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 tcpseq Ar seq
1994 Match if the TCP header sequence number field is set to
1996 .It Cm tcpwin Ar tcpwin-list
1997 Matches TCP packets whose header window field is set to
1999 which is either a single value or a list of values or ranges
2000 specified in the same way as
2002 .It Cm tcpoptions Ar spec
2004 Match if the TCP header contains the comma separated list of
2005 options specified in
2007 The supported TCP options are:
2010 (maximum segment size),
2012 (tcp window advertisement),
2016 (rfc1323 timestamp) and
2018 (rfc1644 t/tcp connection count).
2019 The absence of a particular option may be denoted
2023 Match all TCP or UDP packets sent by or received for a
2027 may be matched by name or identification number.
2029 For incoming packets,
2030 a routing table lookup is done on the packet's source address.
2031 If the interface on which the packet entered the system matches the
2032 outgoing interface for the route,
2034 If the interfaces do not match up,
2035 the packet does not match.
2036 All outgoing packets or packets with no incoming interface match.
2038 The name and functionality of the option is intentionally similar to
2039 the Cisco IOS command:
2041 .Dl ip verify unicast reverse-path
2043 This option can be used to make anti-spoofing rules to reject all
2044 packets with source addresses not from this interface.
2048 For incoming packets,
2049 a routing table lookup is done on the packet's source address.
2050 If a route to the source address exists, but not the default route
2051 or a blackhole/reject route, the packet matches.
2052 Otherwise, the packet does not match.
2053 All outgoing packets match.
2055 The name and functionality of the option is intentionally similar to
2056 the Cisco IOS command:
2058 .Dl ip verify unicast source reachable-via any
2060 This option can be used to make anti-spoofing rules to reject all
2061 packets whose source address is unreachable.
2063 For incoming packets, the packet's source address is checked if it
2064 belongs to a directly connected network.
2065 If the network is directly connected, then the interface the packet
2066 came on in is compared to the interface the network is connected to.
2067 When incoming interface and directly connected interface are not the
2068 same, the packet does not match.
2069 Otherwise, the packet does match.
2070 All outgoing packets match.
2072 This option can be used to make anti-spoofing rules to reject all
2073 packets that pretend to be from a directly connected network but do
2074 not come in through that interface.
2075 This option is similar to but more restricted than
2077 because it engages only on packets with source addresses of directly
2078 connected networks instead of all source addresses.
2081 Lookup tables are useful to handle large sparse sets of
2082 addresses or other search keys (e.g., ports, jail IDs, interface names).
2083 In the rest of this section we will use the term ``key''.
2084 Table name needs to match the following spec:
2086 Tables with the same name can be created in different
2088 However, rule links to the tables in
2091 This behavior can be controlled by
2092 .Va net.inet.ip.fw.tables_sets
2096 section for more information.
2097 There may be up to 65535 different lookup tables.
2099 The following table types are supported:
2100 .Bl -tag -width indent
2101 .It Ar table-type : Ar addr | iface | number | flow
2102 .It Ar table-key : Ar addr Ns Oo / Ns Ar masklen Oc | iface-name | number | flow-spec
2103 .It Ar flow-spec : Ar flow-field Ns Op , Ns Ar flow-spec
2104 .It Ar flow-field : src-ip | proto | src-port | dst-ip | dst-port
2106 Matches IPv4 or IPv6 address.
2107 Each entry is represented by an
2108 .Ar addr Ns Op / Ns Ar masklen
2109 and will match all addresses with base
2111 (specified as an IPv4/IPv6 address, or a hostname) and mask width of
2116 is not specified, it defaults to 32 for IPv4 and 128 for IPv6.
2117 When looking up an IP address in a table, the most specific
2120 Matches interface names.
2121 Each entry is represented by string treated as interface name.
2122 Wildcards are not supported.
2124 Matches protocol ports, uids/gids or jail IDs.
2125 Each entry is represented by 32-bit unsigned integer.
2126 Ranges are not supported.
2128 Matches packet fields specified by
2130 type suboptions with table entries.
2133 Tables require explicit creation via
2137 The following creation options are supported:
2138 .Bl -tag -width indent
2139 .It Ar create-options : Ar create-option | create-options
2140 .It Ar create-option : Cm type Ar table-type | Cm valtype Ar value-mask | Cm algo Ar algo-desc |
2141 .Cm limit Ar number | Cm locked | Cm missing | Cm or-flush
2147 Table algorithm to use (see below).
2149 Maximum number of items that may be inserted into table.
2151 Restrict any table modifications.
2153 Do not fail if table already exists and has exactly same options as new one.
2155 Flush existing table with same name instead of returning error.
2158 so existing table must be compatible with new one.
2161 Some of these options may be modified later via
2164 The following options can be changed:
2165 .Bl -tag -width indent
2166 .It Ar modify-options : Ar modify-option | modify-options
2167 .It Ar modify-option : Cm limit Ar number
2169 Alter maximum number of items that may be inserted into table.
2172 Additionally, table can be locked or unlocked using
2180 can be swapped with each other using
2183 Swap may fail if tables limits are set and data exchange
2184 would result in limits hit.
2185 Operation is performed atomically.
2187 One or more entries can be added to a table at once using
2190 Addition of all items are performed atomically.
2191 By default, error in addition of one entry does not influence
2192 addition of other entries. However, non-zero error code is returned
2196 keyword may be specified before
2198 to indicate all-or-none add request.
2200 One or more entries can be removed from a table at once using
2203 By default, error in removal of one entry does not influence
2204 removing of other entries. However, non-zero error code is returned
2207 It may be possible to check what entry will be found on particular
2213 This functionality is optional and may be unsupported in some algorithms.
2215 The following operations can be performed on
2220 .Bl -tag -width indent
2224 Removes all entries.
2226 Shows generic table information.
2228 Shows generic table information and algo-specific data.
2231 The following lookup algorithms are supported:
2232 .Bl -tag -width indent
2233 .It Ar algo-desc : algo-name | "algo-name algo-data"
2234 .It Ar algo-name: Ar addr:radix | addr:hash | iface:array | number:array | flow:hash
2236 Separate Radix trees for IPv4 and IPv6, the same way as the routing table (see
2242 Separate auto-growing hashes for IPv4 and IPv6.
2243 Accepts entries with the same mask length specified initially via
2244 .Cm "addr:hash masks=/v4,/v6"
2245 algorithm creation options.
2246 Assume /32 and /128 masks by default.
2247 Search removes host bits (according to mask) from supplied address and checks
2248 resulting key in appropriate hash.
2249 Mostly optimized for /64 and byte-ranged IPv6 masks.
2251 Array storing sorted indexes for entries which are presented in the system.
2252 Optimized for very fast lookup.
2254 Array storing sorted u32 numbers.
2256 Auto-growing hash storing flow entries.
2257 Search calculates hash on required packet fields and searches for matching
2258 entries in selected bucket.
2263 feature provides the ability to use a value, looked up in the table, as
2264 the argument for a rule action, action parameter or rule option.
2265 This can significantly reduce number of rules in some configurations.
2266 If two tables are used in a rule, the result of the second (destination)
2269 Each record may hold one or more values according to
2271 This mask is set on table creation via
2274 The following value types are supported:
2275 .Bl -tag -width indent
2276 .It Ar value-mask : Ar value-type Ns Op , Ns Ar value-mask
2277 .It Ar value-type : Ar skipto | pipe | fib | nat | dscp | tag | divert |
2278 .Ar netgraph | limit | ipv4
2280 rule number to jump to.
2284 fib number to match/set.
2286 nat number to jump to.
2288 dscp value to match/set.
2290 tag number to match/set.
2292 port number to divert traffic to.
2294 hook number to move packet to.
2296 maximum number of connections.
2298 IPv4 nexthop to fwd packets to.
2300 IPv6 nexthop to fwd packets to.
2305 argument can be used with the following actions:
2306 .Cm nat, pipe , queue, divert, tee, netgraph, ngtee, fwd, skipto, setfib,
2314 action, the user should be aware that the code will walk the ruleset
2315 up to a rule equal to, or past, the given number.
2319 Section for example usage of tables and the tablearg keyword.
2321 Each rule or table belongs to one of 32 different
2324 Set 31 is reserved for the default rule.
2326 By default, rules or tables are put in set 0, unless you use the
2328 attribute when adding a new rule or table.
2329 Sets can be individually and atomically enabled or disabled,
2330 so this mechanism permits an easy way to store multiple configurations
2331 of the firewall and quickly (and atomically) switch between them.
2333 By default, tables from set 0 are referenced when adding rule with
2334 table opcodes regardless of rule set.
2335 This behavior can be changed by setting
2336 .Va net.inet.ip.fw.tables_sets
2338 Rule's set will then be used for table references.
2340 The command to enable/disable sets is
2341 .Bd -ragged -offset indent
2343 .Cm set Oo Cm disable Ar number ... Oc Op Cm enable Ar number ...
2350 sections can be specified.
2351 Command execution is atomic on all the sets specified in the command.
2352 By default, all sets are enabled.
2354 When you disable a set, its rules behave as if they do not exist
2355 in the firewall configuration, with only one exception:
2356 .Bd -ragged -offset indent
2357 dynamic rules created from a rule before it had been disabled
2358 will still be active until they expire.
2360 dynamic rules you have to explicitly delete the parent rule
2361 which generated them.
2364 The set number of rules can be changed with the command
2365 .Bd -ragged -offset indent
2368 .Brq Cm rule Ar rule-number | old-set
2372 Also, you can atomically swap two rulesets with the command
2373 .Bd -ragged -offset indent
2375 .Cm set swap Ar first-set second-set
2380 Section on some possible uses of sets of rules.
2381 .Sh STATEFUL FIREWALL
2382 Stateful operation is a way for the firewall to dynamically
2383 create rules for specific flows when packets that
2384 match a given pattern are detected.
2385 Support for stateful
2386 operation comes through the
2387 .Cm check-state , keep-state , record-state , limit
2393 Dynamic rules are created when a packet matches a
2399 rule, causing the creation of a
2401 rule which will match all and only packets with
2405 .Em src-ip/src-port dst-ip/dst-port
2410 are used here only to denote the initial match addresses, but they
2411 are completely equivalent afterwards).
2417 This name is used in matching together with addresses, ports and protocol.
2418 Dynamic rules will be checked at the first
2419 .Cm check-state, keep-state
2422 occurrence, and the action performed upon a match will be the same
2423 as in the parent rule.
