expire.
2366 dynamic rules you have to explicitly delete the parent rule
2367 which generated them.
2370 The set number of rules can be changed with the command
2371 .Bd -ragged -offset indent
2374 .Brq Cm rule Ar rule-number | old-set
2378 Also, you can atomically swap two rulesets with the command
2379 .Bd -ragged -offset indent
2381 .Cm set swap Ar first-set second-set
2386 Section on some possible uses of sets of rules.
2387 .Sh STATEFUL FIREWALL
2388 Stateful operation is a way for the firewall to dynamically
2389 create rules for specific flows when packets that
2390 match a given pattern are detected.
2391 Support for stateful
2392 operation comes through the
2393 .Cm check-state , keep-state , record-state , limit
2399 Dynamic rules are created when a packet matches a
2405 rule, causing the creation of a
2407 rule which will match all and only packets with
2411 .Em src-ip/src-port dst-ip/dst-port
2416 are used here only to denote the initial match addresses, but they
2417 are completely equivalent afterwards).
2423 This name is used in matching together with addresses, ports and protocol.
2424 Dynamic rules will be checked at the first
2425 .Cm check-state, keep-state
2428 occurrence, and the action performed upon a match will be the same
2429 as in the parent rule.
2431 Note that no additional attributes other than protocol and IP addresses
2432 and ports and :flowname are checked on dynamic rules.
2434 The typical use of dynamic rules is to keep a closed firewall configuration,
2435 but let the first TCP SYN packet from the inside network install a
2436 dynamic rule for the flow so that packets belonging to that session
2437 will be allowed through the firewall:
2439 .Dl "ipfw add check-state :OUTBOUND"
2440 .Dl "ipfw add allow tcp from my-subnet to any setup keep-state :OUTBOUND"
2441 .Dl "ipfw add deny tcp from any to any"
2443 A similar approach can be used for UDP, where an UDP packet coming
2444 from the inside will install a dynamic rule to let the response through
2447 .Dl "ipfw add check-state :OUTBOUND"
2448 .Dl "ipfw add allow udp from my-subnet to any keep-state :OUTBOUND"
2449 .Dl "ipfw add deny udp from any to any"
2451 Dynamic rules expire after some time, which depends on the status
2452 of the flow and the setting of some
2456 .Sx SYSCTL VARIABLES
2458 For TCP sessions, dynamic rules can be instructed to periodically
2459 send keepalive packets to refresh the state of the rule when it is
2464 for more examples on how to use dynamic rules.
2465 .Sh TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
2467 is also the user interface for the
2469 traffic shaper, packet scheduler and network emulator, a subsystem that
2470 can artificially queue, delay or drop packets
2471 emulating the behaviour of certain network links
2472 or queueing systems.
2475 operates by first using the firewall to select packets
2476 using any match pattern that can be used in
2479 Matching packets are then passed to either of two
2480 different objects, which implement the traffic regulation:
2481 .Bl -hang -offset XXXX
2487 with given bandwidth and propagation delay,
2488 driven by a FIFO scheduler and a single queue with programmable
2489 queue size and packet loss rate.
2490 Packets are appended to the queue as they come out from
2492 and then transferred in FIFO order to the link at the desired rate.
2496 is an abstraction used to implement packet scheduling
2497 using one of several packet scheduling algorithms.
2500 are first grouped into flows according to a mask on the 5-tuple.
2501 Flows are then passed to the scheduler associated to the
2503 and each flow uses scheduling parameters (weight and others)
2504 as configured in the
2507 A scheduler in turn is connected to an emulated link,
2508 and arbitrates the link's bandwidth among backlogged flows according to
2509 weights and to the features of the scheduling algorithm in use.
2514 can be used to set hard limits to the bandwidth that a flow can use, whereas
2516 can be used to determine how different flows share the available bandwidth.
2518 A graphical representation of the binding of queues,
2519 flows, schedulers and links is below.
2520 .Bd -literal -offset indent
2521 (flow_mask|sched_mask) sched_mask
2522 +---------+ weight Wx +-------------+
2523 | |->-[flow]-->--| |-+
2524 -->--| QUEUE x | ... | | |
2525 | |->-[flow]-->--| SCHEDuler N | |
2527 ... | +--[LINK N]-->--
2528 +---------+ weight Wy | | +--[LINK N]-->--
2529 | |->-[flow]-->--| | |
2530 -->--| QUEUE y | ... | | |
2531 | |->-[flow]-->--| | |
2532 +---------+ +-------------+ |
2535 It is important to understand the role of the SCHED_MASK
2536 and FLOW_MASK, which are configured through the commands
2537 .Dl "ipfw sched N config mask SCHED_MASK ..."
2539 .Dl "ipfw queue X config mask FLOW_MASK ..." .
2541 The SCHED_MASK is used to assign flows to one or more
2542 scheduler instances, one for each
2543 value of the packet's 5-tuple after applying SCHED_MASK.
2544 As an example, using ``src-ip 0xffffff00'' creates one instance
2545 for each /24 destination subnet.
2547 The FLOW_MASK, together with the SCHED_MASK, is used to split
2549 As an example, using
2550 ``src-ip 0x000000ff''
2551 together with the previous SCHED_MASK makes a flow for
2552 each individual source address.
2553 In turn, flows for each /24
2554 subnet will be sent to the same scheduler instance.
2556 The above diagram holds even for the
2558 case, with the only restriction that a
2560 only supports a SCHED_MASK, and forces the use of a FIFO
2561 scheduler (these are for backward compatibility reasons;
2562 in fact, internally, a
2564 pipe is implemented exactly as above).
2566 There are two modes of
2574 mode tries to emulate a real link: the
2576 scheduler ensures that the packet will not leave the pipe faster than it
2577 would on the real link with a given bandwidth.
2580 mode allows certain packets to bypass the
2582 scheduler (if packet flow does not exceed pipe's bandwidth).
2583 This is the reason why the
2585 mode requires less CPU cycles per packet (on average) and packet latency
2586 can be significantly lower in comparison to a real link with the same
2592 mode can be enabled by setting the
2593 .Va net.inet.ip.dummynet.io_fast
2595 variable to a non-zero value.
2597 .Ss PIPE, QUEUE AND SCHEDULER CONFIGURATION
2603 configuration commands are the following:
2604 .Bd -ragged -offset indent
2605 .Cm pipe Ar number Cm config Ar pipe-configuration
2607 .Cm queue Ar number Cm config Ar queue-configuration
2609 .Cm sched Ar number Cm config Ar sched-configuration
2612 The following parameters can be configured for a pipe:
2614 .Bl -tag -width indent -compact
2615 .It Cm bw Ar bandwidth | device
2616 Bandwidth, measured in
2619 .Brq Cm bit/s | Byte/s .
2622 A value of 0 (default) means unlimited bandwidth.
2623 The unit must immediately follow the number, as in
2625 .Dl "ipfw pipe 1 config bw 300Kbit/s"
2627 If a device name is specified instead of a numeric value, as in
2629 .Dl "ipfw pipe 1 config bw tun0"
2631 then the transmit clock is supplied by the specified device.
2632 At the moment only the
2634 device supports this
2635 functionality, for use in conjunction with
2638 .It Cm delay Ar ms-delay
2639 Propagation delay, measured in milliseconds.
2640 The value is rounded to the next multiple of the clock tick
2641 (typically 10ms, but it is a good practice to run kernels
2643 .Dq "options HZ=1000"
2645 the granularity to 1ms or less).
2646 The default value is 0, meaning no delay.
2648 .It Cm burst Ar size
2649 If the data to be sent exceeds the pipe's bandwidth limit
2650 (and the pipe was previously idle), up to
2652 bytes of data are allowed to bypass the
2654 scheduler, and will be sent as fast as the physical link allows.
2655 Any additional data will be transmitted at the rate specified
2659 The burst size depends on how long the pipe has been idle;
2660 the effective burst size is calculated as follows:
2667 .It Cm profile Ar filename
2668 A file specifying the additional overhead incurred in the transmission
2669 of a packet on the link.
2671 Some link types introduce extra delays in the transmission
2672 of a packet, e.g., because of MAC level framing, contention on
2673 the use of the channel, MAC level retransmissions and so on.
2674 From our point of view, the channel is effectively unavailable
2675 for this extra time, which is constant or variable depending
2677 Additionally, packets may be dropped after this
2678 time (e.g., on a wireless link after too many retransmissions).
2679 We can model the additional delay with an empirical curve
2680 that represents its distribution.
2681 .Bd -literal -offset indent
2682 cumulative probability
2692 +-------*------------------->
2695 The empirical curve may have both vertical and horizontal lines.
2696 Vertical lines represent constant delay for a range of
2698 Horizontal lines correspond to a discontinuity in the delay
2699 distribution: the pipe will use the largest delay for a
2702 The file format is the following, with whitespace acting as
2703 a separator and '#' indicating the beginning a comment:
2704 .Bl -tag -width indent
2705 .It Cm name Ar identifier
2706 optional name (listed by "ipfw pipe show")
2707 to identify the delay distribution;
2709 the bandwidth used for the pipe.
2710 If not specified here, it must be present
2711 explicitly as a configuration parameter for the pipe;
2712 .It Cm loss-level Ar L
2713 the probability above which packets are lost.
