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,
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 IPv4 packets whose
1608 field contains the comma separated list of IPv4 fragmentation
1609 options specified in
1611 The recognized options are:
1613 .Pq Dv don't fragment ,
1615 .Pq Dv more fragments ,
1617 .Pq Dv reserved fragment bit
1619 .Pq Dv non-zero fragment offset .
1620 The absence of a particular options may be denoted
1624 Empty list of options defaults to matching on non-zero fragment offset.
1625 Such rule would match all not the first fragment datagrams,
1627 This is a backward compatibility with older rulesets.
1629 Matches all TCP or UDP packets sent by or received for a
1633 may be specified by name or number.
1635 Matches all TCP or UDP packets sent by or received for the
1636 jail whose ID or name is
1638 .It Cm icmptypes Ar types
1639 Matches ICMP packets whose ICMP type is in the list
1641 The list may be specified as any combination of
1642 individual types (numeric) separated by commas.
1643 .Em Ranges are not allowed .
1644 The supported ICMP types are:
1648 destination unreachable
1656 router advertisement
1660 time-to-live exceeded
1672 address mask request
1674 and address mask reply
1676 .It Cm icmp6types Ar types
1677 Matches ICMP6 packets whose ICMP6 type is in the list of
1679 The list may be specified as any combination of
1680 individual types (numeric) separated by commas.
1681 .Em Ranges are not allowed .
1683 Matches incoming or outgoing packets, respectively.
1687 are mutually exclusive (in fact,
1691 .It Cm ipid Ar id-list
1692 Matches IPv4 packets whose
1694 field has value included in
1696 which is either a single value or a list of values or ranges
1697 specified in the same way as
1699 .It Cm iplen Ar len-list
1700 Matches IP packets whose total length, including header and data, is
1703 which is either a single value or a list of values or ranges
1704 specified in the same way as
1706 .It Cm ipoptions Ar spec
1707 Matches packets whose IPv4 header contains the comma separated list of
1708 options specified in
1710 The supported IP options are:
1713 (strict source route),
1715 (loose source route),
1717 (record packet route) and
1720 The absence of a particular option may be denoted
1723 .It Cm ipprecedence Ar precedence
1724 Matches IPv4 packets whose precedence field is equal to
1727 Matches packets that have IPSEC history associated with them
1728 (i.e., the packet comes encapsulated in IPSEC, the kernel
1729 has IPSEC support, and can correctly decapsulate it).
1731 Note that specifying
1733 is different from specifying
1735 as the latter will only look at the specific IP protocol field,
1736 irrespective of IPSEC kernel support and the validity of the IPSEC data.
1738 Further note that this flag is silently ignored in kernels without
1740 It does not affect rule processing when given and the
1741 rules are handled as if with no
1744 .It Cm iptos Ar spec
1745 Matches IPv4 packets whose
1747 field contains the comma separated list of
1748 service types specified in
1750 The supported IP types of service are:
1753 .Pq Dv IPTOS_LOWDELAY ,
1755 .Pq Dv IPTOS_THROUGHPUT ,
1757 .Pq Dv IPTOS_RELIABILITY ,
1759 .Pq Dv IPTOS_MINCOST ,
1761 .Pq Dv IPTOS_ECN_CE .
1762 The absence of a particular type may be denoted
1765 .It Cm dscp spec Ns Op , Ns Ar spec
1766 Matches IPv4/IPv6 packets whose
1768 field value is contained in
1771 Multiple values can be specified via
1772 the comma separated list.
1773 Value can be one of keywords used in
1775 action or exact number.
1776 .It Cm ipttl Ar ttl-list
1777 Matches IPv4 packets whose time to live is included in
1779 which is either a single value or a list of values or ranges
1780 specified in the same way as
1782 .It Cm ipversion Ar ver
1783 Matches IP packets whose IP version field is
1785 .It Cm keep-state Op Ar :flowname
1786 Upon a match, the firewall will create a dynamic rule, whose
1787 default behaviour is to match bidirectional traffic between
1788 source and destination IP/port using the same protocol.
1789 The rule has a limited lifetime (controlled by a set of
1791 variables), and the lifetime is refreshed every time a matching
1795 is used to assign additional to addresses, ports and protocol parameter
1796 to dynamic rule. It can be used for more accurate matching by
1801 keyword is special name used for compatibility with old rulesets.
1803 Matches only layer2 packets, i.e., those passed to
1805 from ether_demux() and ether_output_frame().
1806 .It Cm limit Bro Cm src-addr | src-port | dst-addr | dst-port Brc Ar N Op Ar :flowname
1807 The firewall will only allow
1809 connections with the same
1810 set of parameters as specified in the rule.
1812 of source and destination addresses and ports can be
1814 .It Cm lookup Bro Cm dst-ip | dst-port | src-ip | src-port | uid | jail Brc Ar name
1815 Search an entry in lookup table
1817 that matches the field specified as argument.
1818 If not found, the match fails.
1819 Otherwise, the match succeeds and
1821 is set to the value extracted from the table.
1823 This option can be useful to quickly dispatch traffic based on
1824 certain packet fields.
1827 section below for more information on lookup tables.
1828 .It Cm { MAC | mac } Ar dst-mac src-mac
1829 Match packets with a given
1833 addresses, specified as the
1835 keyword (matching any MAC address), or six groups of hex digits
1836 separated by colons,
1837 and optionally followed by a mask indicating the significant bits.
1838 The mask may be specified using either of the following methods:
1839 .Bl -enum -width indent
1843 followed by the number of significant bits.
1844 For example, an address with 33 significant bits could be specified as:
1846 .Dl "MAC 10:20:30:40:50:60/33 any"
1850 followed by a bitmask specified as six groups of hex digits separated
1852 For example, an address in which the last 16 bits are significant could
1855 .Dl "MAC 10:20:30:40:50:60&00:00:00:00:ff:ff any"
1857 Note that the ampersand character has a special meaning in many shells
1858 and should generally be escaped.
1860 Note that the order of MAC addresses (destination first,
1862 the same as on the wire, but the opposite of the one used for
1864 .It Cm mac-type Ar mac-type
1865 Matches packets whose Ethernet Type field
1866 corresponds to one of those specified as argument.
1868 is specified in the same way as
1870 (i.e., one or more comma-separated single values or ranges).
1871 You can use symbolic names for known values such as
1872 .Em vlan , ipv4, ipv6 .
1873 Values can be entered as decimal or hexadecimal (if prefixed by 0x),
1874 and they are always printed as hexadecimal (unless the
1876 option is used, in which case symbolic resolution will be attempted).
1877 .It Cm proto Ar protocol
1878 Matches packets with the corresponding IP protocol.
1880 Upon a match, the firewall will create a dynamic rule as if
1883 However, this option doesn't imply an implicit
1887 .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
1888 Matches packets received, transmitted or going through,
1889 respectively, the interface specified by exact name
1893 by IP address, or through some interface.
1896 may be used to match interface by its kernel ifindex.
1899 section below for more information on lookup tables.
1903 keyword causes the interface to always be checked.
1910 then only the receive or transmit interface (respectively)
1912 By specifying both, it is possible to match packets based on
1913 both receive and transmit interface, e.g.:
1915 .Dl "ipfw add deny ip from any to any out recv ed0 xmit ed1"
1919 interface can be tested on either incoming or outgoing packets,
1922 interface can only be tested on outgoing packets.
1927 is invalid) whenever
1931 A packet might not have a receive or transmit interface: packets
1932 originating from the local host have no receive interface,
1933 while packets destined for the local host have no transmit
1935 .It Cm set-limit Bro Cm src-addr | src-port | dst-addr | dst-port Brc Ar N
1938 but does not have an implicit
1942 Matches TCP packets that have the SYN bit set but no ACK bit.
1943 This is the short form of
1944 .Dq Li tcpflags\ syn,!ack .
1946 Matches packets that are associated to a local socket and
1947 for which the SO_USER_COOKIE socket option has been set
1948 to a non-zero value.
1949 As a side effect, the value of the
1950 option is made available as
1952 value, which in turn can be used as
1957 .It Cm src-ip Ar ip-address
1958 Matches IPv4 packets whose source IP is one of the address(es)
1959 specified as an argument.
1960 .It Cm src-ip6 Ar ip6-address
1961 Matches IPv6 packets whose source IP is one of the address(es)
1962 specified as an argument.
1963 .It Cm src-port Ar ports
1964 Matches IP packets whose source port is one of the port(s)
1965 specified as argument.
1966 .It Cm tagged Ar tag-list
1967 Matches packets whose tags are included in
1969 which is either a single value or a list of values or ranges
1970 specified in the same way as
1972 Tags can be applied to the packet using
1974 rule action parameter (see it's description for details on tags).
1975 .It Cm tcpack Ar ack
1977 Match if the TCP header acknowledgment number field is set to
1979 .It Cm tcpdatalen Ar tcpdatalen-list
1980 Matches TCP packets whose length of TCP data is
1981 .Ar tcpdatalen-list ,
1982 which is either a single value or a list of values or ranges
1983 specified in the same way as
1985 .It Cm tcpflags Ar spec
1987 Match if the TCP header contains the comma separated list of
1990 The supported TCP flags are:
1999 The absence of a particular flag may be denoted
2002 A rule which contains a
2004 specification can never match a fragmented packet which has
2008 option for details on matching fragmented packets.
2009 .It Cm tcpmss Ar tcpmss-list
2010 Matches TCP packets whose MSS (maximum segment size) value is set to
2012 which is either a single value or a list of values or ranges
2013 specified in the same way as
2015 .It Cm tcpseq Ar seq
2017 Match if the TCP header sequence number field is set to
2019 .It Cm tcpwin Ar tcpwin-list
2020 Matches TCP packets whose header window field is set to
2022 which is either a single value or a list of values or ranges
2023 specified in the same way as
2025 .It Cm tcpoptions Ar spec
2027 Match if the TCP header contains the comma separated list of
2028 options specified in
2030 The supported TCP options are:
2033 (maximum segment size),
2035 (tcp window advertisement),
2039 (rfc1323 timestamp) and
2041 (rfc1644 t/tcp connection count).
2042 The absence of a particular option may be denoted
2046 Match all TCP or UDP packets sent by or received for a
2050 may be matched by name or identification number.
2052 For incoming packets,
2053 a routing table lookup is done on the packet's source address.
2054 If the interface on which the packet entered the system matches the
2055 outgoing interface for the route,
2057 If the interfaces do not match up,
2058 the packet does not match.
2059 All outgoing packets or packets with no incoming interface match.
2061 The name and functionality of the option is intentionally similar to
2062 the Cisco IOS command:
2064 .Dl ip verify unicast reverse-path
2066 This option can be used to make anti-spoofing rules to reject all
2067 packets with source addresses not from this interface.
2071 For incoming packets,
2072 a routing table lookup is done on the packet's source address.
2073 If a route to the source address exists, but not the default route
2074 or a blackhole/reject route, the packet matches.
2075 Otherwise, the packet does not match.
2076 All outgoing packets match.
2078 The name and functionality of the option is intentionally similar to
2079 the Cisco IOS command:
2081 .Dl ip verify unicast source reachable-via any
2083 This option can be used to make anti-spoofing rules to reject all
2084 packets whose source address is unreachable.
2086 For incoming packets, the packet's source address is checked if it
2087 belongs to a directly connected network.
2088 If the network is directly connected, then the interface the packet
2089 came on in is compared to the interface the network is connected to.
2090 When incoming interface and directly connected interface are not the
2091 same, the packet does not match.