2425 Note that no additional attributes other than protocol and IP addresses
2426 and ports and :flowname are checked on dynamic rules.
2428 The typical use of dynamic rules is to keep a closed firewall configuration,
2429 but let the first TCP SYN packet from the inside network install a
2430 dynamic rule for the flow so that packets belonging to that session
2431 will be allowed through the firewall:
2433 .Dl "ipfw add check-state :OUTBOUND"
2434 .Dl "ipfw add allow tcp from my-subnet to any setup keep-state :OUTBOUND"
2435 .Dl "ipfw add deny tcp from any to any"
2437 A similar approach can be used for UDP, where an UDP packet coming
2438 from the inside will install a dynamic rule to let the response through
2441 .Dl "ipfw add check-state :OUTBOUND"
2442 .Dl "ipfw add allow udp from my-subnet to any keep-state :OUTBOUND"
2443 .Dl "ipfw add deny udp from any to any"
2445 Dynamic rules expire after some time, which depends on the status
2446 of the flow and the setting of some
2450 .Sx SYSCTL VARIABLES
2452 For TCP sessions, dynamic rules can be instructed to periodically
2453 send keepalive packets to refresh the state of the rule when it is
2458 for more examples on how to use dynamic rules.
2459 .Sh TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
2461 is also the user interface for the
2463 traffic shaper, packet scheduler and network emulator, a subsystem that
2464 can artificially queue, delay or drop packets
2465 emulating the behaviour of certain network links
2466 or queueing systems.
2469 operates by first using the firewall to select packets
2470 using any match pattern that can be used in
2473 Matching packets are then passed to either of two
2474 different objects, which implement the traffic regulation:
2475 .Bl -hang -offset XXXX
2481 with given bandwidth and propagation delay,
2482 driven by a FIFO scheduler and a single queue with programmable
2483 queue size and packet loss rate.
2484 Packets are appended to the queue as they come out from
2486 and then transferred in FIFO order to the link at the desired rate.
2490 is an abstraction used to implement packet scheduling
2491 using one of several packet scheduling algorithms.
2494 are first grouped into flows according to a mask on the 5-tuple.
2495 Flows are then passed to the scheduler associated to the
2497 and each flow uses scheduling parameters (weight and others)
2498 as configured in the
2501 A scheduler in turn is connected to an emulated link,
2502 and arbitrates the link's bandwidth among backlogged flows according to
2503 weights and to the features of the scheduling algorithm in use.
2508 can be used to set hard limits to the bandwidth that a flow can use, whereas
2510 can be used to determine how different flows share the available bandwidth.
2512 A graphical representation of the binding of queues,
2513 flows, schedulers and links is below.
2514 .Bd -literal -offset indent
2515 (flow_mask|sched_mask) sched_mask
2516 +---------+ weight Wx +-------------+
2517 | |->-[flow]-->--| |-+
2518 -->--| QUEUE x | ... | | |
2519 | |->-[flow]-->--| SCHEDuler N | |
2521 ... | +--[LINK N]-->--
2522 +---------+ weight Wy | | +--[LINK N]-->--
2523 | |->-[flow]-->--| | |
2524 -->--| QUEUE y | ... | | |
2525 | |->-[flow]-->--| | |
2526 +---------+ +-------------+ |
2529 It is important to understand the role of the SCHED_MASK
2530 and FLOW_MASK, which are configured through the commands
2531 .Dl "ipfw sched N config mask SCHED_MASK ..."
2533 .Dl "ipfw queue X config mask FLOW_MASK ..." .
2535 The SCHED_MASK is used to assign flows to one or more
2536 scheduler instances, one for each
2537 value of the packet's 5-tuple after applying SCHED_MASK.
2538 As an example, using ``src-ip 0xffffff00'' creates one instance
2539 for each /24 destination subnet.
2541 The FLOW_MASK, together with the SCHED_MASK, is used to split
2543 As an example, using
2544 ``src-ip 0x000000ff''
2545 together with the previous SCHED_MASK makes a flow for
2546 each individual source address.
2547 In turn, flows for each /24
2548 subnet will be sent to the same scheduler instance.
2550 The above diagram holds even for the
2552 case, with the only restriction that a
2554 only supports a SCHED_MASK, and forces the use of a FIFO
2555 scheduler (these are for backward compatibility reasons;
2556 in fact, internally, a
2558 pipe is implemented exactly as above).
2560 There are two modes of
2568 mode tries to emulate a real link: the
2570 scheduler ensures that the packet will not leave the pipe faster than it
2571 would on the real link with a given bandwidth.
2574 mode allows certain packets to bypass the
2576 scheduler (if packet flow does not exceed pipe's bandwidth).
2577 This is the reason why the
2579 mode requires less CPU cycles per packet (on average) and packet latency
2580 can be significantly lower in comparison to a real link with the same
2586 mode can be enabled by setting the
2587 .Va net.inet.ip.dummynet.io_fast
2589 variable to a non-zero value.
2591 .Ss PIPE, QUEUE AND SCHEDULER CONFIGURATION
2597 configuration commands are the following:
2598 .Bd -ragged -offset indent
2599 .Cm pipe Ar number Cm config Ar pipe-configuration
2601 .Cm queue Ar number Cm config Ar queue-configuration
2603 .Cm sched Ar number Cm config Ar sched-configuration
2606 The following parameters can be configured for a pipe:
2608 .Bl -tag -width indent -compact
2609 .It Cm bw Ar bandwidth | device
2610 Bandwidth, measured in
2613 .Brq Cm bit/s | Byte/s .
2616 A value of 0 (default) means unlimited bandwidth.
2617 The unit must immediately follow the number, as in
2619 .Dl "ipfw pipe 1 config bw 300Kbit/s"
2621 If a device name is specified instead of a numeric value, as in
2623 .Dl "ipfw pipe 1 config bw tun0"
2625 then the transmit clock is supplied by the specified device.
2626 At the moment only the
2628 device supports this
2629 functionality, for use in conjunction with
2632 .It Cm delay Ar ms-delay
2633 Propagation delay, measured in milliseconds.
2634 The value is rounded to the next multiple of the clock tick
2635 (typically 10ms, but it is a good practice to run kernels
2637 .Dq "options HZ=1000"
2639 the granularity to 1ms or less).
2640 The default value is 0, meaning no delay.
2642 .It Cm burst Ar size
2643 If the data to be sent exceeds the pipe's bandwidth limit
2644 (and the pipe was previously idle), up to
2646 bytes of data are allowed to bypass the
2648 scheduler, and will be sent as fast as the physical link allows.
2649 Any additional data will be transmitted at the rate specified
2653 The burst size depends on how long the pipe has been idle;
2654 the effective burst size is calculated as follows:
2661 .It Cm profile Ar filename
2662 A file specifying the additional overhead incurred in the transmission
2663 of a packet on the link.
2665 Some link types introduce extra delays in the transmission
2666 of a packet, e.g., because of MAC level framing, contention on
2667 the use of the channel, MAC level retransmissions and so on.
2668 From our point of view, the channel is effectively unavailable
2669 for this extra time, which is constant or variable depending
2671 Additionally, packets may be dropped after this
2672 time (e.g., on a wireless link after too many retransmissions).
2673 We can model the additional delay with an empirical curve
2674 that represents its distribution.
2675 .Bd -literal -offset indent
2676 cumulative probability
2686 +-------*------------------->
2689 The empirical curve may have both vertical and horizontal lines.
2690 Vertical lines represent constant delay for a range of
2692 Horizontal lines correspond to a discontinuity in the delay
2693 distribution: the pipe will use the largest delay for a
2696 The file format is the following, with whitespace acting as
2697 a separator and '#' indicating the beginning a comment:
2698 .Bl -tag -width indent
2699 .It Cm name Ar identifier
2700 optional name (listed by "ipfw pipe show")
2701 to identify the delay distribution;
2703 the bandwidth used for the pipe.
2704 If not specified here, it must be present
2705 explicitly as a configuration parameter for the pipe;
2706 .It Cm loss-level Ar L
2707 the probability above which packets are lost.
2708 (0.0 <= L <= 1.0, default 1.0 i.e., no loss);
2710 the number of samples used in the internal
2711 representation of the curve (2..1024; default 100);
2712 .It Cm "delay prob" | "prob delay"
2713 One of these two lines is mandatory and defines
2714 the format of the following lines with data points.
2716 2 or more lines representing points in the curve,
2717 with either delay or probability first, according
2718 to the chosen format.
2719 The unit for delay is milliseconds.
2720 Data points do not need to be sorted.
2721 Also, the number of actual lines can be different
2722 from the value of the "samples" parameter:
2724 utility will sort and interpolate
2725 the curve as needed.
2728 Example of a profile file:
2729 .Bd -literal -offset indent
2734 0 200 # minimum overhead is 200ms
2740 #configuration file end
2744 The following parameters can be configured for a queue:
2746 .Bl -tag -width indent -compact
2747 .It Cm pipe Ar pipe_nr
2748 Connects a queue to the specified pipe.
2749 Multiple queues (with the same or different weights) can be connected to
2750 the same pipe, which specifies the aggregate rate for the set of queues.
2752 .It Cm weight Ar weight
2753 Specifies the weight to be used for flows matching this queue.
2754 The weight must be in the range 1..100, and defaults to 1.
2757 The following case-insensitive parameters can be configured for a
2760 .Bl -tag -width indent -compact
2761 .It Cm type Ar {fifo | wf2q+ | rr | qfq | fq_codel | fq_pie}
2762 specifies the scheduling algorithm to use.
2763 .Bl -tag -width indent -compact
2765 is just a FIFO scheduler (which means that all packets
2766 are stored in the same queue as they arrive to the scheduler).
2767 FIFO has O(1) per-packet time complexity, with very low
2768 constants (estimate 60-80ns on a 2GHz desktop machine)
2769 but gives no service guarantees.
2771 implements the WF2Q+ algorithm, which is a Weighted Fair Queueing
2772 algorithm which permits flows to share bandwidth according to
2774 Note that weights are not priorities; even a flow
2775 with a minuscule weight will never starve.
2776 WF2Q+ has O(log N) per-packet processing cost, where N is the number
2777 of flows, and is the default algorithm used by previous versions
2780 implements the Deficit Round Robin algorithm, which has O(1) processing
2781 costs (roughly, 100-150ns per packet)
2782 and permits bandwidth allocation according to weights, but
2783 with poor service guarantees.
