{ "content": [ { "type": "text", "text": "# pcap-filter (man)\n\n## NAME\n\npcap-filter - packet filter syntax\n\n## DESCRIPTION\n\npcapcompile(3PCAP) is used to compile a string into a filter program. The resulting filter\nprogram can then be applied to some stream of packets to determine which packets will be sup‐\nplied to pcaploop(3PCAP), pcapdispatch(3PCAP), pcapnext(3PCAP), or pcapnextex(3PCAP).\n\n## Sections\n\n- **NAME**\n- **DESCRIPTION** (9 subsections)\n- **EXAMPLES**\n- **BACKWARD COMPATIBILITY**\n- **SEE ALSO**\n- **BUGS**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n" } ], "structuredContent": { "command": "pcap-filter", "section": "", "mode": "man", "summary": "pcap-filter - packet filter syntax", "synopsis": null, "tldr_summary": null, "tldr_examples": [], "tldr_source": null, "flags": [], "examples": [ "To select all packets arriving at or departing from `sundown':", "host sundown", "To select traffic between `helios' and either `hot' or `ace':", "host helios and (hot or ace)", "To select all IPv4 packets between `ace' and any host except `helios':", "ip host ace and not helios", "To select all traffic between local hosts and hosts at Berkeley:", "net ucb-ether", "To select all FTP traffic through Internet gateway `snup':", "gateway snup and (port ftp or ftp-data)", "To select IPv4 traffic neither sourced from nor destined for local hosts (if you gateway to", "one other net, this stuff should never make it onto your local net).", "ip and not net localnet", "To select the start and end packets (the SYN and FIN packets) of each TCP conversation that", "involves a non-local host.", "tcp[tcpflags] & (tcp-syn|tcp-fin) != 0 and not src and dst net localnet", "To select the TCP packets with flags RST and ACK both set. (i.e. select only the RST and ACK", "flags in the flags field, and if the result is \"RST and ACK both set\", match)", "tcp[tcpflags] & (tcp-rst|tcp-ack) == (tcp-rst|tcp-ack)", "To select all IPv4 HTTP packets to and from port 80, i.e. print only packets that contain", "data, not, for example, SYN and FIN packets and ACK-only packets. (IPv6 is left as an exer‐", "cise for the reader.)", "tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)", "To select IPv4 packets longer than 576 bytes sent through gateway `snup':", "gateway snup and ip[2:2] > 576", "To select IPv4 broadcast or multicast packets that were not sent via Ethernet broadcast or", "multicast:", "ether[0] & 1 = 0 and ip[16] >= 224", "To select all ICMP packets that are not echo requests/replies (i.e., not ping packets):", "icmp[icmptype] != icmp-echo and icmp[icmptype] != icmp-echoreply", "icmp6[icmp6type] != icmp6-echo and icmp6[icmp6type] != icmp6-echoreply" ], "see_also": [ { "name": "pcap", "section": "3PCAP", "url": "https://www.chedong.com/phpMan.php/man/pcap/3PCAP/json" } ], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "DESCRIPTION", "lines": 210, "subsections": [ { "name": "ether broadcast", "lines": 2 }, { "name": "ip broadcast", "lines": 9 }, { "name": "ether multicast", "lines": 3 }, { "name": "ip multicast", "lines": 2 }, { "name": "ip6 multicast", "lines": 110 }, { "name": "inbound", "lines": 5 }, { "name": "outbound", "lines": 197 }, { "name": "connectmsg", "lines": 4 }, { "name": "metaconnect", "lines": 86 } ] }, { "name": "EXAMPLES", "lines": 43, "subsections": [] }, { "name": "BACKWARD COMPATIBILITY", "lines": 5, "subsections": [] }, { "name": "SEE ALSO", "lines": 2, "subsections": [] }, { "name": "BUGS", "lines": 18, "subsections": [] } ], "sections": { "NAME": { "content": "pcap-filter - packet filter syntax\n", "subsections": [] }, "DESCRIPTION": { "content": "pcapcompile(3PCAP) is used to compile a string into a filter program. The resulting filter\nprogram can then be applied to some stream of packets to determine which packets will be sup‐\nplied to pcaploop(3PCAP), pcapdispatch(3PCAP), pcapnext(3PCAP), or pcapnextex(3PCAP).\n\nThe filter expression consists of one or more primitives. Primitives usually consist of an\nid (name or number) preceded by one or more qualifiers. There are three different kinds of\nqualifier:\n\ntype type qualifiers say what kind of thing the id name or number refers to. Possible\ntypes are host, net, port and portrange. E.g., `host foo', `net 128.3', `port 20',\n`portrange 6000-6008'. If there is no type qualifier, host is assumed.