2092 Otherwise, the packet does match.
2093 All outgoing packets match.
2095 This option can be used to make anti-spoofing rules to reject all
2096 packets that pretend to be from a directly connected network but do
2097 not come in through that interface.
2098 This option is similar to but more restricted than
2100 because it engages only on packets with source addresses of directly
2101 connected networks instead of all source addresses.
2104 Lookup tables are useful to handle large sparse sets of
2105 addresses or other search keys (e.g., ports, jail IDs, interface names).
2106 In the rest of this section we will use the term ``key''.
2107 Table name needs to match the following spec:
2109 Tables with the same name can be created in different
2111 However, rule links to the tables in
2114 This behavior can be controlled by
2115 .Va net.inet.ip.fw.tables_sets
2119 section for more information.
2120 There may be up to 65535 different lookup tables.
2122 The following table types are supported:
2123 .Bl -tag -width indent
2124 .It Ar table-type : Ar addr | iface | number | flow
2125 .It Ar table-key : Ar addr Ns Oo / Ns Ar masklen Oc | iface-name | number | flow-spec
2126 .It Ar flow-spec : Ar flow-field Ns Op , Ns Ar flow-spec
2127 .It Ar flow-field : src-ip | proto | src-port | dst-ip | dst-port
2129 Matches IPv4 or IPv6 address.
2130 Each entry is represented by an
2131 .Ar addr Ns Op / Ns Ar masklen
2132 and will match all addresses with base
2134 (specified as an IPv4/IPv6 address, or a hostname) and mask width of
2139 is not specified, it defaults to 32 for IPv4 and 128 for IPv6.
2140 When looking up an IP address in a table, the most specific
2143 Matches interface names.
2144 Each entry is represented by string treated as interface name.
2145 Wildcards are not supported.
2147 Matches protocol ports, uids/gids or jail IDs.
2148 Each entry is represented by 32-bit unsigned integer.
2149 Ranges are not supported.
2151 Matches packet fields specified by
2153 type suboptions with table entries.
2156 Tables require explicit creation via
2160 The following creation options are supported:
2161 .Bl -tag -width indent
2162 .It Ar create-options : Ar create-option | create-options
2163 .It Ar create-option : Cm type Ar table-type | Cm valtype Ar value-mask | Cm algo Ar algo-desc |
2164 .Cm limit Ar number | Cm locked | Cm missing | Cm or-flush
2170 Table algorithm to use (see below).
2172 Maximum number of items that may be inserted into table.
2174 Restrict any table modifications.
2176 Do not fail if table already exists and has exactly same options as new one.
2178 Flush existing table with same name instead of returning error.
2181 so existing table must be compatible with new one.
2184 Some of these options may be modified later via
2187 The following options can be changed:
2188 .Bl -tag -width indent
2189 .It Ar modify-options : Ar modify-option | modify-options
2190 .It Ar modify-option : Cm limit Ar number
2192 Alter maximum number of items that may be inserted into table.
2195 Additionally, table can be locked or unlocked using
2203 can be swapped with each other using
2206 Swap may fail if tables limits are set and data exchange
2207 would result in limits hit.
2208 Operation is performed atomically.
2210 One or more entries can be added to a table at once using
2213 Addition of all items are performed atomically.
2214 By default, error in addition of one entry does not influence
2215 addition of other entries. However, non-zero error code is returned
2219 keyword may be specified before
2221 to indicate all-or-none add request.
2223 One or more entries can be removed from a table at once using
2226 By default, error in removal of one entry does not influence
2227 removing of other entries. However, non-zero error code is returned
2230 It may be possible to check what entry will be found on particular
2236 This functionality is optional and may be unsupported in some algorithms.
2238 The following operations can be performed on
2243 .Bl -tag -width indent
2247 Removes all entries.
2249 Shows generic table information.
2251 Shows generic table information and algo-specific data.
2254 The following lookup algorithms are supported:
2255 .Bl -tag -width indent
2256 .It Ar algo-desc : algo-name | "algo-name algo-data"
2257 .It Ar algo-name: Ar addr:radix | addr:hash | iface:array | number:array | flow:hash
2259 Separate Radix trees for IPv4 and IPv6, the same way as the routing table (see
2265 Separate auto-growing hashes for IPv4 and IPv6.
2266 Accepts entries with the same mask length specified initially via
2267 .Cm "addr:hash masks=/v4,/v6"
2268 algorithm creation options.
2269 Assume /32 and /128 masks by default.
2270 Search removes host bits (according to mask) from supplied address and checks
2271 resulting key in appropriate hash.
2272 Mostly optimized for /64 and byte-ranged IPv6 masks.
2274 Array storing sorted indexes for entries which are presented in the system.
2275 Optimized for very fast lookup.
2277 Array storing sorted u32 numbers.
2279 Auto-growing hash storing flow entries.
2280 Search calculates hash on required packet fields and searches for matching
2281 entries in selected bucket.
2286 feature provides the ability to use a value, looked up in the table, as
2287 the argument for a rule action, action parameter or rule option.
2288 This can significantly reduce number of rules in some configurations.
2289 If two tables are used in a rule, the result of the second (destination)
2292 Each record may hold one or more values according to
2294 This mask is set on table creation via
2297 The following value types are supported:
2298 .Bl -tag -width indent
2299 .It Ar value-mask : Ar value-type Ns Op , Ns Ar value-mask
2300 .It Ar value-type : Ar skipto | pipe | fib | nat | dscp | tag | divert |
2301 .Ar netgraph | limit | ipv4
2303 rule number to jump to.
2307 fib number to match/set.
2309 nat number to jump to.
2311 dscp value to match/set.
2313 tag number to match/set.
2315 port number to divert traffic to.
2317 hook number to move packet to.
2319 maximum number of connections.
2321 IPv4 nexthop to fwd packets to.
2323 IPv6 nexthop to fwd packets to.
2328 argument can be used with the following actions:
2329 .Cm nat, pipe , queue, divert, tee, netgraph, ngtee, fwd, skipto, setfib,
2337 action, the user should be aware that the code will walk the ruleset
2338 up to a rule equal to, or past, the given number.
2342 Section for example usage of tables and the tablearg keyword.
2344 Each rule or table belongs to one of 32 different
2347 Set 31 is reserved for the default rule.
2349 By default, rules or tables are put in set 0, unless you use the
2351 attribute when adding a new rule or table.
2352 Sets can be individually and atomically enabled or disabled,
2353 so this mechanism permits an easy way to store multiple configurations
2354 of the firewall and quickly (and atomically) switch between them.
2356 By default, tables from set 0 are referenced when adding rule with
2357 table opcodes regardless of rule set.
2358 This behavior can be changed by setting
2359 .Va net.inet.ip.fw.tables_sets
2361 Rule's set will then be used for table references.
2363 The command to enable/disable sets is
2364 .Bd -ragged -offset indent
2366 .Cm set Oo Cm disable Ar number ... Oc Op Cm enable Ar number ...
2373 sections can be specified.
2374 Command execution is atomic on all the sets specified in the command.
2375 By default, all sets are enabled.
2377 When you disable a set, its rules behave as if they do not exist
2378 in the firewall configuration, with only one exception:
2379 .Bd -ragged -offset indent
2380 dynamic rules created from a rule before it had been disabled
2381 will still be active until they expire.
2383 dynamic rules you have to explicitly delete the parent rule
2384 which generated them.
2387 The set number of rules can be changed with the command
2388 .Bd -ragged -offset indent
2391 .Brq Cm rule Ar rule-number | old-set
2395 Also, you can atomically swap two rulesets with the command
2396 .Bd -ragged -offset indent
2398 .Cm set swap Ar first-set second-set
2403 Section on some possible uses of sets of rules.
2404 .Sh STATEFUL FIREWALL
2405 Stateful operation is a way for the firewall to dynamically
2406 create rules for specific flows when packets that
2407 match a given pattern are detected.
2408 Support for stateful
2409 operation comes through the
2410 .Cm check-state , keep-state , record-state , limit
2416 Dynamic rules are created when a packet matches a
2422 rule, causing the creation of a
2424 rule which will match all and only packets with
2428 .Em src-ip/src-port dst-ip/dst-port
2433 are used here only to denote the initial match addresses, but they
2434 are completely equivalent afterwards).
2440 This name is used in matching together with addresses, ports and protocol.
2441 Dynamic rules will be checked at the first
2442 .Cm check-state, keep-state
2445 occurrence, and the action performed upon a match will be the same
2446 as in the parent rule.
2448 Note that no additional attributes other than protocol and IP addresses
2449 and ports and :flowname are checked on dynamic rules.
2451 The typical use of dynamic rules is to keep a closed firewall configuration,
2452 but let the first TCP SYN packet from the inside network install a
2453 dynamic rule for the flow so that packets belonging to that session
2454 will be allowed through the firewall:
2456 .Dl "ipfw add check-state :OUTBOUND"
2457 .Dl "ipfw add allow tcp from my-subnet to any setup keep-state :OUTBOUND"
2458 .Dl "ipfw add deny tcp from any to any"
2460 A similar approach can be used for UDP, where an UDP packet coming
2461 from the inside will install a dynamic rule to let the response through
2464 .Dl "ipfw add check-state :OUTBOUND"
2465 .Dl "ipfw add allow udp from my-subnet to any keep-state :OUTBOUND"
2466 .Dl "ipfw add deny udp from any to any"
2468 Dynamic rules expire after some time, which depends on the status
2469 of the flow and the setting of some
2473 .Sx SYSCTL VARIABLES
2475 For TCP sessions, dynamic rules can be instructed to periodically
2476 send keepalive packets to refresh the state of the rule when it is
2481 for more examples on how to use dynamic rules.
2482 .Sh TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
2484 is also the user interface for the
2486 traffic shaper, packet scheduler and network emulator, a subsystem that
2487 can artificially queue, delay or drop packets
2488 emulating the behaviour of certain network links
2489 or queueing systems.
2492 operates by first using the firewall to select packets
2493 using any match pattern that can be used in
2496 Matching packets are then passed to either of two
2497 different objects, which implement the traffic regulation:
2498 .Bl -hang -offset XXXX
2504 with given bandwidth and propagation delay,
2505 driven by a FIFO scheduler and a single queue with programmable
2506 queue size and packet loss rate.
2507 Packets are appended to the queue as they come out from
2509 and then transferred in FIFO order to the link at the desired rate.
2513 is an abstraction used to implement packet scheduling
2514 using one of several packet scheduling algorithms.
2517 are first grouped into flows according to a mask on the 5-tuple.
2518 Flows are then passed to the scheduler associated to the
2520 and each flow uses scheduling parameters (weight and others)
2521 as configured in the
2524 A scheduler in turn is connected to an emulated link,
2525 and arbitrates the link's bandwidth among backlogged flows according to
2526 weights and to the features of the scheduling algorithm in use.
2531 can be used to set hard limits to the bandwidth that a flow can use, whereas
2533 can be used to determine how different flows share the available bandwidth.
2535 A graphical representation of the binding of queues,
2536 flows, schedulers and links is below.
2537 .Bd -literal -offset indent
2538 (flow_mask|sched_mask) sched_mask
2539 +---------+ weight Wx +-------------+
2540 | |->-[flow]-->--| |-+
2541 -->--| QUEUE x | ... | | |
2542 | |->-[flow]-->--| SCHEDuler N | |
2544 ... | +--[LINK N]-->--
2545 +---------+ weight Wy | | +--[LINK N]-->--
2546 | |->-[flow]-->--| | |
2547 -->--| QUEUE y | ... | | |
2548 | |->-[flow]-->--| | |
2549 +---------+ +-------------+ |
2552 It is important to understand the role of the SCHED_MASK
2553 and FLOW_MASK, which are configured through the commands
2554 .Dl "ipfw sched N config mask SCHED_MASK ..."