2785 implements the QFQ algorithm, which is a very fast variant of
2786 WF2Q+, with similar service guarantees and O(1) processing
2787 costs (roughly, 200-250ns per packet).
2789 implements the FQ-CoDel (FlowQueue-CoDel) scheduler/AQM algorithm, which
2790 uses a modified Deficit Round Robin scheduler to manage two lists of sub-queues
2791 (old sub-queues and new sub-queues) for providing brief periods of priority to
2792 lightweight or short burst flows.
2793 By default, the total number of sub-queues is 1024.
2794 FQ-CoDel's internal, dynamically
2795 created sub-queues are controlled by separate instances of CoDel AQM.
2797 implements the FQ-PIE (FlowQueue-PIE) scheduler/AQM algorithm, which similar to
2799 but uses per sub-queue PIE AQM instance to control the queue delay.
2803 inherits AQM parameters and options from
2807 inherits AQM parameters and options from
2810 Additionally, both of
2814 have shared scheduler parameters which are:
2815 .Bl -tag -width indent
2818 specifies the quantum (credit) of the scheduler.
2820 is the number of bytes a queue can serve before being moved to the tail
2822 The default is 1514 bytes, and the maximum acceptable value
2826 specifies the hard size limit (in unit of packets) of all queues managed by an
2827 instance of the scheduler.
2828 The default value of
2830 is 10240 packets, and the maximum acceptable value is 20480 packets.
2833 specifies the total number of flow queues (sub-queues) that fq_*
2834 creates and manages.
2835 By default, 1024 sub-queues are created when an instance
2836 of the fq_{codel/pie} scheduler is created.
2837 The maximum acceptable value is
2841 Note that any token after
2845 is considered a parameter for fq_{codel/pie}.
2846 So, ensure all scheduler
2847 configuration options not related to fq_{codel/pie} are written before
2852 In addition to the type, all parameters allowed for a pipe can also
2853 be specified for a scheduler.
2855 Finally, the following parameters can be configured for both
2858 .Bl -tag -width XXXX -compact
2859 .It Cm buckets Ar hash-table-size
2860 Specifies the size of the hash table used for storing the
2862 Default value is 64 controlled by the
2865 .Va net.inet.ip.dummynet.hash_size ,
2866 allowed range is 16 to 65536.
2868 .It Cm mask Ar mask-specifier
2869 Packets sent to a given pipe or queue by an
2871 rule can be further classified into multiple flows, each of which is then
2875 A flow identifier is constructed by masking the IP addresses,
2876 ports and protocol types as specified with the
2878 options in the configuration of the pipe or queue.
2879 For each different flow identifier, a new pipe or queue is created
2880 with the same parameters as the original object, and matching packets
2885 are used, each flow will get the same bandwidth as defined by the pipe,
2888 are used, each flow will share the parent's pipe bandwidth evenly
2889 with other flows generated by the same queue (note that other queues
2890 with different weights might be connected to the same pipe).
2892 Available mask specifiers are a combination of one or more of the following:
2894 .Cm dst-ip Ar mask ,
2895 .Cm dst-ip6 Ar mask ,
2896 .Cm src-ip Ar mask ,
2897 .Cm src-ip6 Ar mask ,
2898 .Cm dst-port Ar mask ,
2899 .Cm src-port Ar mask ,
2900 .Cm flow-id Ar mask ,
2905 where the latter means all bits in all fields are significant.
2908 When a packet is dropped by a
2910 queue or pipe, the error
2911 is normally reported to the caller routine in the kernel, in the
2912 same way as it happens when a device queue fills up.
2914 option reports the packet as successfully delivered, which can be
2915 needed for some experimental setups where you want to simulate
2916 loss or congestion at a remote router.
2918 .It Cm plr Ar packet-loss-rate
2921 .Ar packet-loss-rate
2922 is a floating-point number between 0 and 1, with 0 meaning no
2923 loss, 1 meaning 100% loss.
2924 The loss rate is internally represented on 31 bits.
2926 .It Cm queue Brq Ar slots | size Ns Cm Kbytes
2931 Default value is 50 slots, which
2932 is the typical queue size for Ethernet devices.
2933 Note that for slow speed links you should keep the queue
2934 size short or your traffic might be affected by a significant
2936 E.g., 50 max-sized Ethernet packets (1500 bytes) mean 600Kbit
2937 or 20s of queue on a 30Kbit/s pipe.
2938 Even worse effects can result if you get packets from an
2939 interface with a much larger MTU, e.g.\& the loopback interface
2940 with its 16KB packets.
2944 .Em net.inet.ip.dummynet.pipe_byte_limit
2946 .Em net.inet.ip.dummynet.pipe_slot_limit
2947 control the maximum lengths that can be specified.
2949 .It Cm red | gred Ar w_q Ns / Ns Ar min_th Ns / Ns Ar max_th Ns / Ns Ar max_p
2951 Make use of the RED (Random Early Detection) queue management algorithm.
2956 point numbers between 0 and 1 (inclusive), while
2960 are integer numbers specifying thresholds for queue management
2961 (thresholds are computed in bytes if the queue has been defined
2962 in bytes, in slots otherwise).
2963 The two parameters can also be of the same value if needed. The
2965 also supports the gentle RED variant (gred) and ECN (Explicit Congestion
2966 Notification) as optional. Three
2968 variables can be used to control the RED behaviour:
2969 .Bl -tag -width indent
2970 .It Va net.inet.ip.dummynet.red_lookup_depth
2971 specifies the accuracy in computing the average queue
2972 when the link is idle (defaults to 256, must be greater than zero)
2973 .It Va net.inet.ip.dummynet.red_avg_pkt_size
2974 specifies the expected average packet size (defaults to 512, must be
2976 .It Va net.inet.ip.dummynet.red_max_pkt_size
2977 specifies the expected maximum packet size, only used when queue
2978 thresholds are in bytes (defaults to 1500, must be greater than zero).
2981 .It Cm codel Oo Cm target Ar time Oc Oo Cm interval Ar time Oc Oo Cm ecn |
2983 Make use of the CoDel (Controlled-Delay) queue management algorithm.
2985 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
2986 microseconds (us) can be specified instead.
2987 CoDel drops or marks (ECN) packets
2988 depending on packet sojourn time in the queue.
2991 (5ms by default) is the minimum acceptable persistent queue delay that CoDel
2993 CoDel does not drop packets directly after packets sojourn time becomes
3000 (100ms default) before dropping.
3003 should be set to maximum RTT for all expected connections.
3005 enables (disabled by default) packet marking (instead of dropping) for
3006 ECN-enabled TCP flows when queue delay becomes high.
3008 Note that any token after
3010 is considered a parameter for CoDel.
3011 So, ensure all pipe/queue
3012 configuration options are written before
3019 .Va net.inet.ip.dummynet.codel.target
3021 .Va net.inet.ip.dummynet.codel.interval
3022 can be used to set CoDel default parameters.
3024 .It Cm pie Oo Cm target Ar time Oc Oo Cm tupdate Ar time Oc Oo
3025 .Cm alpha Ar n Oc Oo Cm beta Ar n Oc Oo Cm max_burst Ar time Oc Oo
3026 .Cm max_ecnth Ar n Oc Oo Cm ecn | Cm noecn Oc Oo Cm capdrop |
3027 .Cm nocapdrop Oc Oo Cm drand | Cm nodrand Oc Oo Cm onoff
3028 .Oc Oo Cm dre | Cm ts Oc
3029 Make use of the PIE (Proportional Integral controller Enhanced) queue management
3031 PIE drops or marks packets depending on a calculated drop probability during
3032 en-queue process, with the aim of achieving high throughput while keeping queue
3034 At regular time intervals of
3037 (15ms by default) a background process (re)calculates the probability based on queue delay
3041 (15ms by default) and queue delay trends.
3042 PIE approximates current queue
3043 delay by using a departure rate estimation method, or (optionally) by using a
3044 packet timestamp method similar to CoDel.
3046 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
3047 microseconds (us) can be specified instead.
3048 The other PIE parameters and options are as follows:
3049 .Bl -tag -width indent
3052 is a floating point number between 0 and 7 which specifies the weight of queue
3053 delay deviations that is used in drop probability calculation.
3054 0.125 is the default.
3057 is a floating point number between 0 and 7 which specifies is the weight of queue
3058 delay trend that is used in drop probability calculation.
3059 1.25 is the default.
3060 .It Cm max_burst Ar time
3061 The maximum period of time that PIE does not drop/mark packets.
3063 default and 10s is the maximum value.
3064 .It Cm max_ecnth Ar n
3065 Even when ECN is enabled, PIE drops packets instead of marking them when drop
3066 probability becomes higher than ECN probability threshold
3068 , the default is 0.1 (i.e 10%) and 1 is the maximum value.
3070 enable or disable ECN marking for ECN-enabled TCP flows.
3071 Disabled by default.
3072 .It Cm capdrop | nocapdrop
3073 enable or disable cap drop adjustment.
3074 Cap drop adjustment is enabled by default.
3075 .It Cm drand | nodrand
3076 enable or disable drop probability de-randomisation.
3077 De-randomisation eliminates
3078 the problem of dropping packets too close or too far.
3079 De-randomisation is enabled by default.
3081 enable turning PIE on and off depending on queue load.
3082 If this option is enabled,
3083 PIE turns on when over 1/3 of queue becomes full.
3084 This option is disabled by
3087 Calculate queue delay using departure rate estimation
3095 Note that any token after
3097 is considered a parameter for PIE.
3098 So ensure all pipe/queue
3099 the configuration options are written before
3103 variables can be used to control the
3107 .Sx SYSCTL VARIABLES
3108 section for more details.
3111 When used with IPv6 data,
3113 currently has several limitations.
3114 Information necessary to route link-local packets to an
3115 interface is not available after processing by
3117 so those packets are dropped in the output path.
3118 Care should be taken to ensure that link-local packets are not passed to
3121 Here are some important points to consider when designing your
3125 Remember that you filter both packets going
3129 Most connections need packets going in both directions.
3131 Remember to test very carefully.
3132 It is a good idea to be near the console when doing this.
3133 If you cannot be near the console,
3134 use an auto-recovery script such as the one in
3135 .Pa /usr/share/examples/ipfw/change_rules.sh .