\n\ndir dir qualifiers specify a particular transfer direction to and/or from id. Possible\ndirections are src, dst, src or dst, src and dst, ra, ta, addr1, addr2, addr3, and\naddr4. E.g., `src foo', `dst net 128.3', `src or dst port ftp-data'. If there is no\ndir qualifier, `src or dst' is assumed. The ra, ta, addr1, addr2, addr3, and addr4\nqualifiers are only valid for IEEE 802.11 Wireless LAN link layers.\n\nproto proto qualifiers restrict the match to a particular protocol. Possible protocols are:\nether, fddi, tr, wlan, ip, ip6, arp, rarp, decnet, sctp, tcp and udp. E.g., `ether\nsrc foo', `arp net 128.3', `tcp port 21', `udp portrange 7000-7009', `wlan addr2\n0:2:3:4:5:6'. If there is no proto qualifier, all protocols consistent with the type\nare assumed. E.g., `src foo' means `(ip or arp or rarp) src foo', `net bar' means\n`(ip or arp or rarp) net bar' and `port 53' means `(tcp or udp or sctp) port 53' (note\nthat these examples use invalid syntax to illustrate the principle).\n\n[fddi is actually an alias for ether; the parser treats them identically as meaning ``the\ndata link level used on the specified network interface''. FDDI headers contain Ethernet-\nlike source and destination addresses, and often contain Ethernet-like packet types, so you\ncan filter on these FDDI fields just as with the analogous Ethernet fields. FDDI headers\nalso contain other fields, but you cannot name them explicitly in a filter expression.\n\nSimilarly, tr and wlan are aliases for ether; the previous paragraph's statements about FDDI\nheaders also apply to Token Ring and 802.11 wireless LAN headers. For 802.11 headers, the\ndestination address is the DA field and the source address is the SA field; the BSSID, RA,\nand TA fields aren't tested.]\n\nIn addition to the above, there are some special `primitive' keywords that don't follow the\npattern: gateway, broadcast, less, greater and arithmetic expressions. All of these are de‐\nscribed below.\n\nMore complex filter expressions are built up by using the words and, or and not (or equiva‐\nlently: `&&', `||' and `!' respectively) to combine primitives. E.g., `host foo and not port\nftp and not port ftp-data'. To save typing, identical qualifier lists can be omitted. E.g.,\n`tcp dst port ftp or ftp-data or domain' is exactly the same as `tcp dst port ftp or tcp dst\nport ftp-data or tcp dst port domain'.\n\nAllowable primitives are:\n\ndst host hostnameaddr\nTrue if the IPv4/v6 destination field of the packet is hostnameaddr, which may be ei‐\nther an address or a name.\n\nsrc host hostnameaddr\nTrue if the IPv4/v6 source field of the packet is hostnameaddr.\n\nhost hostnameaddr\nTrue if either the IPv4/v6 source or destination of the packet is hostnameaddr.\n\nAny of the above host expressions can be prepended with the keywords, ip, arp, rarp,\nor ip6 as in:\nip host hostnameaddr\nwhich is equivalent to:\nether proto \\ip and host hostnameaddr\nIf hostnameaddr is a name with multiple IPv4/v6 addresses, each address will be\nchecked for a match.\n\nether dst ethernameaddr\nTrue if the Ethernet destination address is ethernameaddr. ethernameaddr may be ei‐\nther a name from /etc/ethers or a numerical MAC address of the form\n\"xx:xx:xx:xx:xx:xx\", \"xx.xx.xx.xx.xx.xx\", \"xx-xx-xx-xx-xx-xx\", \"xxxx.xxxx.xxxx\",\n\"xxxxxxxxxxxx\", or various mixes of ':', '.', and '-', where each \"x\" is a hex digit\n(0-9, a-f, or A-F).\n\nether src ethernameaddr\nTrue if the Ethernet source address is ethernameaddr.\n\nether host ethernameaddr\nTrue if either the Ethernet source or destination address is ethernameaddr.\n\ngateway host\nTrue if the packet used host as a gateway. I.e., the Ethernet source or destination\naddress was host but neither the IP source nor the IP destination was host. Host must\nbe a name and must be found both by the machine's host-name-to-IP-address resolution\nmechanisms (host name file, DNS, NIS, etc.) and by the machine's host-name-to-Ether‐\nnet-address resolution mechanism (/etc/ethers, etc.). (An equivalent expression is\nether host ethernameaddr and not host hostnameaddr\nwhich can be used with either names or numbers for hostnameaddr / ethernameaddr.)\nThis syntax does not work in IPv6-enabled configuration at this moment.\n\ndst net netnameaddr\nTrue if the IPv4/v6 destination address of the packet has a network number of net‐\nnameaddr. Net may be either a name from the networks database (/etc/networks, etc.)