2556 .Dl "ipfw queue X config mask FLOW_MASK ..." .
2558 The SCHED_MASK is used to assign flows to one or more
2559 scheduler instances, one for each
2560 value of the packet's 5-tuple after applying SCHED_MASK.
2561 As an example, using ``src-ip 0xffffff00'' creates one instance
2562 for each /24 destination subnet.
2564 The FLOW_MASK, together with the SCHED_MASK, is used to split
2566 As an example, using
2567 ``src-ip 0x000000ff''
2568 together with the previous SCHED_MASK makes a flow for
2569 each individual source address.
2570 In turn, flows for each /24
2571 subnet will be sent to the same scheduler instance.
2573 The above diagram holds even for the
2575 case, with the only restriction that a
2577 only supports a SCHED_MASK, and forces the use of a FIFO
2578 scheduler (these are for backward compatibility reasons;
2579 in fact, internally, a
2581 pipe is implemented exactly as above).
2583 There are two modes of
2591 mode tries to emulate a real link: the
2593 scheduler ensures that the packet will not leave the pipe faster than it
2594 would on the real link with a given bandwidth.
2597 mode allows certain packets to bypass the
2599 scheduler (if packet flow does not exceed pipe's bandwidth).
2600 This is the reason why the
2602 mode requires less CPU cycles per packet (on average) and packet latency
2603 can be significantly lower in comparison to a real link with the same
2609 mode can be enabled by setting the
2610 .Va net.inet.ip.dummynet.io_fast
2612 variable to a non-zero value.
2614 .Ss PIPE, QUEUE AND SCHEDULER CONFIGURATION
2620 configuration commands are the following:
2621 .Bd -ragged -offset indent
2622 .Cm pipe Ar number Cm config Ar pipe-configuration
2624 .Cm queue Ar number Cm config Ar queue-configuration
2626 .Cm sched Ar number Cm config Ar sched-configuration
2629 The following parameters can be configured for a pipe:
2631 .Bl -tag -width indent -compact
2632 .It Cm bw Ar bandwidth | device
2633 Bandwidth, measured in
2636 .Brq Cm bit/s | Byte/s .
2639 A value of 0 (default) means unlimited bandwidth.
2640 The unit must immediately follow the number, as in
2642 .Dl "ipfw pipe 1 config bw 300Kbit/s"
2644 If a device name is specified instead of a numeric value, as in
2646 .Dl "ipfw pipe 1 config bw tun0"
2648 then the transmit clock is supplied by the specified device.
2649 At the moment only the
2651 device supports this
2652 functionality, for use in conjunction with
2655 .It Cm delay Ar ms-delay
2656 Propagation delay, measured in milliseconds.
2657 The value is rounded to the next multiple of the clock tick
2658 (typically 10ms, but it is a good practice to run kernels
2660 .Dq "options HZ=1000"
2662 the granularity to 1ms or less).
2663 The default value is 0, meaning no delay.
2665 .It Cm burst Ar size
2666 If the data to be sent exceeds the pipe's bandwidth limit
2667 (and the pipe was previously idle), up to
2669 bytes of data are allowed to bypass the
2671 scheduler, and will be sent as fast as the physical link allows.
2672 Any additional data will be transmitted at the rate specified
2676 The burst size depends on how long the pipe has been idle;
2677 the effective burst size is calculated as follows:
2684 .It Cm profile Ar filename
2685 A file specifying the additional overhead incurred in the transmission
2686 of a packet on the link.
2688 Some link types introduce extra delays in the transmission
2689 of a packet, e.g., because of MAC level framing, contention on
2690 the use of the channel, MAC level retransmissions and so on.
2691 From our point of view, the channel is effectively unavailable
2692 for this extra time, which is constant or variable depending
2694 Additionally, packets may be dropped after this
2695 time (e.g., on a wireless link after too many retransmissions).
2696 We can model the additional delay with an empirical curve
2697 that represents its distribution.
2698 .Bd -literal -offset indent
2699 cumulative probability
2709 +-------*------------------->
2712 The empirical curve may have both vertical and horizontal lines.
2713 Vertical lines represent constant delay for a range of
2715 Horizontal lines correspond to a discontinuity in the delay
2716 distribution: the pipe will use the largest delay for a
2719 The file format is the following, with whitespace acting as
2720 a separator and '#' indicating the beginning a comment:
2721 .Bl -tag -width indent
2722 .It Cm name Ar identifier
2723 optional name (listed by "ipfw pipe show")
2724 to identify the delay distribution;
2726 the bandwidth used for the pipe.
2727 If not specified here, it must be present
2728 explicitly as a configuration parameter for the pipe;
2729 .It Cm loss-level Ar L
2730 the probability above which packets are lost.
2731 (0.0 <= L <= 1.0, default 1.0 i.e., no loss);
2733 the number of samples used in the internal
2734 representation of the curve (2..1024; default 100);
2735 .It Cm "delay prob" | "prob delay"
2736 One of these two lines is mandatory and defines
2737 the format of the following lines with data points.
2739 2 or more lines representing points in the curve,
2740 with either delay or probability first, according
2741 to the chosen format.
2742 The unit for delay is milliseconds.
2743 Data points do not need to be sorted.
2744 Also, the number of actual lines can be different
2745 from the value of the "samples" parameter:
2747 utility will sort and interpolate
2748 the curve as needed.
2751 Example of a profile file:
2752 .Bd -literal -offset indent
2757 0 200 # minimum overhead is 200ms
2763 #configuration file end
2767 The following parameters can be configured for a queue:
2769 .Bl -tag -width indent -compact
2770 .It Cm pipe Ar pipe_nr
2771 Connects a queue to the specified pipe.
2772 Multiple queues (with the same or different weights) can be connected to
2773 the same pipe, which specifies the aggregate rate for the set of queues.
2775 .It Cm weight Ar weight
2776 Specifies the weight to be used for flows matching this queue.
2777 The weight must be in the range 1..100, and defaults to 1.
2780 The following case-insensitive parameters can be configured for a
2783 .Bl -tag -width indent -compact
2784 .It Cm type Ar {fifo | wf2q+ | rr | qfq | fq_codel | fq_pie}
2785 specifies the scheduling algorithm to use.
2786 .Bl -tag -width indent -compact
2788 is just a FIFO scheduler (which means that all packets
2789 are stored in the same queue as they arrive to the scheduler).
2790 FIFO has O(1) per-packet time complexity, with very low
2791 constants (estimate 60-80ns on a 2GHz desktop machine)
2792 but gives no service guarantees.
2794 implements the WF2Q+ algorithm, which is a Weighted Fair Queueing
2795 algorithm which permits flows to share bandwidth according to
2797 Note that weights are not priorities; even a flow
2798 with a minuscule weight will never starve.
2799 WF2Q+ has O(log N) per-packet processing cost, where N is the number
2800 of flows, and is the default algorithm used by previous versions
2803 implements the Deficit Round Robin algorithm, which has O(1) processing
2804 costs (roughly, 100-150ns per packet)
2805 and permits bandwidth allocation according to weights, but
2806 with poor service guarantees.
2808 implements the QFQ algorithm, which is a very fast variant of
2809 WF2Q+, with similar service guarantees and O(1) processing
2810 costs (roughly, 200-250ns per packet).
2812 implements the FQ-CoDel (FlowQueue-CoDel) scheduler/AQM algorithm, which
2813 uses a modified Deficit Round Robin scheduler to manage two lists of sub-queues
2814 (old sub-queues and new sub-queues) for providing brief periods of priority to
2815 lightweight or short burst flows.
2816 By default, the total number of sub-queues is 1024.
2817 FQ-CoDel's internal, dynamically
2818 created sub-queues are controlled by separate instances of CoDel AQM.
2820 implements the FQ-PIE (FlowQueue-PIE) scheduler/AQM algorithm, which similar to
2822 but uses per sub-queue PIE AQM instance to control the queue delay.
2826 inherits AQM parameters and options from
2830 inherits AQM parameters and options from
2833 Additionally, both of
2837 have shared scheduler parameters which are:
2838 .Bl -tag -width indent
2841 specifies the quantum (credit) of the scheduler.
2843 is the number of bytes a queue can serve before being moved to the tail
2845 The default is 1514 bytes, and the maximum acceptable value
2849 specifies the hard size limit (in unit of packets) of all queues managed by an
2850 instance of the scheduler.
2851 The default value of
2853 is 10240 packets, and the maximum acceptable value is 20480 packets.
2856 specifies the total number of flow queues (sub-queues) that fq_*
2857 creates and manages.
2858 By default, 1024 sub-queues are created when an instance
2859 of the fq_{codel/pie} scheduler is created.
2860 The maximum acceptable value is
2864 Note that any token after
2868 is considered a parameter for fq_{codel/pie}.
2869 So, ensure all scheduler
2870 configuration options not related to fq_{codel/pie} are written before
2875 In addition to the type, all parameters allowed for a pipe can also
2876 be specified for a scheduler.
2878 Finally, the following parameters can be configured for both
2881 .Bl -tag -width XXXX -compact
2882 .It Cm buckets Ar hash-table-size
2883 Specifies the size of the hash table used for storing the
2885 Default value is 64 controlled by the
2888 .Va net.inet.ip.dummynet.hash_size ,
2889 allowed range is 16 to 65536.
2891 .It Cm mask Ar mask-specifier
2892 Packets sent to a given pipe or queue by an
2894 rule can be further classified into multiple flows, each of which is then
2898 A flow identifier is constructed by masking the IP addresses,
2899 ports and protocol types as specified with the
2901 options in the configuration of the pipe or queue.
2902 For each different flow identifier, a new pipe or queue is created
2903 with the same parameters as the original object, and matching packets
2908 are used, each flow will get the same bandwidth as defined by the pipe,
2911 are used, each flow will share the parent's pipe bandwidth evenly
2912 with other flows generated by the same queue (note that other queues
2913 with different weights might be connected to the same pipe).
2915 Available mask specifiers are a combination of one or more of the following:
2917 .Cm dst-ip Ar mask ,
2918 .Cm dst-ip6 Ar mask ,
2919 .Cm src-ip Ar mask ,
2920 .Cm src-ip6 Ar mask ,
2921 .Cm dst-port Ar mask ,
2922 .Cm src-port Ar mask ,
2923 .Cm flow-id Ar mask ,
2928 where the latter means all bits in all fields are significant.
2931 When a packet is dropped by a
2933 queue or pipe, the error
2934 is normally reported to the caller routine in the kernel, in the
2935 same way as it happens when a device queue fills up.
2937 option reports the packet as successfully delivered, which can be
2938 needed for some experimental setups where you want to simulate
2939 loss or congestion at a remote router.
2941 .It Cm plr Ar packet-loss-rate
2944 .Ar packet-loss-rate
2945 is a floating-point number between 0 and 1, with 0 meaning no
2946 loss, 1 meaning 100% loss.
2947 The loss rate is internally represented on 31 bits.
2949 .It Cm queue Brq Ar slots | size Ns Cm Kbytes
2954 Default value is 50 slots, which
2955 is the typical queue size for Ethernet devices.
2956 Note that for slow speed links you should keep the queue
2957 size short or your traffic might be affected by a significant
2959 E.g., 50 max-sized Ethernet packets (1500 bytes) mean 600Kbit
2960 or 20s of queue on a 30Kbit/s pipe.
