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21 .TH PCAP-FILTER @MAN_MISC_INFO@ "19 November 2022"
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(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", "xxxxxxxxxxxx", or various mixes of ':', '.', and '-',
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 ff:ff:ff:ff:ff:ff:ff:ff, 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)
295 (as in e.g. `\fBgetent\fR(1) protocols'), typically from an entry in
296 .IR \%/etc/protocols ,
301 (only in Linux, FreeBSD, NetBSD, DragonFly BSD, and macOS),
312 Note that most of these example identifiers
313 are also keywords and must be escaped via backslash (\\).
314 Note that this primitive does not chase the protocol header chain.
322 .IP "\fBip6 proto \fIprotocol\fR"
323 True if the packet is an IPv6 packet of protocol type \fIprotocol\fP.
324 (See `\fBip proto\fP' above for the meaning of \fIprotocol\fR.)
325 Note that the IPv6 variant of ICMP uses a different protocol number, named
327 in AIX, FreeBSD, illumos, Linux, macOS, NetBSD, OpenBSD, Solaris and Windows.
328 Note that this primitive does not chase the protocol header chain.
336 .IP "\fBproto \fIprotocol\fR"
337 True if the packet is an IPv4 or IPv6 packet of protocol type
338 \fIprotocol\fP. (See `\fBip proto\fP' above for the meaning of
339 \fIprotocol\fP.) Note that this primitive does not chase the protocol
341 .IP "\fBah\fR, \fBesp\fR, \fBpim\fR, \fBsctp\fR, \fBtcp\fR, \fBudp\fR"
345 \fBproto \\\fIprotocol\fR
348 where \fIprotocol\fR is one of the above protocols.
349 .IP "\fBip6 protochain \fIprotocol\fR"
350 True if the packet is IPv6 packet,
351 and contains protocol header with type \fIprotocol\fR
352 in its protocol header chain.
353 (See `\fBip proto\fP' above for the meaning of \fIprotocol\fP.)
357 \fBip6 protochain\fR 6
360 matches any IPv6 packet with TCP protocol header in the protocol header chain.
361 The packet may contain, for example,
362 authentication header, routing header, or hop-by-hop option header,
363 between IPv6 header and TCP header.
364 The BPF code emitted by this primitive is complex and
365 cannot be optimized by the BPF optimizer code, and is not supported by
366 filter engines in the kernel, so this can be somewhat slow, and may
367 cause more packets to be dropped.
368 .IP "\fBip protochain \fIprotocol\fR"
369 Equivalent to \fBip6 protochain \fIprotocol\fR, but this is for IPv4.
370 (See `\fBip proto\fP' above for the meaning of \fIprotocol\fP.)
371 .IP "\fBprotochain \fIprotocol\fR"
372 True if the packet is an IPv4 or IPv6 packet of protocol type
373 \fIprotocol\fP. (See `\fBip proto\fP' above for the meaning of
374 \fIprotocol\fP.) Note that this primitive chases the protocol
376 .IP "\fBether broadcast\fR"
377 True if the packet is an Ethernet broadcast packet.
380 .IP "\fBip broadcast\fR"
381 True if the packet is an IPv4 broadcast packet.
382 It checks for both the all-zeroes and all-ones broadcast conventions,
383 and looks up the subnet mask on the interface on which the capture is
386 If the subnet mask of the interface on which the capture is being done
387 is not available, either because the interface on which capture is being
388 done has no netmask or because the capture is being done on the Linux
389 "any" interface, which can capture on more than one interface, this
390 check will not work correctly.
391 .IP "\fBether multicast\fR"
392 True if the packet is an Ethernet multicast packet.
395 This is shorthand for `\fBether[\fP0\fB] & \fP1\fB != \fP0'.
396 .IP "\fBip multicast\fR"
397 True if the packet is an IPv4 multicast packet.
398 .IP "\fBip6 multicast\fR"
399 True if the packet is an IPv6 multicast packet.
400 .IP "\fBether proto \fIprotocol\fR"
401 True if the packet is of ether type \fIprotocol\fR.
402 \fIProtocol\fP can be a number or one of the names
403 \fBaarp\fP, \fBarp\fP, \fBatalk\fP, \fBdecnet\fP, \fBip\fP, \fBip6\fP,
404 \fBipx\fP, \fBiso\fP, \fBlat\fP, \fBloopback\fP, \fBmopdl\fP, \fBmoprc\fP, \fBnetbeui\fP,
405 \fBrarp\fP, \fBsca\fP or \fBstp\fP.