2714 (0.0 <= L <= 1.0, default 1.0 i.e., no loss);
2716 the number of samples used in the internal
2717 representation of the curve (2..1024; default 100);
2718 .It Cm "delay prob" | "prob delay"
2719 One of these two lines is mandatory and defines
2720 the format of the following lines with data points.
2722 2 or more lines representing points in the curve,
2723 with either delay or probability first, according
2724 to the chosen format.
2725 The unit for delay is milliseconds.
2726 Data points do not need to be sorted.
2727 Also, the number of actual lines can be different
2728 from the value of the "samples" parameter:
2730 utility will sort and interpolate
2731 the curve as needed.
2734 Example of a profile file:
2735 .Bd -literal -offset indent
2740 0 200 # minimum overhead is 200ms
2746 #configuration file end
2750 The following parameters can be configured for a queue:
2752 .Bl -tag -width indent -compact
2753 .It Cm pipe Ar pipe_nr
2754 Connects a queue to the specified pipe.
2755 Multiple queues (with the same or different weights) can be connected to
2756 the same pipe, which specifies the aggregate rate for the set of queues.
2758 .It Cm weight Ar weight
2759 Specifies the weight to be used for flows matching this queue.
2760 The weight must be in the range 1..100, and defaults to 1.
2763 The following case-insensitive parameters can be configured for a
2766 .Bl -tag -width indent -compact
2767 .It Cm type Ar {fifo | wf2q+ | rr | qfq | fq_codel | fq_pie}
2768 specifies the scheduling algorithm to use.
2769 .Bl -tag -width indent -compact
2771 is just a FIFO scheduler (which means that all packets
2772 are stored in the same queue as they arrive to the scheduler).
2773 FIFO has O(1) per-packet time complexity, with very low
2774 constants (estimate 60-80ns on a 2GHz desktop machine)
2775 but gives no service guarantees.
2777 implements the WF2Q+ algorithm, which is a Weighted Fair Queueing
2778 algorithm which permits flows to share bandwidth according to
2780 Note that weights are not priorities; even a flow
2781 with a minuscule weight will never starve.
2782 WF2Q+ has O(log N) per-packet processing cost, where N is the number
2783 of flows, and is the default algorithm used by previous versions
2786 implements the Deficit Round Robin algorithm, which has O(1) processing
2787 costs (roughly, 100-150ns per packet)
2788 and permits bandwidth allocation according to weights, but
2789 with poor service guarantees.
2791 implements the QFQ algorithm, which is a very fast variant of
2792 WF2Q+, with similar service guarantees and O(1) processing
2793 costs (roughly, 200-250ns per packet).
2795 implements the FQ-CoDel (FlowQueue-CoDel) scheduler/AQM algorithm, which
2796 uses a modified Deficit Round Robin scheduler to manage two lists of sub-queues
2797 (old sub-queues and new sub-queues) for providing brief periods of priority to
2798 lightweight or short burst flows.
2799 By default, the total number of sub-queues is 1024.
2800 FQ-CoDel's internal, dynamically
2801 created sub-queues are controlled by separate instances of CoDel AQM.
2803 implements the FQ-PIE (FlowQueue-PIE) scheduler/AQM algorithm, which similar to
2805 but uses per sub-queue PIE AQM instance to control the queue delay.
2809 inherits AQM parameters and options from
2813 inherits AQM parameters and options from
2816 Additionally, both of
2820 have shared scheduler parameters which are:
2821 .Bl -tag -width indent
2824 specifies the quantum (credit) of the scheduler.
2826 is the number of bytes a queue can serve before being moved to the tail
2828 The default is 1514 bytes, and the maximum acceptable value
2832 specifies the hard size limit (in unit of packets) of all queues managed by an
2833 instance of the scheduler.
2834 The default value of
2836 is 10240 packets, and the maximum acceptable value is 20480 packets.
2839 specifies the total number of flow queues (sub-queues) that fq_*
2840 creates and manages.
2841 By default, 1024 sub-queues are created when an instance
2842 of the fq_{codel/pie} scheduler is created.
2843 The maximum acceptable value is
2847 Note that any token after
2851 is considered a parameter for fq_{codel/pie}.
2852 So, ensure all scheduler
2853 configuration options not related to fq_{codel/pie} are written before
2858 In addition to the type, all parameters allowed for a pipe can also
2859 be specified for a scheduler.
2861 Finally, the following parameters can be configured for both
2864 .Bl -tag -width XXXX -compact
2865 .It Cm buckets Ar hash-table-size
2866 Specifies the size of the hash table used for storing the
2868 Default value is 64 controlled by the
2871 .Va net.inet.ip.dummynet.hash_size ,
2872 allowed range is 16 to 65536.
2874 .It Cm mask Ar mask-specifier
2875 Packets sent to a given pipe or queue by an
2877 rule can be further classified into multiple flows, each of which is then
2881 A flow identifier is constructed by masking the IP addresses,
2882 ports and protocol types as specified with the
2884 options in the configuration of the pipe or queue.
2885 For each different flow identifier, a new pipe or queue is created
2886 with the same parameters as the original object, and matching packets
2891 are used, each flow will get the same bandwidth as defined by the pipe,
2894 are used, each flow will share the parent's pipe bandwidth evenly
2895 with other flows generated by the same queue (note that other queues
2896 with different weights might be connected to the same pipe).
2898 Available mask specifiers are a combination of one or more of the following:
2900 .Cm dst-ip Ar mask ,
2901 .Cm dst-ip6 Ar mask ,
2902 .Cm src-ip Ar mask ,
2903 .Cm src-ip6 Ar mask ,
2904 .Cm dst-port Ar mask ,
2905 .Cm src-port Ar mask ,
2906 .Cm flow-id Ar mask ,
2911 where the latter means all bits in all fields are significant.
2914 When a packet is dropped by a
2916 queue or pipe, the error
2917 is normally reported to the caller routine in the kernel, in the
2918 same way as it happens when a device queue fills up.
2920 option reports the packet as successfully delivered, which can be
2921 needed for some experimental setups where you want to simulate
2922 loss or congestion at a remote router.
2924 .It Cm plr Ar packet-loss-rate
2927 .Ar packet-loss-rate
2928 is a floating-point number between 0 and 1, with 0 meaning no
2929 loss, 1 meaning 100% loss.
2930 The loss rate is internally represented on 31 bits.
2932 .It Cm queue Brq Ar slots | size Ns Cm Kbytes
2937 Default value is 50 slots, which
2938 is the typical queue size for Ethernet devices.
2939 Note that for slow speed links you should keep the queue
2940 size short or your traffic might be affected by a significant
2942 E.g., 50 max-sized Ethernet packets (1500 bytes) mean 600Kbit
2943 or 20s of queue on a 30Kbit/s pipe.
2944 Even worse effects can result if you get packets from an
2945 interface with a much larger MTU, e.g.\& the loopback interface
2946 with its 16KB packets.
2950 .Em net.inet.ip.dummynet.pipe_byte_limit
2952 .Em net.inet.ip.dummynet.pipe_slot_limit
2953 control the maximum lengths that can be specified.
2955 .It Cm red | gred Ar w_q Ns / Ns Ar min_th Ns / Ns Ar max_th Ns / Ns Ar max_p
2957 Make use of the RED (Random Early Detection) queue management algorithm.
2962 point numbers between 0 and 1 (inclusive), while
2966 are integer numbers specifying thresholds for queue management
2967 (thresholds are computed in bytes if the queue has been defined
2968 in bytes, in slots otherwise).
2969 The two parameters can also be of the same value if needed. The
2971 also supports the gentle RED variant (gred) and ECN (Explicit Congestion
2972 Notification) as optional. Three
2974 variables can be used to control the RED behaviour:
2975 .Bl -tag -width indent
2976 .It Va net.inet.ip.dummynet.red_lookup_depth
2977 specifies the accuracy in computing the average queue
2978 when the link is idle (defaults to 256, must be greater than zero)
2979 .It Va net.inet.ip.dummynet.red_avg_pkt_size
2980 specifies the expected average packet size (defaults to 512, must be
2982 .It Va net.inet.ip.dummynet.red_max_pkt_size
2983 specifies the expected maximum packet size, only used when queue
2984 thresholds are in bytes (defaults to 1500, must be greater than zero).
2987 .It Cm codel Oo Cm target Ar time Oc Oo Cm interval Ar time Oc Oo Cm ecn |
2989 Make use of the CoDel (Controlled-Delay) queue management algorithm.
2991 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
2992 microseconds (us) can be specified instead.
2993 CoDel drops or marks (ECN) packets
2994 depending on packet sojourn time in the queue.
2997 (5ms by default) is the minimum acceptable persistent queue delay that CoDel
2999 CoDel does not drop packets directly after packets sojourn time becomes
3006 (100ms default) before dropping.
3009 should be set to maximum RTT for all expected connections.
3011 enables (disabled by default) packet marking (instead of dropping) for
3012 ECN-enabled TCP flows when queue delay becomes high.
3014 Note that any token after
3016 is considered a parameter for CoDel.
3017 So, ensure all pipe/queue
3018 configuration options are written before
3025 .Va net.inet.ip.dummynet.codel.target
3027 .Va net.inet.ip.dummynet.codel.interval
3028 can be used to set CoDel default parameters.