2961 Even worse effects can result if you get packets from an
2962 interface with a much larger MTU, e.g.\& the loopback interface
2963 with its 16KB packets.
2967 .Em net.inet.ip.dummynet.pipe_byte_limit
2969 .Em net.inet.ip.dummynet.pipe_slot_limit
2970 control the maximum lengths that can be specified.
2972 .It Cm red | gred Ar w_q Ns / Ns Ar min_th Ns / Ns Ar max_th Ns / Ns Ar max_p
2974 Make use of the RED (Random Early Detection) queue management algorithm.
2979 point numbers between 0 and 1 (inclusive), while
2983 are integer numbers specifying thresholds for queue management
2984 (thresholds are computed in bytes if the queue has been defined
2985 in bytes, in slots otherwise).
2986 The two parameters can also be of the same value if needed. The
2988 also supports the gentle RED variant (gred) and ECN (Explicit Congestion
2989 Notification) as optional. Three
2991 variables can be used to control the RED behaviour:
2992 .Bl -tag -width indent
2993 .It Va net.inet.ip.dummynet.red_lookup_depth
2994 specifies the accuracy in computing the average queue
2995 when the link is idle (defaults to 256, must be greater than zero)
2996 .It Va net.inet.ip.dummynet.red_avg_pkt_size
2997 specifies the expected average packet size (defaults to 512, must be
2999 .It Va net.inet.ip.dummynet.red_max_pkt_size
3000 specifies the expected maximum packet size, only used when queue
3001 thresholds are in bytes (defaults to 1500, must be greater than zero).
3004 .It Cm codel Oo Cm target Ar time Oc Oo Cm interval Ar time Oc Oo Cm ecn |
3006 Make use of the CoDel (Controlled-Delay) queue management algorithm.
3008 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
3009 microseconds (us) can be specified instead.
3010 CoDel drops or marks (ECN) packets
3011 depending on packet sojourn time in the queue.
3014 (5ms by default) is the minimum acceptable persistent queue delay that CoDel
3016 CoDel does not drop packets directly after packets sojourn time becomes
3023 (100ms default) before dropping.
3026 should be set to maximum RTT for all expected connections.
3028 enables (disabled by default) packet marking (instead of dropping) for
3029 ECN-enabled TCP flows when queue delay becomes high.
3031 Note that any token after
3033 is considered a parameter for CoDel.
3034 So, ensure all pipe/queue
3035 configuration options are written before
3042 .Va net.inet.ip.dummynet.codel.target
3044 .Va net.inet.ip.dummynet.codel.interval
3045 can be used to set CoDel default parameters.
3047 .It Cm pie Oo Cm target Ar time Oc Oo Cm tupdate Ar time Oc Oo
3048 .Cm alpha Ar n Oc Oo Cm beta Ar n Oc Oo Cm max_burst Ar time Oc Oo
3049 .Cm max_ecnth Ar n Oc Oo Cm ecn | Cm noecn Oc Oo Cm capdrop |
3050 .Cm nocapdrop Oc Oo Cm drand | Cm nodrand Oc Oo Cm onoff
3051 .Oc Oo Cm dre | Cm ts Oc
3052 Make use of the PIE (Proportional Integral controller Enhanced) queue management
3054 PIE drops or marks packets depending on a calculated drop probability during
3055 en-queue process, with the aim of achieving high throughput while keeping queue
3057 At regular time intervals of
3060 (15ms by default) a background process (re)calculates the probability based on queue delay
3064 (15ms by default) and queue delay trends.
3065 PIE approximates current queue
3066 delay by using a departure rate estimation method, or (optionally) by using a
3067 packet timestamp method similar to CoDel.
3069 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
3070 microseconds (us) can be specified instead.
3071 The other PIE parameters and options are as follows:
3072 .Bl -tag -width indent
3075 is a floating point number between 0 and 7 which specifies the weight of queue
3076 delay deviations that is used in drop probability calculation.
3077 0.125 is the default.
3080 is a floating point number between 0 and 7 which specifies is the weight of queue
3081 delay trend that is used in drop probability calculation.
3082 1.25 is the default.
3083 .It Cm max_burst Ar time
3084 The maximum period of time that PIE does not drop/mark packets.
3086 default and 10s is the maximum value.
3087 .It Cm max_ecnth Ar n
3088 Even when ECN is enabled, PIE drops packets instead of marking them when drop
3089 probability becomes higher than ECN probability threshold
3091 , the default is 0.1 (i.e 10%) and 1 is the maximum value.
3093 enable or disable ECN marking for ECN-enabled TCP flows.
3094 Disabled by default.
3095 .It Cm capdrop | nocapdrop
3096 enable or disable cap drop adjustment.
3097 Cap drop adjustment is enabled by default.
3098 .It Cm drand | nodrand
3099 enable or disable drop probability de-randomisation.
3100 De-randomisation eliminates
3101 the problem of dropping packets too close or too far.
3102 De-randomisation is enabled by default.
3104 enable turning PIE on and off depending on queue load.
3105 If this option is enabled,
3106 PIE turns on when over 1/3 of queue becomes full.
3107 This option is disabled by
3110 Calculate queue delay using departure rate estimation
3118 Note that any token after
3120 is considered a parameter for PIE.
3121 So ensure all pipe/queue
3122 the configuration options are written before
3126 variables can be used to control the
3130 .Sx SYSCTL VARIABLES
3131 section for more details.
3134 When used with IPv6 data,
3136 currently has several limitations.
3137 Information necessary to route link-local packets to an
3138 interface is not available after processing by
3140 so those packets are dropped in the output path.
3141 Care should be taken to ensure that link-local packets are not passed to
3144 Here are some important points to consider when designing your
3148 Remember that you filter both packets going
3152 Most connections need packets going in both directions.
3154 Remember to test very carefully.
3155 It is a good idea to be near the console when doing this.
3156 If you cannot be near the console,
3157 use an auto-recovery script such as the one in
3158 .Pa /usr/share/examples/ipfw/change_rules.sh .
3160 Do not forget the loopback interface.
3165 There are circumstances where fragmented datagrams are unconditionally
3167 TCP packets are dropped if they do not contain at least 20 bytes of
3168 TCP header, UDP packets are dropped if they do not contain a full 8
3169 byte UDP header, and ICMP packets are dropped if they do not contain
3170 4 bytes of ICMP header, enough to specify the ICMP type, code, and
3172 These packets are simply logged as
3174 since there may not be enough good data in the packet to produce a
3175 meaningful log entry.
3177 Another type of packet is unconditionally dropped, a TCP packet with a
3178 fragment offset of one.
3179 This is a valid packet, but it only has one use, to try
3180 to circumvent firewalls.
3181 When logging is enabled, these packets are
3182 reported as being dropped by rule -1.
3184 If you are logged in over a network, loading the
3188 is probably not as straightforward as you would think.
3189 The following command line is recommended:
3190 .Bd -literal -offset indent
3192 ipfw add 32000 allow ip from any to any
3195 Along the same lines, doing an
3196 .Bd -literal -offset indent
3200 in similar surroundings is also a bad idea.
3204 filter list may not be modified if the system security level
3205 is set to 3 or higher
3208 for information on system security levels).
3210 .Sh PACKET DIVERSION
3213 socket bound to the specified port will receive all packets
3214 diverted to that port.
3215 If no socket is bound to the destination port, or if the divert module is
3216 not loaded, or if the kernel was not compiled with divert socket support,
3217 the packets are dropped.
3218 .Sh NETWORK ADDRESS TRANSLATION (NAT)
3220 support in-kernel NAT using the kernel version of
3224 should be loaded or kernel should have
3225 .Cm options IPFIREWALL_NAT
3228 The nat configuration command is the following:
3229 .Bd -ragged -offset indent
3234 .Ar nat-configuration
3238 The following parameters can be configured:
3239 .Bl -tag -width indent
3240 .It Cm ip Ar ip_address
3241 Define an ip address to use for aliasing.
3243 Use ip address of NIC for aliasing, dynamically changing
3244 it if NIC's ip address changes.
3246 Enable logging on this nat instance.
3248 Deny any incoming connection from outside world.
3250 Try to leave the alias port numbers unchanged from
3251 the actual local port numbers.
3253 Traffic on the local network not originating from a RFC 1918
3254 unregistered address spaces will be ignored.
3256 Like unreg_only, but includes the RFC 6598 (Carrier Grade NAT)
3259 Reset table of the packet aliasing engine on address change.
3261 Reverse the way libalias handles aliasing.
3263 Obey transparent proxy rules only, packet aliasing is not performed.
3265 Skip instance in case of global state lookup (see below).
3268 Some specials value can be supplied instead of
3270 .Bl -tag -width indent
3272 Looks up translation state in all configured nat instances.
3273 If an entry is found, packet is aliased according to that entry.
3274 If no entry was found in any of the instances, packet is passed unchanged,
3275 and no new entry will be created.
3277 .Sx MULTIPLE INSTANCES
3280 for more information.
3282 Uses argument supplied in lookup table.
3285 section below for more information on lookup tables.
3288 To let the packet continue after being (de)aliased, set the sysctl variable
3289 .Va net.inet.ip.fw.one_pass
3291 For more information about aliasing modes, refer to
3295 for some examples about nat usage.
3296 .Ss REDIRECT AND LSNAT SUPPORT IN IPFW
3297 Redirect and LSNAT support follow closely the syntax used in
3301 for some examples on how to do redirect and lsnat.
3302 .Ss SCTP NAT SUPPORT
3303 SCTP nat can be configured in a similar manner to TCP through the
3306 The main difference is that
3308 does not do port translation.
3309 Since the local and global side ports will be the same,
3310 there is no need to specify both.
3311 Ports are redirected as follows:
3312 .Bd -ragged -offset indent
3318 .Cm redirect_port sctp
3319 .Ar ip_address [,addr_list] {[port | port-port] [,ports]}
3325 configuration can be done in real-time through the
3328 All may be changed dynamically, though the hash_table size will only
3333 .Sx SYSCTL VARIABLES
3335 .Sh IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
3336 .Ss Stateful translation
3338 supports in-kernel IPv6/IPv4 network address and protocol translation.
3339 Stateful NAT64 translation allows IPv6-only clients to contact IPv4 servers
3340 using unicast TCP, UDP or ICMP protocols.
3341 One or more IPv4 addresses assigned to a stateful NAT64 translator are shared
3342 among several IPv6-only clients.
3343 When stateful NAT64 is used in conjunction with DNS64, no changes are usually
3344 required in the IPv6 client or the IPv4 server.
3347 should be loaded or kernel should have
3348 .Cm options IPFIREWALL_NAT64
3349 to be able use stateful NAT64 translator.
3351 Stateful NAT64 uses a bunch of memory for several types of objects.
3352 When IPv6 client initiates connection, NAT64 translator creates a host entry
3353 in the states table.
3354 Each host entry uses preallocated IPv4 alias entry.
3355 Each alias entry has a number of ports group entries allocated on demand.
3356 Ports group entries contains connection state entries.
3357 There are several options to control limits and lifetime for these objects.
3359 NAT64 translator follows RFC7915 when does ICMPv6/ICMP translation,
3360 unsupported message types will be silently dropped.
3361 IPv6 needs several ICMPv6 message types to be explicitly allowed for correct
3363 Make sure that ND6 neighbor solicitation (ICMPv6 type 135) and neighbor
3364 advertisement (ICMPv6 type 136) messages will not be handled by translation
3367 After translation NAT64 translator by default sends packets through
3368 corresponding netisr queue.
3369 Thus translator host should be configured as IPv4 and IPv6 router.
3370 Also this means, that a packet is handled by firewall twice.
3371 First time an original packet is handled and consumed by translator,
3372 and then it is handled again as translated packet.