\nor a network number. An IPv4 network number can be written as a dotted quad (e.g.,\n192.168.1.0), dotted triple (e.g., 192.168.1), dotted pair (e.g, 172.16), or single\nnumber (e.g., 10); the netmask is 255.255.255.255 for a dotted quad (which means that\nit's really a host match), 255.255.255.0 for a dotted triple, 255.255.0.0 for a dotted\npair, or 255.0.0.0 for a single number. An IPv6 network number must be written out\nfully; the netmask is ff:ff:ff:ff:ff:ff:ff:ff, so IPv6 \"network\" matches are really\nalways host matches, and a network match requires a netmask length.\n\nsrc net netnameaddr\nTrue if the IPv4/v6 source address of the packet has a network number of netnameaddr.\n\nnet netnameaddr\nTrue if either the IPv4/v6 source or destination address of the packet has a network\nnumber of netnameaddr.\n\nnet netaddr mask netmask\nTrue if the IPv4 address matches netaddr with the specific netmask. May be qualified\nwith src or dst. Note that this syntax is not valid for IPv6 netaddr.\n\nnet netaddr/len\nTrue if the IPv4/v6 address matches netaddr with a netmask len bits wide. May be\nqualified with src or dst.\n\ndst port portnamenum\nTrue if the packet is IPv4/v6 TCP, UDP or SCTP and has a destination port value of\nportnamenum. The portnamenum can be a number or a name used in /etc/services (see\ntcp(4P) and udp(4P)). If a name is used, both the port number and protocol are\nchecked. If a number or ambiguous name is used, only the port number is checked\n(e.g., `dst port 513' will print both tcp/login traffic and udp/who traffic, and `port\ndomain' will print both tcp/domain and udp/domain traffic).\n\nsrc port portnamenum\nTrue if the packet has a source port value of portnamenum.\n\nport portnamenum\nTrue if either the source or destination port of the packet is portnamenum.\n\ndst portrange portnamenum1-portnamenum2\nTrue if the packet is IPv4/v6 TCP, UDP or SCTP and has a destination port value be‐\ntween portnamenum1 and portnamenum2 (both inclusive). portnamenum1 and portnamenum2\nare interpreted in the same fashion as the portnamenum parameter for port.\n\nsrc portrange portnamenum1-portnamenum2\nTrue if the packet has a source port value between portnamenum1 and portnamenum2 (both\ninclusive).\n\nportrange portnamenum1-portnamenum2\nTrue if either the source or destination port of the packet is between portnamenum1\nand portnamenum2 (both inclusive).\n\nAny of the above port or port range expressions can be prepended with the keywords,\ntcp, udp or sctp, as in:\ntcp src port portnamenum\nwhich matches only TCP packets whose source port is portnamenum.\n\nless length\nTrue if the packet has a length less than or equal to length. This is equivalent to:\nlen <= length\n\ngreater length\nTrue if the packet has a length greater than or equal to length. This is equivalent\nto:\nlen >= length\n\nip proto protocol\nTrue if the packet is an IPv4 packet (see ip(4P)) of protocol type protocol. Protocol\ncan be a number or one of the names recognized by getprotobyname(3) (as in e.g.\n`getent(1) protocols'), typically from an entry in /etc/protocols, for example: ah,\nesp, eigrp (only in Linux, FreeBSD, NetBSD, DragonFly BSD, and macOS), icmp, igmp,\nigrp (only in OpenBSD), pim, sctp, tcp, udp or vrrp. Note that most of these example\nidentifiers are also keywords and must be escaped via backslash (\\). Note that this\nprimitive does not chase the protocol header chain.\n\nicmp Abbreviation for:\nip proto 1\n\nip6 proto protocol\nTrue if the packet is an IPv6 packet of protocol type protocol. (See `ip proto' above\nfor the meaning of protocol.) Note that the IPv6 variant of ICMP uses a different\nprotocol number, named ipv6-icmp in AIX, FreeBSD, illumos, Linux, macOS, NetBSD,\nOpenBSD, Solaris and Windows. Note that this primitive does not chase the protocol\nheader chain.\n\nicmp6 Abbreviation for:\nip6 proto 58\n\nproto protocol\nTrue if the packet is an IPv4 or IPv6 packet of protocol type protocol. (See `ip\nproto' above for the meaning of protocol.) Note that this primitive does not chase\nthe protocol header chain.\n\nah, esp, pim, sctp, tcp, udp\nAbbreviations for:\nproto \\protocol\nwhere protocol is one of the above protocols.