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21 .TH PCAP-FILTER @MAN_MISC_INFO@ "4 January 2025"
23 pcap-filter \- packet filter syntax
28 .BR pcap_compile (3PCAP)
29 is used to compile a string into a filter program.
30 The resulting filter program can then be applied to
31 some stream of packets to determine which packets will be supplied to
32 .BR pcap_loop (3PCAP),
33 .BR pcap_dispatch (3PCAP),
34 .BR pcap_next (3PCAP),
36 .BR pcap_next_ex (3PCAP).
38 The \fIfilter expression\fP consists of one or more
40 Primitives usually consist of an
42 (name or number) preceded by one or more qualifiers.
44 different kinds of qualifier:
47 qualifiers say what kind of thing the id name or number refers to.
54 E.g., `\fBhost\fP foo', `\fBnet\fP 128.3', `\fBport\fP 20', `\fBportrange\fP 6000-6008'.
61 qualifiers specify a particular transfer direction to and/or from
63 Possible directions are
75 E.g., `\fBsrc\fP foo', `\fBdst net\fP 128.3', `\fBsrc or dst port\fP ftp-data'.
77 there is no dir qualifier, `\fBsrc or dst\fP' is assumed.
86 qualifiers are only valid for IEEE 802.11 Wireless LAN link layers.
89 qualifiers restrict the match to a particular protocol.
105 E.g., `\fBether src\fP foo', `\fBarp net\fP 128.3', `\fBtcp port\fP 21',
106 `\fBudp portrange\fP 7000-7009', `\fBwlan addr2\fP 0:2:3:4:5:6'.
109 qualifier, all protocols consistent with the type are assumed.
110 E.g., `\fBsrc\fP foo' means `\fB(ip6 or ip or arp or rarp) src\fP foo',
111 `\fBnet\fP bar' means `\fB(ip or arp or rarp) net\fP bar' and
112 `\fBport\fP 53' means `\fB(tcp or udp or sctp) port\fP 53'
113 (note that these examples use invalid syntax to illustrate the principle).
115 [\fBfddi\fP is actually an alias for \fBether\fP; the parser treats them
116 identically as meaning ``the data link level used on the specified
117 network interface''. FDDI headers contain Ethernet-like source
118 and destination addresses, and often contain Ethernet-like packet
119 types, so you can filter on these FDDI fields just as with the
120 analogous Ethernet fields.
121 FDDI headers also contain other fields,
122 but you cannot name them explicitly in a filter expression.
124 Similarly, \fBtr\fP and \fBwlan\fP are aliases for \fBether\fP; the previous
125 paragraph's statements about FDDI headers also apply to Token Ring
126 and 802.11 wireless LAN headers. For 802.11 headers, the destination
127 address is the DA field and the source address is the SA field; the
128 BSSID, RA, and TA fields aren't tested.]
130 In addition to the above, there are some special `primitive' keywords
131 that don't follow the pattern:
136 and arithmetic expressions.
137 All of these are described below.
139 More complex filter expressions are built up by using the words
144 (or equivalently: `\fB&&\fP', `\fB||\fP' and `\fB!\fP' respectively)
145 to combine primitives.
146 E.g., `\fBhost\fP foo \fBand not port\fP ftp \fBand not port\fP ftp-data'.
147 To save typing, identical qualifier lists can be omitted.
149 `\fBtcp dst port\fP ftp \fBor\fP ftp-data \fBor\fP domain' is exactly the same as
150 `\fBtcp dst port\fP ftp \fBor tcp dst port\fP ftp-data \fBor tcp dst port\fP domain'.
152 Allowable primitives are:
153 .IP "\fBdst host \fIhostnameaddr\fR"
154 True if the IPv4/v6 destination field of the packet is \fIhostnameaddr\fP,
155 which may be either an address or a name.
156 .IP "\fBsrc host \fIhostnameaddr\fR"
157 True if the IPv4/v6 source field of the packet is \fIhostnameaddr\fP.
158 .IP "\fBhost \fIhostnameaddr\fP"
159 True if either the IPv4/v6 source or destination of the packet is \fIhostnameaddr\fP.
161 Any of the above host expressions can be prepended with the keywords,
162 \fBip\fP, \fBarp\fP, \fBrarp\fP, or \fBip6\fP as in:
165 \fBip host \fIhostnameaddr\fR
168 which is equivalent to:
171 \fBether proto \\\fRip \fBand host \fIhostnameaddr\fR
174 If \fIhostnameaddr\fR is a name with multiple IPv4/v6 addresses, each address will
175 be checked for a match.
176 .IP "\fBether dst \fIethernameaddr\fP"
177 True if the Ethernet destination address is \fIethernameaddr\fP.
179 may be either a name from /etc/ethers or a numerical MAC address of the
180 form "xx:xx:xx:xx:xx:xx", "xx.xx.xx.xx.xx.xx", "xx-xx-xx-xx-xx-xx",
181 "xxxx.xxxx.xxxx" or "xxxxxxxxxxxx",
182 where each "x" is a hex digit (0-9, a-f, or A-F).