3137 Do not forget the loopback interface.
3142 There are circumstances where fragmented datagrams are unconditionally
3144 TCP packets are dropped if they do not contain at least 20 bytes of
3145 TCP header, UDP packets are dropped if they do not contain a full 8
3146 byte UDP header, and ICMP packets are dropped if they do not contain
3147 4 bytes of ICMP header, enough to specify the ICMP type, code, and
3149 These packets are simply logged as
3151 since there may not be enough good data in the packet to produce a
3152 meaningful log entry.
3154 Another type of packet is unconditionally dropped, a TCP packet with a
3155 fragment offset of one.
3156 This is a valid packet, but it only has one use, to try
3157 to circumvent firewalls.
3158 When logging is enabled, these packets are
3159 reported as being dropped by rule -1.
3161 If you are logged in over a network, loading the
3165 is probably not as straightforward as you would think.
3166 The following command line is recommended:
3167 .Bd -literal -offset indent
3169 ipfw add 32000 allow ip from any to any
3172 Along the same lines, doing an
3173 .Bd -literal -offset indent
3177 in similar surroundings is also a bad idea.
3181 filter list may not be modified if the system security level
3182 is set to 3 or higher
3185 for information on system security levels).
3187 .Sh PACKET DIVERSION
3190 socket bound to the specified port will receive all packets
3191 diverted to that port.
3192 If no socket is bound to the destination port, or if the divert module is
3193 not loaded, or if the kernel was not compiled with divert socket support,
3194 the packets are dropped.
3195 .Sh NETWORK ADDRESS TRANSLATION (NAT)
3197 support in-kernel NAT using the kernel version of
3201 should be loaded or kernel should have
3202 .Cm options IPFIREWALL_NAT
3205 The nat configuration command is the following:
3206 .Bd -ragged -offset indent
3211 .Ar nat-configuration
3215 The following parameters can be configured:
3216 .Bl -tag -width indent
3217 .It Cm ip Ar ip_address
3218 Define an ip address to use for aliasing.
3220 Use ip address of NIC for aliasing, dynamically changing
3221 it if NIC's ip address changes.
3223 Enable logging on this nat instance.
3225 Deny any incoming connection from outside world.
3227 Try to leave the alias port numbers unchanged from
3228 the actual local port numbers.
3230 Traffic on the local network not originating from an
3231 unregistered address spaces will be ignored.
3233 Reset table of the packet aliasing engine on address change.
3235 Reverse the way libalias handles aliasing.
3237 Obey transparent proxy rules only, packet aliasing is not performed.
3239 Skip instance in case of global state lookup (see below).
3242 Some specials value can be supplied instead of
3244 .Bl -tag -width indent
3246 Looks up translation state in all configured nat instances.
3247 If an entry is found, packet is aliased according to that entry.
3248 If no entry was found in any of the instances, packet is passed unchanged,
3249 and no new entry will be created.
3251 .Sx MULTIPLE INSTANCES
3254 for more information.
3256 Uses argument supplied in lookup table.
3259 section below for more information on lookup tables.
3262 To let the packet continue after being (de)aliased, set the sysctl variable
3263 .Va net.inet.ip.fw.one_pass
3265 For more information about aliasing modes, refer to
3269 for some examples about nat usage.
3270 .Ss REDIRECT AND LSNAT SUPPORT IN IPFW
3271 Redirect and LSNAT support follow closely the syntax used in
3275 for some examples on how to do redirect and lsnat.
3276 .Ss SCTP NAT SUPPORT
3277 SCTP nat can be configured in a similar manner to TCP through the
3280 The main difference is that
3282 does not do port translation.
3283 Since the local and global side ports will be the same,
3284 there is no need to specify both.
3285 Ports are redirected as follows:
3286 .Bd -ragged -offset indent
3292 .Cm redirect_port sctp
3293 .Ar ip_address [,addr_list] {[port | port-port] [,ports]}
3299 configuration can be done in real-time through the
3302 All may be changed dynamically, though the hash_table size will only
3307 .Sx SYSCTL VARIABLES
3309 .Sh IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
3310 .Ss Stateful translation
3312 supports in-kernel IPv6/IPv4 network address and protocol translation.
3313 Stateful NAT64 translation allows IPv6-only clients to contact IPv4 servers
3314 using unicast TCP, UDP or ICMP protocols.
3315 One or more IPv4 addresses assigned to a stateful NAT64 translator are shared
3316 among several IPv6-only clients.
3317 When stateful NAT64 is used in conjunction with DNS64, no changes are usually
3318 required in the IPv6 client or the IPv4 server.
3321 should be loaded or kernel should have
3322 .Cm options IPFIREWALL_NAT64
3323 to be able use stateful NAT64 translator.
3325 Stateful NAT64 uses a bunch of memory for several types of objects.
3326 When IPv6 client initiates connection, NAT64 translator creates a host entry
3327 in the states table.
3328 Each host entry uses preallocated IPv4 alias entry.
3329 Each alias entry has a number of ports group entries allocated on demand.
3330 Ports group entries contains connection state entries.
3331 There are several options to control limits and lifetime for these objects.
3333 NAT64 translator follows RFC7915 when does ICMPv6/ICMP translation,
3334 unsupported message types will be silently dropped.
3335 IPv6 needs several ICMPv6 message types to be explicitly allowed for correct
3337 Make sure that ND6 neighbor solicitation (ICMPv6 type 135) and neighbor
3338 advertisement (ICMPv6 type 136) messages will not be handled by translation
3341 After translation NAT64 translator by default sends packets through
3342 corresponding netisr queue.
3343 Thus translator host should be configured as IPv4 and IPv6 router.
3344 Also this means, that a packet is handled by firewall twice.
3345 First time an original packet is handled and consumed by translator,
3346 and then it is handled again as translated packet.
3347 This behavior can be changed by sysctl variable
3348 .Va net.inet.ip.fw.nat64_direct_output .
3349 Also translated packet can be tagged using
3351 rule action, and then matched by
3353 opcode to avoid loops and extra overhead.
3355 The stateful NAT64 configuration command is the following:
3356 .Bd -ragged -offset indent
3365 The following parameters can be configured:
3366 .Bl -tag -width indent
3367 .It Cm prefix4 Ar ipv4_prefix/plen
3368 The IPv4 prefix with mask defines the pool of IPv4 addresses used as
3369 source address after translation.
3370 Stateful NAT64 module translates IPv6 source address of client to one
3371 IPv4 address from this pool.
3372 Note that incoming IPv4 packets that don't have corresponding state entry
3373 in the states table will be dropped by translator.
3374 Make sure that translation rules handle packets, destined to configured prefix.
3375 .It Cm prefix6 Ar ipv6_prefix/length
3376 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3377 to represent IPv4 addresses. This IPv6 prefix should be configured in DNS64.
3378 The translator implementation follows RFC6052, that restricts the length of
3379 prefixes to one of following: 32, 40, 48, 56, 64, or 96.
3380 The Well-Known IPv6 Prefix 64:ff9b:: must be 96 bits long.
3383 prefix can be used to handle several IPv6 prefixes with one NAT64 instance.
3384 The NAT64 instance will determine a destination IPv4 address from prefix
3386 .It Cm states_chunks Ar number
3387 The number of states chunks in single ports group.
3388 Each ports group by default can keep 64 state entries in single chunk.
3389 The above value affects the maximum number of states that can be associated with single IPv4 alias address and port.
3390 The value must be power of 2, and up to 128.
3391 .It Cm host_del_age Ar seconds
3392 The number of seconds until the host entry for a IPv6 client will be deleted
3393 and all its resources will be released due to inactivity.
3396 .It Cm pg_del_age Ar seconds
3397 The number of seconds until a ports group with unused state entries will
3401 .It Cm tcp_syn_age Ar seconds
3402 The number of seconds while a state entry for TCP connection with only SYN
3404 If TCP connection establishing will not be finished,
3405 state entry will be deleted.
3408 .It Cm tcp_est_age Ar seconds
3409 The number of seconds while a state entry for established TCP connection
3413 .It Cm tcp_close_age Ar seconds
3414 The number of seconds while a state entry for closed TCP connection
3416 Keeping state entries for closed connections is needed, because IPv4 servers
3417 typically keep closed connections in a TIME_WAIT state for a several minutes.
3418 Since translator's IPv4 addresses are shared among all IPv6 clients,
3419 new connections from the same addresses and ports may be rejected by server,
3420 because these connections are still in a TIME_WAIT state.
3421 Keeping them in translator's state table protects from such rejects.
3424 .It Cm udp_age Ar seconds
3425 The number of seconds while translator keeps state entry in a waiting for
3426 reply to the sent UDP datagram.
3429 .It Cm icmp_age Ar seconds
3430 The number of seconds while translator keeps state entry in a waiting for
3431 reply to the sent ICMP message.
3435 Turn on logging of all handled packets via BPF through
3439 is a pseudo interface and can be created after a boot manually with
3442 Note that it has different purpose than
3445 Translators sends to BPF an additional information with each packet.
3448 you are able to see each handled packet before and after translation.
3450 Turn off logging of all handled packets via BPF.
3451 .It Cm allow_private
3452 Turn on processing private IPv4 addresses. By default IPv6 packets with
3453 destinations mapped to private address ranges defined by RFC1918 are not
3455 .It Cm -allow_private
3456 Turn off private address handling in
3461 To inspect a states table of stateful NAT64 the following command can be used:
3462 .Bd -ragged -offset indent
3471 Stateless NAT64 translator doesn't use a states table for translation
3472 and converts IPv4 addresses to IPv6 and vice versa solely based on the
3473 mappings taken from configured lookup tables.
3474 Since a states table doesn't used by stateless translator,
3475 it can be configured to pass IPv4 clients to IPv6-only servers.
3477 The stateless NAT64 configuration command is the following:
3478 .Bd -ragged -offset indent
3487 The following parameters can be configured:
3488 .Bl -tag -width indent
3489 .It Cm prefix6 Ar ipv6_prefix/length
3490 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3491 to represent IPv4 addresses. This IPv6 prefix should be configured in DNS64.
3492 .It Cm table4 Ar table46
3495 contains mapping how IPv4 addresses should be translated to IPv6 addresses.
3496 .It Cm table6 Ar table64
3499 contains mapping how IPv6 addresses should be translated to IPv4 addresses.