\n\nip6 protochain protocol\nTrue if the packet is IPv6 packet, and contains protocol header with type protocol in\nits protocol header chain. (See `ip proto' above for the meaning of protocol.) For\nexample,\nip6 protochain 6\nmatches any IPv6 packet with TCP protocol header in the protocol header chain. The\npacket may contain, for example, authentication header, routing header, or hop-by-hop\noption header, between IPv6 header and TCP header. The BPF code emitted by this prim‐\nitive is complex and cannot be optimized by the BPF optimizer code, and is not sup‐\nported by filter engines in the kernel, so this can be somewhat slow, and may cause\nmore packets to be dropped.\n\nip protochain protocol\nEquivalent to ip6 protochain protocol, but this is for IPv4. (See `ip proto' above\nfor the meaning of protocol.)\n\nprotochain protocol\nTrue if the packet is an IPv4 or IPv6 packet of protocol type protocol. (See `ip\nproto' above for the meaning of protocol.) Note that this primitive chases the proto‐\ncol header chain.\n", "subsections": [ { "name": "ether broadcast", "content": "True if the packet is an Ethernet broadcast packet. The ether keyword is optional.\n" }, { "name": "ip broadcast", "content": "True if the packet is an IPv4 broadcast packet. It checks for both the all-zeroes and\nall-ones broadcast conventions, and looks up the subnet mask on the interface on which\nthe capture is being done.\n\nIf the subnet mask of the interface on which the capture is being done is not avail‐\nable, either because the interface on which capture is being done has no netmask or\nbecause the capture is being done on the Linux \"any\" interface, which can capture on\nmore than one interface, this check will not work correctly.\n" }, { "name": "ether multicast", "content": "True if the packet is an Ethernet multicast packet. The ether keyword is optional.\nThis is shorthand for `ether[0] & 1 != 0'.\n" }, { "name": "ip multicast", "content": "True if the packet is an IPv4 multicast packet.\n" }, { "name": "ip6 multicast", "content": "True if the packet is an IPv6 multicast packet.\n\nether proto protocol\nTrue if the packet is of ether type protocol. Protocol can be a number or one of the\nnames aarp, arp, atalk, decnet, ip, ip6, ipx, iso, lat, loopback, mopdl, moprc, net‐\nbeui, rarp, sca or stp. Note these identifiers (except loopback) are also keywords\nand must be escaped via backslash (\\).\n\n[In the case of FDDI (e.g., `fddi proto \\arp'), Token Ring (e.g., `tr proto \\arp'),\nand IEEE 802.11 wireless LANs (e.g., `wlan proto \\arp'), for most of those protocols,\nthe protocol identification comes from the 802.2 Logical Link Control (LLC) header,\nwhich is usually layered on top of the FDDI, Token Ring, or 802.11 header.\n\nWhen filtering for most protocol identifiers on FDDI, Token Ring, or 802.11, the fil‐\nter checks only the protocol ID field of an LLC header in so-called SNAP format with\nan Organizational Unit Identifier (OUI) of 0x000000, for encapsulated Ethernet; it\ndoesn't check whether the packet is in SNAP format with an OUI of 0x000000. The ex‐\nceptions are:\n\niso the filter checks the DSAP (Destination Service Access Point) and SSAP (Source\nService Access Point) fields of the LLC header;\n\nstp and netbeui\nthe filter checks the DSAP of the LLC header;\n\natalk the filter checks for a SNAP-format packet with an OUI of 0x080007 and the Ap‐\npleTalk etype.\n\nIn the case of Ethernet, the filter checks the Ethernet type field for most of those\nprotocols. The exceptions are:\n\niso, stp, and netbeui\nthe filter checks for an 802.3 frame and then checks the LLC header as it does\nfor FDDI, Token Ring, and 802.11;\n\natalk the filter checks both for the AppleTalk etype in an Ethernet frame and for a\nSNAP-format packet as it does for FDDI, Token Ring, and 802.11;\n\naarp the filter checks for the AppleTalk ARP etype in either an Ethernet frame or an\n802.2 SNAP frame with an OUI of 0x000000;\n\nipx the filter checks for the IPX etype in an Ethernet frame, the IPX DSAP in the\nLLC header, the 802.3-with-no-LLC-header encapsulation of IPX, and the IPX\netype in a SNAP frame.\n\nip, ip6, arp, rarp, atalk, aarp, decnet, iso, stp, ipx, netbeui\nAbbreviations for:\nether proto \\protocol\nwhere protocol is one of the above protocols.\n\nlat, moprc, mopdl\nAbbreviations for:\nether proto \\protocol\nwhere protocol is one of the above protocols. Note that not all applications using\npcap(3PCAP) currently know how to parse these protocols.\n\ndecnet src decnetaddr\nTrue if the DECnet source address is decnetaddr, which may be an address of the form\n``10.123'', or a DECnet host name. [DECnet host name support is only available on UL‐\nTRIX systems that are configured to run DECnet.]