3373 This behavior can be changed by sysctl variable
3374 .Va net.inet.ip.fw.nat64_direct_output .
3375 Also translated packet can be tagged using
3377 rule action, and then matched by
3379 opcode to avoid loops and extra overhead.
3381 The stateful NAT64 configuration command is the following:
3382 .Bd -ragged -offset indent
3391 The following parameters can be configured:
3392 .Bl -tag -width indent
3393 .It Cm prefix4 Ar ipv4_prefix/plen
3394 The IPv4 prefix with mask defines the pool of IPv4 addresses used as
3395 source address after translation.
3396 Stateful NAT64 module translates IPv6 source address of client to one
3397 IPv4 address from this pool.
3398 Note that incoming IPv4 packets that don't have corresponding state entry
3399 in the states table will be dropped by translator.
3400 Make sure that translation rules handle packets, destined to configured prefix.
3401 .It Cm prefix6 Ar ipv6_prefix/length
3402 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3403 to represent IPv4 addresses. This IPv6 prefix should be configured in DNS64.
3404 The translator implementation follows RFC6052, that restricts the length of
3405 prefixes to one of following: 32, 40, 48, 56, 64, or 96.
3406 The Well-Known IPv6 Prefix 64:ff9b:: must be 96 bits long.
3409 prefix can be used to handle several IPv6 prefixes with one NAT64 instance.
3410 The NAT64 instance will determine a destination IPv4 address from prefix
3412 .It Cm states_chunks Ar number
3413 The number of states chunks in single ports group.
3414 Each ports group by default can keep 64 state entries in single chunk.
3415 The above value affects the maximum number of states that can be associated with single IPv4 alias address and port.
3416 The value must be power of 2, and up to 128.
3417 .It Cm host_del_age Ar seconds
3418 The number of seconds until the host entry for a IPv6 client will be deleted
3419 and all its resources will be released due to inactivity.
3422 .It Cm pg_del_age Ar seconds
3423 The number of seconds until a ports group with unused state entries will
3427 .It Cm tcp_syn_age Ar seconds
3428 The number of seconds while a state entry for TCP connection with only SYN
3430 If TCP connection establishing will not be finished,
3431 state entry will be deleted.
3434 .It Cm tcp_est_age Ar seconds
3435 The number of seconds while a state entry for established TCP connection
3439 .It Cm tcp_close_age Ar seconds
3440 The number of seconds while a state entry for closed TCP connection
3442 Keeping state entries for closed connections is needed, because IPv4 servers
3443 typically keep closed connections in a TIME_WAIT state for a several minutes.
3444 Since translator's IPv4 addresses are shared among all IPv6 clients,
3445 new connections from the same addresses and ports may be rejected by server,
3446 because these connections are still in a TIME_WAIT state.
3447 Keeping them in translator's state table protects from such rejects.
3450 .It Cm udp_age Ar seconds
3451 The number of seconds while translator keeps state entry in a waiting for
3452 reply to the sent UDP datagram.
3455 .It Cm icmp_age Ar seconds
3456 The number of seconds while translator keeps state entry in a waiting for
3457 reply to the sent ICMP message.
3461 Turn on logging of all handled packets via BPF through
3465 is a pseudo interface and can be created after a boot manually with
3468 Note that it has different purpose than
3471 Translators sends to BPF an additional information with each packet.
3474 you are able to see each handled packet before and after translation.
3476 Turn off logging of all handled packets via BPF.
3477 .It Cm allow_private
3478 Turn on processing private IPv4 addresses. By default IPv6 packets with
3479 destinations mapped to private address ranges defined by RFC1918 are not
3481 .It Cm -allow_private
3482 Turn off private address handling in
3487 To inspect a states table of stateful NAT64 the following command can be used:
3488 .Bd -ragged -offset indent
3497 Stateless NAT64 translator doesn't use a states table for translation
3498 and converts IPv4 addresses to IPv6 and vice versa solely based on the
3499 mappings taken from configured lookup tables.
3500 Since a states table doesn't used by stateless translator,
3501 it can be configured to pass IPv4 clients to IPv6-only servers.
3503 The stateless NAT64 configuration command is the following:
3504 .Bd -ragged -offset indent
3513 The following parameters can be configured:
3514 .Bl -tag -width indent
3515 .It Cm prefix6 Ar ipv6_prefix/length
3516 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3517 to represent IPv4 addresses. This IPv6 prefix should be configured in DNS64.
3518 .It Cm table4 Ar table46
3521 contains mapping how IPv4 addresses should be translated to IPv6 addresses.
3522 .It Cm table6 Ar table64
3525 contains mapping how IPv6 addresses should be translated to IPv4 addresses.
3527 Turn on logging of all handled packets via BPF through
3531 Turn off logging of all handled packets via BPF.
3532 .It Cm allow_private
3533 Turn on processing private IPv4 addresses. By default IPv6 packets with
3534 destinations mapped to private address ranges defined by RFC1918 are not
3536 .It Cm -allow_private
3537 Turn off private address handling in
3542 Note that the behavior of stateless translator with respect to not matched
3543 packets differs from stateful translator.
3544 If corresponding addresses was not found in the lookup tables, the packet
3545 will not be dropped and the search continues.
3548 .Ss XLAT464 CLAT translation
3549 XLAT464 CLAT NAT64 translator implements client-side stateless translation as
3550 defined in RFC6877 and is very similar to statless NAT64 translator
3551 explained above. Instead of lookup tables it uses one-to-one mapping
3552 between IPv4 and IPv6 addresses using configured prefixes.
3553 This mode can be used as a replacement of DNS64 service for applications
3554 that are not using it (e.g. VoIP) allowing them to access IPv4-only Internet
3555 over IPv6-only networks with help of remote NAT64 translator.
3557 The CLAT NAT64 configuration command is the following:
3558 .Bd -ragged -offset indent
3567 The following parameters can be configured:
3568 .Bl -tag -width indent
3569 .It Cm clat_prefix Ar ipv6_prefix/length
3570 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3571 to represent source IPv4 addresses.
3572 .It Cm plat_prefix Ar ipv6_prefix/length
3573 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3574 to represent destination IPv4 addresses. This IPv6 prefix should be configured
3575 on a remote NAT64 translator.
3577 Turn on logging of all handled packets via BPF through
3581 Turn off logging of all handled packets via BPF.
3582 .It Cm allow_private
3583 Turn on processing private IPv4 addresses. By default
3585 instance will not process IPv4 packets with destination address from private
3586 ranges as defined in RFC1918.
3587 .It Cm -allow_private
3588 Turn off private address handling in
3593 Note that the behavior of CLAT translator with respect to not matched
3594 packets differs from stateful translator.
3595 If corresponding addresses were not matched against prefixes configured,
3596 the packet will not be dropped and the search continues.
3597 .Sh IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
3599 supports in-kernel IPv6-to-IPv6 network prefix translation as described
3603 should be loaded or kernel should has
3604 .Cm options IPFIREWALL_NPTV6
3605 to be able use NPTv6 translator.
3607 The NPTv6 configuration command is the following:
3608 .Bd -ragged -offset indent
3617 The following parameters can be configured:
3618 .Bl -tag -width indent
3619 .It Cm int_prefix Ar ipv6_prefix
3620 IPv6 prefix used in internal network.
3621 NPTv6 module translates source address when it matches this prefix.
3622 .It Cm ext_prefix Ar ipv6_prefix
3623 IPv6 prefix used in external network.
3624 NPTv6 module translates destination address when it matches this prefix.
3625 .It Cm ext_if Ar nic
3626 The NPTv6 module will use first global IPv6 address from interface
3629 It can be useful when IPv6 prefix of external network is dynamically obtained.
3633 options are mutually exclusive.
3634 .It Cm prefixlen Ar length
3635 The length of specified IPv6 prefixes. It must be in range from 8 to 64.
3638 Note that the prefix translation rules are silently ignored when IPv6 packet
3639 forwarding is disabled.
3640 To enable the packet forwarding, set the sysctl variable
3641 .Va net.inet6.ip6.forwarding
3644 To let the packet continue after being translated, set the sysctl variable
3645 .Va net.inet.ip.fw.one_pass
3648 Tunables can be set in
3654 before ipfw module gets loaded.
3655 .Bl -tag -width indent
3656 .It Va net.inet.ip.fw.default_to_accept: No 0
3657 Defines ipfw last rule behavior.
3658 This value overrides
3659 .Cd "options IPFW_DEFAULT_TO_(ACCEPT|DENY)"
3660 from kernel configuration file.
3661 .It Va net.inet.ip.fw.tables_max: No 128
3662 Defines number of tables available in ipfw.
3663 Number cannot exceed 65534.
3665 .Sh SYSCTL VARIABLES
3668 variables controls the behaviour of the firewall and
3670 .Pq Nm dummynet , bridge , sctp nat .
3671 These are shown below together with their default value
3672 (but always check with the
3674 command what value is actually in use) and meaning:
3675 .Bl -tag -width indent
3676 .It Va net.inet.ip.alias.sctp.accept_global_ootb_addip: No 0
3679 responds to receipt of global OOTB ASCONF-AddIP:
3680 .Bl -tag -width indent
3682 No response (unless a partially matching association exists -
3683 ports and vtags match but global address does not)
3686 will accept and process all OOTB global AddIP messages.
3689 Option 1 should never be selected as this forms a security risk.
3691 establish multiple fake associations by sending AddIP messages.
3692 .It Va net.inet.ip.alias.sctp.chunk_proc_limit: No 5
3693 Defines the maximum number of chunks in an SCTP packet that will be
3695 packet that matches an existing association.
3696 This value is enforced to be greater or equal than
3697 .Cm net.inet.ip.alias.sctp.initialising_chunk_proc_limit .
3699 a DoS risk yet setting too low a value may result in
3700 important control chunks in
3701 the packet not being located and parsed.
3702 .It Va net.inet.ip.alias.sctp.error_on_ootb: No 1
3705 responds to any Out-of-the-Blue (OOTB) packets with ErrorM packets.
3706 An OOTB packet is a packet that arrives with no existing association
3709 and is not an INIT or ASCONF-AddIP packet:
3710 .Bl -tag -width indent
3712 ErrorM is never sent in response to OOTB packets.
3714 ErrorM is only sent to OOTB packets received on the local side.
3716 ErrorM is sent to the local side and on the global side ONLY if there is a
3717 partial match (ports and vtags match but the source global IP does not).
3718 This value is only useful if the
3720 is tracking global IP addresses.
3722 ErrorM is sent in response to all OOTB packets on both
3723 the local and global side
3727 At the moment the default is 0, since the ErrorM packet is not yet
3728 supported by most SCTP stacks.
3729 When it is supported, and if not tracking
3730 global addresses, we recommend setting this value to 1 to allow
3731 multi-homed local hosts to function with the
3733 To track global addresses, we recommend setting this value to 2 to
3734 allow global hosts to be informed when they need to (re)send an
3736 Value 3 should never be chosen (except for debugging) as the
3738 will respond to all OOTB global packets (a DoS risk).
3739 .It Va net.inet.ip.alias.sctp.hashtable_size: No 2003
3740 Size of hash tables used for
3742 lookups (100 < prime_number > 1000001).
3745 size for any future created
3747 instance and therefore must be set prior to creating a
3750 The table sizes may be changed to suit specific needs.
3751 If there will be few
3752 concurrent associations, and memory is scarce, you may make these smaller.
3753 If there will be many thousands (or millions) of concurrent associations, you
3754 should make these larger.