3501 Turn on logging of all handled packets via BPF through
3505 Turn off logging of all handled packets via BPF.
3506 .It Cm allow_private
3507 Turn on processing private IPv4 addresses. By default IPv6 packets with
3508 destinations mapped to private address ranges defined by RFC1918 are not
3510 .It Cm -allow_private
3511 Turn off private address handling in
3516 Note that the behavior of stateless translator with respect to not matched
3517 packets differs from stateful translator.
3518 If corresponding addresses was not found in the lookup tables, the packet
3519 will not be dropped and the search continues.
3522 .Ss XLAT464 CLAT translation
3523 XLAT464 CLAT NAT64 translator implements client-side stateless translation as
3524 defined in RFC6877 and is very similar to statless NAT64 translator
3525 explained above. Instead of lookup tables it uses one-to-one mapping
3526 between IPv4 and IPv6 addresses using configured prefixes.
3527 This mode can be used as a replacement of DNS64 service for applications
3528 that are not using it (e.g. VoIP) allowing them to access IPv4-only Internet
3529 over IPv6-only networks with help of remote NAT64 translator.
3531 The CLAT NAT64 configuration command is the following:
3532 .Bd -ragged -offset indent
3541 The following parameters can be configured:
3542 .Bl -tag -width indent
3543 .It Cm clat_prefix Ar ipv6_prefix/length
3544 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3545 to represent source IPv4 addresses.
3546 .It Cm plat_prefix Ar ipv6_prefix/length
3547 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3548 to represent destination IPv4 addresses. This IPv6 prefix should be configured
3549 on a remote NAT64 translator.
3551 Turn on logging of all handled packets via BPF through
3555 Turn off logging of all handled packets via BPF.
3556 .It Cm allow_private
3557 Turn on processing private IPv4 addresses. By default
3559 instance will not process IPv4 packets with destination address from private
3560 ranges as defined in RFC1918.
3561 .It Cm -allow_private
3562 Turn off private address handling in
3567 Note that the behavior of CLAT translator with respect to not matched
3568 packets differs from stateful translator.
3569 If corresponding addresses were not matched against prefixes configured,
3570 the packet will not be dropped and the search continues.
3571 .Sh IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
3573 supports in-kernel IPv6-to-IPv6 network prefix translation as described
3577 should be loaded or kernel should has
3578 .Cm options IPFIREWALL_NPTV6
3579 to be able use NPTv6 translator.
3581 The NPTv6 configuration command is the following:
3582 .Bd -ragged -offset indent
3591 The following parameters can be configured:
3592 .Bl -tag -width indent
3593 .It Cm int_prefix Ar ipv6_prefix
3594 IPv6 prefix used in internal network.
3595 NPTv6 module translates source address when it matches this prefix.
3596 .It Cm ext_prefix Ar ipv6_prefix
3597 IPv6 prefix used in external network.
3598 NPTv6 module translates destination address when it matches this prefix.
3599 .It Cm ext_if Ar nic
3600 The NPTv6 module will use first global IPv6 address from interface
3603 It can be useful when IPv6 prefix of external network is dynamically obtained.
3607 options are mutually exclusive.
3608 .It Cm prefixlen Ar length
3609 The length of specified IPv6 prefixes. It must be in range from 8 to 64.
3612 Note that the prefix translation rules are silently ignored when IPv6 packet
3613 forwarding is disabled.
3614 To enable the packet forwarding, set the sysctl variable
3615 .Va net.inet6.ip6.forwarding
3618 To let the packet continue after being translated, set the sysctl variable
3619 .Va net.inet.ip.fw.one_pass
3622 Tunables can be set in
3628 before ipfw module gets loaded.
3629 .Bl -tag -width indent
3630 .It Va net.inet.ip.fw.default_to_accept: No 0
3631 Defines ipfw last rule behavior.
3632 This value overrides
3633 .Cd "options IPFW_DEFAULT_TO_(ACCEPT|DENY)"
3634 from kernel configuration file.
3635 .It Va net.inet.ip.fw.tables_max: No 128
3636 Defines number of tables available in ipfw.
3637 Number cannot exceed 65534.
3639 .Sh SYSCTL VARIABLES
3642 variables controls the behaviour of the firewall and
3644 .Pq Nm dummynet , bridge , sctp nat .
3645 These are shown below together with their default value
3646 (but always check with the
3648 command what value is actually in use) and meaning:
3649 .Bl -tag -width indent
3650 .It Va net.inet.ip.alias.sctp.accept_global_ootb_addip: No 0
3653 responds to receipt of global OOTB ASCONF-AddIP:
3654 .Bl -tag -width indent
3656 No response (unless a partially matching association exists -
3657 ports and vtags match but global address does not)
3660 will accept and process all OOTB global AddIP messages.
3663 Option 1 should never be selected as this forms a security risk.
3665 establish multiple fake associations by sending AddIP messages.
3666 .It Va net.inet.ip.alias.sctp.chunk_proc_limit: No 5
3667 Defines the maximum number of chunks in an SCTP packet that will be
3669 packet that matches an existing association.
3670 This value is enforced to be greater or equal than
3671 .Cm net.inet.ip.alias.sctp.initialising_chunk_proc_limit .
3673 a DoS risk yet setting too low a value may result in
3674 important control chunks in
3675 the packet not being located and parsed.
3676 .It Va net.inet.ip.alias.sctp.error_on_ootb: No 1
3679 responds to any Out-of-the-Blue (OOTB) packets with ErrorM packets.
3680 An OOTB packet is a packet that arrives with no existing association
3683 and is not an INIT or ASCONF-AddIP packet:
3684 .Bl -tag -width indent
3686 ErrorM is never sent in response to OOTB packets.
3688 ErrorM is only sent to OOTB packets received on the local side.
3690 ErrorM is sent to the local side and on the global side ONLY if there is a
3691 partial match (ports and vtags match but the source global IP does not).
3692 This value is only useful if the
3694 is tracking global IP addresses.
3696 ErrorM is sent in response to all OOTB packets on both
3697 the local and global side
3701 At the moment the default is 0, since the ErrorM packet is not yet
3702 supported by most SCTP stacks.
3703 When it is supported, and if not tracking
3704 global addresses, we recommend setting this value to 1 to allow
3705 multi-homed local hosts to function with the
3707 To track global addresses, we recommend setting this value to 2 to
3708 allow global hosts to be informed when they need to (re)send an
3710 Value 3 should never be chosen (except for debugging) as the
3712 will respond to all OOTB global packets (a DoS risk).
3713 .It Va net.inet.ip.alias.sctp.hashtable_size: No 2003
3714 Size of hash tables used for
3716 lookups (100 < prime_number > 1000001).
3719 size for any future created
3721 instance and therefore must be set prior to creating a
3724 The table sizes may be changed to suit specific needs.
3725 If there will be few
3726 concurrent associations, and memory is scarce, you may make these smaller.
3727 If there will be many thousands (or millions) of concurrent associations, you
3728 should make these larger.
3729 A prime number is best for the table size.
3731 update function will adjust your input value to the next highest prime number.
3732 .It Va net.inet.ip.alias.sctp.holddown_time: No 0
3733 Hold association in table for this many seconds after receiving a
3735 This allows endpoints to correct shutdown gracefully if a
3736 shutdown_complete is lost and retransmissions are required.
3737 .It Va net.inet.ip.alias.sctp.init_timer: No 15
3738 Timeout value while waiting for (INIT-ACK|AddIP-ACK).
3739 This value cannot be 0.
3740 .It Va net.inet.ip.alias.sctp.initialising_chunk_proc_limit: No 2
3741 Defines the maximum number of chunks in an SCTP packet that will be parsed when
3742 no existing association exists that matches that packet.
3744 will only be an INIT or ASCONF-AddIP packet.
3745 A higher value may become a DoS
3746 risk as malformed packets can consume processing resources.
3747 .It Va net.inet.ip.alias.sctp.param_proc_limit: No 25
3748 Defines the maximum number of parameters within a chunk that will be
3751 As for other similar sysctl variables, larger values pose a DoS risk.
3752 .It Va net.inet.ip.alias.sctp.log_level: No 0
3753 Level of detail in the system log messages (0 \- minimal, 1 \- event,
3754 2 \- info, 3 \- detail, 4 \- debug, 5 \- max debug).
3756 option in high loss environments.
3757 .It Va net.inet.ip.alias.sctp.shutdown_time: No 15
3758 Timeout value while waiting for SHUTDOWN-COMPLETE.
3759 This value cannot be 0.
3760 .It Va net.inet.ip.alias.sctp.track_global_addresses: No 0
3761 Enables/disables global IP address tracking within the
3764 upper limit on the number of addresses tracked for each association:
3765 .Bl -tag -width indent
3767 Global tracking is disabled
3769 Enables tracking, the maximum number of addresses tracked for each
3770 association is limited to this value
3773 This variable is fully dynamic, the new value will be adopted for all newly
3774 arriving associations, existing associations are treated
3775 as they were previously.
3776 Global tracking will decrease the number of collisions within the
3779 of increased processing load, memory usage, complexity, and possible
3782 problems in complex networks with multiple
3784 We recommend not tracking
3785 global IP addresses, this will still result in a fully functional
3787 .It Va net.inet.ip.alias.sctp.up_timer: No 300
3788 Timeout value to keep an association up with no traffic.
3789 This value cannot be 0.
3790 .It Va net.inet.ip.dummynet.codel.interval : No 100000
3793 AQM interval in microseconds.
3794 The value must be in the range 1..5000000.
3795 .It Va net.inet.ip.dummynet.codel.target : No 5000
3798 AQM target delay time in microseconds (the minimum acceptable persistent queue
3800 The value must be in the range 1..5000000.
3801 .It Va net.inet.ip.dummynet.expire : No 1
3802 Lazily delete dynamic pipes/queue once they have no pending traffic.
3803 You can disable this by setting the variable to 0, in which case
3804 the pipes/queues will only be deleted when the threshold is reached.
3805 .It Va net.inet.ip.dummynet.fqcodel.flows : No 1024
3806 Defines the default total number of flow queues (sub-queues) that
3808 creates and manages.
3809 The value must be in the range 1..65536.
3810 .It Va net.inet.ip.dummynet.fqcodel.interval : No 100000
3813 scheduler/AQM interval in microseconds.