406 Note these identifiers (except \fBloopback\fP) are also keywords
407 and must be escaped via backslash (\\).
409 [In the case of FDDI (e.g., `\fBfddi proto \\arp\fR'), Token Ring
410 (e.g., `\fBtr proto \\arp\fR'), and IEEE 802.11 wireless LANs (e.g.,
411 `\fBwlan proto \\arp\fR'), for most of those protocols, the
412 protocol identification comes from the 802.2 Logical Link Control (LLC)
413 header, which is usually layered on top of the FDDI, Token Ring, or
416 When filtering for most protocol identifiers on FDDI, Token Ring, or
417 802.11, the filter checks only the protocol ID field of an LLC header
418 in so-called SNAP format with an Organizational Unit Identifier (OUI) of
419 0x000000, for encapsulated Ethernet; it doesn't check whether the packet
420 is in SNAP format with an OUI of 0x000000.
425 the filter checks the DSAP (Destination Service Access Point) and
426 SSAP (Source Service Access Point) fields of the LLC header;
428 \fBstp\fP and \fBnetbeui\fP
429 the filter checks the DSAP of the LLC header;
432 the filter checks for a SNAP-format packet with an OUI of 0x080007
433 and the AppleTalk etype.
436 In the case of Ethernet, the filter checks the Ethernet type field
437 for most of those protocols. The exceptions are:
440 \fBiso\fP, \fBstp\fP, and \fBnetbeui\fP
441 the filter checks for an 802.3 frame and then checks the LLC header as
442 it does for FDDI, Token Ring, and 802.11;
445 the filter checks both for the AppleTalk etype in an Ethernet frame and
446 for a SNAP-format packet as it does for FDDI, Token Ring, and 802.11;
449 the filter checks for the AppleTalk ARP etype in either an Ethernet
450 frame or an 802.2 SNAP frame with an OUI of 0x000000;
453 the filter checks for the IPX etype in an Ethernet frame, the IPX
454 DSAP in the LLC header, the 802.3-with-no-LLC-header encapsulation of
455 IPX, and the IPX etype in a SNAP frame.
457 .IP "\fBip\fR, \fBip6\fR, \fBarp\fR, \fBrarp\fR, \fBatalk\fR, \fBaarp\fR, \fBdecnet\fR, \fBiso\fR, \fBstp\fR, \fBipx\fR, \fBnetbeui\fP"
461 \fBether proto \\\fIprotocol\fR
464 where \fIprotocol\fR is one of the above protocols.
465 .IP "\fBlat\fR, \fBmoprc\fR, \fBmopdl\fR"
469 \fBether proto \\\fIprotocol\fR
472 where \fIprotocol\fR is one of the above protocols.
473 Note that not all applications using
475 currently know how to parse these protocols.
476 .IP "\fBdecnet src \fIdecnetaddr\fR"
477 True if the DECnet source address is
479 which may be an address of the form ``10.123'', or a DECnet host
481 [DECnet host name support is only available on ULTRIX systems
482 that are configured to run DECnet.]