3755 A prime number is best for the table size.
3757 update function will adjust your input value to the next highest prime number.
3758 .It Va net.inet.ip.alias.sctp.holddown_time: No 0
3759 Hold association in table for this many seconds after receiving a
3761 This allows endpoints to correct shutdown gracefully if a
3762 shutdown_complete is lost and retransmissions are required.
3763 .It Va net.inet.ip.alias.sctp.init_timer: No 15
3764 Timeout value while waiting for (INIT-ACK|AddIP-ACK).
3765 This value cannot be 0.
3766 .It Va net.inet.ip.alias.sctp.initialising_chunk_proc_limit: No 2
3767 Defines the maximum number of chunks in an SCTP packet that will be parsed when
3768 no existing association exists that matches that packet.
3770 will only be an INIT or ASCONF-AddIP packet.
3771 A higher value may become a DoS
3772 risk as malformed packets can consume processing resources.
3773 .It Va net.inet.ip.alias.sctp.param_proc_limit: No 25
3774 Defines the maximum number of parameters within a chunk that will be
3777 As for other similar sysctl variables, larger values pose a DoS risk.
3778 .It Va net.inet.ip.alias.sctp.log_level: No 0
3779 Level of detail in the system log messages (0 \- minimal, 1 \- event,
3780 2 \- info, 3 \- detail, 4 \- debug, 5 \- max debug).
3782 option in high loss environments.
3783 .It Va net.inet.ip.alias.sctp.shutdown_time: No 15
3784 Timeout value while waiting for SHUTDOWN-COMPLETE.
3785 This value cannot be 0.
3786 .It Va net.inet.ip.alias.sctp.track_global_addresses: No 0
3787 Enables/disables global IP address tracking within the
3790 upper limit on the number of addresses tracked for each association:
3791 .Bl -tag -width indent
3793 Global tracking is disabled
3795 Enables tracking, the maximum number of addresses tracked for each
3796 association is limited to this value
3799 This variable is fully dynamic, the new value will be adopted for all newly
3800 arriving associations, existing associations are treated
3801 as they were previously.
3802 Global tracking will decrease the number of collisions within the
3805 of increased processing load, memory usage, complexity, and possible
3808 problems in complex networks with multiple
3810 We recommend not tracking
3811 global IP addresses, this will still result in a fully functional
3813 .It Va net.inet.ip.alias.sctp.up_timer: No 300
3814 Timeout value to keep an association up with no traffic.
3815 This value cannot be 0.
3816 .It Va net.inet.ip.dummynet.codel.interval : No 100000
3819 AQM interval in microseconds.
3820 The value must be in the range 1..5000000.
3821 .It Va net.inet.ip.dummynet.codel.target : No 5000
3824 AQM target delay time in microseconds (the minimum acceptable persistent queue
3826 The value must be in the range 1..5000000.
3827 .It Va net.inet.ip.dummynet.expire : No 1
3828 Lazily delete dynamic pipes/queue once they have no pending traffic.
3829 You can disable this by setting the variable to 0, in which case
3830 the pipes/queues will only be deleted when the threshold is reached.
3831 .It Va net.inet.ip.dummynet.fqcodel.flows : No 1024
3832 Defines the default total number of flow queues (sub-queues) that
3834 creates and manages.
3835 The value must be in the range 1..65536.
3836 .It Va net.inet.ip.dummynet.fqcodel.interval : No 100000
3839 scheduler/AQM interval in microseconds.
3840 The value must be in the range 1..5000000.
3841 .It Va net.inet.ip.dummynet.fqcodel.limit : No 10240
3842 The default hard size limit (in unit of packet) of all queues managed by an
3846 The value must be in the range 1..20480.
3847 .It Va net.inet.ip.dummynet.fqcodel.quantum : No 1514
3848 The default quantum (credit) of the
3851 The value must be in the range 1..9000.
3852 .It Va net.inet.ip.dummynet.fqcodel.target : No 5000
3855 scheduler/AQM target delay time in microseconds (the minimum acceptable
3856 persistent queue delay).
3857 The value must be in the range 1..5000000.
3858 .It Va net.inet.ip.dummynet.fqpie.alpha : No 125
3861 parameter (scaled by 1000) for
3864 The value must be in the range 1..7000.
3865 .It Va net.inet.ip.dummynet.fqpie.beta : No 1250
3868 parameter (scaled by 1000) for
3871 The value must be in the range 1..7000.
3872 .It Va net.inet.ip.dummynet.fqpie.flows : No 1024
3873 Defines the default total number of flow queues (sub-queues) that
3875 creates and manages.
3876 The value must be in the range 1..65536.
3877 .It Va net.inet.ip.dummynet.fqpie.limit : No 10240
3878 The default hard size limit (in unit of packet) of all queues managed by an
3882 The value must be in the range 1..20480.
3883 .It Va net.inet.ip.dummynet.fqpie.max_burst : No 150000
3884 The default maximum period of microseconds that
3886 scheduler/AQM does not drop/mark packets.
3887 The value must be in the range 1..10000000.
3888 .It Va net.inet.ip.dummynet.fqpie.max_ecnth : No 99
3889 The default maximum ECN probability threshold (scaled by 1000) for
3892 The value must be in the range 1..7000.
3893 .It Va net.inet.ip.dummynet.fqpie.quantum : No 1514
3894 The default quantum (credit) of the
3897 The value must be in the range 1..9000.
3898 .It Va net.inet.ip.dummynet.fqpie.target : No 15000
3903 in unit of microsecond.
3904 The value must be in the range 1..5000000.
3905 .It Va net.inet.ip.dummynet.fqpie.tupdate : No 15000
3910 in unit of microsecond.
3911 The value must be in the range 1..5000000.
3912 .It Va net.inet.ip.dummynet.hash_size : No 64
3913 Default size of the hash table used for dynamic pipes/queues.
3914 This value is used when no
3916 option is specified when configuring a pipe/queue.
3917 .It Va net.inet.ip.dummynet.io_fast : No 0
3918 If set to a non-zero value,
3923 operation (see above) is enabled.
3924 .It Va net.inet.ip.dummynet.io_pkt
3925 Number of packets passed to
3927 .It Va net.inet.ip.dummynet.io_pkt_drop
3928 Number of packets dropped by
3930 .It Va net.inet.ip.dummynet.io_pkt_fast
3931 Number of packets bypassed by the
3934 .It Va net.inet.ip.dummynet.max_chain_len : No 16
3935 Target value for the maximum number of pipes/queues in a hash bucket.
3937 .Cm max_chain_len*hash_size
3938 is used to determine the threshold over which empty pipes/queues
3939 will be expired even when
3940 .Cm net.inet.ip.dummynet.expire=0 .
3941 .It Va net.inet.ip.dummynet.red_lookup_depth : No 256
3942 .It Va net.inet.ip.dummynet.red_avg_pkt_size : No 512
3943 .It Va net.inet.ip.dummynet.red_max_pkt_size : No 1500
3944 Parameters used in the computations of the drop probability
3945 for the RED algorithm.
3946 .It Va net.inet.ip.dummynet.pie.alpha : No 125
3949 parameter (scaled by 1000) for
3952 The value must be in the range 1..7000.
3953 .It Va net.inet.ip.dummynet.pie.beta : No 1250
3956 parameter (scaled by 1000) for
3959 The value must be in the range 1..7000.
3960 .It Va net.inet.ip.dummynet.pie.max_burst : No 150000
3961 The default maximum period of microseconds that
3963 AQM does not drop/mark packets.
3964 The value must be in the range 1..10000000.
3965 .It Va net.inet.ip.dummynet.pie.max_ecnth : No 99
3966 The default maximum ECN probability threshold (scaled by 1000) for
3969 The value must be in the range 1..7000.
3970 .It Va net.inet.ip.dummynet.pie.target : No 15000
3975 AQM in unit of microsecond.
3976 The value must be in the range 1..5000000.
3977 .It Va net.inet.ip.dummynet.pie.tupdate : No 15000
3982 AQM in unit of microsecond.
3983 The value must be in the range 1..5000000.
3984 .It Va net.inet.ip.dummynet.pipe_byte_limit : No 1048576
3985 .It Va net.inet.ip.dummynet.pipe_slot_limit : No 100
3986 The maximum queue size that can be specified in bytes or packets.
3987 These limits prevent accidental exhaustion of resources such as mbufs.
3988 If you raise these limits,
3989 you should make sure the system is configured so that sufficient resources
3991 .It Va net.inet.ip.fw.autoinc_step : No 100
3992 Delta between rule numbers when auto-generating them.
3993 The value must be in the range 1..1000.
3994 .It Va net.inet.ip.fw.curr_dyn_buckets : Va net.inet.ip.fw.dyn_buckets
3995 The current number of buckets in the hash table for dynamic rules
3997 .It Va net.inet.ip.fw.debug : No 1
3998 Controls debugging messages produced by
4000 .It Va net.inet.ip.fw.default_rule : No 65535
4001 The default rule number (read-only).
4003 .Nm , the default rule is the last one, so its number
4004 can also serve as the highest number allowed for a rule.
4005 .It Va net.inet.ip.fw.dyn_buckets : No 256
4006 The number of buckets in the hash table for dynamic rules.
4007 Must be a power of 2, up to 65536.
4008 It only takes effect when all dynamic rules have expired, so you
4009 are advised to use a
4011 command to make sure that the hash table is resized.
4012 .It Va net.inet.ip.fw.dyn_count : No 3
4013 Current number of dynamic rules
4015 .It Va net.inet.ip.fw.dyn_keepalive : No 1
4016 Enables generation of keepalive packets for
4018 rules on TCP sessions.
4019 A keepalive is generated to both
4020 sides of the connection every 5 seconds for the last 20
4021 seconds of the lifetime of the rule.
4022 .It Va net.inet.ip.fw.dyn_max : No 8192
4023 Maximum number of dynamic rules.
4024 When you hit this limit, no more dynamic rules can be
4025 installed until old ones expire.
4026 .It Va net.inet.ip.fw.dyn_ack_lifetime : No 300
4027 .It Va net.inet.ip.fw.dyn_syn_lifetime : No 20
4028 .It Va net.inet.ip.fw.dyn_fin_lifetime : No 1
4029 .It Va net.inet.ip.fw.dyn_rst_lifetime : No 1
4030 .It Va net.inet.ip.fw.dyn_udp_lifetime : No 5
4031 .It Va net.inet.ip.fw.dyn_short_lifetime : No 30
4032 These variables control the lifetime, in seconds, of dynamic
4034 Upon the initial SYN exchange the lifetime is kept short,
4035 then increased after both SYN have been seen, then decreased
4036 again during the final FIN exchange or when a RST is received.
4038 .Em dyn_fin_lifetime
4040 .Em dyn_rst_lifetime
4041 must be strictly lower than 5 seconds, the period of
4042 repetition of keepalives.
4043 The firewall enforces that.
4044 .It Va net.inet.ip.fw.dyn_keep_states: No 0
4045 Keep dynamic states on rule/set deletion.
4046 States are relinked to default rule (65535).
4047 This can be handly for ruleset reload.
4048 Turned off by default.
4049 .It Va net.inet.ip.fw.enable : No 1
4050 Enables the firewall.
4051 Setting this variable to 0 lets you run your machine without
4052 firewall even if compiled in.
4053 .It Va net.inet6.ip6.fw.enable : No 1
4054 provides the same functionality as above for the IPv6 case.
4055 .It Va net.inet.ip.fw.one_pass : No 1
4056 When set, the packet exiting from the
4060 node is not passed though the firewall again.