183 .IP "\fBether src \fIethernameaddr\fP"
184 True if the Ethernet source address is \fIethernameaddr\fP.
185 .IP "\fBether host \fIethernameaddr\fP"
186 True if either the Ethernet source or destination address is \fIethernameaddr\fP.
187 .IP "\fBgateway\fP \fIhost\fP"
188 True if the packet used \fIhost\fP as a gateway.
190 source or destination address was \fIhost\fP but neither the IP source
191 nor the IP destination was \fIhost\fP.
192 \fIHost\fP must be a name and
193 must be found both by the machine's host-name-to-IP-address resolution
194 mechanisms (host name file, DNS, NIS, etc.) and by the machine's
195 host-name-to-Ethernet-address resolution mechanism (/etc/ethers, etc.).
196 (An equivalent expression is
199 \fBether host \fIethernameaddr \fBand not host \fIhostnameaddr\fR
202 which can be used with either names or numbers for \fIhostnameaddr / ethernameaddr\fP.)
203 This syntax does not work in IPv6-enabled configuration at this moment.
204 .IP "\fBdst net \fInetnameaddr\fR"
205 True if the IPv4/v6 destination address of the packet has a network
206 number of \fInetnameaddr\fP.
207 \fINet\fP may be either a name from the networks database
208 (/etc/networks, etc.) or a network number.
209 An IPv4 network number can be written as a dotted quad (e.g., 192.168.1.0),
210 dotted triple (e.g., 192.168.1), dotted pair (e.g, 172.16), or single
211 number (e.g., 10); the netmask is 255.255.255.255 for a dotted quad
212 (which means that it's really a host match), 255.255.255.0 for a dotted
213 triple, 255.255.0.0 for a dotted pair, or 255.0.0.0 for a single number.
214 An IPv6 network number must be written out fully; the netmask is
215 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff, so IPv6 "network" matches are really always
216 host matches, and a network match requires a netmask length.
217 .IP "\fBsrc net \fInetnameaddr\fR"
218 True if the IPv4/v6 source address of the packet has a network
219 number of \fInetnameaddr\fP.
220 .IP "\fBnet \fInetnameaddr\fR"
221 True if either the IPv4/v6 source or destination address of the packet has a network
222 number of \fInetnameaddr\fP.
223 .IP "\fBnet \fInetaddr\fR \fBmask \fInetmask\fR"
224 True if the IPv4 address matches \fInetaddr\fR with the specific \fInetmask\fR.
225 May be qualified with \fBsrc\fR or \fBdst\fR.
226 Note that this syntax is not valid for IPv6 \fInetaddr\fR.
227 .IP "\fBnet \fInetaddr\fR/\fIlen\fR"
228 True if the IPv4/v6 address matches \fInetaddr\fR with a netmask \fIlen\fR
230 May be qualified with \fBsrc\fR or \fBdst\fR.
231 .IP "\fBdst port \fIportnamenum\fR"
232 True if the packet is IPv4/v6 TCP, UDP or SCTP and has a
233 destination port value of \fIportnamenum\fP.
234 The \fIportnamenum\fP can be a number or a name used in /etc/services (see
238 If a name is used, both the port
239 number and protocol are checked.
240 If a number or ambiguous name is used,
241 only the port number is checked (e.g., `\fBdst port\fR 513' will print both
242 tcp/login traffic and udp/who traffic, and `\fBport\fR domain' will print
243 both tcp/domain and udp/domain traffic).
244 .IP "\fBsrc port \fIportnamenum\fR"
245 True if the packet has a source port value of \fIportnamenum\fP.
246 .IP "\fBport \fIportnamenum\fR"
247 True if either the source or destination port of the packet is \fIportnamenum\fP.
248 .IP "\fBdst portrange \fIportnamenum1-portnamenum2\fR"
249 True if the packet is IPv4/v6 TCP, UDP or SCTP and has a
250 destination port value between \fIportnamenum1\fP and \fIportnamenum2\fP (both inclusive).
254 are interpreted in the same fashion as the
258 .IP "\fBsrc portrange \fIportnamenum1-portnamenum2\fR"
259 True if the packet has a source port value between \fIportnamenum1\fP and
260 \fIportnamenum2\fP (both inclusive).
261 .IP "\fBportrange \fIportnamenum1-portnamenum2\fR"
262 True if either the source or destination port of the packet is between
263 \fIportnamenum1\fP and \fIportnamenum2\fP (both inclusive).
265 Any of the above port or port range expressions can be prepended with
266 the keywords, \fBtcp\fP, \fBudp\fP or \fBsctp\fP, as in:
269 \fBtcp src port \fIportnamenum\fR
272 which matches only TCP packets whose source port is \fIportnamenum\fP.
273 .IP "\fBless \fIlength\fR"
274 True if the packet has a length less than or equal to \fIlength\fP.
275 This is equivalent to:
278 \fBlen <= \fIlength\fP
281 .IP "\fBgreater \fIlength\fR"
282 True if the packet has a length greater than or equal to \fIlength\fP.
283 This is equivalent to:
286 \fBlen >= \fIlength\fP
289 .IP "\fBip proto \fIprotocol\fR"
290 True if the packet is an IPv4 packet (see
292 of protocol type \fIprotocol\fP.
293 \fIProtocol\fP can be a number or one of the names recognized by
294 .BR getprotobyname (3),
299 (only in Linux with glibc, FreeBSD, NetBSD, DragonFly BSD, and macOS),
303 (only in Haiku and OpenBSD),
310 Note that most of these example identifiers
311 are also keywords and must be escaped via backslash (\\).