483 .IP "\fBdecnet dst \fIdecnetaddr\fR"
484 True if the DECnet destination address is
486 .IP "\fBdecnet host \fIdecnetaddr\fR"
487 True if either the DECnet source or destination address is
490 True if the packet has an 802.2 LLC header. This includes:
492 Ethernet packets with a length field rather than a type field that
493 aren't raw NetWare-over-802.3 packets;
495 IEEE 802.11 data packets;
497 Token Ring packets (no check is done for LLC frames);
499 FDDI packets (no check is done for LLC frames);
501 LLC-encapsulated ATM packets, for SunATM on Solaris.
502 .IP "\fBllc\fP \fItype\fR"
503 True if the packet has an 802.2 LLC header and has the specified
519 Receiver Ready (RR) S PDUs
522 Receiver Not Ready (RNR) S PDUs
528 Unnumbered Information (UI) U PDUs
531 Unnumbered Acknowledgment (UA) U PDUs
534 Disconnect (DISC) U PDUs
537 Set Asynchronous Balanced Mode Extended (SABME) U PDUs
543 Exchange Identification (XID) U PDUs
546 Frame Reject (FRMR) U PDUs
549 Packet was received by the host performing the capture rather than being
550 sent by that host. This is only supported for certain link-layer types,
551 such as SLIP and the ``cooked'' Linux capture mode
552 used for the ``any'' device and for some other device types.
554 Packet was sent by the host performing the capture rather than being
555 received by that host. This is only supported for certain link-layer types,
556 such as SLIP and the ``cooked'' Linux capture mode
557 used for the ``any'' device and for some other device types.
558 .IP "\fBifname \fIinterface\fR"
559 True if the packet was logged as coming from the specified interface (applies
560 only to packets logged by OpenBSD's or FreeBSD's
562 .IP "\fBon \fIinterface\fR"
566 .IP "\fBrnr \fInum\fR"
567 True if the packet was logged as matching the specified PF rule number
568 (applies only to packets logged by OpenBSD's or FreeBSD's
570 .IP "\fBrulenum \fInum\fR"
574 .IP "\fBreason \fIcode\fR"
575 True if the packet was logged with the specified PF reason code. The known
584 (applies only to packets logged by OpenBSD's or FreeBSD's
586 .IP "\fBrset \fIname\fR"
587 True if the packet was logged as matching the specified PF ruleset
588 name of an anchored ruleset (applies only to packets logged by OpenBSD's
591 .IP "\fBruleset \fIname\fR"
595 .IP "\fBsrnr \fInum\fR"
596 True if the packet was logged as matching the specified PF rule number
597 of an anchored ruleset (applies only to packets logged by OpenBSD's or
600 .IP "\fBsubrulenum \fInum\fR"
604 .IP "\fBaction \fIact\fR"
605 True if PF took the specified action when the packet was logged. Known actions
610 and, with later versions of
617 (applies only to packets logged by OpenBSD's or FreeBSD's
619 .IP "\fBwlan ra \fIehost\fR"
620 True if the IEEE 802.11 RA is
622 The RA field is used in all frames except for management frames.
623 .IP "\fBwlan ta \fIehost\fR"
624 True if the IEEE 802.11 TA is
626 The TA field is used in all frames except for management frames and
627 CTS (Clear To Send) and ACK (Acknowledgment) control frames.
628 .IP "\fBwlan addr1 \fIehost\fR"
629 True if the first IEEE 802.11 address is
631 .IP "\fBwlan addr2 \fIehost\fR"
632 True if the second IEEE 802.11 address, if present, is
634 The second address field is used in all frames except for CTS (Clear To
635 Send) and ACK (Acknowledgment) control frames.
636 .IP "\fBwlan addr3 \fIehost\fR"
637 True if the third IEEE 802.11 address, if present, is
639 The third address field is used in management and data frames, but not
641 .IP "\fBwlan addr4 \fIehost\fR"
642 True if the fourth IEEE 802.11 address, if present, is
644 The fourth address field is only used for
645 WDS (Wireless Distribution System) frames.
646 .IP "\fBtype \fIwlan_type\fR"
647 True if the IEEE 802.11 frame type matches the specified \fIwlan_type\fR.
648 Valid \fIwlan_type\fRs are:
652 .IP "\fBtype \fIwlan_type \fBsubtype \fIwlan_subtype\fR"
653 True if the IEEE 802.11 frame type matches the specified \fIwlan_type\fR
654 and frame subtype matches the specified \fIwlan_subtype\fR.