3030 .It Cm pie Oo Cm target Ar time Oc Oo Cm tupdate Ar time Oc Oo
3031 .Cm alpha Ar n Oc Oo Cm beta Ar n Oc Oo Cm max_burst Ar time Oc Oo
3032 .Cm max_ecnth Ar n Oc Oo Cm ecn | Cm noecn Oc Oo Cm capdrop |
3033 .Cm nocapdrop Oc Oo Cm drand | Cm nodrand Oc Oo Cm onoff
3034 .Oc Oo Cm dre | Cm ts Oc
3035 Make use of the PIE (Proportional Integral controller Enhanced) queue management
3037 PIE drops or marks packets depending on a calculated drop probability during
3038 en-queue process, with the aim of achieving high throughput while keeping queue
3040 At regular time intervals of
3043 (15ms by default) a background process (re)calculates the probability based on queue delay
3047 (15ms by default) and queue delay trends.
3048 PIE approximates current queue
3049 delay by using a departure rate estimation method, or (optionally) by using a
3050 packet timestamp method similar to CoDel.
3052 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
3053 microseconds (us) can be specified instead.
3054 The other PIE parameters and options are as follows:
3055 .Bl -tag -width indent
3058 is a floating point number between 0 and 7 which specifies the weight of queue
3059 delay deviations that is used in drop probability calculation.
3060 0.125 is the default.
3063 is a floating point number between 0 and 7 which specifies is the weight of queue
3064 delay trend that is used in drop probability calculation.
3065 1.25 is the default.
3066 .It Cm max_burst Ar time
3067 The maximum period of time that PIE does not drop/mark packets.
3069 default and 10s is the maximum value.
3070 .It Cm max_ecnth Ar n
3071 Even when ECN is enabled, PIE drops packets instead of marking them when drop
3072 probability becomes higher than ECN probability threshold
3074 , the default is 0.1 (i.e 10%) and 1 is the maximum value.
3076 enable or disable ECN marking for ECN-enabled TCP flows.
3077 Disabled by default.
3078 .It Cm capdrop | nocapdrop
3079 enable or disable cap drop adjustment.
3080 Cap drop adjustment is enabled by default.
3081 .It Cm drand | nodrand
3082 enable or disable drop probability de-randomisation.
3083 De-randomisation eliminates
3084 the problem of dropping packets too close or too far.
3085 De-randomisation is enabled by default.
3087 enable turning PIE on and off depending on queue load.
3088 If this option is enabled,
3089 PIE turns on when over 1/3 of queue becomes full.
3090 This option is disabled by
3093 Calculate queue delay using departure rate estimation
3101 Note that any token after
3103 is considered a parameter for PIE.
3104 So ensure all pipe/queue
3105 the configuration options are written before
3109 variables can be used to control the
3113 .Sx SYSCTL VARIABLES
3114 section for more details.
3117 When used with IPv6 data,
3119 currently has several limitations.
3120 Information necessary to route link-local packets to an
3121 interface is not available after processing by
3123 so those packets are dropped in the output path.
3124 Care should be taken to ensure that link-local packets are not passed to
3127 Here are some important points to consider when designing your
3131 Remember that you filter both packets going
3135 Most connections need packets going in both directions.
3137 Remember to test very carefully.
3138 It is a good idea to be near the console when doing this.
3139 If you cannot be near the console,
3140 use an auto-recovery script such as the one in
3141 .Pa /usr/share/examples/ipfw/change_rules.sh .
3143 Do not forget the loopback interface.
3148 There are circumstances where fragmented datagrams are unconditionally
3150 TCP packets are dropped if they do not contain at least 20 bytes of
3151 TCP header, UDP packets are dropped if they do not contain a full 8
3152 byte UDP header, and ICMP packets are dropped if they do not contain
3153 4 bytes of ICMP header, enough to specify the ICMP type, code, and
3155 These packets are simply logged as
3157 since there may not be enough good data in the packet to produce a
3158 meaningful log entry.
3160 Another type of packet is unconditionally dropped, a TCP packet with a
3161 fragment offset of one.
3162 This is a valid packet, but it only has one use, to try
3163 to circumvent firewalls.
3164 When logging is enabled, these packets are
3165 reported as being dropped by rule -1.
3167 If you are logged in over a network, loading the
3171 is probably not as straightforward as you would think.
3172 The following command line is recommended:
3173 .Bd -literal -offset indent
3175 ipfw add 32000 allow ip from any to any
3178 Along the same lines, doing an
3179 .Bd -literal -offset indent
3183 in similar surroundings is also a bad idea.
3187 filter list may not be modified if the system security level
3188 is set to 3 or higher
3191 for information on system security levels).
3193 .Sh PACKET DIVERSION
3196 socket bound to the specified port will receive all packets
3197 diverted to that port.
3198 If no socket is bound to the destination port, or if the divert module is
3199 not loaded, or if the kernel was not compiled with divert socket support,
3200 the packets are dropped.
3201 .Sh NETWORK ADDRESS TRANSLATION (NAT)
3203 support in-kernel NAT using the kernel version of
3207 should be loaded or kernel should have
3208 .Cm options IPFIREWALL_NAT
3211 The nat configuration command is the following:
3212 .Bd -ragged -offset indent
3217 .Ar nat-configuration
3221 The following parameters can be configured:
3222 .Bl -tag -width indent
3223 .It Cm ip Ar ip_address
3224 Define an ip address to use for aliasing.
3226 Use ip address of NIC for aliasing, dynamically changing
3227 it if NIC's ip address changes.
3229 Enable logging on this nat instance.
3231 Deny any incoming connection from outside world.
3233 Try to leave the alias port numbers unchanged from
3234 the actual local port numbers.
3236 Traffic on the local network not originating from a RFC 1918
3237 unregistered address spaces will be ignored.
3239 Like unreg_only, but includes the RFC 6598 (Carrier Grade NAT)
3242 Reset table of the packet aliasing engine on address change.
3244 Reverse the way libalias handles aliasing.
3246 Obey transparent proxy rules only, packet aliasing is not performed.
3248 Skip instance in case of global state lookup (see below).
3251 Some specials value can be supplied instead of
3253 .Bl -tag -width indent
3255 Looks up translation state in all configured nat instances.
3256 If an entry is found, packet is aliased according to that entry.
3257 If no entry was found in any of the instances, packet is passed unchanged,
3258 and no new entry will be created.
3260 .Sx MULTIPLE INSTANCES
3263 for more information.
3265 Uses argument supplied in lookup table.
3268 section below for more information on lookup tables.
3271 To let the packet continue after being (de)aliased, set the sysctl variable
3272 .Va net.inet.ip.fw.one_pass
3274 For more information about aliasing modes, refer to
3278 for some examples about nat usage.
3279 .Ss REDIRECT AND LSNAT SUPPORT IN IPFW
3280 Redirect and LSNAT support follow closely the syntax used in
3284 for some examples on how to do redirect and lsnat.
3285 .Ss SCTP NAT SUPPORT
3286 SCTP nat can be configured in a similar manner to TCP through the
3289 The main difference is that
3291 does not do port translation.
3292 Since the local and global side ports will be the same,
3293 there is no need to specify both.
3294 Ports are redirected as follows:
3295 .Bd -ragged -offset indent
3301 .Cm redirect_port sctp
3302 .Ar ip_address [,addr_list] {[port | port-port] [,ports]}
3308 configuration can be done in real-time through the
3311 All may be changed dynamically, though the hash_table size will only
3316 .Sx SYSCTL VARIABLES
3318 .Sh IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
3319 .Ss Stateful translation
3321 supports in-kernel IPv6/IPv4 network address and protocol translation.
3322 Stateful NAT64 translation allows IPv6-only clients to contact IPv4 servers
3323 using unicast TCP, UDP or ICMP protocols.
3324 One or more IPv4 addresses assigned to a stateful NAT64 translator are shared
3325 among several IPv6-only clients.
3326 When stateful NAT64 is used in conjunction with DNS64, no changes are usually
3327 required in the IPv6 client or the IPv4 server.
3330 should be loaded or kernel should have
3331 .Cm options IPFIREWALL_NAT64
3332 to be able use stateful NAT64 translator.
3334 Stateful NAT64 uses a bunch of memory for several types of objects.
3335 When IPv6 client initiates connection, NAT64 translator creates a host entry
3336 in the states table.
3337 Each host entry uses preallocated IPv4 alias entry.
3338 Each alias entry has a number of ports group entries allocated on demand.
3339 Ports group entries contains connection state entries.
3340 There are several options to control limits and lifetime for these objects.
3342 NAT64 translator follows RFC7915 when does ICMPv6/ICMP translation,
3343 unsupported message types will be silently dropped.
3344 IPv6 needs several ICMPv6 message types to be explicitly allowed for correct
3346 Make sure that ND6 neighbor solicitation (ICMPv6 type 135) and neighbor
3347 advertisement (ICMPv6 type 136) messages will not be handled by translation
3350 After translation NAT64 translator by default sends packets through
3351 corresponding netisr queue.
3352 Thus translator host should be configured as IPv4 and IPv6 router.
3353 Also this means, that a packet is handled by firewall twice.
3354 First time an original packet is handled and consumed by translator,
3355 and then it is handled again as translated packet.