312 Note that this primitive does not chase the protocol header chain.
315 .BR getprotobyname (3)
318 file to translate protocol names to numbers, and the
319 .B "getent protocols"
320 command lists the protocols recognised by the function. This is not entirely
321 so in AIX (which does not have the command), Haiku (which has the file at
322 .IR \%/system/data/network/protocols
323 and does not have the command), on Linux with musl libc (which hard-codes the
324 list of protocols) and on hosts that use a network database to resolve
325 protocol names to numbers (see
326 .BR nsswitch.conf (5)).
327 If a protocol name fails to translate to a number, this version of libpcap
328 will treat the filter expression as invalid.
329 .IP "\fBcarp\fR, \fBvrrp\fR"
357 .IP "\fBip6 proto \fIprotocol\fR"
358 True if the packet is an IPv6 packet of protocol type \fIprotocol\fP.
359 (See `\fBip proto\fP' above for the meaning of \fIprotocol\fR.)
360 Note that the IPv6 variant of ICMP uses a different protocol number, named
362 in AIX, FreeBSD, illumos, Haiku, GNU/Hurd, Linux, macOS, NetBSD, OpenBSD,
364 Note that this primitive does not chase the protocol header chain.
372 .IP "\fBproto \fIprotocol\fR"
373 True if the packet is an IPv4 or IPv6 packet of protocol type
374 \fIprotocol\fP. (See `\fBip proto\fP' above for the meaning of
375 \fIprotocol\fP.) Note that this primitive does not chase the protocol
377 .IP "\fBah\fR, \fBesp\fR, \fBpim\fR, \fBsctp\fR, \fBtcp\fR, \fBudp\fR"
381 \fBproto \\\fIprotocol\fR
384 where \fIprotocol\fR is one of the above protocols.
385 .IP "\fBip6 protochain \fIprotocol\fR"
386 True if the packet is IPv6 packet,
387 and contains protocol header with type \fIprotocol\fR
388 in its protocol header chain.
389 (See `\fBip proto\fP' above for the meaning of \fIprotocol\fP.)
393 \fBip6 protochain\fR 6
396 matches any IPv6 packet with TCP protocol header in the protocol header chain.
397 The packet may contain, for example,
398 authentication header, routing header, or hop-by-hop option header,
399 between IPv6 header and TCP header.
400 The BPF code emitted by this primitive is complex and
401 cannot be optimized by the BPF optimizer code, and is not supported by
402 filter engines in the kernel, so this can be somewhat slow, and may
403 cause more packets to be dropped.
404 .IP "\fBip protochain \fIprotocol\fR"
405 Equivalent to \fBip6 protochain \fIprotocol\fR, but this is for IPv4.
406 (See `\fBip proto\fP' above for the meaning of \fIprotocol\fP.)
407 .IP "\fBprotochain \fIprotocol\fR"
408 True if the packet is an IPv4 or IPv6 packet of protocol type
409 \fIprotocol\fP. (See `\fBip proto\fP' above for the meaning of
410 \fIprotocol\fP.) Note that this primitive chases the protocol
412 .IP "\fBether broadcast\fR"
413 True if the packet is an Ethernet broadcast packet.
416 .IP "\fBip broadcast\fR"
417 True if the packet is an IPv4 broadcast packet.
418 It checks for both the all-zeroes and all-ones broadcast conventions,
419 and looks up the subnet mask on the interface on which the capture is
422 If the subnet mask of the interface on which the capture is being done
423 is not available, either because the interface on which capture is being
424 done has no netmask or because the capture is being done on the Linux
425 "any" interface, which can capture on more than one interface, this
426 check will not work correctly.
427 .IP "\fBether multicast\fR"
428 True if the packet is an Ethernet multicast packet.
431 This is shorthand for `\fBether[\fP0\fB] & \fP1\fB != \fP0'.
432 .IP "\fBip multicast\fR"
433 True if the packet is an IPv4 multicast packet.
434 .IP "\fBip6 multicast\fR"
435 True if the packet is an IPv6 multicast packet.
436 .IP "\fBether proto \fIprotocol\fR"
437 True if the packet is of ether type \fIprotocol\fR.
438 \fIProtocol\fP can be a number or one of the names
439 \fBaarp\fP, \fBarp\fP, \fBatalk\fP, \fBdecnet\fP, \fBip\fP, \fBip6\fP,
440 \fBipx\fP, \fBiso\fP, \fBlat\fP, \fBloopback\fP, \fBmopdl\fP, \fBmoprc\fP, \fBnetbeui\fP,
441 \fBrarp\fP, \fBsca\fP or \fBstp\fP.
442 Note these identifiers (except \fBloopback\fP) are also keywords
443 and must be escaped via backslash (\\).
445 [In the case of FDDI (e.g., `\fBfddi proto \\arp\fR'), Token Ring
446 (e.g., `\fBtr proto \\arp\fR'), and IEEE 802.11 wireless LANs (e.g.,
447 `\fBwlan proto \\arp\fR'), for most of those protocols, the
448 protocol identification comes from the 802.2 Logical Link Control (LLC)
449 header, which is usually layered on top of the FDDI, Token Ring, or
452 When filtering for most protocol identifiers on FDDI, Token Ring, or
453 802.11, the filter checks only the protocol ID field of an LLC header
454 in so-called SNAP format with an Organizational Unit Identifier (OUI) of
455 0x000000, for encapsulated Ethernet; it doesn't check whether the packet
456 is in SNAP format with an OUI of 0x000000.