656 If the specified \fIwlan_type\fR is \fBmgt\fP,
657 then valid \fIwlan_subtype\fRs are:
670 If the specified \fIwlan_type\fR is \fBctl\fP,
671 then valid \fIwlan_subtype\fRs are:
679 If the specified \fIwlan_type\fR is \fBdata\fP,
680 then valid \fIwlan_subtype\fRs are:
684 .BR \%data-cf-ack-poll ,
690 .BR \%qos-data-cf-ack ,
691 .BR \%qos-data-cf-poll ,
692 .BR \%qos-data-cf-ack-poll ,
696 .BR \%qos-cf-ack-poll .
697 .IP "\fBsubtype \fIwlan_subtype\fR"
698 True if the IEEE 802.11 frame subtype matches the specified \fIwlan_subtype\fR
699 and frame has the type to which the specified \fIwlan_subtype\fR belongs.
700 .IP "\fBdir \fIdirection\fR"
701 True if the IEEE 802.11 frame direction matches the specified
703 Valid directions are:
709 .IP "\fBvlan \fI[vlan_id]\fR"
710 True if the packet is an IEEE 802.1Q VLAN packet.
711 If the optional \fIvlan_id\fR is specified, only true if the packet has the specified
713 Note that the first \fBvlan\fR keyword encountered in an expression
714 changes the decoding offsets for the remainder of the expression on
715 the assumption that the packet is a VLAN packet. The `\fBvlan
716 \fI[vlan_id]\fR` keyword may be used more than once, to filter on VLAN
717 hierarchies. Each use of that keyword increments the filter offsets
723 \fBvlan\fP 100 \fB&& vlan\fR 200
726 filters on VLAN 200 encapsulated within VLAN 100, and
729 \fBvlan && vlan \fP300 \fB&& ip\fR
732 filters IPv4 protocol encapsulated in VLAN 300 encapsulated within any
734 .IP "\fBmpls \fI[label_num]\fR"
735 True if the packet is an MPLS packet.
736 If the optional \fIlabel_num\fR is specified, only true if the packet has the specified
738 Note that the first \fBmpls\fR keyword encountered in an expression
739 changes the decoding offsets for the remainder of the expression on
740 the assumption that the packet is a MPLS-encapsulated IP packet. The
741 `\fBmpls \fI[label_num]\fR` keyword may be used more than once, to
742 filter on MPLS hierarchies. Each use of that keyword increments the
748 \fBmpls\fP 100000 \fB&& mpls\fR 1024
751 filters packets with an outer label of 100000 and an inner label of
755 \fBmpls && mpls\fP 1024 \fB&& host\fR 192.9.200.1
758 filters packets to or from 192.9.200.1 with an inner label of 1024 and
761 True if the packet is a PPP-over-Ethernet Discovery packet (Ethernet
763 .IP "\fBpppoes \fI[session_id]\fR"
764 True if the packet is a PPP-over-Ethernet Session packet (Ethernet
766 If the optional \fIsession_id\fR is specified, only true if the packet has the specified
768 Note that the first \fBpppoes\fR keyword encountered in an expression
769 changes the decoding offsets for the remainder of the expression on
770 the assumption that the packet is a PPPoE session packet.
775 \fBpppoes\fP 0x27 \fB&& ip\fR
778 filters IPv4 protocol encapsulated in PPPoE session id 0x27.
779 .IP "\fBgeneve \fI[vni]\fR"
780 True if the packet is a Geneve packet (UDP port 6081). If the optional \fIvni\fR
781 is specified, only true if the packet has the specified \fIvni\fR.
782 Note that when the \fBgeneve\fR keyword is encountered in
783 an expression, it changes the decoding offsets for the remainder of
784 the expression on the assumption that the packet is a Geneve packet.
789 \fBgeneve\fP 0xb \fB&& ip\fR
792 filters IPv4 protocol encapsulated in Geneve with VNI 0xb. This will
793 match both IPv4 directly encapsulated in Geneve as well as IPv4 contained
794 inside an Ethernet frame.
795 .IP "\fBiso proto \fIprotocol\fR"
796 True if the packet is an OSI packet of protocol type \fIprotocol\fP.
797 \fIProtocol\fP can be a number or one of the names
798 \fBclnp\fP, \fBesis\fP, or \fBisis\fP.