3356 This behavior can be changed by sysctl variable
3357 .Va net.inet.ip.fw.nat64_direct_output .
3358 Also translated packet can be tagged using
3360 rule action, and then matched by
3362 opcode to avoid loops and extra overhead.
3364 The stateful NAT64 configuration command is the following:
3365 .Bd -ragged -offset indent
3374 The following parameters can be configured:
3375 .Bl -tag -width indent
3376 .It Cm prefix4 Ar ipv4_prefix/plen
3377 The IPv4 prefix with mask defines the pool of IPv4 addresses used as
3378 source address after translation.
3379 Stateful NAT64 module translates IPv6 source address of client to one
3380 IPv4 address from this pool.
3381 Note that incoming IPv4 packets that don't have corresponding state entry
3382 in the states table will be dropped by translator.
3383 Make sure that translation rules handle packets, destined to configured prefix.
3384 .It Cm prefix6 Ar ipv6_prefix/length
3385 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3386 to represent IPv4 addresses. This IPv6 prefix should be configured in DNS64.
3387 The translator implementation follows RFC6052, that restricts the length of
3388 prefixes to one of following: 32, 40, 48, 56, 64, or 96.
3389 The Well-Known IPv6 Prefix 64:ff9b:: must be 96 bits long.
3392 prefix can be used to handle several IPv6 prefixes with one NAT64 instance.
3393 The NAT64 instance will determine a destination IPv4 address from prefix
3395 .It Cm states_chunks Ar number
3396 The number of states chunks in single ports group.
3397 Each ports group by default can keep 64 state entries in single chunk.
3398 The above value affects the maximum number of states that can be associated with single IPv4 alias address and port.
3399 The value must be power of 2, and up to 128.
3400 .It Cm host_del_age Ar seconds
3401 The number of seconds until the host entry for a IPv6 client will be deleted
3402 and all its resources will be released due to inactivity.
3405 .It Cm pg_del_age Ar seconds
3406 The number of seconds until a ports group with unused state entries will
3410 .It Cm tcp_syn_age Ar seconds
3411 The number of seconds while a state entry for TCP connection with only SYN
3413 If TCP connection establishing will not be finished,
3414 state entry will be deleted.
3417 .It Cm tcp_est_age Ar seconds
3418 The number of seconds while a state entry for established TCP connection
3422 .It Cm tcp_close_age Ar seconds
3423 The number of seconds while a state entry for closed TCP connection
3425 Keeping state entries for closed connections is needed, because IPv4 servers
3426 typically keep closed connections in a TIME_WAIT state for a several minutes.
3427 Since translator's IPv4 addresses are shared among all IPv6 clients,
3428 new connections from the same addresses and ports may be rejected by server,
3429 because these connections are still in a TIME_WAIT state.
3430 Keeping them in translator's state table protects from such rejects.
3433 .It Cm udp_age Ar seconds
3434 The number of seconds while translator keeps state entry in a waiting for
3435 reply to the sent UDP datagram.
3438 .It Cm icmp_age Ar seconds
3439 The number of seconds while translator keeps state entry in a waiting for
3440 reply to the sent ICMP message.
3444 Turn on logging of all handled packets via BPF through
3448 is a pseudo interface and can be created after a boot manually with
3451 Note that it has different purpose than
3454 Translators sends to BPF an additional information with each packet.
3457 you are able to see each handled packet before and after translation.
3459 Turn off logging of all handled packets via BPF.
3460 .It Cm allow_private
3461 Turn on processing private IPv4 addresses. By default IPv6 packets with
3462 destinations mapped to private address ranges defined by RFC1918 are not
3464 .It Cm -allow_private
3465 Turn off private address handling in
3470 To inspect a states table of stateful NAT64 the following command can be used:
3471 .Bd -ragged -offset indent
3480 Stateless NAT64 translator doesn't use a states table for translation
3481 and converts IPv4 addresses to IPv6 and vice versa solely based on the
3482 mappings taken from configured lookup tables.
3483 Since a states table doesn't used by stateless translator,
3484 it can be configured to pass IPv4 clients to IPv6-only servers.
3486 The stateless NAT64 configuration command is the following:
3487 .Bd -ragged -offset indent
3496 The following parameters can be configured:
3497 .Bl -tag -width indent
3498 .It Cm prefix6 Ar ipv6_prefix/length
3499 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3500 to represent IPv4 addresses. This IPv6 prefix should be configured in DNS64.
3501 .It Cm table4 Ar table46
3504 contains mapping how IPv4 addresses should be translated to IPv6 addresses.
3505 .It Cm table6 Ar table64
3508 contains mapping how IPv6 addresses should be translated to IPv4 addresses.
3510 Turn on logging of all handled packets via BPF through
3514 Turn off logging of all handled packets via BPF.
3515 .It Cm allow_private
3516 Turn on processing private IPv4 addresses. By default IPv6 packets with
3517 destinations mapped to private address ranges defined by RFC1918 are not
3519 .It Cm -allow_private
3520 Turn off private address handling in
3525 Note that the behavior of stateless translator with respect to not matched
3526 packets differs from stateful translator.
3527 If corresponding addresses was not found in the lookup tables, the packet
3528 will not be dropped and the search continues.
3531 .Ss XLAT464 CLAT translation
3532 XLAT464 CLAT NAT64 translator implements client-side stateless translation as
3533 defined in RFC6877 and is very similar to statless NAT64 translator
3534 explained above. Instead of lookup tables it uses one-to-one mapping
3535 between IPv4 and IPv6 addresses using configured prefixes.
3536 This mode can be used as a replacement of DNS64 service for applications
3537 that are not using it (e.g. VoIP) allowing them to access IPv4-only Internet
3538 over IPv6-only networks with help of remote NAT64 translator.
3540 The CLAT NAT64 configuration command is the following:
3541 .Bd -ragged -offset indent
3550 The following parameters can be configured:
3551 .Bl -tag -width indent
3552 .It Cm clat_prefix Ar ipv6_prefix/length
3553 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3554 to represent source IPv4 addresses.
3555 .It Cm plat_prefix Ar ipv6_prefix/length
3556 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3557 to represent destination IPv4 addresses. This IPv6 prefix should be configured
3558 on a remote NAT64 translator.
3560 Turn on logging of all handled packets via BPF through
3564 Turn off logging of all handled packets via BPF.
3565 .It Cm allow_private
3566 Turn on processing private IPv4 addresses. By default
3568 instance will not process IPv4 packets with destination address from private
3569 ranges as defined in RFC1918.
3570 .It Cm -allow_private
3571 Turn off private address handling in
3576 Note that the behavior of CLAT translator with respect to not matched
3577 packets differs from stateful translator.
3578 If corresponding addresses were not matched against prefixes configured,
3579 the packet will not be dropped and the search continues.
3580 .Sh IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
3582 supports in-kernel IPv6-to-IPv6 network prefix translation as described
3586 should be loaded or kernel should has
3587 .Cm options IPFIREWALL_NPTV6
3588 to be able use NPTv6 translator.
3590 The NPTv6 configuration command is the following:
3591 .Bd -ragged -offset indent
3600 The following parameters can be configured:
3601 .Bl -tag -width indent
3602 .It Cm int_prefix Ar ipv6_prefix
3603 IPv6 prefix used in internal network.
3604 NPTv6 module translates source address when it matches this prefix.
3605 .It Cm ext_prefix Ar ipv6_prefix
3606 IPv6 prefix used in external network.
3607 NPTv6 module translates destination address when it matches this prefix.
3608 .It Cm ext_if Ar nic
3609 The NPTv6 module will use first global IPv6 address from interface
3612 It can be useful when IPv6 prefix of external network is dynamically obtained.
3616 options are mutually exclusive.
3617 .It Cm prefixlen Ar length
3618 The length of specified IPv6 prefixes. It must be in range from 8 to 64.
3621 Note that the prefix translation rules are silently ignored when IPv6 packet
3622 forwarding is disabled.
3623 To enable the packet forwarding, set the sysctl variable
3624 .Va net.inet6.ip6.forwarding
3627 To let the packet continue after being translated, set the sysctl variable
3628 .Va net.inet.ip.fw.one_pass
3631 Tunables can be set in
3637 before ipfw module gets loaded.
3638 .Bl -tag -width indent
3639 .It Va net.inet.ip.fw.default_to_accept: No 0
3640 Defines ipfw last rule behavior.
3641 This value overrides
3642 .Cd "options IPFW_DEFAULT_TO_(ACCEPT|DENY)"
3643 from kernel configuration file.
3644 .It Va net.inet.ip.fw.tables_max: No 128
3645 Defines number of tables available in ipfw.
3646 Number cannot exceed 65534.
3648 .Sh SYSCTL VARIABLES
3651 variables controls the behaviour of the firewall and
3653 .Pq Nm dummynet , bridge , sctp nat .
3654 These are shown below together with their default value
3655 (but always check with the
3657 command what value is actually in use) and meaning:
3658 .Bl -tag -width indent
3659 .It Va net.inet.ip.alias.sctp.accept_global_ootb_addip: No 0
3662 responds to receipt of global OOTB ASCONF-AddIP:
3663 .Bl -tag -width indent
3665 No response (unless a partially matching association exists -
3666 ports and vtags match but global address does not)
3669 will accept and process all OOTB global AddIP messages.