461 the filter checks the DSAP (Destination Service Access Point) and
462 SSAP (Source Service Access Point) fields of the LLC header;
464 \fBstp\fP and \fBnetbeui\fP
465 the filter checks the DSAP of the LLC header;
468 the filter checks for a SNAP-format packet with an OUI of 0x080007
469 and the AppleTalk etype.
472 In the case of Ethernet, the filter checks the Ethernet type field
473 for most of those protocols. The exceptions are:
476 \fBiso\fP, \fBstp\fP, and \fBnetbeui\fP
477 the filter checks for an 802.3 frame and then checks the LLC header as
478 it does for FDDI, Token Ring, and 802.11;
481 the filter checks both for the AppleTalk etype in an Ethernet frame and
482 for a SNAP-format packet as it does for FDDI, Token Ring, and 802.11;
485 the filter checks for the AppleTalk ARP etype in either an Ethernet
486 frame or an 802.2 SNAP frame with an OUI of 0x000000;
489 the filter checks for the IPX etype in an Ethernet frame, the IPX
490 DSAP in the LLC header, the 802.3-with-no-LLC-header encapsulation of
491 IPX, and the IPX etype in a SNAP frame.
493 .IP "\fBip\fR, \fBip6\fR, \fBarp\fR, \fBrarp\fR, \fBatalk\fR, \fBaarp\fR, \fBdecnet\fR, \fBiso\fR, \fBstp\fR, \fBipx\fR, \fBnetbeui\fP"
497 \fBether proto \\\fIprotocol\fR
500 where \fIprotocol\fR is one of the above protocols.
501 .IP "\fBlat\fR, \fBmopdl\fR, \fBmoprc\fR, \fBsca\fR"
505 \fBether proto \\\fIprotocol\fR
508 where \fIprotocol\fR is one of the above protocols, all of which originated
509 at DEC, but are not the same as DECnet. Namely,
511 is Local Area Transport (LAT),
513 is DNA Dump/Load (MOP),
515 is DNA Remote Console (MOP) and
517 is System Communication Architecture (SCA).
518 .IP "\fBdecnet src \fIdecnetaddr\fR"
519 True if the DECnet source address is
521 which is an address of the form
522 .B AREANUMBER.NODENUMBER
523 (for example, "10.123"), where the area number can be between 0 and 63
524 and the node number can be between 0 and 1023 and both numbers always use
526 .IP "\fBdecnet dst \fIdecnetaddr\fR"
527 True if the DECnet destination address is
529 .IP "\fBdecnet host \fIdecnetaddr\fR"
530 True if either the DECnet source or destination address is
533 True if the packet has an 802.2 LLC header. This includes:
535 Ethernet packets with a length field rather than a type field that
536 aren't raw NetWare-over-802.3 packets;
538 IEEE 802.11 data packets;
540 Token Ring packets (no check is done for LLC frames);
542 FDDI packets (no check is done for LLC frames);
544 LLC-encapsulated ATM packets, for SunATM on Solaris.
545 .IP "\fBllc\fP \fItype\fR"
546 True if the packet has an 802.2 LLC header and has the specified
562 Receiver Ready (RR) S PDUs
565 Receiver Not Ready (RNR) S PDUs
571 Unnumbered Information (UI) U PDUs
574 Unnumbered Acknowledgment (UA) U PDUs
577 Disconnect (DISC) U PDUs
580 Disconnected Mode (DM) U PDUs
583 Set Asynchronous Balanced Mode Extended (SABME) U PDUs
589 Exchange Identification (XID) U PDUs
592 Frame Reject (FRMR) U PDUs
595 Packet was received by the host performing the capture rather than being
596 sent by that host. This is only supported for certain link-layer types,
597 such as SLIP and the ``cooked'' Linux capture mode
598 used for the ``any'' device and for some other device types.
600 Packet was sent by the host performing the capture rather than being
601 received by that host. This is only supported for certain link-layer types,
602 such as SLIP and the ``cooked'' Linux capture mode
603 used for the ``any'' device and for some other device types.
604 .IP "\fBifindex \fIinterface_index\fR"
605 True if the packet was logged via the specified interface (applies only to
606 packets logged by the Linux "any" cooked v2 interface).
607 .IP "\fBifname \fIinterface\fR"
608 True if the packet was logged as coming from the specified interface (applies
609 only to packets logged by OpenBSD's or FreeBSD's
611 .IP "\fBon \fIinterface\fR"
615 .IP "\fBrnr \fInum\fR"
616 True if the packet was logged as matching the specified PF rule number
617 (applies only to packets logged by OpenBSD's or FreeBSD's
619 .IP "\fBrulenum \fInum\fR"
623 .IP "\fBreason \fIcode\fR"
624 True if the packet was logged with the specified PF reason code. The known
633 (applies only to packets logged by OpenBSD's or FreeBSD's
635 .IP "\fBrset \fIname\fR"
636 True if the packet was logged as matching the specified PF ruleset
637 name of an anchored ruleset (applies only to packets logged by OpenBSD's
640 .IP "\fBruleset \fIname\fR"
644 .IP "\fBsrnr \fInum\fR"
645 True if the packet was logged as matching the specified PF rule number
646 of an anchored ruleset (applies only to packets logged by OpenBSD's or
649 .IP "\fBsubrulenum \fInum\fR"
653 .IP "\fBaction \fIact\fR"
654 True if PF took the specified action when the packet was logged. Known actions
659 and, with later versions of
666 (applies only to packets logged by OpenBSD's or FreeBSD's
668 .IP "\fBwlan ra \fIehost\fR"