\n\ndecnet dst decnetaddr\nTrue if the DECnet destination address is decnetaddr.\n\ndecnet host decnetaddr\nTrue if either the DECnet source or destination address is decnetaddr.\n\nllc True if the packet has an 802.2 LLC header. This includes:\n\nEthernet packets with a length field rather than a type field that aren't raw NetWare-\nover-802.3 packets;\n\nIEEE 802.11 data packets;\n\nToken Ring packets (no check is done for LLC frames);\n\nFDDI packets (no check is done for LLC frames);\n\nLLC-encapsulated ATM packets, for SunATM on Solaris.\n\nllc type\nTrue if the packet has an 802.2 LLC header and has the specified type. type can be\none of:\n\ni Information (I) PDUs\n\ns Supervisory (S) PDUs\n\nu Unnumbered (U) PDUs\n\nrr Receiver Ready (RR) S PDUs\n\nrnr Receiver Not Ready (RNR) S PDUs\n\nrej Reject (REJ) S PDUs\n\nui Unnumbered Information (UI) U PDUs\n\nua Unnumbered Acknowledgment (UA) U PDUs\n\ndisc Disconnect (DISC) U PDUs\n\nsabme Set Asynchronous Balanced Mode Extended (SABME) U PDUs\n\ntest Test (TEST) U PDUs\n\nxid Exchange Identification (XID) U PDUs\n\nfrmr Frame Reject (FRMR) U PDUs\n" }, { "name": "inbound", "content": "Packet was received by the host performing the capture rather than being sent by that\nhost. This is only supported for certain link-layer types, such as SLIP and the\n``cooked'' Linux capture mode used for the ``any'' device and for some other device\ntypes.\n" }, { "name": "outbound", "content": "Packet was sent by the host performing the capture rather than being received by that\nhost. This is only supported for certain link-layer types, such as SLIP and the\n``cooked'' Linux capture mode used for the ``any'' device and for some other device\ntypes.\n\nifname interface\nTrue if the packet was logged as coming from the specified interface (applies only to\npackets logged by OpenBSD's or FreeBSD's pf(4)).\n\non interface\nSynonymous with the ifname modifier.\n\nrnr num\nTrue if the packet was logged as matching the specified PF rule number (applies only\nto packets logged by OpenBSD's or FreeBSD's pf(4)).\n\nrulenum num\nSynonymous with the rnr modifier.\n\nreason code\nTrue if the packet was logged with the specified PF reason code. The known codes are:\nmatch, bad-offset, fragment, short, normalize, and memory (applies only to packets\nlogged by OpenBSD's or FreeBSD's pf(4)).\n\nrset name\nTrue if the packet was logged as matching the specified PF ruleset name of an anchored\nruleset (applies only to packets logged by OpenBSD's or FreeBSD's pf(4)).\n\nruleset name\nSynonymous with the rset modifier.\n\nsrnr num\nTrue if the packet was logged as matching the specified PF rule number of an anchored\nruleset (applies only to packets logged by OpenBSD's or FreeBSD's pf(4)).\n\nsubrulenum num\nSynonymous with the srnr modifier.\n\naction act\nTrue if PF took the specified action when the packet was logged. Known actions are:\npass and block and, with later versions of pf(4), nat, rdr, binat and scrub (applies\nonly to packets logged by OpenBSD's or FreeBSD's pf(4)).\n\nwlan ra ehost\nTrue if the IEEE 802.11 RA is ehost. The RA field is used in all frames except for\nmanagement frames.\n\nwlan ta ehost\nTrue if the IEEE 802.11 TA is ehost. The TA field is used in all frames except for\nmanagement frames and CTS (Clear To Send) and ACK (Acknowledgment) control frames.\n\nwlan addr1 ehost\nTrue if the first IEEE 802.11 address is ehost.\n\nwlan addr2 ehost\nTrue if the second IEEE 802.11 address, if present, is ehost. The second address\nfield is used in all frames except for CTS (Clear To Send) and ACK (Acknowledgment)\ncontrol frames.\n\nwlan addr3 ehost\nTrue if the third IEEE 802.11 address, if present, is ehost. The third address field\nis used in management and data frames, but not in control frames.\n\nwlan addr4 ehost\nTrue if the fourth IEEE 802.11 address, if present, is ehost. The fourth address\nfield is only used for WDS (Wireless Distribution System) frames.\n\ntype wlantype\nTrue if the IEEE 802.11 frame type matches the specified wlantype. Valid wlantypes\nare: mgt, ctl and data.\n\ntype wlantype subtype wlansubtype\nTrue if the IEEE 802.11 frame type matches the specified wlantype and frame subtype\nmatches the specified wlansubtype.\n\nIf the specified wlantype is mgt, then valid wlansubtypes are: assoc-req, assoc-\nresp, reassoc-req, reassoc-resp, probe-req, probe-resp, beacon, atim, disassoc, auth\nand deauth.