4061 Otherwise, after an action, the packet is
4062 reinjected into the firewall at the next rule.
4063 .It Va net.inet.ip.fw.tables_max : No 128
4064 Maximum number of tables.
4065 .It Va net.inet.ip.fw.verbose : No 1
4066 Enables verbose messages.
4067 .It Va net.inet.ip.fw.verbose_limit : No 0
4068 Limits the number of messages produced by a verbose firewall.
4069 .It Va net.inet6.ip6.fw.deny_unknown_exthdrs : No 1
4070 If enabled packets with unknown IPv6 Extension Headers will be denied.
4071 .It Va net.link.ether.ipfw : No 0
4072 Controls whether layer-2 packets are passed to
4075 .It Va net.link.bridge.ipfw : No 0
4076 Controls whether bridged packets are passed to
4079 .It Va net.inet.ip.fw.nat64_debug : No 0
4080 Controls debugging messages produced by
4083 .It Va net.inet.ip.fw.nat64_direct_output : No 0
4084 Controls the output method used by
4087 .Bl -tag -width indent
4089 A packet is handled by
4092 First time an original packet is handled by
4097 Then translated packet is queued via netisr to input processing again.
4099 A packet is handled by
4101 only once, and after translation it will be pushed directly to outgoing
4105 .Sh INTERNAL DIAGNOSTICS
4106 There are some commands that may be useful to understand current state
4107 of certain subsystems inside kernel module.
4108 These commands provide debugging output which may change without notice.
4110 Currently the following commands are available as
4113 .Bl -tag -width indent
4115 Lists all interface which are currently tracked by
4117 with their in-kernel status.
4119 List all table lookup algorithms currently available.
4122 There are far too many possible uses of
4124 so this Section will only give a small set of examples.
4126 .Ss BASIC PACKET FILTERING
4127 This command adds an entry which denies all tcp packets from
4128 .Em cracker.evil.org
4129 to the telnet port of
4131 from being forwarded by the host:
4133 .Dl "ipfw add deny tcp from cracker.evil.org to wolf.tambov.su telnet"
4135 This one disallows any connection from the entire cracker's
4138 .Dl "ipfw add deny ip from 123.45.67.0/24 to my.host.org"
4140 A first and efficient way to limit access (not using dynamic rules)
4141 is the use of the following rules:
4143 .Dl "ipfw add allow tcp from any to any established"
4144 .Dl "ipfw add allow tcp from net1 portlist1 to net2 portlist2 setup"
4145 .Dl "ipfw add allow tcp from net3 portlist3 to net3 portlist3 setup"
4147 .Dl "ipfw add deny tcp from any to any"
4149 The first rule will be a quick match for normal TCP packets,
4150 but it will not match the initial SYN packet, which will be
4153 rules only for selected source/destination pairs.
4154 All other SYN packets will be rejected by the final
4158 If you administer one or more subnets, you can take advantage
4159 of the address sets and or-blocks and write extremely
4160 compact rulesets which selectively enable services to blocks
4161 of clients, as below:
4163 .Dl "goodguys=\*q{ 10.1.2.0/24{20,35,66,18} or 10.2.3.0/28{6,3,11} }\*q"
4164 .Dl "badguys=\*q10.1.2.0/24{8,38,60}\*q"
4166 .Dl "ipfw add allow ip from ${goodguys} to any"
4167 .Dl "ipfw add deny ip from ${badguys} to any"
4168 .Dl "... normal policies ..."
4172 option could be used to do automated anti-spoofing by adding the
4173 following to the top of a ruleset:
4175 .Dl "ipfw add deny ip from any to any not verrevpath in"
4177 This rule drops all incoming packets that appear to be coming to the
4178 system on the wrong interface.
4179 For example, a packet with a source
4180 address belonging to a host on a protected internal network would be
4181 dropped if it tried to enter the system from an external interface.
4185 option could be used to do similar but more restricted anti-spoofing
4186 by adding the following to the top of a ruleset:
4188 .Dl "ipfw add deny ip from any to any not antispoof in"
4190 This rule drops all incoming packets that appear to be coming from another
4191 directly connected system but on the wrong interface.
4192 For example, a packet with a source address of
4193 .Li 192.168.0.0/24 ,
4202 option could be used to (re)mark user traffic,
4203 by adding the following to the appropriate place in ruleset:
4205 .Dl "ipfw add setdscp be ip from any to any dscp af11,af21"
4206 .Ss SELECTIVE MIRRORING
4207 If your network has network traffic analyzer
4208 connected to your host directly via dedicated interface
4209 or remotely via RSPAN vlan, you can selectively mirror
4210 some Ethernet layer2 frames to the analyzer.
4212 First, make sure your firewall is already configured and runs.
4213 Then, enable layer2 processing if not already enabled:
4215 .Dl "sysctl net.link.ether.ipfw=1"
4217 Next, load needed additional kernel modules:
4219 .Dl "kldload ng_ether ng_ipfw"
4221 Optionally, make system load these modules automatically
4224 .Dl sysrc kld_list+="ng_ether ng_ipfw"
4228 kernel module to transmit mirrored copies of layer2 frames
4229 out via vlan900 interface:
4231 .Dl "ngctl connect ipfw: vlan900: 1 lower"
4233 Think of "1" here as of "mirroring instance index" and vlan900 is its
4235 You can have arbitrary number of instances.
4240 At last, actually start mirroring of selected frames using "instance 1".
4241 For frames incoming from em0 interface:
4243 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 in recv em0"
4245 For frames outgoing to em0 interface:
4247 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 out xmit em0"
4249 For both incoming and outgoing frames while flowing through em0:
4251 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 via em0"
4253 Make sure you do not perform mirroring for already duplicated frames
4254 or kernel may hang as there is no safety net.
4256 In order to protect a site from flood attacks involving fake
4257 TCP packets, it is safer to use dynamic rules:
4259 .Dl "ipfw add check-state"
4260 .Dl "ipfw add deny tcp from any to any established"
4261 .Dl "ipfw add allow tcp from my-net to any setup keep-state"
4263 This will let the firewall install dynamic rules only for
4264 those connection which start with a regular SYN packet coming
4265 from the inside of our network.
4266 Dynamic rules are checked when encountering the first
4275 rule should usually be placed near the beginning of the
4276 ruleset to minimize the amount of work scanning the ruleset.
4277 Your mileage may vary.
4279 For more complex scenarios with dynamic rules
4283 can be used to precisely control creation and checking of dynamic rules.
4284 Example of usage of these options are provided in
4285 .Sx NETWORK ADDRESS TRANSLATION (NAT)
4288 To limit the number of connections a user can open
4289 you can use the following type of rules:
4291 .Dl "ipfw add allow tcp from my-net/24 to any setup limit src-addr 10"
4292 .Dl "ipfw add allow tcp from any to me setup limit src-addr 4"
4294 The former (assuming it runs on a gateway) will allow each host
4295 on a /24 network to open at most 10 TCP connections.
4296 The latter can be placed on a server to make sure that a single
4297 client does not use more than 4 simultaneous connections.
4300 stateful rules can be subject to denial-of-service attacks
4301 by a SYN-flood which opens a huge number of dynamic rules.
4302 The effects of such attacks can be partially limited by
4305 variables which control the operation of the firewall.
4307 Here is a good usage of the
4309 command to see accounting records and timestamp information:
4313 or in short form without timestamps:
4317 which is equivalent to:
4321 Next rule diverts all incoming packets from 192.168.2.0/24
4322 to divert port 5000:
4324 .Dl ipfw divert 5000 ip from 192.168.2.0/24 to any in
4326 The following rules show some of the applications of
4330 for simulations and the like.
4332 This rule drops random incoming packets with a probability
4335 .Dl "ipfw add prob 0.05 deny ip from any to any in"
4337 A similar effect can be achieved making use of
4341 .Dl "ipfw add pipe 10 ip from any to any"
4342 .Dl "ipfw pipe 10 config plr 0.05"
4344 We can use pipes to artificially limit bandwidth, e.g.\& on a
4345 machine acting as a router, if we want to limit traffic from
4346 local clients on 192.168.2.0/24 we do:
4348 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4349 .Dl "ipfw pipe 1 config bw 300Kbit/s queue 50KBytes"
4351 note that we use the
4353 modifier so that the rule is not used twice.
4354 Remember in fact that
4356 rules are checked both on incoming and outgoing packets.
4358 Should we want to simulate a bidirectional link with bandwidth
4359 limitations, the correct way is the following:
4361 .Dl "ipfw add pipe 1 ip from any to any out"
4362 .Dl "ipfw add pipe 2 ip from any to any in"
4363 .Dl "ipfw pipe 1 config bw 64Kbit/s queue 10Kbytes"
4364 .Dl "ipfw pipe 2 config bw 64Kbit/s queue 10Kbytes"
4366 The above can be very useful, e.g.\& if you want to see how
4367 your fancy Web page will look for a residential user who
4368 is connected only through a slow link.
4369 You should not use only one pipe for both directions, unless
4370 you want to simulate a half-duplex medium (e.g.\& AppleTalk,
4372 It is not necessary that both pipes have the same configuration,
4373 so we can also simulate asymmetric links.
4375 Should we want to verify network performance with the RED queue
4376 management algorithm:
4378 .Dl "ipfw add pipe 1 ip from any to any"
4379 .Dl "ipfw pipe 1 config bw 500Kbit/s queue 100 red 0.002/30/80/0.1"
4381 Another typical application of the traffic shaper is to
4382 introduce some delay in the communication.
4383 This can significantly affect applications which do a lot of Remote
4384 Procedure Calls, and where the round-trip-time of the
4385 connection often becomes a limiting factor much more than
4388 .Dl "ipfw add pipe 1 ip from any to any out"
4389 .Dl "ipfw add pipe 2 ip from any to any in"
4390 .Dl "ipfw pipe 1 config delay 250ms bw 1Mbit/s"
4391 .Dl "ipfw pipe 2 config delay 250ms bw 1Mbit/s"
4393 Per-flow queueing can be useful for a variety of purposes.
4394 A very simple one is counting traffic:
4396 .Dl "ipfw add pipe 1 tcp from any to any"
4397 .Dl "ipfw add pipe 1 udp from any to any"
4398 .Dl "ipfw add pipe 1 ip from any to any"
4399 .Dl "ipfw pipe 1 config mask all"
4401 The above set of rules will create queues (and collect
4402 statistics) for all traffic.
4403 Because the pipes have no limitations, the only effect is
4404 collecting statistics.
4405 Note that we need 3 rules, not just the last one, because
4408 tries to match IP packets it will not consider ports, so we
4409 would not see connections on separate ports as different
4412 A more sophisticated example is limiting the outbound traffic
4413 on a net with per-host limits, rather than per-network limits:
4415 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4416 .Dl "ipfw add pipe 2 ip from any to 192.168.2.0/24 in"
4417 .Dl "ipfw pipe 1 config mask src-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4418 .Dl "ipfw pipe 2 config mask dst-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4420 In the following example, we need to create several traffic bandwidth
4421 classes and we need different hosts/networks to fall into different classes.
4422 We create one pipe for each class and configure them accordingly.
4423 Then we create a single table and fill it with IP subnets and addresses.
4424 For each subnet/host we set the argument equal to the number of the pipe
4426 Then we classify traffic using a single rule:
4428 .Dl "ipfw pipe 1 config bw 1000Kbyte/s"
4429 .Dl "ipfw pipe 4 config bw 4000Kbyte/s"
4431 .Dl "ipfw table T1 create type addr"
4432 .Dl "ipfw table T1 add 192.168.2.0/24 1"
4433 .Dl "ipfw table T1 add 192.168.0.0/27 4"
4434 .Dl "ipfw table T1 add 192.168.0.2 1"
4436 .Dl "ipfw add pipe tablearg ip from 'table(T1)' to any"
4440 action, the table entries may include hostnames and IP addresses.