669 True if the IEEE 802.11 RA is
671 The RA field is used in all frames except for management frames.
672 .IP "\fBwlan ta \fIehost\fR"
673 True if the IEEE 802.11 TA is
675 The TA field is used in all frames except for management frames and
676 CTS (Clear To Send) and ACK (Acknowledgment) control frames.
677 .IP "\fBwlan addr1 \fIehost\fR"
678 True if the first IEEE 802.11 address is
680 .IP "\fBwlan addr2 \fIehost\fR"
681 True if the second IEEE 802.11 address, if present, is
683 The second address field is used in all frames except for CTS (Clear To
684 Send) and ACK (Acknowledgment) control frames.
685 .IP "\fBwlan addr3 \fIehost\fR"
686 True if the third IEEE 802.11 address, if present, is
688 The third address field is used in management and data frames, but not
690 .IP "\fBwlan addr4 \fIehost\fR"
691 True if the fourth IEEE 802.11 address, if present, is
693 The fourth address field is only used for
694 WDS (Wireless Distribution System) frames.
695 .IP "\fBtype \fIwlan_type\fR"
696 True if the IEEE 802.11 frame type matches the specified \fIwlan_type\fR.
697 Valid \fIwlan_type\fRs are:
701 .IP "\fBtype \fIwlan_type \fBsubtype \fIwlan_subtype\fR"
702 True if the IEEE 802.11 frame type matches the specified \fIwlan_type\fR
703 and frame subtype matches the specified \fIwlan_subtype\fR.
705 If the specified \fIwlan_type\fR is \fBmgt\fP,
706 then valid \fIwlan_subtype\fRs are:
719 If the specified \fIwlan_type\fR is \fBctl\fP,
720 then valid \fIwlan_subtype\fRs are:
730 If the specified \fIwlan_type\fR is \fBdata\fP,
731 then valid \fIwlan_subtype\fRs are:
735 .BR \%data-cf-ack-poll ,
741 .BR \%qos-data-cf-ack ,
742 .BR \%qos-data-cf-poll ,
743 .BR \%qos-data-cf-ack-poll ,
747 .BR \%qos-cf-ack-poll .
748 .IP "\fBsubtype \fIwlan_subtype\fR"
749 True if the IEEE 802.11 frame subtype matches the specified \fIwlan_subtype\fR
750 and frame has the type to which the specified \fIwlan_subtype\fR belongs.
751 .IP "\fBdir \fIdirection\fR"
752 True if the IEEE 802.11 frame direction matches the specified
754 Valid directions are:
760 .IP "\fBvlan \fI[vlan_id]\fR"
761 True if the packet is an IEEE 802.1Q VLAN packet.
762 If the optional \fIvlan_id\fR is specified, only true if the packet has the specified
764 Note that the first \fBvlan\fR keyword encountered in an expression
765 changes the decoding offsets for the remainder of the expression on
766 the assumption that the packet is a VLAN packet. The `\fBvlan
767 \fI[vlan_id]\fR` keyword may be used more than once, to filter on VLAN
768 hierarchies. Each use of that keyword increments the filter offsets
774 \fBvlan\fP 100 \fB&& vlan\fR 200
777 filters on VLAN 200 encapsulated within VLAN 100, and
780 \fBvlan && vlan \fP300 \fB&& ip\fR
783 filters IPv4 protocol encapsulated in VLAN 300 encapsulated within any
785 .IP "\fBmpls \fI[label_num]\fR"
786 True if the packet is an MPLS packet.
787 If the optional \fIlabel_num\fR is specified, only true if the packet has the specified
789 Note that the first \fBmpls\fR keyword encountered in an expression
790 changes the decoding offsets for the remainder of the expression on
791 the assumption that the packet is a MPLS-encapsulated IP packet. The
792 `\fBmpls \fI[label_num]\fR` keyword may be used more than once, to
793 filter on MPLS hierarchies. Each use of that keyword increments the
799 \fBmpls\fP 100000 \fB&& mpls\fR 1024
802 filters packets with an outer label of 100000 and an inner label of
806 \fBmpls && mpls\fP 1024 \fB&& host\fR 192.9.200.1
809 filters packets to or from 192.9.200.1 with an inner label of 1024 and
812 True if the packet is a PPP-over-Ethernet Discovery packet (Ethernet
814 .IP "\fBpppoes \fI[session_id]\fR"
815 True if the packet is a PPP-over-Ethernet Session packet (Ethernet
817 If the optional \fIsession_id\fR is specified, only true if the packet has the specified
819 Note that the first \fBpppoes\fR keyword encountered in an expression
820 changes the decoding offsets for the remainder of the expression on
821 the assumption that the packet is a PPPoE session packet.