\n\nIf the specified wlantype is ctl, then valid wlansubtypes are: ps-poll, rts, cts,\nack, cf-end and cf-end-ack.\n\nIf the specified wlantype is data, then valid wlansubtypes are: data, data-cf-ack,\ndata-cf-poll, data-cf-ack-poll, null, cf-ack, cf-poll, cf-ack-poll, qos-data,\nqos-data-cf-ack, qos-data-cf-poll, qos-data-cf-ack-poll, qos, qos-cf-poll and\nqos-cf-ack-poll.\n\nsubtype wlansubtype\nTrue if the IEEE 802.11 frame subtype matches the specified wlansubtype and frame has\nthe type to which the specified wlansubtype belongs.\n\ndir direction\nTrue if the IEEE 802.11 frame direction matches the specified direction. Valid direc‐\ntions are: nods, tods, fromds, dstods, or a numeric value.\n\nvlan [vlanid]\nTrue if the packet is an IEEE 802.1Q VLAN packet. If the optional vlanid is speci‐\nfied, only true if the packet has the specified vlanid. Note that the first vlan\nkeyword encountered in an expression changes the decoding offsets for the remainder of\nthe expression on the assumption that the packet is a VLAN packet. The `vlan\n[vlanid]` keyword may be used more than once, to filter on VLAN hierarchies. Each\nuse of that keyword increments the filter offsets by 4.\n\nFor example:\nvlan 100 && vlan 200\nfilters on VLAN 200 encapsulated within VLAN 100, and\nvlan && vlan 300 && ip\nfilters IPv4 protocol encapsulated in VLAN 300 encapsulated within any higher order\nVLAN.\n\nmpls [labelnum]\nTrue if the packet is an MPLS packet. If the optional labelnum is specified, only\ntrue if the packet has the specified labelnum. Note that the first mpls keyword en‐\ncountered in an expression changes the decoding offsets for the remainder of the ex‐\npression on the assumption that the packet is a MPLS-encapsulated IP packet. The\n`mpls [labelnum]` keyword may be used more than once, to filter on MPLS hierarchies.\nEach use of that keyword increments the filter offsets by 4.\n\nFor example:\nmpls 100000 && mpls 1024\nfilters packets with an outer label of 100000 and an inner label of 1024, and\nmpls && mpls 1024 && host 192.9.200.1\nfilters packets to or from 192.9.200.1 with an inner label of 1024 and any outer la‐\nbel.\n\npppoed True if the packet is a PPP-over-Ethernet Discovery packet (Ethernet type 0x8863).\n\npppoes [sessionid]\nTrue if the packet is a PPP-over-Ethernet Session packet (Ethernet type 0x8864). If\nthe optional sessionid is specified, only true if the packet has the specified ses‐\nsionid. Note that the first pppoes keyword encountered in an expression changes the\ndecoding offsets for the remainder of the expression on the assumption that the packet\nis a PPPoE session packet.\n\nFor example:\npppoes 0x27 && ip\nfilters IPv4 protocol encapsulated in PPPoE session id 0x27.\n\ngeneve [vni]\nTrue if the packet is a Geneve packet (UDP port 6081). If the optional vni is speci‐\nfied, only true if the packet has the specified vni. Note that when the geneve key‐\nword is encountered in an expression, it changes the decoding offsets for the remain‐\nder of the expression on the assumption that the packet is a Geneve packet.\n\nFor example:\ngeneve 0xb && ip\nfilters IPv4 protocol encapsulated in Geneve with VNI 0xb. This will match both IPv4\ndirectly encapsulated in Geneve as well as IPv4 contained inside an Ethernet frame.\n\niso proto protocol\nTrue if the packet is an OSI packet of protocol type protocol. Protocol can be a num‐\nber or one of the names clnp, esis, or isis.\n\nclnp, esis, isis\nAbbreviations for:\niso proto \\protocol\nwhere protocol is one of the above protocols.\n\nl1, l2, iih, lsp, snp, csnp, psnp\nAbbreviations for IS-IS PDU types.\n\nvpi n True if the packet is an ATM packet, for SunATM on Solaris, with a virtual path iden‐\ntifier of n.\n\nvci n True if the packet is an ATM packet, for SunATM on Solaris, with a virtual channel\nidentifier of n.\n\nlane True if the packet is an ATM packet, for SunATM on Solaris, and is an ATM LANE packet.\nNote that the first lane keyword encountered in an expression changes the tests done\nin the remainder of the expression on the assumption that the packet is either a LANE\nemulated Ethernet packet or a LANE LE Control packet. If lane isn't specified, the\ntests are done under the assumption that the packet is an LLC-encapsulated packet.\n\noamf4s True if the packet is an ATM packet, for SunATM on Solaris, and is a segment OAM F4\nflow cell (VPI=0 & VCI=3).