799 .IP "\fBclnp\fR, \fBesis\fR, \fBisis\fR"
803 \fBiso proto \\\fIprotocol\fR
806 where \fIprotocol\fR is one of the above protocols.
807 .IP "\fBl1\fR, \fBl2\fR, \fBiih\fR, \fBlsp\fR, \fBsnp\fR, \fBcsnp\fR, \fBpsnp\fR"
808 Abbreviations for IS-IS PDU types.
809 .IP "\fBvpi\fP \fIn\fR"
810 True if the packet is an ATM packet, for SunATM on Solaris, with a
811 virtual path identifier of
813 .IP "\fBvci\fP \fIn\fR"
814 True if the packet is an ATM packet, for SunATM on Solaris, with a
815 virtual channel identifier of
818 True if the packet is an ATM packet, for SunATM on Solaris, and is
820 Note that the first \fBlane\fR keyword encountered in an expression
821 changes the tests done in the remainder of the expression
822 on the assumption that the packet is either a LANE emulated Ethernet
823 packet or a LANE LE Control packet. If \fBlane\fR isn't specified, the
824 tests are done under the assumption that the packet is an
825 LLC-encapsulated packet.
827 True if the packet is an ATM packet, for SunATM on Solaris, and is
828 a segment OAM F4 flow cell (VPI=0 & VCI=3).
830 True if the packet is an ATM packet, for SunATM on Solaris, and is
831 an end-to-end OAM F4 flow cell (VPI=0 & VCI=4).
833 True if the packet is an ATM packet, for SunATM on Solaris, and is
834 a segment or end-to-end OAM F4 flow cell (VPI=0 & (VCI=3 | VCI=4)).
836 True if the packet is an ATM packet, for SunATM on Solaris, and is
837 a segment or end-to-end OAM F4 flow cell (VPI=0 & (VCI=3 | VCI=4)).
839 True if the packet is an ATM packet, for SunATM on Solaris, and is
840 on a meta signaling circuit (VPI=0 & VCI=1).
842 True if the packet is an ATM packet, for SunATM on Solaris, and is
843 on a broadcast signaling circuit (VPI=0 & VCI=2).
845 True if the packet is an ATM packet, for SunATM on Solaris, and is
846 on a signaling circuit (VPI=0 & VCI=5).
848 True if the packet is an ATM packet, for SunATM on Solaris, and is
849 on an ILMI circuit (VPI=0 & VCI=16).
851 True if the packet is an ATM packet, for SunATM on Solaris, and is
852 on a signaling circuit and is a Q.2931 Setup, Call Proceeding, Connect,
853 Connect Ack, Release, or Release Done message.
854 .IP \fBmetaconnect\fP
855 True if the packet is an ATM packet, for SunATM on Solaris, and is
856 on a meta signaling circuit and is a Q.2931 Setup, Call Proceeding, Connect,
857 Release, or Release Done message.
858 .IP "\fIexpr1 relop expr2\fR"
859 True if the relation holds. \fIRelop\fR is one of
871 Each of \fIexpr1\fR and \fIexpr2\fR is an arithmetic expression composed of
872 integer constants (expressed in standard C syntax), the normal binary operators
883 a length operator, and special packet data
884 accessors. Note that all comparisons are unsigned, so that, for example,
885 0x80000000 and 0xffffffff are > 0.
891 operators are currently only supported for filtering in the kernel on
892 particular operating systems (for example: FreeBSD, Linux with 3.7 and later
893 kernels, NetBSD); on all other systems (for example: AIX, illumos, Solaris,
895 those operators are used, filtering will be done in user mode, which
896 will increase the overhead of capturing packets and may cause more
897 packets to be dropped.
899 The length operator, indicated by the keyword \fBlen\fP, gives the
900 length of the packet.
902 To access data inside the packet, use the following syntax:
905 \fIproto\fB [ \fIexpr\fB : \fIsize\fB ]\fR
940 indicates the protocol layer for the index operation.