3814 The value must be in the range 1..5000000.
3815 .It Va net.inet.ip.dummynet.fqcodel.limit : No 10240
3816 The default hard size limit (in unit of packet) of all queues managed by an
3820 The value must be in the range 1..20480.
3821 .It Va net.inet.ip.dummynet.fqcodel.quantum : No 1514
3822 The default quantum (credit) of the
3825 The value must be in the range 1..9000.
3826 .It Va net.inet.ip.dummynet.fqcodel.target : No 5000
3829 scheduler/AQM target delay time in microseconds (the minimum acceptable
3830 persistent queue delay).
3831 The value must be in the range 1..5000000.
3832 .It Va net.inet.ip.dummynet.fqpie.alpha : No 125
3835 parameter (scaled by 1000) for
3838 The value must be in the range 1..7000.
3839 .It Va net.inet.ip.dummynet.fqpie.beta : No 1250
3842 parameter (scaled by 1000) for
3845 The value must be in the range 1..7000.
3846 .It Va net.inet.ip.dummynet.fqpie.flows : No 1024
3847 Defines the default total number of flow queues (sub-queues) that
3849 creates and manages.
3850 The value must be in the range 1..65536.
3851 .It Va net.inet.ip.dummynet.fqpie.limit : No 10240
3852 The default hard size limit (in unit of packet) of all queues managed by an
3856 The value must be in the range 1..20480.
3857 .It Va net.inet.ip.dummynet.fqpie.max_burst : No 150000
3858 The default maximum period of microseconds that
3860 scheduler/AQM does not drop/mark packets.
3861 The value must be in the range 1..10000000.
3862 .It Va net.inet.ip.dummynet.fqpie.max_ecnth : No 99
3863 The default maximum ECN probability threshold (scaled by 1000) for
3866 The value must be in the range 1..7000.
3867 .It Va net.inet.ip.dummynet.fqpie.quantum : No 1514
3868 The default quantum (credit) of the
3871 The value must be in the range 1..9000.
3872 .It Va net.inet.ip.dummynet.fqpie.target : No 15000
3877 in unit of microsecond.
3878 The value must be in the range 1..5000000.
3879 .It Va net.inet.ip.dummynet.fqpie.tupdate : No 15000
3884 in unit of microsecond.
3885 The value must be in the range 1..5000000.
3886 .It Va net.inet.ip.dummynet.hash_size : No 64
3887 Default size of the hash table used for dynamic pipes/queues.
3888 This value is used when no
3890 option is specified when configuring a pipe/queue.
3891 .It Va net.inet.ip.dummynet.io_fast : No 0
3892 If set to a non-zero value,
3897 operation (see above) is enabled.
3898 .It Va net.inet.ip.dummynet.io_pkt
3899 Number of packets passed to
3901 .It Va net.inet.ip.dummynet.io_pkt_drop
3902 Number of packets dropped by
3904 .It Va net.inet.ip.dummynet.io_pkt_fast
3905 Number of packets bypassed by the
3908 .It Va net.inet.ip.dummynet.max_chain_len : No 16
3909 Target value for the maximum number of pipes/queues in a hash bucket.
3911 .Cm max_chain_len*hash_size
3912 is used to determine the threshold over which empty pipes/queues
3913 will be expired even when
3914 .Cm net.inet.ip.dummynet.expire=0 .
3915 .It Va net.inet.ip.dummynet.red_lookup_depth : No 256
3916 .It Va net.inet.ip.dummynet.red_avg_pkt_size : No 512
3917 .It Va net.inet.ip.dummynet.red_max_pkt_size : No 1500
3918 Parameters used in the computations of the drop probability
3919 for the RED algorithm.
3920 .It Va net.inet.ip.dummynet.pie.alpha : No 125
3923 parameter (scaled by 1000) for
3926 The value must be in the range 1..7000.
3927 .It Va net.inet.ip.dummynet.pie.beta : No 1250
3930 parameter (scaled by 1000) for
3933 The value must be in the range 1..7000.
3934 .It Va net.inet.ip.dummynet.pie.max_burst : No 150000
3935 The default maximum period of microseconds that
3937 AQM does not drop/mark packets.
3938 The value must be in the range 1..10000000.
3939 .It Va net.inet.ip.dummynet.pie.max_ecnth : No 99
3940 The default maximum ECN probability threshold (scaled by 1000) for
3943 The value must be in the range 1..7000.
3944 .It Va net.inet.ip.dummynet.pie.target : No 15000
3949 AQM in unit of microsecond.
3950 The value must be in the range 1..5000000.
3951 .It Va net.inet.ip.dummynet.pie.tupdate : No 15000
3956 AQM in unit of microsecond.
3957 The value must be in the range 1..5000000.
3958 .It Va net.inet.ip.dummynet.pipe_byte_limit : No 1048576
3959 .It Va net.inet.ip.dummynet.pipe_slot_limit : No 100
3960 The maximum queue size that can be specified in bytes or packets.
3961 These limits prevent accidental exhaustion of resources such as mbufs.
3962 If you raise these limits,
3963 you should make sure the system is configured so that sufficient resources
3965 .It Va net.inet.ip.fw.autoinc_step : No 100
3966 Delta between rule numbers when auto-generating them.
3967 The value must be in the range 1..1000.
3968 .It Va net.inet.ip.fw.curr_dyn_buckets : Va net.inet.ip.fw.dyn_buckets
3969 The current number of buckets in the hash table for dynamic rules
3971 .It Va net.inet.ip.fw.debug : No 1
3972 Controls debugging messages produced by
3974 .It Va net.inet.ip.fw.default_rule : No 65535
3975 The default rule number (read-only).
3977 .Nm , the default rule is the last one, so its number
3978 can also serve as the highest number allowed for a rule.
3979 .It Va net.inet.ip.fw.dyn_buckets : No 256
3980 The number of buckets in the hash table for dynamic rules.
3981 Must be a power of 2, up to 65536.
3982 It only takes effect when all dynamic rules have expired, so you
3983 are advised to use a
3985 command to make sure that the hash table is resized.
3986 .It Va net.inet.ip.fw.dyn_count : No 3
3987 Current number of dynamic rules
3989 .It Va net.inet.ip.fw.dyn_keepalive : No 1
3990 Enables generation of keepalive packets for
3992 rules on TCP sessions.
3993 A keepalive is generated to both
3994 sides of the connection every 5 seconds for the last 20
3995 seconds of the lifetime of the rule.
3996 .It Va net.inet.ip.fw.dyn_max : No 8192
3997 Maximum number of dynamic rules.
3998 When you hit this limit, no more dynamic rules can be
3999 installed until old ones expire.
4000 .It Va net.inet.ip.fw.dyn_ack_lifetime : No 300
4001 .It Va net.inet.ip.fw.dyn_syn_lifetime : No 20
4002 .It Va net.inet.ip.fw.dyn_fin_lifetime : No 1
4003 .It Va net.inet.ip.fw.dyn_rst_lifetime : No 1
4004 .It Va net.inet.ip.fw.dyn_udp_lifetime : No 5
4005 .It Va net.inet.ip.fw.dyn_short_lifetime : No 30
4006 These variables control the lifetime, in seconds, of dynamic
4008 Upon the initial SYN exchange the lifetime is kept short,
4009 then increased after both SYN have been seen, then decreased
4010 again during the final FIN exchange or when a RST is received.
4012 .Em dyn_fin_lifetime
4014 .Em dyn_rst_lifetime
4015 must be strictly lower than 5 seconds, the period of
4016 repetition of keepalives.
4017 The firewall enforces that.
4018 .It Va net.inet.ip.fw.dyn_keep_states: No 0
4019 Keep dynamic states on rule/set deletion.
4020 States are relinked to default rule (65535).
4021 This can be handly for ruleset reload.
4022 Turned off by default.
4023 .It Va net.inet.ip.fw.enable : No 1
4024 Enables the firewall.
4025 Setting this variable to 0 lets you run your machine without
4026 firewall even if compiled in.
4027 .It Va net.inet6.ip6.fw.enable : No 1
4028 provides the same functionality as above for the IPv6 case.
4029 .It Va net.inet.ip.fw.one_pass : No 1
4030 When set, the packet exiting from the
4034 node is not passed though the firewall again.
4035 Otherwise, after an action, the packet is
4036 reinjected into the firewall at the next rule.
4037 .It Va net.inet.ip.fw.tables_max : No 128
4038 Maximum number of tables.
4039 .It Va net.inet.ip.fw.verbose : No 1
4040 Enables verbose messages.
4041 .It Va net.inet.ip.fw.verbose_limit : No 0
4042 Limits the number of messages produced by a verbose firewall.
4043 .It Va net.inet6.ip6.fw.deny_unknown_exthdrs : No 1
4044 If enabled packets with unknown IPv6 Extension Headers will be denied.
4045 .It Va net.link.ether.ipfw : No 0
4046 Controls whether layer-2 packets are passed to
4049 .It Va net.link.bridge.ipfw : No 0
4050 Controls whether bridged packets are passed to
4053 .It Va net.inet.ip.fw.nat64_debug : No 0
4054 Controls debugging messages produced by
4057 .It Va net.inet.ip.fw.nat64_direct_output : No 0
4058 Controls the output method used by
4061 .Bl -tag -width indent
4063 A packet is handled by
4066 First time an original packet is handled by
4071 Then translated packet is queued via netisr to input processing again.
4073 A packet is handled by
4075 only once, and after translation it will be pushed directly to outgoing
4079 .Sh INTERNAL DIAGNOSTICS
4080 There are some commands that may be useful to understand current state
4081 of certain subsystems inside kernel module.
4082 These commands provide debugging output which may change without notice.
4084 Currently the following commands are available as
4087 .Bl -tag -width indent
4089 Lists all interface which are currently tracked by
4091 with their in-kernel status.
4093 List all table lookup algorithms currently available.
4096 There are far too many possible uses of
4098 so this Section will only give a small set of examples.
4100 .Ss BASIC PACKET FILTERING
4101 This command adds an entry which denies all tcp packets from
4102 .Em cracker.evil.org
4103 to the telnet port of
4105 from being forwarded by the host:
4107 .Dl "ipfw add deny tcp from cracker.evil.org to wolf.tambov.su telnet"
4109 This one disallows any connection from the entire cracker's
4112 .Dl "ipfw add deny ip from 123.45.67.0/24 to my.host.org"
4114 A first and efficient way to limit access (not using dynamic rules)
4115 is the use of the following rules:
4117 .Dl "ipfw add allow tcp from any to any established"
4118 .Dl "ipfw add allow tcp from net1 portlist1 to net2 portlist2 setup"
4119 .Dl "ipfw add allow tcp from net3 portlist3 to net3 portlist3 setup"
4121 .Dl "ipfw add deny tcp from any to any"
4123 The first rule will be a quick match for normal TCP packets,
4124 but it will not match the initial SYN packet, which will be
4127 rules only for selected source/destination pairs.