\n\noamf4e True if the packet is an ATM packet, for SunATM on Solaris, and is an end-to-end OAM\nF4 flow cell (VPI=0 & VCI=4).\n\noamf4 True if the packet is an ATM packet, for SunATM on Solaris, and is a segment or end-\nto-end OAM F4 flow cell (VPI=0 & (VCI=3 | VCI=4)).\n\noam True if the packet is an ATM packet, for SunATM on Solaris, and is a segment or end-\nto-end OAM F4 flow cell (VPI=0 & (VCI=3 | VCI=4)).\n\nmetac True if the packet is an ATM packet, for SunATM on Solaris, and is on a meta signaling\ncircuit (VPI=0 & VCI=1).\n\nbcc True if the packet is an ATM packet, for SunATM on Solaris, and is on a broadcast sig‐\nnaling circuit (VPI=0 & VCI=2).\n\nsc True if the packet is an ATM packet, for SunATM on Solaris, and is on a signaling cir‐\ncuit (VPI=0 & VCI=5).\n\nilmic True if the packet is an ATM packet, for SunATM on Solaris, and is on an ILMI circuit\n(VPI=0 & VCI=16).\n" }, { "name": "connectmsg", "content": "True if the packet is an ATM packet, for SunATM on Solaris, and is on a signaling cir‐\ncuit and is a Q.2931 Setup, Call Proceeding, Connect, Connect Ack, Release, or Release\nDone message.\n" }, { "name": "metaconnect", "content": "True if the packet is an ATM packet, for SunATM on Solaris, and is on a meta signaling\ncircuit and is a Q.2931 Setup, Call Proceeding, Connect, Release, or Release Done mes‐\nsage.\n\nexpr1 relop expr2\nTrue if the relation holds. Relop is one of {>, <, >=, <=, =, ==, !=} (where = means\nthe same as ==). Each of expr1 and expr2 is an arithmetic expression composed of in‐\nteger constants (expressed in standard C syntax), the normal binary operators {+, -,\n*, /, %, &, |, ^, <<, >>}, a length operator, and special packet data accessors. Note\nthat all comparisons are unsigned, so that, for example, 0x80000000 and 0xffffffff are\n> 0.\n\nThe % and ^ operators are currently only supported for filtering in the kernel on par‐\nticular operating systems (for example: FreeBSD, Linux with 3.7 and later kernels,\nNetBSD); on all other systems (for example: AIX, illumos, Solaris, OpenBSD), if those\noperators are used, filtering will be done in user mode, which will increase the over‐\nhead of capturing packets and may cause more packets to be dropped.\n\nThe length operator, indicated by the keyword len, gives the length of the packet.\n\nTo access data inside the packet, use the following syntax:\nproto [ expr : size ]\nProto is one of arp, atalk, carp, decnet, ether, fddi, icmp, icmp6, igmp, igrp, ip,\nip6, lat, link, mopdl, moprc, pim, ppp, radio, rarp, sca, sctp, slip, tcp, tr, udp,\nvrrp or wlan, and indicates the protocol layer for the index operation. (ether, fddi,\nlink, ppp, slip, tr and wlan all refer to the link layer. radio refers to the \"radio\nheader\" added to some 802.11 captures.) Note that tcp, udp and other upper-layer pro‐\ntocol types only apply to IPv4, not IPv6 (this will be fixed in the future). The byte\noffset, relative to the indicated protocol layer, is given by expr. Size is optional\nand indicates the number of bytes in the field of interest; it can be either one, two,\nor four, and defaults to one.\n\nFor example, `ether[0] & 1 != 0' catches all multicast traffic. The expression `ip[0]\n& 0xf != 5' catches all IPv4 packets with options. The expression `ip[6:2] & 0x1fff =\n0' catches only unfragmented IPv4 datagrams and frag zero of fragmented IPv4 data‐\ngrams. This check is implicitly applied to the tcp and udp index operations. For in‐\nstance, tcp[0] always means the first byte of the TCP header, and never means the\nfirst byte of an intervening fragment.\n\nSome offsets and field values may be expressed as names rather than as numeric values.\nThe following protocol header field offsets are available: icmptype (ICMP type field),\nicmp6type (ICMPv6 type field), icmpcode (ICMP code field), icmp6code (ICMPv6 code\nfield) and tcpflags (TCP flags field).\n\nThe following ICMP type field values are available: icmp-echoreply, icmp-unreach,\nicmp-sourcequench, icmp-redirect, icmp-echo, icmp-routeradvert, icmp-routersolicit,\nicmp-timxceed, icmp-paramprob, icmp-tstamp, icmp-tstampreply, icmp-ireq,\nicmp-ireqreply, icmp-maskreq, icmp-maskreply.