3672 Option 1 should never be selected as this forms a security risk.
3674 establish multiple fake associations by sending AddIP messages.
3675 .It Va net.inet.ip.alias.sctp.chunk_proc_limit: No 5
3676 Defines the maximum number of chunks in an SCTP packet that will be
3678 packet that matches an existing association.
3679 This value is enforced to be greater or equal than
3680 .Cm net.inet.ip.alias.sctp.initialising_chunk_proc_limit .
3682 a DoS risk yet setting too low a value may result in
3683 important control chunks in
3684 the packet not being located and parsed.
3685 .It Va net.inet.ip.alias.sctp.error_on_ootb: No 1
3688 responds to any Out-of-the-Blue (OOTB) packets with ErrorM packets.
3689 An OOTB packet is a packet that arrives with no existing association
3692 and is not an INIT or ASCONF-AddIP packet:
3693 .Bl -tag -width indent
3695 ErrorM is never sent in response to OOTB packets.
3697 ErrorM is only sent to OOTB packets received on the local side.
3699 ErrorM is sent to the local side and on the global side ONLY if there is a
3700 partial match (ports and vtags match but the source global IP does not).
3701 This value is only useful if the
3703 is tracking global IP addresses.
3705 ErrorM is sent in response to all OOTB packets on both
3706 the local and global side
3710 At the moment the default is 0, since the ErrorM packet is not yet
3711 supported by most SCTP stacks.
3712 When it is supported, and if not tracking
3713 global addresses, we recommend setting this value to 1 to allow
3714 multi-homed local hosts to function with the
3716 To track global addresses, we recommend setting this value to 2 to
3717 allow global hosts to be informed when they need to (re)send an
3719 Value 3 should never be chosen (except for debugging) as the
3721 will respond to all OOTB global packets (a DoS risk).
3722 .It Va net.inet.ip.alias.sctp.hashtable_size: No 2003
3723 Size of hash tables used for
3725 lookups (100 < prime_number > 1000001).
3728 size for any future created
3730 instance and therefore must be set prior to creating a
3733 The table sizes may be changed to suit specific needs.
3734 If there will be few
3735 concurrent associations, and memory is scarce, you may make these smaller.
3736 If there will be many thousands (or millions) of concurrent associations, you
3737 should make these larger.
3738 A prime number is best for the table size.
3740 update function will adjust your input value to the next highest prime number.
3741 .It Va net.inet.ip.alias.sctp.holddown_time: No 0
3742 Hold association in table for this many seconds after receiving a
3744 This allows endpoints to correct shutdown gracefully if a
3745 shutdown_complete is lost and retransmissions are required.
3746 .It Va net.inet.ip.alias.sctp.init_timer: No 15
3747 Timeout value while waiting for (INIT-ACK|AddIP-ACK).
3748 This value cannot be 0.
3749 .It Va net.inet.ip.alias.sctp.initialising_chunk_proc_limit: No 2
3750 Defines the maximum number of chunks in an SCTP packet that will be parsed when
3751 no existing association exists that matches that packet.
3753 will only be an INIT or ASCONF-AddIP packet.
3754 A higher value may become a DoS
3755 risk as malformed packets can consume processing resources.
3756 .It Va net.inet.ip.alias.sctp.param_proc_limit: No 25
3757 Defines the maximum number of parameters within a chunk that will be
3760 As for other similar sysctl variables, larger values pose a DoS risk.
3761 .It Va net.inet.ip.alias.sctp.log_level: No 0
3762 Level of detail in the system log messages (0 \- minimal, 1 \- event,
3763 2 \- info, 3 \- detail, 4 \- debug, 5 \- max debug).
3765 option in high loss environments.
3766 .It Va net.inet.ip.alias.sctp.shutdown_time: No 15
3767 Timeout value while waiting for SHUTDOWN-COMPLETE.
3768 This value cannot be 0.
3769 .It Va net.inet.ip.alias.sctp.track_global_addresses: No 0
3770 Enables/disables global IP address tracking within the
3773 upper limit on the number of addresses tracked for each association:
3774 .Bl -tag -width indent
3776 Global tracking is disabled
3778 Enables tracking, the maximum number of addresses tracked for each
3779 association is limited to this value
3782 This variable is fully dynamic, the new value will be adopted for all newly
3783 arriving associations, existing associations are treated
3784 as they were previously.
3785 Global tracking will decrease the number of collisions within the
3788 of increased processing load, memory usage, complexity, and possible
3791 problems in complex networks with multiple
3793 We recommend not tracking
3794 global IP addresses, this will still result in a fully functional
3796 .It Va net.inet.ip.alias.sctp.up_timer: No 300
3797 Timeout value to keep an association up with no traffic.
3798 This value cannot be 0.
3799 .It Va net.inet.ip.dummynet.codel.interval : No 100000
3802 AQM interval in microseconds.
3803 The value must be in the range 1..5000000.
3804 .It Va net.inet.ip.dummynet.codel.target : No 5000
3807 AQM target delay time in microseconds (the minimum acceptable persistent queue
3809 The value must be in the range 1..5000000.
3810 .It Va net.inet.ip.dummynet.expire : No 1
3811 Lazily delete dynamic pipes/queue once they have no pending traffic.
3812 You can disable this by setting the variable to 0, in which case
3813 the pipes/queues will only be deleted when the threshold is reached.
3814 .It Va net.inet.ip.dummynet.fqcodel.flows : No 1024
3815 Defines the default total number of flow queues (sub-queues) that
3817 creates and manages.
3818 The value must be in the range 1..65536.
3819 .It Va net.inet.ip.dummynet.fqcodel.interval : No 100000
3822 scheduler/AQM interval in microseconds.
3823 The value must be in the range 1..5000000.
3824 .It Va net.inet.ip.dummynet.fqcodel.limit : No 10240
3825 The default hard size limit (in unit of packet) of all queues managed by an
3829 The value must be in the range 1..20480.
3830 .It Va net.inet.ip.dummynet.fqcodel.quantum : No 1514
3831 The default quantum (credit) of the
3834 The value must be in the range 1..9000.
3835 .It Va net.inet.ip.dummynet.fqcodel.target : No 5000
3838 scheduler/AQM target delay time in microseconds (the minimum acceptable
3839 persistent queue delay).
3840 The value must be in the range 1..5000000.
3841 .It Va net.inet.ip.dummynet.fqpie.alpha : No 125
3844 parameter (scaled by 1000) for
3847 The value must be in the range 1..7000.
3848 .It Va net.inet.ip.dummynet.fqpie.beta : No 1250
3851 parameter (scaled by 1000) for
3854 The value must be in the range 1..7000.
3855 .It Va net.inet.ip.dummynet.fqpie.flows : No 1024
3856 Defines the default total number of flow queues (sub-queues) that
3858 creates and manages.
3859 The value must be in the range 1..65536.
3860 .It Va net.inet.ip.dummynet.fqpie.limit : No 10240
3861 The default hard size limit (in unit of packet) of all queues managed by an
3865 The value must be in the range 1..20480.
3866 .It Va net.inet.ip.dummynet.fqpie.max_burst : No 150000
3867 The default maximum period of microseconds that
3869 scheduler/AQM does not drop/mark packets.
3870 The value must be in the range 1..10000000.
3871 .It Va net.inet.ip.dummynet.fqpie.max_ecnth : No 99
3872 The default maximum ECN probability threshold (scaled by 1000) for
3875 The value must be in the range 1..7000.
3876 .It Va net.inet.ip.dummynet.fqpie.quantum : No 1514
3877 The default quantum (credit) of the
3880 The value must be in the range 1..9000.
3881 .It Va net.inet.ip.dummynet.fqpie.target : No 15000
3886 in unit of microsecond.
3887 The value must be in the range 1..5000000.
3888 .It Va net.inet.ip.dummynet.fqpie.tupdate : No 15000
3893 in unit of microsecond.
3894 The value must be in the range 1..5000000.
3895 .It Va net.inet.ip.dummynet.hash_size : No 64
3896 Default size of the hash table used for dynamic pipes/queues.
3897 This value is used when no
3899 option is specified when configuring a pipe/queue.
3900 .It Va net.inet.ip.dummynet.io_fast : No 0
3901 If set to a non-zero value,
3906 operation (see above) is enabled.
3907 .It Va net.inet.ip.dummynet.io_pkt
3908 Number of packets passed to
3910 .It Va net.inet.ip.dummynet.io_pkt_drop
3911 Number of packets dropped by
3913 .It Va net.inet.ip.dummynet.io_pkt_fast
3914 Number of packets bypassed by the
3917 .It Va net.inet.ip.dummynet.max_chain_len : No 16
3918 Target value for the maximum number of pipes/queues in a hash bucket.
3920 .Cm max_chain_len*hash_size
3921 is used to determine the threshold over which empty pipes/queues
3922 will be expired even when
3923 .Cm net.inet.ip.dummynet.expire=0 .
3924 .It Va net.inet.ip.dummynet.red_lookup_depth : No 256
3925 .It Va net.inet.ip.dummynet.red_avg_pkt_size : No 512
3926 .It Va net.inet.ip.dummynet.red_max_pkt_size : No 1500
3927 Parameters used in the computations of the drop probability
3928 for the RED algorithm.