4128 All other SYN packets will be rejected by the final
4132 If you administer one or more subnets, you can take advantage
4133 of the address sets and or-blocks and write extremely
4134 compact rulesets which selectively enable services to blocks
4135 of clients, as below:
4137 .Dl "goodguys=\*q{ 10.1.2.0/24{20,35,66,18} or 10.2.3.0/28{6,3,11} }\*q"
4138 .Dl "badguys=\*q10.1.2.0/24{8,38,60}\*q"
4140 .Dl "ipfw add allow ip from ${goodguys} to any"
4141 .Dl "ipfw add deny ip from ${badguys} to any"
4142 .Dl "... normal policies ..."
4146 option could be used to do automated anti-spoofing by adding the
4147 following to the top of a ruleset:
4149 .Dl "ipfw add deny ip from any to any not verrevpath in"
4151 This rule drops all incoming packets that appear to be coming to the
4152 system on the wrong interface.
4153 For example, a packet with a source
4154 address belonging to a host on a protected internal network would be
4155 dropped if it tried to enter the system from an external interface.
4159 option could be used to do similar but more restricted anti-spoofing
4160 by adding the following to the top of a ruleset:
4162 .Dl "ipfw add deny ip from any to any not antispoof in"
4164 This rule drops all incoming packets that appear to be coming from another
4165 directly connected system but on the wrong interface.
4166 For example, a packet with a source address of
4167 .Li 192.168.0.0/24 ,
4176 option could be used to (re)mark user traffic,
4177 by adding the following to the appropriate place in ruleset:
4179 .Dl "ipfw add setdscp be ip from any to any dscp af11,af21"
4180 .Ss SELECTIVE MIRRORING
4181 If your network has network traffic analyzer
4182 connected to your host directly via dedicated interface
4183 or remotely via RSPAN vlan, you can selectively mirror
4184 some Ethernet layer2 frames to the analyzer.
4186 First, make sure your firewall is already configured and runs.
4187 Then, enable layer2 processing if not already enabled:
4189 .Dl "sysctl net.link.ether.ipfw=1"
4191 Next, load needed additional kernel modules:
4193 .Dl "kldload ng_ether ng_ipfw"
4195 Optionally, make system load these modules automatically
4198 .Dl sysrc kld_list+="ng_ether ng_ipfw"
4202 kernel module to transmit mirrored copies of layer2 frames
4203 out via vlan900 interface:
4205 .Dl "ngctl connect ipfw: vlan900: 1 lower"
4207 Think of "1" here as of "mirroring instance index" and vlan900 is its
4209 You can have arbitrary number of instances.
4214 At last, actually start mirroring of selected frames using "instance 1".
4215 For frames incoming from em0 interface:
4217 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 in recv em0"
4219 For frames outgoing to em0 interface:
4221 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 out xmit em0"
4223 For both incoming and outgoing frames while flowing through em0:
4225 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 via em0"
4227 Make sure you do not perform mirroring for already duplicated frames
4228 or kernel may hang as there is no safety net.
4230 In order to protect a site from flood attacks involving fake
4231 TCP packets, it is safer to use dynamic rules:
4233 .Dl "ipfw add check-state"
4234 .Dl "ipfw add deny tcp from any to any established"
4235 .Dl "ipfw add allow tcp from my-net to any setup keep-state"
4237 This will let the firewall install dynamic rules only for
4238 those connection which start with a regular SYN packet coming
4239 from the inside of our network.
4240 Dynamic rules are checked when encountering the first
4249 rule should usually be placed near the beginning of the
4250 ruleset to minimize the amount of work scanning the ruleset.
4251 Your mileage may vary.
4253 For more complex scenarios with dynamic rules
4257 can be used to precisely control creation and checking of dynamic rules.
4258 Example of usage of these options are provided in
4259 .Sx NETWORK ADDRESS TRANSLATION (NAT)
4262 To limit the number of connections a user can open
4263 you can use the following type of rules:
4265 .Dl "ipfw add allow tcp from my-net/24 to any setup limit src-addr 10"
4266 .Dl "ipfw add allow tcp from any to me setup limit src-addr 4"
4268 The former (assuming it runs on a gateway) will allow each host
4269 on a /24 network to open at most 10 TCP connections.
4270 The latter can be placed on a server to make sure that a single
4271 client does not use more than 4 simultaneous connections.
4274 stateful rules can be subject to denial-of-service attacks
4275 by a SYN-flood which opens a huge number of dynamic rules.
4276 The effects of such attacks can be partially limited by
4279 variables which control the operation of the firewall.
4281 Here is a good usage of the
4283 command to see accounting records and timestamp information:
4287 or in short form without timestamps:
4291 which is equivalent to:
4295 Next rule diverts all incoming packets from 192.168.2.0/24
4296 to divert port 5000:
4298 .Dl ipfw divert 5000 ip from 192.168.2.0/24 to any in
4300 The following rules show some of the applications of
4304 for simulations and the like.
4306 This rule drops random incoming packets with a probability
4309 .Dl "ipfw add prob 0.05 deny ip from any to any in"
4311 A similar effect can be achieved making use of
4315 .Dl "ipfw add pipe 10 ip from any to any"
4316 .Dl "ipfw pipe 10 config plr 0.05"
4318 We can use pipes to artificially limit bandwidth, e.g.\& on a
4319 machine acting as a router, if we want to limit traffic from
4320 local clients on 192.168.2.0/24 we do:
4322 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4323 .Dl "ipfw pipe 1 config bw 300Kbit/s queue 50KBytes"
4325 note that we use the
4327 modifier so that the rule is not used twice.
4328 Remember in fact that
4330 rules are checked both on incoming and outgoing packets.
4332 Should we want to simulate a bidirectional link with bandwidth
4333 limitations, the correct way is the following:
4335 .Dl "ipfw add pipe 1 ip from any to any out"
4336 .Dl "ipfw add pipe 2 ip from any to any in"
4337 .Dl "ipfw pipe 1 config bw 64Kbit/s queue 10Kbytes"
4338 .Dl "ipfw pipe 2 config bw 64Kbit/s queue 10Kbytes"
4340 The above can be very useful, e.g.\& if you want to see how
4341 your fancy Web page will look for a residential user who
4342 is connected only through a slow link.
4343 You should not use only one pipe for both directions, unless
4344 you want to simulate a half-duplex medium (e.g.\& AppleTalk,
4346 It is not necessary that both pipes have the same configuration,
4347 so we can also simulate asymmetric links.
4349 Should we want to verify network performance with the RED queue
4350 management algorithm:
4352 .Dl "ipfw add pipe 1 ip from any to any"
4353 .Dl "ipfw pipe 1 config bw 500Kbit/s queue 100 red 0.002/30/80/0.1"
4355 Another typical application of the traffic shaper is to
4356 introduce some delay in the communication.
4357 This can significantly affect applications which do a lot of Remote
4358 Procedure Calls, and where the round-trip-time of the
4359 connection often becomes a limiting factor much more than
4362 .Dl "ipfw add pipe 1 ip from any to any out"
4363 .Dl "ipfw add pipe 2 ip from any to any in"
4364 .Dl "ipfw pipe 1 config delay 250ms bw 1Mbit/s"
4365 .Dl "ipfw pipe 2 config delay 250ms bw 1Mbit/s"
4367 Per-flow queueing can be useful for a variety of purposes.
4368 A very simple one is counting traffic:
4370 .Dl "ipfw add pipe 1 tcp from any to any"
4371 .Dl "ipfw add pipe 1 udp from any to any"
4372 .Dl "ipfw add pipe 1 ip from any to any"
4373 .Dl "ipfw pipe 1 config mask all"
4375 The above set of rules will create queues (and collect
4376 statistics) for all traffic.
4377 Because the pipes have no limitations, the only effect is
4378 collecting statistics.
4379 Note that we need 3 rules, not just the last one, because
4382 tries to match IP packets it will not consider ports, so we
4383 would not see connections on separate ports as different
4386 A more sophisticated example is limiting the outbound traffic
4387 on a net with per-host limits, rather than per-network limits:
4389 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4390 .Dl "ipfw add pipe 2 ip from any to 192.168.2.0/24 in"
4391 .Dl "ipfw pipe 1 config mask src-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4392 .Dl "ipfw pipe 2 config mask dst-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4394 In the following example, we need to create several traffic bandwidth
4395 classes and we need different hosts/networks to fall into different classes.
4396 We create one pipe for each class and configure them accordingly.
4397 Then we create a single table and fill it with IP subnets and addresses.
4398 For each subnet/host we set the argument equal to the number of the pipe
4400 Then we classify traffic using a single rule:
4402 .Dl "ipfw pipe 1 config bw 1000Kbyte/s"
4403 .Dl "ipfw pipe 4 config bw 4000Kbyte/s"
4405 .Dl "ipfw table T1 create type addr"
4406 .Dl "ipfw table T1 add 192.168.2.0/24 1"
4407 .Dl "ipfw table T1 add 192.168.0.0/27 4"
4408 .Dl "ipfw table T1 add 192.168.0.2 1"
4410 .Dl "ipfw add pipe tablearg ip from 'table(T1)' to any"
4414 action, the table entries may include hostnames and IP addresses.