826 \fBpppoes\fP 0x27 \fB&& ip\fR
829 filters IPv4 protocol encapsulated in PPPoE session id 0x27.
830 .IP "\fBgeneve \fI[vni]\fR"
831 True if the packet is a Geneve packet (UDP port 6081). If the optional \fIvni\fR
832 is specified, only true if the packet has the specified \fIvni\fR.
833 Note that when the \fBgeneve\fR keyword is encountered in
834 an expression, it changes the decoding offsets for the remainder of
835 the expression on the assumption that the packet is a Geneve packet.
840 \fBgeneve\fP 0xb \fB&& ip\fR
843 filters IPv4 protocol encapsulated in Geneve with VNI 0xb. This will
844 match both IPv4 directly encapsulated in Geneve as well as IPv4 contained
845 inside an Ethernet frame.
846 .IP "\fBvxlan \fI[vni]\fR"
847 True if the packet is a VXLAN packet (UDP port 4789). If the optional
848 \fIvni\fR is specified, only true if the packet has the specified
849 \fIvni\fR. Note that when the \fBvxlan\fR keyword is encountered in
850 an expression, it changes the decoding offsets for the remainder of
851 the expression on the assumption that the packet is a VXLAN packet.
856 \fBvxlan\fP 0x7 \fB&& ip6 \fR
859 filters IPv6 protocol encapsulated in VXLAN with VNI 0x7.
860 .IP "\fBiso proto \fIprotocol\fR"
861 True if the packet is an OSI packet of protocol type \fIprotocol\fP.
862 \fIProtocol\fP can be a number or one of the names
863 \fBclnp\fP, \fBesis\fP, or \fBisis\fP.
864 .IP "\fBclnp\fR, \fBesis\fR, \fBisis\fR"
868 \fBiso proto \\\fIprotocol\fR
871 where \fIprotocol\fR is one of the above protocols.
872 .IP "\fBl1\fR, \fBl2\fR, \fBiih\fR, \fBlsp\fR, \fBsnp\fR, \fBcsnp\fR, \fBpsnp\fR"
873 Abbreviations for IS-IS PDU types.
874 .IP "\fBvpi\fP \fIn\fR"
875 True if the packet is an ATM packet, for SunATM on Solaris, with a
876 virtual path identifier of
878 .IP "\fBvci\fP \fIn\fR"
879 True if the packet is an ATM packet, for SunATM on Solaris, with a
880 virtual channel identifier of
883 True if the packet is an ATM packet, for SunATM on Solaris, and is
885 Note that the first \fBlane\fR keyword encountered in an expression
886 changes the tests done in the remainder of the expression
887 on the assumption that the packet is either a LANE emulated Ethernet
888 packet or a LANE LE Control packet. If \fBlane\fR isn't specified, the
889 tests are done under the assumption that the packet is an
890 LLC-encapsulated packet.
892 True if the packet is an ATM packet, for SunATM on Solaris, and is
893 a segment OAM F4 flow cell (VPI=0 & VCI=3).
895 True if the packet is an ATM packet, for SunATM on Solaris, and is
896 an end-to-end OAM F4 flow cell (VPI=0 & VCI=4).
898 True if the packet is an ATM packet, for SunATM on Solaris, and is
899 a segment or end-to-end OAM F4 flow cell (VPI=0 & (VCI=3 | VCI=4)).
901 True if the packet is an ATM packet, for SunATM on Solaris, and is
902 a segment or end-to-end OAM F4 flow cell (VPI=0 & (VCI=3 | VCI=4)).
904 True if the packet is an ATM packet, for SunATM on Solaris, and is
905 on a meta signaling circuit (VPI=0 & VCI=1).
907 True if the packet is an ATM packet, for SunATM on Solaris, and is
908 on a broadcast signaling circuit (VPI=0 & VCI=2).
910 True if the packet is an ATM packet, for SunATM on Solaris, and is
911 on a signaling circuit (VPI=0 & VCI=5).
913 True if the packet is an ATM packet, for SunATM on Solaris, and is
914 on an ILMI circuit (VPI=0 & VCI=16).
916 True if the packet is an ATM packet, for SunATM on Solaris, and is
917 on a signaling circuit and is a Q.2931 Setup, Call Proceeding, Connect,
918 Connect Ack, Release, or Release Done message.
919 .IP \fBmetaconnect\fP
920 True if the packet is an ATM packet, for SunATM on Solaris, and is
921 on a meta signaling circuit and is a Q.2931 Setup, Call Proceeding, Connect,
922 Release, or Release Done message.
924 True if the packet is a Fill-In Signal Unit (FISU) MTP2 packet.
926 True if the packet is a Link Status Signal Unit (LSSU) MTP2 packet.
928 True if the packet is a Message Signal Unit (MSU) MTP2 packet.
929 .IP "\fBsio\fP \fIval\fR"
930 True if the packet has the Service Information Octet (SIO) field of the MTP2
931 MSU header set to the value
933 Note that this keyword does not test whether the packet is an MSU packet.
934 .IP "\fBdpc\fP \fIval\fR"