\n\nThe following ICMPv6 type field values are available: icmp6-destinationunreach,\nicmp6-packettoobig, icmp6-timeexceeded, icmp6-parameterproblem, icmp6-echo,\nicmp6-echoreply, icmp6-multicastlistenerquery, icmp6-multicastlistenerreportv1,\nicmp6-multicastlistenerdone, icmp6-routersolicit, icmp6-routeradvert,\nicmp6-neighborsolicit, icmp6-neighboradvert, icmp6-redirect, icmp6-routerrenum,\nicmp6-nodeinformationquery, icmp6-nodeinformationresponse,\nicmp6-ineighbordiscoverysolicit, icmp6-ineighbordiscoveryadvert,\nicmp6-multicastlistenerreportv2, icmp6-homeagentdiscoveryrequest,\nicmp6-homeagentdiscoveryreply, icmp6-mobileprefixsolicit, icmp6-mobileprefixadvert,\nicmp6-certpathsolicit, icmp6-certpathadvert, icmp6-multicastrouteradvert,\nicmp6-multicastroutersolicit, icmp6-multicastrouterterm.\n\nThe following TCP flags field values are available: tcp-fin, tcp-syn, tcp-rst, tcp-\npush, tcp-ack, tcp-urg, tcp-ece, tcp-cwr.\n\nPrimitives may be combined using:\n\nA parenthesized group of primitives and operators.\n\nNegation (`!' or `not').\n\nConcatenation (`&&' or `and').\n\nAlternation (`||' or `or').\n\nNegation has the highest precedence. Alternation and concatenation have equal precedence and\nassociate left to right. Note that explicit and tokens, not juxtaposition, are now required\nfor concatenation.\n\nIf an identifier is given without a keyword, the most recent keyword is assumed. For exam‐\nple,\nnot host vs and ace\nis short for\nnot host vs and host ace\nwhich should not be confused with\nnot (host vs or ace)\n" } ] }, "EXAMPLES": { "content": "To select all packets arriving at or departing from `sundown':\nhost sundown\n\nTo select traffic between `helios' and either `hot' or `ace':\nhost helios and (hot or ace)\n\nTo select all IPv4 packets between `ace' and any host except `helios':\nip host ace and not helios\n\nTo select all traffic between local hosts and hosts at Berkeley:\nnet ucb-ether\n\nTo select all FTP traffic through Internet gateway `snup':\ngateway snup and (port ftp or ftp-data)\n\nTo select IPv4 traffic neither sourced from nor destined for local hosts (if you gateway to\none other net, this stuff should never make it onto your local net).\nip and not net localnet\n\nTo select the start and end packets (the SYN and FIN packets) of each TCP conversation that\ninvolves a non-local host.\ntcp[tcpflags] & (tcp-syn|tcp-fin) != 0 and not src and dst net localnet\n\nTo select the TCP packets with flags RST and ACK both set. (i.e. select only the RST and ACK\nflags in the flags field, and if the result is \"RST and ACK both set\", match)\ntcp[tcpflags] & (tcp-rst|tcp-ack) == (tcp-rst|tcp-ack)\n\nTo select all IPv4 HTTP packets to and from port 80, i.e. print only packets that contain\ndata, not, for example, SYN and FIN packets and ACK-only packets. (IPv6 is left as an exer‐\ncise for the reader.)\ntcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)\n\nTo select IPv4 packets longer than 576 bytes sent through gateway `snup':\ngateway snup and ip[2:2] > 576\n\nTo select IPv4 broadcast or multicast packets that were not sent via Ethernet broadcast or\nmulticast:\nether[0] & 1 = 0 and ip[16] >= 224\n\nTo select all ICMP packets that are not echo requests/replies (i.e., not ping packets):\nicmp[icmptype] != icmp-echo and icmp[icmptype] != icmp-echoreply\nicmp6[icmp6type] != icmp6-echo and icmp6[icmp6type] != icmp6-echoreply\n", "subsections": [] }, "BACKWARD COMPATIBILITY": { "content": "The ICMPv6 type code names, as well as the tcp-ece and tcp-cwr TCP flag names became avail‐\nable in libpcap 1.9.0.\n\nThe geneve keyword became available in libpcap 1.8.0.\n", "subsections": [] }, "SEE ALSO": { "content": "pcap(3PCAP)\n", "subsections": [] }, "BUGS": { "content": "To report a security issue please send an e-mail to security@tcpdump.org.\n\nTo report bugs and other problems, contribute patches, request a feature, provide generic\nfeedback etc please see the file CONTRIBUTING.md in the libpcap source tree root.\n\nFilter expressions on fields other than those in Token Ring headers will not correctly handle\nsource-routed Token Ring packets.\n\nFilter expressions on fields other than those in 802.11 headers will not correctly handle\n802.11 data packets with both To DS and From DS set.\n\n`ip6 proto' should chase header chain, but at this moment it does not. `ip6 protochain' is\nsupplied for this behavior. For example, to match IPv6 fragments: `ip6 protochain 44'\n\nArithmetic expression against transport layer headers, like tcp[0], does not work against\nIPv6 packets. It only looks at IPv4 packets.\n\n19 November 2022 PCAP-FILTER(7)", "subsections": [] } } } }