4416 .Dl "ipfw table T2 create type addr ftype ip"
4417 .Dl "ipfw table T2 add 192.168.2.0/24 10.23.2.1"
4418 .Dl "ipfw table T21 add 192.168.0.0/27 router1.dmz"
4420 .Dl "ipfw add 100 fwd tablearg ip from any to table(1)"
4422 In the following example per-interface firewall is created:
4424 .Dl "ipfw table IN create type iface valtype skipto,fib"
4425 .Dl "ipfw table IN add vlan20 12000,12"
4426 .Dl "ipfw table IN add vlan30 13000,13"
4427 .Dl "ipfw table OUT create type iface valtype skipto"
4428 .Dl "ipfw table OUT add vlan20 22000"
4429 .Dl "ipfw table OUT add vlan30 23000"
4431 .Dl "ipfw add 100 setfib tablearg ip from any to any recv 'table(IN)' in"
4432 .Dl "ipfw add 200 skipto tablearg ip from any to any recv 'table(IN)' in"
4433 .Dl "ipfw add 300 skipto tablearg ip from any to any xmit 'table(OUT)' out"
4435 The following example illustrate usage of flow tables:
4437 .Dl "ipfw table fl create type flow:src-ip,proto,dst-ip,dst-port"
4438 .Dl "ipfw table fl add 2a02:6b8:77::88,tcp,2a02:6b8:77::99,80 11"
4439 .Dl "ipfw table fl add 10.0.0.1,udp,10.0.0.2,53 12"
4441 .Dl "ipfw add 100 allow ip from any to any flow 'table(fl,11)' recv ix0"
4443 To add a set of rules atomically, e.g.\& set 18:
4445 .Dl "ipfw set disable 18"
4446 .Dl "ipfw add NN set 18 ... # repeat as needed"
4447 .Dl "ipfw set enable 18"
4449 To delete a set of rules atomically the command is simply:
4451 .Dl "ipfw delete set 18"
4453 To test a ruleset and disable it and regain control if something goes wrong:
4455 .Dl "ipfw set disable 18"
4456 .Dl "ipfw add NN set 18 ... # repeat as needed"
4457 .Dl "ipfw set enable 18; echo done; sleep 30 && ipfw set disable 18"
4459 Here if everything goes well, you press control-C before the "sleep"
4460 terminates, and your ruleset will be left active.
4461 Otherwise, e.g.\& if
4462 you cannot access your box, the ruleset will be disabled after
4463 the sleep terminates thus restoring the previous situation.
4465 To show rules of the specific set:
4467 .Dl "ipfw set 18 show"
4469 To show rules of the disabled set:
4471 .Dl "ipfw -S set 18 show"
4473 To clear a specific rule counters of the specific set:
4475 .Dl "ipfw set 18 zero NN"
4477 To delete a specific rule of the specific set:
4479 .Dl "ipfw set 18 delete NN"
4480 .Ss NAT, REDIRECT AND LSNAT
4481 First redirect all the traffic to nat instance 123:
4483 .Dl "ipfw add nat 123 all from any to any"
4485 Then to configure nat instance 123 to alias all the outgoing traffic with ip
4486 192.168.0.123, blocking all incoming connections, trying to keep
4487 same ports on both sides, clearing aliasing table on address change
4488 and keeping a log of traffic/link statistics:
4490 .Dl "ipfw nat 123 config ip 192.168.0.123 log deny_in reset same_ports"
4492 Or to change address of instance 123, aliasing table will be cleared (see
4495 .Dl "ipfw nat 123 config ip 10.0.0.1"
4497 To see configuration of nat instance 123:
4499 .Dl "ipfw nat 123 show config"
4501 To show logs of all the instances in range 111-999:
4503 .Dl "ipfw nat 111-999 show"
4505 To see configurations of all instances:
4507 .Dl "ipfw nat show config"
4509 Or a redirect rule with mixed modes could looks like:
4511 .Dl "ipfw nat 123 config redirect_addr 10.0.0.1 10.0.0.66"
4512 .Dl " redirect_port tcp 192.168.0.1:80 500"
4513 .Dl " redirect_proto udp 192.168.1.43 192.168.1.1"
4514 .Dl " redirect_addr 192.168.0.10,192.168.0.11"
4515 .Dl " 10.0.0.100 # LSNAT"
4516 .Dl " redirect_port tcp 192.168.0.1:80,192.168.0.10:22"
4519 or it could be split in:
4521 .Dl "ipfw nat 1 config redirect_addr 10.0.0.1 10.0.0.66"
4522 .Dl "ipfw nat 2 config redirect_port tcp 192.168.0.1:80 500"
4523 .Dl "ipfw nat 3 config redirect_proto udp 192.168.1.43 192.168.1.1"
4524 .Dl "ipfw nat 4 config redirect_addr 192.168.0.10,192.168.0.11,192.168.0.12"
4526 .Dl "ipfw nat 5 config redirect_port tcp"
4527 .Dl " 192.168.0.1:80,192.168.0.10:22,192.168.0.20:25 500"
4529 Sometimes you may want to mix NAT and dynamic rules. It could be achieved with
4533 options. Problem is, you need to create dynamic rule before NAT and check it
4534 after NAT actions (or vice versa) to have consistent addresses and ports.
4537 option will trigger activation of existing dynamic state, and action of such
4538 rule will be performed as soon as rule is matched. In case of NAT and
4540 rule packet need to be passed to NAT, not allowed as soon is possible.
4542 There is example of set of rules to achieve this. Bear in mind that this
4543 is exmaple only and it is not very useful by itself.
4545 On way out, after all checks place this rules:
4547 .Dl "ipfw add allow record-state skip-action"
4548 .Dl "ipfw add nat 1"
4550 And on way in there should be something like this:
4552 .Dl "ipfw add nat 1"
4553 .Dl "ipfw add check-state"
4555 Please note, that first rule on way out doesn't allow packet and doesn't
4556 execute existing dynamic rules. All it does, create new dynamic rule with
4558 action, if it is not created yet. Later, this dynamic rule is used on way
4562 .Ss CONFIGURING CODEL, PIE, FQ-CODEL and FQ-PIE AQM
4566 AQM can be configured for
4576 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4579 .Dl "ipfw pipe 1 config bw 1mbits/s codel"
4580 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4586 AQM using different configurations parameters for traffic from
4587 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4589 .Dl "ipfw pipe 1 config bw 1mbits/s"
4590 .Dl "ipfw queue 1 config pipe 1 codel target 8ms interval 160ms ecn"
4591 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4597 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4600 .Dl "ipfw pipe 1 config bw 1mbits/s pie"
4601 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4607 AQM using different configuration parameters for traffic from
4608 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4610 .Dl "ipfw pipe 1 config bw 1mbits/s"
4611 .Dl "ipfw queue 1 config pipe 1 pie target 20ms tupdate 30ms ecn"
4612 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4617 AQM can be configured for
4623 scheduler using different configurations parameters for traffic from
4624 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4626 .Dl "ipfw pipe 1 config bw 1mbits/s"
4627 .Dl "ipfw sched 1 config pipe 1 type fq_codel"
4628 .Dl "ipfw queue 1 config sched 1"
4629 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4633 default configuration for a
4635 such as disable ECN and change the
4639 .Dl "ipfw sched 1 config pipe 1 type fq_codel target 10ms noecn"
4645 scheduler using different configurations parameters for traffic from
4646 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4648 .Dl "ipfw pipe 1 config bw 1mbits/s"
4649 .Dl "ipfw sched 1 config pipe 1 type fq_pie"
4650 .Dl "ipfw queue 1 config sched 1"
4651 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4653 The configurations of
4656 can be changed in a similar way as for
4680 utility first appeared in
4685 Stateful extensions were introduced in
4688 was introduced in Summer 2002.
4690 .An Ugen J. S. Antsilevich ,
4691 .An Poul-Henning Kamp ,
4695 .An Rasool Al-Saadi .
4698 API based upon code written by
4702 Dummynet has been introduced by Luigi Rizzo in 1997-1998.
4704 Some early work (1999-2000) on the
4706 traffic shaper supported by Akamba Corp.
4708 The ipfw core (ipfw2) has been completely redesigned and
4709 reimplemented by Luigi Rizzo in summer 2002.
4712 options have been added by various developers over the years.
4715 In-kernel NAT support written by
4716 .An Paolo Pisati Aq Mt piso@FreeBSD.org
4717 as part of a Summer of Code 2005 project.
4721 support has been developed by
4722 .An The Centre for Advanced Internet Architectures (CAIA) Aq http://www.caia.swin.edu.au .
4723 The primary developers and maintainers are David Hayes and Jason But.
4724 For further information visit:
4725 .Aq http://www.caia.swin.edu.au/urp/SONATA
4727 Delay profiles have been developed by Alessandro Cerri and
4728 Luigi Rizzo, supported by the
4729 European Commission within Projects Onelab and Onelab2.
4731 CoDel, PIE, FQ-CoDel and FQ-PIE AQM for Dummynet have been implemented by
4732 .An The Centre for Advanced Internet Architectures (CAIA)
4733 in 2016, supported by The Comcast Innovation Fund.
4734 The primary developer is
4737 The syntax has grown over the years and sometimes it might be confusing.
4738 Unfortunately, backward compatibility prevents cleaning up mistakes
4739 made in the definition of the syntax.
4743 Misconfiguring the firewall can put your computer in an unusable state,
4744 possibly shutting down network services and requiring console access to
4745 regain control of it.
4747 Incoming packet fragments diverted by
4749 are reassembled before delivery to the socket.
4750 The action used on those packet is the one from the
4751 rule which matches the first fragment of the packet.
4753 Packets diverted to userland, and then reinserted by a userland process
4754 may lose various packet attributes.
4755 The packet source interface name
4756 will be preserved if it is shorter than 8 bytes and the userland process
4757 saves and reuses the sockaddr_in
4760 otherwise, it may be lost.
4761 If a packet is reinserted in this manner, later rules may be incorrectly
4762 applied, making the order of
4764 rules in the rule sequence very important.
4766 Dummynet drops all packets with IPv6 link-local addresses.
4772 may not behave as expected.
4773 In particular, incoming SYN packets may
4774 have no uid or gid associated with them since they do not yet belong
4775 to a TCP connection, and the uid/gid associated with a packet may not
4776 be as expected if the associated process calls
4778 or similar system calls.
4780 Rule syntax is subject to the command line environment and some patterns
4781 may need to be escaped with the backslash character
4782 or quoted appropriately.
4784 Due to the architecture of
4786 ipfw nat is not compatible with the TCP segmentation offloading (TSO).
4787 Thus, to reliably nat your network traffic, please disable TSO
4791 ICMP error messages are not implicitly matched by dynamic rules
4792 for the respective conversations.
4793 To avoid failures of network error detection and path MTU discovery,
4794 ICMP error messages may need to be allowed explicitly through static
4801 actions may lead to confusing behaviour if ruleset has mistakes,
4802 and/or interaction with other subsystems (netgraph, dummynet, etc.) is used.
4803 One possible case for this is packet leaving
4805 in subroutine on the input pass, while later on output encountering unpaired
4808 As the call stack is kept intact after input pass, packet will suddenly
4809 return to the rule number used on input pass, not on output one.
4810 Order of processing should be checked carefully to avoid such mistakes.
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