3929 .It Va net.inet.ip.dummynet.pie.alpha : No 125
3932 parameter (scaled by 1000) for
3935 The value must be in the range 1..7000.
3936 .It Va net.inet.ip.dummynet.pie.beta : No 1250
3939 parameter (scaled by 1000) for
3942 The value must be in the range 1..7000.
3943 .It Va net.inet.ip.dummynet.pie.max_burst : No 150000
3944 The default maximum period of microseconds that
3946 AQM does not drop/mark packets.
3947 The value must be in the range 1..10000000.
3948 .It Va net.inet.ip.dummynet.pie.max_ecnth : No 99
3949 The default maximum ECN probability threshold (scaled by 1000) for
3952 The value must be in the range 1..7000.
3953 .It Va net.inet.ip.dummynet.pie.target : No 15000
3958 AQM in unit of microsecond.
3959 The value must be in the range 1..5000000.
3960 .It Va net.inet.ip.dummynet.pie.tupdate : No 15000
3965 AQM in unit of microsecond.
3966 The value must be in the range 1..5000000.
3967 .It Va net.inet.ip.dummynet.pipe_byte_limit : No 1048576
3968 .It Va net.inet.ip.dummynet.pipe_slot_limit : No 100
3969 The maximum queue size that can be specified in bytes or packets.
3970 These limits prevent accidental exhaustion of resources such as mbufs.
3971 If you raise these limits,
3972 you should make sure the system is configured so that sufficient resources
3974 .It Va net.inet.ip.fw.autoinc_step : No 100
3975 Delta between rule numbers when auto-generating them.
3976 The value must be in the range 1..1000.
3977 .It Va net.inet.ip.fw.curr_dyn_buckets : Va net.inet.ip.fw.dyn_buckets
3978 The current number of buckets in the hash table for dynamic rules
3980 .It Va net.inet.ip.fw.debug : No 1
3981 Controls debugging messages produced by
3983 .It Va net.inet.ip.fw.default_rule : No 65535
3984 The default rule number (read-only).
3986 .Nm , the default rule is the last one, so its number
3987 can also serve as the highest number allowed for a rule.
3988 .It Va net.inet.ip.fw.dyn_buckets : No 256
3989 The number of buckets in the hash table for dynamic rules.
3990 Must be a power of 2, up to 65536.
3991 It only takes effect when all dynamic rules have expired, so you
3992 are advised to use a
3994 command to make sure that the hash table is resized.
3995 .It Va net.inet.ip.fw.dyn_count : No 3
3996 Current number of dynamic rules
3998 .It Va net.inet.ip.fw.dyn_keepalive : No 1
3999 Enables generation of keepalive packets for
4001 rules on TCP sessions.
4002 A keepalive is generated to both
4003 sides of the connection every 5 seconds for the last 20
4004 seconds of the lifetime of the rule.
4005 .It Va net.inet.ip.fw.dyn_max : No 8192
4006 Maximum number of dynamic rules.
4007 When you hit this limit, no more dynamic rules can be
4008 installed until old ones expire.
4009 .It Va net.inet.ip.fw.dyn_ack_lifetime : No 300
4010 .It Va net.inet.ip.fw.dyn_syn_lifetime : No 20
4011 .It Va net.inet.ip.fw.dyn_fin_lifetime : No 1
4012 .It Va net.inet.ip.fw.dyn_rst_lifetime : No 1
4013 .It Va net.inet.ip.fw.dyn_udp_lifetime : No 5
4014 .It Va net.inet.ip.fw.dyn_short_lifetime : No 30
4015 These variables control the lifetime, in seconds, of dynamic
4017 Upon the initial SYN exchange the lifetime is kept short,
4018 then increased after both SYN have been seen, then decreased
4019 again during the final FIN exchange or when a RST is received.
4021 .Em dyn_fin_lifetime
4023 .Em dyn_rst_lifetime
4024 must be strictly lower than 5 seconds, the period of
4025 repetition of keepalives.
4026 The firewall enforces that.
4027 .It Va net.inet.ip.fw.dyn_keep_states: No 0
4028 Keep dynamic states on rule/set deletion.
4029 States are relinked to default rule (65535).
4030 This can be handly for ruleset reload.
4031 Turned off by default.
4032 .It Va net.inet.ip.fw.enable : No 1
4033 Enables the firewall.
4034 Setting this variable to 0 lets you run your machine without
4035 firewall even if compiled in.
4036 .It Va net.inet6.ip6.fw.enable : No 1
4037 provides the same functionality as above for the IPv6 case.
4038 .It Va net.inet.ip.fw.one_pass : No 1
4039 When set, the packet exiting from the
4043 node is not passed though the firewall again.
4044 Otherwise, after an action, the packet is
4045 reinjected into the firewall at the next rule.
4046 .It Va net.inet.ip.fw.tables_max : No 128
4047 Maximum number of tables.
4048 .It Va net.inet.ip.fw.verbose : No 1
4049 Enables verbose messages.
4050 .It Va net.inet.ip.fw.verbose_limit : No 0
4051 Limits the number of messages produced by a verbose firewall.
4052 .It Va net.inet6.ip6.fw.deny_unknown_exthdrs : No 1
4053 If enabled packets with unknown IPv6 Extension Headers will be denied.
4054 .It Va net.link.ether.ipfw : No 0
4055 Controls whether layer-2 packets are passed to
4058 .It Va net.link.bridge.ipfw : No 0
4059 Controls whether bridged packets are passed to
4062 .It Va net.inet.ip.fw.nat64_debug : No 0
4063 Controls debugging messages produced by
4066 .It Va net.inet.ip.fw.nat64_direct_output : No 0
4067 Controls the output method used by
4070 .Bl -tag -width indent
4072 A packet is handled by
4075 First time an original packet is handled by
4080 Then translated packet is queued via netisr to input processing again.
4082 A packet is handled by
4084 only once, and after translation it will be pushed directly to outgoing
4088 .Sh INTERNAL DIAGNOSTICS
4089 There are some commands that may be useful to understand current state
4090 of certain subsystems inside kernel module.
4091 These commands provide debugging output which may change without notice.
4093 Currently the following commands are available as
4096 .Bl -tag -width indent
4098 Lists all interface which are currently tracked by
4100 with their in-kernel status.
4102 List all table lookup algorithms currently available.
4105 There are far too many possible uses of
4107 so this Section will only give a small set of examples.
4109 .Ss BASIC PACKET FILTERING
4110 This command adds an entry which denies all tcp packets from
4111 .Em cracker.evil.org
4112 to the telnet port of
4114 from being forwarded by the host:
4116 .Dl "ipfw add deny tcp from cracker.evil.org to wolf.tambov.su telnet"
4118 This one disallows any connection from the entire cracker's
4121 .Dl "ipfw add deny ip from 123.45.67.0/24 to my.host.org"
4123 A first and efficient way to limit access (not using dynamic rules)
4124 is the use of the following rules:
4126 .Dl "ipfw add allow tcp from any to any established"
4127 .Dl "ipfw add allow tcp from net1 portlist1 to net2 portlist2 setup"
4128 .Dl "ipfw add allow tcp from net3 portlist3 to net3 portlist3 setup"
4130 .Dl "ipfw add deny tcp from any to any"
4132 The first rule will be a quick match for normal TCP packets,
4133 but it will not match the initial SYN packet, which will be
4136 rules only for selected source/destination pairs.
4137 All other SYN packets will be rejected by the final
4141 If you administer one or more subnets, you can take advantage
4142 of the address sets and or-blocks and write extremely
4143 compact rulesets which selectively enable services to blocks
4144 of clients, as below:
4146 .Dl "goodguys=\*q{ 10.1.2.0/24{20,35,66,18} or 10.2.3.0/28{6,3,11} }\*q"
4147 .Dl "badguys=\*q10.1.2.0/24{8,38,60}\*q"
4149 .Dl "ipfw add allow ip from ${goodguys} to any"
4150 .Dl "ipfw add deny ip from ${badguys} to any"
4151 .Dl "... normal policies ..."
4155 option could be used to do automated anti-spoofing by adding the
4156 following to the top of a ruleset:
4158 .Dl "ipfw add deny ip from any to any not verrevpath in"
4160 This rule drops all incoming packets that appear to be coming to the
4161 system on the wrong interface.
4162 For example, a packet with a source
4163 address belonging to a host on a protected internal network would be
4164 dropped if it tried to enter the system from an external interface.
4168 option could be used to do similar but more restricted anti-spoofing
4169 by adding the following to the top of a ruleset:
4171 .Dl "ipfw add deny ip from any to any not antispoof in"
4173 This rule drops all incoming packets that appear to be coming from another
4174 directly connected system but on the wrong interface.
4175 For example, a packet with a source address of
4176 .Li 192.168.0.0/24 ,
4185 option could be used to (re)mark user traffic,
4186 by adding the following to the appropriate place in ruleset:
4188 .Dl "ipfw add setdscp be ip from any to any dscp af11,af21"
4189 .Ss SELECTIVE MIRRORING
4190 If your network has network traffic analyzer
4191 connected to your host directly via dedicated interface
4192 or remotely via RSPAN vlan, you can selectively mirror
4193 some Ethernet layer2 frames to the analyzer.