935 True if the packet has the Destination Point Code (DPC) field of the MTP3
936 standard routing label set to the value
938 Note that this keyword does not test whether the packet is an MTP3 packet.
939 .IP "\fBopc\fP \fIval\fR"
940 True if the packet has the Originating Point Code (OPC) field of the MTP3
941 standard routing label set to the value
943 Note that this keyword does not test whether the packet is an MTP3 packet.
944 .IP "\fBsls\fP \fIval\fR"
945 True if the packet has the Signalling Link Selection (SLS) field of the MTP3
946 standard routing label set to the value
948 Note that this keyword does not test whether the packet is an MTP3 packet.
949 .IP "\fBhfisu\fR, \fBhlssu\fR, \fBhmsu\fR, \fBhsio\fR, \fBhdpc\fR, \fBhopc\fR, \fBhsls\fP"
959 respectively, but only if the MTP2 link uses the extended sequence numbers
960 encoding specified for high speed signalling links (HSL) in ITU-T
961 Recommendation Q.703 Annex A.
962 .IP "\fIexpr1 relop expr2\fR"
963 True if the relation holds. \fIRelop\fR is one of
975 Each of \fIexpr1\fR and \fIexpr2\fR is an arithmetic expression composed of
976 integer constants (expressed in standard C syntax), the normal binary operators
987 a length operator, and special packet data
988 accessors. Note that all comparisons are unsigned, so that, for example,
989 0x80000000 and 0xffffffff are > 0.
995 operators are currently only supported for filtering in the kernel on
996 particular operating systems (for example: FreeBSD, Linux with 3.7 and later
997 kernels, NetBSD); on all other systems (for example: AIX, Hurd, illumos, Solaris,
999 those operators are used, filtering will be done in user mode, which
1000 will increase the overhead of capturing packets and may cause more
1001 packets to be dropped.
1003 The length operator, indicated by the keyword \fBlen\fP, gives the
1004 length of the packet.
1006 To access data inside the packet, use the following syntax:
1009 \fIproto\fB [ \fIexpr\fB : \fIsize\fB ]\fR
1044 indicates the protocol layer for the index operation.
1054 link layer. \fBradio\fR refers to the "radio header" added to some
1056 Note that \fBtcp\fR, \fBudp\fR and other upper-layer protocol types only
1057 apply to IPv4, not IPv6 (this will be fixed in the future).
1058 The byte offset, relative to the indicated protocol layer, is
1059 given by \fIexpr\fR.
1060 \fISize\fR is optional and indicates the number of bytes in the
1061 field of interest; it can be either one, two, or four, and defaults to one.
1063 For example, `\fBether[\fP0\fB] &\fP 1 \fB!=\fP 0' catches all multicast traffic.
1064 The expression `\fBip[\fP0\fB] &\fP 0xf \fB!=\fP 5'
1065 catches all IPv4 packets with options.
1067 `\fBip[\fP6:2\fB] &\fP 0x1fff \fB=\fP 0'
1068 catches only unfragmented IPv4 datagrams and frag zero of fragmented
1070 This check is implicitly applied to the
1082 For instance, \fBtcp[\fP0\fB]\fP always means the first
1083 byte of the TCP \fIheader\fP, and never means the first byte of an
1084 intervening fragment.
1086 Some offsets and field values may be expressed as names rather than
1088 The following protocol header field offsets are
1089 available: \fBicmptype\fP (ICMP type field), \fBicmp6type\fP (ICMPv6 type field),
1090 \fBicmpcode\fP (ICMP code field), \fBicmp6code\fP (ICMPv6 code field) and
1091 \fBtcpflags\fP (TCP flags field).
1093 The following ICMP type field values are available:
1094 .BR \%icmp-echoreply ,
1095 .BR \%icmp-unreach ,
1096 .BR \%icmp-sourcequench ,
1097 .BR \%icmp-redirect ,
1099 .BR \%icmp-routeradvert ,
1100 .BR \%icmp-routersolicit ,
1101 .BR \%icmp-timxceed ,
1102 .BR \%icmp-paramprob ,
1104 .BR \%icmp-tstampreply ,
1106 .BR \%icmp-ireqreply ,
1107 .BR \%icmp-maskreq ,
1108 .BR \%icmp-maskreply .
1110 The following ICMPv6 type field values are available:
1111 .BR \%icmp6-destinationunreach ,
1112 .BR \%icmp6-packettoobig ,
1113 .BR \%icmp6-timeexceeded ,
1114 .BR \%icmp6-parameterproblem ,
1116 .BR \%icmp6-echoreply ,
1117 .BR \%icmp6-multicastlistenerquery ,
1118 .BR \%icmp6-multicastlistenerreportv1 ,
1119 .BR \%icmp6-multicastlistenerdone ,
1120 .BR \%icmp6-routersolicit ,
1121 .BR \%icmp6-routeradvert ,
1122 .BR \%icmp6-neighborsolicit ,
1123 .BR \%icmp6-neighboradvert ,
1124 .BR \%icmp6-redirect ,
1125 .BR \%icmp6-routerrenum ,
1126 .BR \%icmp6-nodeinformationquery ,
1127 .BR \%icmp6-nodeinformationresponse ,
1128 .BR \%icmp6-ineighbordiscoverysolicit ,
1129 .BR \%icmp6-ineighbordiscoveryadvert ,
1130 .BR \%icmp6-multicastlistenerreportv2 ,
1131 .BR \%icmp6-homeagentdiscoveryrequest ,
1132 .BR \%icmp6-homeagentdiscoveryreply ,
1133 .BR \%icmp6-mobileprefixsolicit ,
1134 .BR \%icmp6-mobileprefixadvert ,
1135 .BR \%icmp6-certpathsolicit ,
1136 .BR \%icmp6-certpathadvert ,
1137 .BR \%icmp6-multicastrouteradvert ,
1138 .BR \%icmp6-multicastroutersolicit ,
1139 .BR \%icmp6-multicastrouterterm .