950 link layer. \fBradio\fR refers to the "radio header" added to some
952 Note that \fBtcp\fR, \fBudp\fR and other upper-layer protocol types only
953 apply to IPv4, not IPv6 (this will be fixed in the future).
954 The byte offset, relative to the indicated protocol layer, is
956 \fISize\fR is optional and indicates the number of bytes in the
957 field of interest; it can be either one, two, or four, and defaults to one.
959 For example, `\fBether[\fP0\fB] &\fP 1 \fB!=\fP 0' catches all multicast traffic.
960 The expression `\fBip[\fP0\fB] &\fP 0xf \fB!=\fP 5'
961 catches all IPv4 packets with options.
963 `\fBip[\fP6:2\fB] &\fP 0x1fff \fB=\fP 0'
964 catches only unfragmented IPv4 datagrams and frag zero of fragmented
966 This check is implicitly applied to the \fBtcp\fP and \fBudp\fP
968 For instance, \fBtcp[\fP0\fB]\fP always means the first
969 byte of the TCP \fIheader\fP, and never means the first byte of an
970 intervening fragment.
972 Some offsets and field values may be expressed as names rather than
974 The following protocol header field offsets are
975 available: \fBicmptype\fP (ICMP type field), \fBicmp6type\fP (ICMPv6 type field),
976 \fBicmpcode\fP (ICMP code field), \fBicmp6code\fP (ICMPv6 code field) and
977 \fBtcpflags\fP (TCP flags field).
979 The following ICMP type field values are available:
980 .BR \%icmp-echoreply ,
982 .BR \%icmp-sourcequench ,
983 .BR \%icmp-redirect ,
985 .BR \%icmp-routeradvert ,
986 .BR \%icmp-routersolicit ,
987 .BR \%icmp-timxceed ,
988 .BR \%icmp-paramprob ,
990 .BR \%icmp-tstampreply ,
992 .BR \%icmp-ireqreply ,
994 .BR \%icmp-maskreply .
996 The following ICMPv6 type field values are available:
997 .BR \%icmp6-destinationunreach ,
998 .BR \%icmp6-packettoobig ,
999 .BR \%icmp6-timeexceeded ,
1000 .BR \%icmp6-parameterproblem ,
1002 .BR \%icmp6-echoreply ,
1003 .BR \%icmp6-multicastlistenerquery ,
1004 .BR \%icmp6-multicastlistenerreportv1 ,
1005 .BR \%icmp6-multicastlistenerdone ,
1006 .BR \%icmp6-routersolicit ,
1007 .BR \%icmp6-routeradvert ,
1008 .BR \%icmp6-neighborsolicit ,
1009 .BR \%icmp6-neighboradvert ,
1010 .BR \%icmp6-redirect ,
1011 .BR \%icmp6-routerrenum ,
1012 .BR \%icmp6-nodeinformationquery ,
1013 .BR \%icmp6-nodeinformationresponse ,
1014 .BR \%icmp6-ineighbordiscoverysolicit ,
1015 .BR \%icmp6-ineighbordiscoveryadvert ,
1016 .BR \%icmp6-multicastlistenerreportv2 ,
1017 .BR \%icmp6-homeagentdiscoveryrequest ,
1018 .BR \%icmp6-homeagentdiscoveryreply ,
1019 .BR \%icmp6-mobileprefixsolicit ,
1020 .BR \%icmp6-mobileprefixadvert ,
1021 .BR \%icmp6-certpathsolicit ,
1022 .BR \%icmp6-certpathadvert ,
1023 .BR \%icmp6-multicastrouteradvert ,
1024 .BR \%icmp6-multicastroutersolicit ,
1025 .BR \%icmp6-multicastrouterterm .