4195 First, make sure your firewall is already configured and runs.
4196 Then, enable layer2 processing if not already enabled:
4198 .Dl "sysctl net.link.ether.ipfw=1"
4200 Next, load needed additional kernel modules:
4202 .Dl "kldload ng_ether ng_ipfw"
4204 Optionally, make system load these modules automatically
4207 .Dl sysrc kld_list+="ng_ether ng_ipfw"
4211 kernel module to transmit mirrored copies of layer2 frames
4212 out via vlan900 interface:
4214 .Dl "ngctl connect ipfw: vlan900: 1 lower"
4216 Think of "1" here as of "mirroring instance index" and vlan900 is its
4218 You can have arbitrary number of instances.
4223 At last, actually start mirroring of selected frames using "instance 1".
4224 For frames incoming from em0 interface:
4226 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 in recv em0"
4228 For frames outgoing to em0 interface:
4230 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 out xmit em0"
4232 For both incoming and outgoing frames while flowing through em0:
4234 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 via em0"
4236 Make sure you do not perform mirroring for already duplicated frames
4237 or kernel may hang as there is no safety net.
4239 In order to protect a site from flood attacks involving fake
4240 TCP packets, it is safer to use dynamic rules:
4242 .Dl "ipfw add check-state"
4243 .Dl "ipfw add deny tcp from any to any established"
4244 .Dl "ipfw add allow tcp from my-net to any setup keep-state"
4246 This will let the firewall install dynamic rules only for
4247 those connection which start with a regular SYN packet coming
4248 from the inside of our network.
4249 Dynamic rules are checked when encountering the first
4258 rule should usually be placed near the beginning of the
4259 ruleset to minimize the amount of work scanning the ruleset.
4260 Your mileage may vary.
4262 For more complex scenarios with dynamic rules
4266 can be used to precisely control creation and checking of dynamic rules.
4267 Example of usage of these options are provided in
4268 .Sx NETWORK ADDRESS TRANSLATION (NAT)
4271 To limit the number of connections a user can open
4272 you can use the following type of rules:
4274 .Dl "ipfw add allow tcp from my-net/24 to any setup limit src-addr 10"
4275 .Dl "ipfw add allow tcp from any to me setup limit src-addr 4"
4277 The former (assuming it runs on a gateway) will allow each host
4278 on a /24 network to open at most 10 TCP connections.
4279 The latter can be placed on a server to make sure that a single
4280 client does not use more than 4 simultaneous connections.
4283 stateful rules can be subject to denial-of-service attacks
4284 by a SYN-flood which opens a huge number of dynamic rules.
4285 The effects of such attacks can be partially limited by
4288 variables which control the operation of the firewall.
4290 Here is a good usage of the
4292 command to see accounting records and timestamp information:
4296 or in short form without timestamps:
4300 which is equivalent to:
4304 Next rule diverts all incoming packets from 192.168.2.0/24
4305 to divert port 5000:
4307 .Dl ipfw divert 5000 ip from 192.168.2.0/24 to any in
4309 The following rules show some of the applications of
4313 for simulations and the like.
4315 This rule drops random incoming packets with a probability
4318 .Dl "ipfw add prob 0.05 deny ip from any to any in"
4320 A similar effect can be achieved making use of
4324 .Dl "ipfw add pipe 10 ip from any to any"
4325 .Dl "ipfw pipe 10 config plr 0.05"
4327 We can use pipes to artificially limit bandwidth, e.g.\& on a
4328 machine acting as a router, if we want to limit traffic from
4329 local clients on 192.168.2.0/24 we do:
4331 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4332 .Dl "ipfw pipe 1 config bw 300Kbit/s queue 50KBytes"
4334 note that we use the
4336 modifier so that the rule is not used twice.
4337 Remember in fact that
4339 rules are checked both on incoming and outgoing packets.
4341 Should we want to simulate a bidirectional link with bandwidth
4342 limitations, the correct way is the following:
4344 .Dl "ipfw add pipe 1 ip from any to any out"
4345 .Dl "ipfw add pipe 2 ip from any to any in"
4346 .Dl "ipfw pipe 1 config bw 64Kbit/s queue 10Kbytes"
4347 .Dl "ipfw pipe 2 config bw 64Kbit/s queue 10Kbytes"
4349 The above can be very useful, e.g.\& if you want to see how
4350 your fancy Web page will look for a residential user who
4351 is connected only through a slow link.
4352 You should not use only one pipe for both directions, unless
4353 you want to simulate a half-duplex medium (e.g.\& AppleTalk,
4355 It is not necessary that both pipes have the same configuration,
4356 so we can also simulate asymmetric links.
4358 Should we want to verify network performance with the RED queue
4359 management algorithm:
4361 .Dl "ipfw add pipe 1 ip from any to any"
4362 .Dl "ipfw pipe 1 config bw 500Kbit/s queue 100 red 0.002/30/80/0.1"
4364 Another typical application of the traffic shaper is to
4365 introduce some delay in the communication.
4366 This can significantly affect applications which do a lot of Remote
4367 Procedure Calls, and where the round-trip-time of the
4368 connection often becomes a limiting factor much more than
4371 .Dl "ipfw add pipe 1 ip from any to any out"
4372 .Dl "ipfw add pipe 2 ip from any to any in"
4373 .Dl "ipfw pipe 1 config delay 250ms bw 1Mbit/s"
4374 .Dl "ipfw pipe 2 config delay 250ms bw 1Mbit/s"
4376 Per-flow queueing can be useful for a variety of purposes.
4377 A very simple one is counting traffic:
4379 .Dl "ipfw add pipe 1 tcp from any to any"
4380 .Dl "ipfw add pipe 1 udp from any to any"
4381 .Dl "ipfw add pipe 1 ip from any to any"
4382 .Dl "ipfw pipe 1 config mask all"
4384 The above set of rules will create queues (and collect
4385 statistics) for all traffic.
4386 Because the pipes have no limitations, the only effect is
4387 collecting statistics.
4388 Note that we need 3 rules, not just the last one, because
4391 tries to match IP packets it will not consider ports, so we
4392 would not see connections on separate ports as different
4395 A more sophisticated example is limiting the outbound traffic
4396 on a net with per-host limits, rather than per-network limits:
4398 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4399 .Dl "ipfw add pipe 2 ip from any to 192.168.2.0/24 in"
4400 .Dl "ipfw pipe 1 config mask src-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4401 .Dl "ipfw pipe 2 config mask dst-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4403 In the following example, we need to create several traffic bandwidth
4404 classes and we need different hosts/networks to fall into different classes.
4405 We create one pipe for each class and configure them accordingly.
4406 Then we create a single table and fill it with IP subnets and addresses.
4407 For each subnet/host we set the argument equal to the number of the pipe
4409 Then we classify traffic using a single rule:
4411 .Dl "ipfw pipe 1 config bw 1000Kbyte/s"
4412 .Dl "ipfw pipe 4 config bw 4000Kbyte/s"
4414 .Dl "ipfw table T1 create type addr"
4415 .Dl "ipfw table T1 add 192.168.2.0/24 1"
4416 .Dl "ipfw table T1 add 192.168.0.0/27 4"
4417 .Dl "ipfw table T1 add 192.168.0.2 1"
4419 .Dl "ipfw add pipe tablearg ip from 'table(T1)' to any"
4423 action, the table entries may include hostnames and IP addresses.
4425 .Dl "ipfw table T2 create type addr ftype ip"
4426 .Dl "ipfw table T2 add 192.168.2.0/24 10.23.2.1"
4427 .Dl "ipfw table T21 add 192.168.0.0/27 router1.dmz"
4429 .Dl "ipfw add 100 fwd tablearg ip from any to table(1)"
4431 In the following example per-interface firewall is created:
4433 .Dl "ipfw table IN create type iface valtype skipto,fib"
4434 .Dl "ipfw table IN add vlan20 12000,12"
4435 .Dl "ipfw table IN add vlan30 13000,13"
4436 .Dl "ipfw table OUT create type iface valtype skipto"
4437 .Dl "ipfw table OUT add vlan20 22000"
4438 .Dl "ipfw table OUT add vlan30 23000"
4440 .Dl "ipfw add 100 setfib tablearg ip from any to any recv 'table(IN)' in"
4441 .Dl "ipfw add 200 skipto tablearg ip from any to any recv 'table(IN)' in"
4442 .Dl "ipfw add 300 skipto tablearg ip from any to any xmit 'table(OUT)' out"
4444 The following example illustrate usage of flow tables:
4446 .Dl "ipfw table fl create type flow:src-ip,proto,dst-ip,dst-port"
4447 .Dl "ipfw table fl add 2a02:6b8:77::88,tcp,2a02:6b8:77::99,80 11"
4448 .Dl "ipfw table fl add 10.0.0.1,udp,10.0.0.2,53 12"
4450 .Dl "ipfw add 100 allow ip from any to any flow 'table(fl,11)' recv ix0"
4452 To add a set of rules atomically, e.g.\& set 18:
4454 .Dl "ipfw set disable 18"
4455 .Dl "ipfw add NN set 18 ... # repeat as needed"
4456 .Dl "ipfw set enable 18"
4458 To delete a set of rules atomically the command is simply:
4460 .Dl "ipfw delete set 18"
4462 To test a ruleset and disable it and regain control if something goes wrong:
4464 .Dl "ipfw set disable 18"
4465 .Dl "ipfw add NN set 18 ... # repeat as needed"
4466 .Dl "ipfw set enable 18; echo done; sleep 30 && ipfw set disable 18"
4468 Here if everything goes well, you press control-C before the "sleep"
4469 terminates, and your ruleset will be left active.