4442 .Dl "ipfw table T2 create type addr ftype ip"
4443 .Dl "ipfw table T2 add 192.168.2.0/24 10.23.2.1"
4444 .Dl "ipfw table T21 add 192.168.0.0/27 router1.dmz"
4446 .Dl "ipfw add 100 fwd tablearg ip from any to table(1)"
4448 In the following example per-interface firewall is created:
4450 .Dl "ipfw table IN create type iface valtype skipto,fib"
4451 .Dl "ipfw table IN add vlan20 12000,12"
4452 .Dl "ipfw table IN add vlan30 13000,13"
4453 .Dl "ipfw table OUT create type iface valtype skipto"
4454 .Dl "ipfw table OUT add vlan20 22000"
4455 .Dl "ipfw table OUT add vlan30 23000"
4457 .Dl "ipfw add 100 setfib tablearg ip from any to any recv 'table(IN)' in"
4458 .Dl "ipfw add 200 skipto tablearg ip from any to any recv 'table(IN)' in"
4459 .Dl "ipfw add 300 skipto tablearg ip from any to any xmit 'table(OUT)' out"
4461 The following example illustrate usage of flow tables:
4463 .Dl "ipfw table fl create type flow:src-ip,proto,dst-ip,dst-port"
4464 .Dl "ipfw table fl add 2a02:6b8:77::88,tcp,2a02:6b8:77::99,80 11"
4465 .Dl "ipfw table fl add 10.0.0.1,udp,10.0.0.2,53 12"
4467 .Dl "ipfw add 100 allow ip from any to any flow 'table(fl,11)' recv ix0"
4469 To add a set of rules atomically, e.g.\& set 18:
4471 .Dl "ipfw set disable 18"
4472 .Dl "ipfw add NN set 18 ... # repeat as needed"
4473 .Dl "ipfw set enable 18"
4475 To delete a set of rules atomically the command is simply:
4477 .Dl "ipfw delete set 18"
4479 To test a ruleset and disable it and regain control if something goes wrong:
4481 .Dl "ipfw set disable 18"
4482 .Dl "ipfw add NN set 18 ... # repeat as needed"
4483 .Dl "ipfw set enable 18; echo done; sleep 30 && ipfw set disable 18"
4485 Here if everything goes well, you press control-C before the "sleep"
4486 terminates, and your ruleset will be left active.
4487 Otherwise, e.g.\& if
4488 you cannot access your box, the ruleset will be disabled after
4489 the sleep terminates thus restoring the previous situation.
4491 To show rules of the specific set:
4493 .Dl "ipfw set 18 show"
4495 To show rules of the disabled set:
4497 .Dl "ipfw -S set 18 show"
4499 To clear a specific rule counters of the specific set:
4501 .Dl "ipfw set 18 zero NN"
4503 To delete a specific rule of the specific set:
4505 .Dl "ipfw set 18 delete NN"
4506 .Ss NAT, REDIRECT AND LSNAT
4507 First redirect all the traffic to nat instance 123:
4509 .Dl "ipfw add nat 123 all from any to any"
4511 Then to configure nat instance 123 to alias all the outgoing traffic with ip
4512 192.168.0.123, blocking all incoming connections, trying to keep
4513 same ports on both sides, clearing aliasing table on address change
4514 and keeping a log of traffic/link statistics:
4516 .Dl "ipfw nat 123 config ip 192.168.0.123 log deny_in reset same_ports"
4518 Or to change address of instance 123, aliasing table will be cleared (see
4521 .Dl "ipfw nat 123 config ip 10.0.0.1"
4523 To see configuration of nat instance 123:
4525 .Dl "ipfw nat 123 show config"
4527 To show logs of all the instances in range 111-999:
4529 .Dl "ipfw nat 111-999 show"
4531 To see configurations of all instances:
4533 .Dl "ipfw nat show config"
4535 Or a redirect rule with mixed modes could looks like:
4537 .Dl "ipfw nat 123 config redirect_addr 10.0.0.1 10.0.0.66"
4538 .Dl " redirect_port tcp 192.168.0.1:80 500"
4539 .Dl " redirect_proto udp 192.168.1.43 192.168.1.1"
4540 .Dl " redirect_addr 192.168.0.10,192.168.0.11"
4541 .Dl " 10.0.0.100 # LSNAT"
4542 .Dl " redirect_port tcp 192.168.0.1:80,192.168.0.10:22"
4545 or it could be split in:
4547 .Dl "ipfw nat 1 config redirect_addr 10.0.0.1 10.0.0.66"
4548 .Dl "ipfw nat 2 config redirect_port tcp 192.168.0.1:80 500"
4549 .Dl "ipfw nat 3 config redirect_proto udp 192.168.1.43 192.168.1.1"
4550 .Dl "ipfw nat 4 config redirect_addr 192.168.0.10,192.168.0.11,192.168.0.12"
4552 .Dl "ipfw nat 5 config redirect_port tcp"
4553 .Dl " 192.168.0.1:80,192.168.0.10:22,192.168.0.20:25 500"
4555 Sometimes you may want to mix NAT and dynamic rules. It could be achieved with
4559 options. Problem is, you need to create dynamic rule before NAT and check it
4560 after NAT actions (or vice versa) to have consistent addresses and ports.
4563 option will trigger activation of existing dynamic state, and action of such
4564 rule will be performed as soon as rule is matched. In case of NAT and
4566 rule packet need to be passed to NAT, not allowed as soon is possible.
4568 There is example of set of rules to achieve this. Bear in mind that this
4569 is example only and it is not very useful by itself.
4571 On way out, after all checks place this rules:
4573 .Dl "ipfw add allow record-state skip-action"
4574 .Dl "ipfw add nat 1"
4576 And on way in there should be something like this:
4578 .Dl "ipfw add nat 1"
4579 .Dl "ipfw add check-state"
4581 Please note, that first rule on way out doesn't allow packet and doesn't
4582 execute existing dynamic rules. All it does, create new dynamic rule with
4584 action, if it is not created yet. Later, this dynamic rule is used on way
4588 .Ss CONFIGURING CODEL, PIE, FQ-CODEL and FQ-PIE AQM
4592 AQM can be configured for
4602 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4605 .Dl "ipfw pipe 1 config bw 1mbits/s codel"
4606 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4612 AQM using different configurations parameters for traffic from
4613 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4615 .Dl "ipfw pipe 1 config bw 1mbits/s"
4616 .Dl "ipfw queue 1 config pipe 1 codel target 8ms interval 160ms ecn"
4617 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4623 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4626 .Dl "ipfw pipe 1 config bw 1mbits/s pie"
4627 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4633 AQM using different configuration parameters for traffic from
4634 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4636 .Dl "ipfw pipe 1 config bw 1mbits/s"
4637 .Dl "ipfw queue 1 config pipe 1 pie target 20ms tupdate 30ms ecn"
4638 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4643 AQM can be configured for
4649 scheduler using different configurations parameters for traffic from
4650 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4652 .Dl "ipfw pipe 1 config bw 1mbits/s"
4653 .Dl "ipfw sched 1 config pipe 1 type fq_codel"
4654 .Dl "ipfw queue 1 config sched 1"
4655 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4659 default configuration for a
4661 such as disable ECN and change the
4665 .Dl "ipfw sched 1 config pipe 1 type fq_codel target 10ms noecn"
4671 scheduler using different configurations parameters for traffic from
4672 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4674 .Dl "ipfw pipe 1 config bw 1mbits/s"
4675 .Dl "ipfw sched 1 config pipe 1 type fq_pie"
4676 .Dl "ipfw queue 1 config sched 1"
4677 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4679 The configurations of
4682 can be changed in a similar way as for
4706 utility first appeared in
4711 Stateful extensions were introduced in
4714 was introduced in Summer 2002.
4716 .An Ugen J. S. Antsilevich ,
4717 .An Poul-Henning Kamp ,
4721 .An Rasool Al-Saadi .
4724 API based upon code written by
4728 Dummynet has been introduced by Luigi Rizzo in 1997-1998.
4730 Some early work (1999-2000) on the
4732 traffic shaper supported by Akamba Corp.
4734 The ipfw core (ipfw2) has been completely redesigned and
4735 reimplemented by Luigi Rizzo in summer 2002.
4738 options have been added by various developers over the years.
4741 In-kernel NAT support written by
4742 .An Paolo Pisati Aq Mt piso@FreeBSD.org
4743 as part of a Summer of Code 2005 project.
4747 support has been developed by
4748 .An The Centre for Advanced Internet Architectures (CAIA) Aq http://www.caia.swin.edu.au .
4749 The primary developers and maintainers are David Hayes and Jason But.
4750 For further information visit:
4751 .Aq http://www.caia.swin.edu.au/urp/SONATA
4753 Delay profiles have been developed by Alessandro Cerri and
4754 Luigi Rizzo, supported by the
4755 European Commission within Projects Onelab and Onelab2.
4757 CoDel, PIE, FQ-CoDel and FQ-PIE AQM for Dummynet have been implemented by
4758 .An The Centre for Advanced Internet Architectures (CAIA)
4759 in 2016, supported by The Comcast Innovation Fund.
4760 The primary developer is
4763 The syntax has grown over the years and sometimes it might be confusing.
4764 Unfortunately, backward compatibility prevents cleaning up mistakes
4765 made in the definition of the syntax.
4769 Misconfiguring the firewall can put your computer in an unusable state,
4770 possibly shutting down network services and requiring console access to
4771 regain control of it.
4773 Incoming packet fragments diverted by
4775 are reassembled before delivery to the socket.
4776 The action used on those packet is the one from the
4777 rule which matches the first fragment of the packet.
4779 Packets diverted to userland, and then reinserted by a userland process
4780 may lose various packet attributes.
4781 The packet source interface name
4782 will be preserved if it is shorter than 8 bytes and the userland process
4783 saves and reuses the sockaddr_in
4786 otherwise, it may be lost.
4787 If a packet is reinserted in this manner, later rules may be incorrectly
4788 applied, making the order of
4790 rules in the rule sequence very important.
4792 Dummynet drops all packets with IPv6 link-local addresses.
4798 may not behave as expected.
4799 In particular, incoming SYN packets may
4800 have no uid or gid associated with them since they do not yet belong
4801 to a TCP connection, and the uid/gid associated with a packet may not
4802 be as expected if the associated process calls
4804 or similar system calls.
4806 Rule syntax is subject to the command line environment and some patterns
4807 may need to be escaped with the backslash character
4808 or quoted appropriately.
4810 Due to the architecture of
4812 ipfw nat is not compatible with the TCP segmentation offloading (TSO).
4813 Thus, to reliably nat your network traffic, please disable TSO
4817 ICMP error messages are not implicitly matched by dynamic rules
4818 for the respective conversations.
4819 To avoid failures of network error detection and path MTU discovery,
4820 ICMP error messages may need to be allowed explicitly through static
4827 actions may lead to confusing behaviour if ruleset has mistakes,
4828 and/or interaction with other subsystems (netgraph, dummynet, etc.) is used.
4829 One possible case for this is packet leaving
4831 in subroutine on the input pass, while later on output encountering unpaired
4834 As the call stack is kept intact after input pass, packet will suddenly
4835 return to the rule number used on input pass, not on output one.
4836 Order of processing should be checked carefully to avoid such mistakes.
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