1027 The following TCP flags field values are available: \fBtcp-fin\fP,
1028 \fBtcp-syn\fP, \fBtcp-rst\fP, \fBtcp-push\fP,
1029 \fBtcp-ack\fP, \fBtcp-urg\fP, \fBtcp-ece\fP,
1032 Primitives may be combined using:
1034 A parenthesized group of primitives and operators.
1036 Negation (`\fB!\fP' or `\fBnot\fP').
1038 Concatenation (`\fB&&\fP' or `\fBand\fP').
1040 Alternation (`\fB||\fP' or `\fBor\fP').
1042 Negation has the highest precedence.
1043 Alternation and concatenation have equal precedence and associate
1045 Note that explicit \fBand\fR tokens, not juxtaposition,
1046 are now required for concatenation.
1048 If an identifier is given without a keyword, the most recent keyword
1053 \fBnot host\fP vs \fBand\fR ace
1059 \fBnot host\fP vs \fBand host\fR ace
1062 which should not be confused with
1065 \fBnot (host \fPvs\fB or \fPace\fB)\fR
1070 To select all packets arriving at or departing from `sundown':
1077 To select traffic between `helios' and either `hot' or `ace':
1080 \fBhost\fP helios \fBand (\fPhot \fBor\fP ace\fB)\fP
1084 To select all IPv4 packets between `ace' and any host except `helios':
1087 \fBip host\fP ace \fBand not\fP helios
1091 To select all traffic between local hosts and hosts at Berkeley:
1098 To select all FTP traffic through Internet gateway `snup':
1101 \fBgateway\fP snup \fBand (port\fP ftp \fBor\fP ftp-data\fB)\fP
1105 To select IPv4 traffic neither sourced from nor destined for local hosts
1106 (if you gateway to one other net, this stuff should never make it
1107 onto your local net).
1110 \fBip and not net \fPlocalnet
1114 To select the start and end packets (the SYN and FIN packets) of each
1115 TCP conversation that involves a non-local host.
1118 \fBtcp[tcpflags] & (tcp-syn|tcp-fin) !=\fP 0 \fBand not src and dst net\fP localnet
1122 To select the TCP packets with flags RST and ACK both set.
1123 (i.e. select only the RST and ACK flags in the flags field, and if the result
1124 is "RST and ACK both set", match)
1128 tcp[tcpflags] & (tcp-rst|tcp-ack) == (tcp-rst|tcp-ack)
1132 To select all IPv4 HTTP packets to and from port 80, i.e. print only
1133 packets that contain data, not, for example, SYN and FIN packets and
1134 ACK-only packets. (IPv6 is left as an exercise for the reader.)
1137 \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)
1141 To select IPv4 packets longer than 576 bytes sent through gateway `snup':
1144 \fBgateway\fP snup \fBand ip[\fP2:2\fB] >\fP 576
1148 To select IPv4 broadcast or multicast packets that were
1150 sent via Ethernet broadcast or multicast:
1153 \fBether[\fP0\fB] &\fP 1 \fB=\fP 0 \fBand ip[\fP16\fB] >=\fP 224
1157 To select all ICMP packets that are not echo requests/replies (i.e., not
1162 icmp[icmptype] != icmp-echo and icmp[icmptype] != icmp-echoreply
1164 icmp6[icmp6type] != icmp6-echo and icmp6[icmp6type] != icmp6-echoreply
1167 .SH BACKWARD COMPATIBILITY
1168 The ICMPv6 type code names, as well as the
1172 TCP flag names became available in libpcap 1.9.0.
1176 keyword became available in libpcap 1.8.0.
1180 To report a security issue please send an e-mail to \%security@tcpdump.org.
1182 To report bugs and other problems, contribute patches, request a
1183 feature, provide generic feedback etc please see the file
1185 in the libpcap source tree root.
1187 Filter expressions on fields other than those in Token Ring headers will
1188 not correctly handle source-routed Token Ring packets.
1190 Filter expressions on fields other than those in 802.11 headers will not
1191 correctly handle 802.11 data packets with both To DS and From DS set.
1194 should chase header chain, but at this moment it does not.
1195 `\fBip6 protochain\fP'
1196 is supplied for this behavior. For example, to match IPv6 fragments:
1197 `\fBip6 protochain\fP 44'
1199 Arithmetic expression against transport layer headers, like \fBtcp[0]\fP,
1200 does not work against IPv6 packets.
1201 It only looks at IPv4 packets.