4470 Otherwise, e.g.\& if
4471 you cannot access your box, the ruleset will be disabled after
4472 the sleep terminates thus restoring the previous situation.
4474 To show rules of the specific set:
4476 .Dl "ipfw set 18 show"
4478 To show rules of the disabled set:
4480 .Dl "ipfw -S set 18 show"
4482 To clear a specific rule counters of the specific set:
4484 .Dl "ipfw set 18 zero NN"
4486 To delete a specific rule of the specific set:
4488 .Dl "ipfw set 18 delete NN"
4489 .Ss NAT, REDIRECT AND LSNAT
4490 First redirect all the traffic to nat instance 123:
4492 .Dl "ipfw add nat 123 all from any to any"
4494 Then to configure nat instance 123 to alias all the outgoing traffic with ip
4495 192.168.0.123, blocking all incoming connections, trying to keep
4496 same ports on both sides, clearing aliasing table on address change
4497 and keeping a log of traffic/link statistics:
4499 .Dl "ipfw nat 123 config ip 192.168.0.123 log deny_in reset same_ports"
4501 Or to change address of instance 123, aliasing table will be cleared (see
4504 .Dl "ipfw nat 123 config ip 10.0.0.1"
4506 To see configuration of nat instance 123:
4508 .Dl "ipfw nat 123 show config"
4510 To show logs of all the instances in range 111-999:
4512 .Dl "ipfw nat 111-999 show"
4514 To see configurations of all instances:
4516 .Dl "ipfw nat show config"
4518 Or a redirect rule with mixed modes could looks like:
4520 .Dl "ipfw nat 123 config redirect_addr 10.0.0.1 10.0.0.66"
4521 .Dl " redirect_port tcp 192.168.0.1:80 500"
4522 .Dl " redirect_proto udp 192.168.1.43 192.168.1.1"
4523 .Dl " redirect_addr 192.168.0.10,192.168.0.11"
4524 .Dl " 10.0.0.100 # LSNAT"
4525 .Dl " redirect_port tcp 192.168.0.1:80,192.168.0.10:22"
4528 or it could be split in:
4530 .Dl "ipfw nat 1 config redirect_addr 10.0.0.1 10.0.0.66"
4531 .Dl "ipfw nat 2 config redirect_port tcp 192.168.0.1:80 500"
4532 .Dl "ipfw nat 3 config redirect_proto udp 192.168.1.43 192.168.1.1"
4533 .Dl "ipfw nat 4 config redirect_addr 192.168.0.10,192.168.0.11,192.168.0.12"
4535 .Dl "ipfw nat 5 config redirect_port tcp"
4536 .Dl " 192.168.0.1:80,192.168.0.10:22,192.168.0.20:25 500"
4538 Sometimes you may want to mix NAT and dynamic rules. It could be achieved with
4542 options. Problem is, you need to create dynamic rule before NAT and check it
4543 after NAT actions (or vice versa) to have consistent addresses and ports.
4546 option will trigger activation of existing dynamic state, and action of such
4547 rule will be performed as soon as rule is matched. In case of NAT and
4549 rule packet need to be passed to NAT, not allowed as soon is possible.
4551 There is example of set of rules to achieve this. Bear in mind that this
4552 is exmaple only and it is not very useful by itself.
4554 On way out, after all checks place this rules:
4556 .Dl "ipfw add allow record-state skip-action"
4557 .Dl "ipfw add nat 1"
4559 And on way in there should be something like this:
4561 .Dl "ipfw add nat 1"
4562 .Dl "ipfw add check-state"
4564 Please note, that first rule on way out doesn't allow packet and doesn't
4565 execute existing dynamic rules. All it does, create new dynamic rule with
4567 action, if it is not created yet. Later, this dynamic rule is used on way
4571 .Ss CONFIGURING CODEL, PIE, FQ-CODEL and FQ-PIE AQM
4575 AQM can be configured for
4585 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4588 .Dl "ipfw pipe 1 config bw 1mbits/s codel"
4589 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4595 AQM using different configurations parameters for traffic from
4596 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4598 .Dl "ipfw pipe 1 config bw 1mbits/s"
4599 .Dl "ipfw queue 1 config pipe 1 codel target 8ms interval 160ms ecn"
4600 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4606 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4609 .Dl "ipfw pipe 1 config bw 1mbits/s pie"
4610 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4616 AQM using different configuration parameters for traffic from
4617 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4619 .Dl "ipfw pipe 1 config bw 1mbits/s"
4620 .Dl "ipfw queue 1 config pipe 1 pie target 20ms tupdate 30ms ecn"
4621 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4626 AQM can be configured for
4632 scheduler using different configurations parameters for traffic from
4633 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4635 .Dl "ipfw pipe 1 config bw 1mbits/s"
4636 .Dl "ipfw sched 1 config pipe 1 type fq_codel"
4637 .Dl "ipfw queue 1 config sched 1"
4638 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4642 default configuration for a
4644 such as disable ECN and change the
4648 .Dl "ipfw sched 1 config pipe 1 type fq_codel target 10ms noecn"
4654 scheduler using different configurations parameters for traffic from
4655 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4657 .Dl "ipfw pipe 1 config bw 1mbits/s"
4658 .Dl "ipfw sched 1 config pipe 1 type fq_pie"
4659 .Dl "ipfw queue 1 config sched 1"
4660 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4662 The configurations of
4665 can be changed in a similar way as for
4689 utility first appeared in
4694 Stateful extensions were introduced in
4697 was introduced in Summer 2002.
4699 .An Ugen J. S. Antsilevich ,
4700 .An Poul-Henning Kamp ,
4704 .An Rasool Al-Saadi .
4707 API based upon code written by
4711 Dummynet has been introduced by Luigi Rizzo in 1997-1998.
4713 Some early work (1999-2000) on the
4715 traffic shaper supported by Akamba Corp.
4717 The ipfw core (ipfw2) has been completely redesigned and
4718 reimplemented by Luigi Rizzo in summer 2002.
4721 options have been added by various developers over the years.
4724 In-kernel NAT support written by
4725 .An Paolo Pisati Aq Mt piso@FreeBSD.org
4726 as part of a Summer of Code 2005 project.
4730 support has been developed by
4731 .An The Centre for Advanced Internet Architectures (CAIA) Aq http://www.caia.swin.edu.au .
4732 The primary developers and maintainers are David Hayes and Jason But.
4733 For further information visit:
4734 .Aq http://www.caia.swin.edu.au/urp/SONATA
4736 Delay profiles have been developed by Alessandro Cerri and
4737 Luigi Rizzo, supported by the
4738 European Commission within Projects Onelab and Onelab2.
4740 CoDel, PIE, FQ-CoDel and FQ-PIE AQM for Dummynet have been implemented by
4741 .An The Centre for Advanced Internet Architectures (CAIA)
4742 in 2016, supported by The Comcast Innovation Fund.
4743 The primary developer is
4746 The syntax has grown over the years and sometimes it might be confusing.
4747 Unfortunately, backward compatibility prevents cleaning up mistakes
4748 made in the definition of the syntax.
4752 Misconfiguring the firewall can put your computer in an unusable state,
4753 possibly shutting down network services and requiring console access to
4754 regain control of it.
4756 Incoming packet fragments diverted by
4758 are reassembled before delivery to the socket.
4759 The action used on those packet is the one from the
4760 rule which matches the first fragment of the packet.
4762 Packets diverted to userland, and then reinserted by a userland process
4763 may lose various packet attributes.
4764 The packet source interface name
4765 will be preserved if it is shorter than 8 bytes and the userland process
4766 saves and reuses the sockaddr_in
4769 otherwise, it may be lost.
4770 If a packet is reinserted in this manner, later rules may be incorrectly
4771 applied, making the order of
4773 rules in the rule sequence very important.
4775 Dummynet drops all packets with IPv6 link-local addresses.
4781 may not behave as expected.
4782 In particular, incoming SYN packets may
4783 have no uid or gid associated with them since they do not yet belong
4784 to a TCP connection, and the uid/gid associated with a packet may not
4785 be as expected if the associated process calls
4787 or similar system calls.
4789 Rule syntax is subject to the command line environment and some patterns
4790 may need to be escaped with the backslash character
4791 or quoted appropriately.
4793 Due to the architecture of
4795 ipfw nat is not compatible with the TCP segmentation offloading (TSO).
4796 Thus, to reliably nat your network traffic, please disable TSO
4800 ICMP error messages are not implicitly matched by dynamic rules
4801 for the respective conversations.
4802 To avoid failures of network error detection and path MTU discovery,
4803 ICMP error messages may need to be allowed explicitly through static
4810 actions may lead to confusing behaviour if ruleset has mistakes,
4811 and/or interaction with other subsystems (netgraph, dummynet, etc.) is used.
4812 One possible case for this is packet leaving
4814 in subroutine on the input pass, while later on output encountering unpaired
4817 As the call stack is kept intact after input pass, packet will suddenly
4818 return to the rule number used on input pass, not on output one.
4819 Order of processing should be checked carefully to avoid such mistakes.
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