1141 The following TCP flags field values are available: \fBtcp-fin\fP,
1142 \fBtcp-syn\fP, \fBtcp-rst\fP, \fBtcp-push\fP,
1143 \fBtcp-ack\fP, \fBtcp-urg\fP, \fBtcp-ece\fP,
1146 Primitives may be combined using:
1148 A parenthesized group of primitives and operators.
1150 Negation (`\fB!\fP' or `\fBnot\fP').
1152 Concatenation (`\fB&&\fP' or `\fBand\fP').
1154 Alternation (`\fB||\fP' or `\fBor\fP').
1156 Negation has the highest precedence.
1157 Alternation and concatenation have equal precedence and associate
1160 If an identifier is given without a keyword, the most recent keyword
1165 \fBnot host\fP vs \fBand\fR ace
1171 \fBnot host\fP vs \fBand host\fR ace
1174 which should not be confused with
1177 \fBnot (host \fPvs\fB or \fPace\fB)\fR
1182 To select all packets arriving at or departing from `sundown':
1189 To select traffic between `helios' and either `hot' or `ace':
1192 \fBhost\fP helios \fBand (\fPhot \fBor\fP ace\fB)\fP
1196 To select all IPv4 packets between `ace' and any host except `helios':
1199 \fBip host\fP ace \fBand not\fP helios
1203 To select all traffic between local hosts and hosts at Berkeley:
1210 To select all FTP traffic through Internet gateway `snup':
1213 \fBgateway\fP snup \fBand (port\fP ftp \fBor\fP ftp-data\fB)\fP
1217 To select IPv4 traffic neither sourced from nor destined for local hosts
1218 (if you gateway to one other net, this stuff should never make it
1219 onto your local net).
1222 \fBip and not net \fPlocalnet
1226 To select the start and end packets (the SYN and FIN packets) of each
1227 TCP conversation that involves a non-local host.
1230 \fBtcp[tcpflags] & (tcp-syn|tcp-fin) !=\fP 0 \fBand not src and dst net\fP localnet
1234 To select the TCP packets with flags RST and ACK both set.
1235 (i.e. select only the RST and ACK flags in the flags field, and if the result
1236 is "RST and ACK both set", match)
1240 tcp[tcpflags] & (tcp-rst|tcp-ack) == (tcp-rst|tcp-ack)
1244 To select all IPv4 HTTP packets to and from port 80, i.e. print only
1245 packets that contain data, not, for example, SYN and FIN packets and
1246 ACK-only packets. (IPv6 is left as an exercise for the reader.)
1249 \fBtcp port\fP 80 \fBand (((ip[\fP2:2\fB] - ((ip[\fP0\fB]&\fP0xf\fB)<<\fP2\fB)) - ((tcp[\fP12\fB]&\fP0xf0\fB)>>\fP2\fB)) != \fP0\fB)
1253 To select IPv4 packets longer than 576 bytes sent through gateway `snup':
1256 \fBgateway\fP snup \fBand ip[\fP2:2\fB] >\fP 576
1260 To select IPv4 broadcast or multicast packets that were
1262 sent via Ethernet broadcast or multicast:
1265 \fBether[\fP0\fB] &\fP 1 \fB=\fP 0 \fBand ip[\fP16\fB] >=\fP 224
1269 To select all ICMP packets that are not echo requests/replies (i.e., not
1274 icmp[icmptype] != icmp-echo and icmp[icmptype] != icmp-echoreply
1276 icmp6[icmp6type] != icmp6-echo and icmp6[icmp6type] != icmp6-echoreply
1279 .SH BACKWARD COMPATIBILITY
1282 keyword became available in libpcap 1.2.1.
1293 keywords became available in libpcap 1.5.3.
1295 The ICMPv6 type code names, as well as the
1299 TCP flag names became available in libpcap 1.9.0.
1303 keyword became available in libpcap 1.8.0.
1307 keyword became available in libpcap 1.10.0.
1311 keyword became available in libpcap 1.11.0.
1315 To report a security issue please send an e-mail to \%security@tcpdump.org.
1317 To report bugs and other problems, contribute patches, request a
1318 feature, provide generic feedback etc please see the file
1320 in the libpcap source tree root.
1322 Filter expressions on fields other than those in Token Ring headers will
1323 not correctly handle source-routed Token Ring packets.
1325 Filter expressions on fields other than those in 802.11 headers will not
1326 correctly handle 802.11 data packets with both To DS and From DS set.
1329 should chase header chain, but at this moment it does not.
1330 `\fBip6 protochain\fP'
1331 is supplied for this behavior. For example, to match IPv6 fragments:
1332 `\fBip6 protochain\fP 44'
1334 Arithmetic expression against transport layer headers, like \fBtcp[0]\fP,
1335 does not work against IPv6 packets.
1336 It only looks at IPv4 packets.
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