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.TH PCAP-FILTER @MAN_MISC_INFO@ "5 November 2017"

.SH NAME

pcap-filter \- packet filter syntax

.br

.ad

.SH DESCRIPTION

.LP

.B pcap_compile()

is used to compile a string into a filter program.

The resulting filter program can then be applied to

some stream of packets to determine which packets will be supplied to

.BR pcap_loop(3PCAP) ,

.BR pcap_dispatch(3PCAP) ,

.BR pcap_next(3PCAP) ,

or

.BR pcap_next_ex(3PCAP) .

.LP

The \fIfilter expression\fP consists of one or more

.IR primitives .

Primitives usually consist of an

.I id

(name or number) preceded by one or more qualifiers.

There are three

different kinds of qualifier:

.IP \fItype\fP

.I type

qualifiers say what kind of thing the id name or number refers to.

Possible types are

.BR host ,

.B net ,

.B port

and

.BR portrange .

E.g., `host foo', `net 128.3', `port 20', `portrange 6000-6008'.

If there is no type

qualifier,

.B host

is assumed.

.IP \fIdir\fP

.I dir

qualifiers specify a particular transfer direction to and/or from

.IR id .

Possible directions are

.BR src ,

.BR dst ,

.BR "src or dst" ,

.BR "src and dst" ,

.BR ra ,

.BR ta ,

.BR addr1 ,

.BR addr2 ,

.BR addr3 ,

and

.BR addr4 .

E.g., `src foo', `dst net 128.3', `src or dst port ftp-data'.

If

there is no dir qualifier,

.B "src or dst"

is assumed.

The

.BR ra ,

.BR ta ,

.BR addr1 ,

.BR addr2 ,

.BR addr3 ,

and

.B addr4

qualifiers are only valid for IEEE 802.11 Wireless LAN link layers.

.IP \fIproto\fP

.I proto

qualifiers restrict the match to a particular protocol.

Possible

protos are:

.BR ether ,

.BR fddi ,

.BR tr ,

.BR wlan ,

.BR ip ,

.BR ip6 ,

.BR arp ,

.BR rarp ,

.BR decnet ,

.B tcp

and

.BR udp .

E.g., `ether src foo', `arp net 128.3', `tcp port 21', `udp portrange

7000-7009', `wlan addr2 0:2:3:4:5:6'.

If there is

no proto qualifier, all protocols consistent with the type are

assumed.

E.g., `src foo' means `(ip or arp or rarp) src foo'

(except the latter is not legal syntax), `net bar' means `(ip or

arp or rarp) net bar' and `port 53' means `(tcp or udp) port 53'.

.LP

[`fddi' is actually an alias for `ether'; the parser treats them

identically as meaning ``the data link level used on the specified

network interface.''  FDDI headers contain Ethernet-like source

and destination addresses, and often contain Ethernet-like packet

types, so you can filter on these FDDI fields just as with the

analogous Ethernet fields.

FDDI headers also contain other fields,

but you cannot name them explicitly in a filter expression.

.LP

Similarly, `tr' and `wlan' are aliases for `ether'; the previous

paragraph's statements about FDDI headers also apply to Token Ring

and 802.11 wireless LAN headers.  For 802.11 headers, the destination

address is the DA field and the source address is the SA field; the

BSSID, RA, and TA fields aren't tested.]

.LP

In addition to the above, there are some special `primitive' keywords

that don't follow the pattern:

.BR gateway ,

.BR broadcast ,

.BR less ,

.B greater

and arithmetic expressions.

All of these are described below.

.LP

More complex filter expressions are built up by using the words

.BR and ,

.B or

and

.B not

to combine primitives.

E.g., `host foo and not port ftp and not port ftp-data'.

To save typing, identical qualifier lists can be omitted.

E.g.,

`tcp dst port ftp or ftp-data or domain' is exactly the same as

`tcp dst port ftp or tcp dst port ftp-data or tcp dst port domain'.

.LP

Allowable primitives are:

.IP "\fBdst host \fIhost\fR"

True if the IPv4/v6 destination field of the packet is \fIhost\fP,

which may be either an address or a name.

.IP "\fBsrc host \fIhost\fR"

True if the IPv4/v6 source field of the packet is \fIhost\fP.

.IP "\fBhost \fIhost\fP"

True if either the IPv4/v6 source or destination of the packet is \fIhost\fP.

.IP

Any of the above host expressions can be prepended with the keywords,

\fBip\fP, \fBarp\fP, \fBrarp\fP, or \fBip6\fP as in:

.in +.5i

.nf

\fBip host \fIhost\fR

.fi

.in -.5i

which is equivalent to:

.in +.5i

.nf

\fBether proto \fI\\ip\fB and host \fIhost\fR

.fi

.in -.5i

If \fIhost\fR is a name with multiple IP addresses, each address will

be checked for a match.

.IP "\fBether dst \fIehost\fP"

True if the Ethernet destination address is \fIehost\fP.

\fIEhost\fP

may be either a name from /etc/ethers or a numerical MAC address of the

form "xx:xx:xx:xx:xx:xx", "xx.xx.xx.xx.xx.xx", "xx-xx-xx-xx-xx-xx",

"xxxx.xxxx.xxxx", "xxxxxxxxxxxx", or various mixes of ':', '.', and '-',

where each "x" is a hex digit (0-9, a-f, or A-F).

.IP "\fBether src \fIehost\fP"

True if the Ethernet source address is \fIehost\fP.

.IP "\fBether host \fIehost\fP"

True if either the Ethernet source or destination address is \fIehost\fP.

.IP "\fBgateway\fP \fIhost\fP"

True if the packet used \fIhost\fP as a gateway.

I.e., the Ethernet

source or destination address was \fIhost\fP but neither the IP source

nor the IP destination was \fIhost\fP.

\fIHost\fP must be a name and

must be found both by the machine's host-name-to-IP-address resolution

mechanisms (host name file, DNS, NIS, etc.) and by the machine's

host-name-to-Ethernet-address resolution mechanism (/etc/ethers, etc.).

(An equivalent expression is

.in +.5i

.nf

\fBether host \fIehost \fBand not host \fIhost\fR

.fi

.in -.5i

which can be used with either names or numbers for \fIhost / ehost\fP.)

This syntax does not work in IPv6-enabled configuration at this moment.

.IP "\fBdst net \fInet\fR"

True if the IPv4/v6 destination address of the packet has a network

number of \fInet\fP.

\fINet\fP may be either a name from the networks database

(/etc/networks, etc.) or a network number.

An IPv4 network number can be written as a dotted quad (e.g., 192.168.1.0),

dotted triple (e.g., 192.168.1), dotted pair (e.g, 172.16), or single

number (e.g., 10); the netmask is 255.255.255.255 for a dotted quad

(which means that it's really a host match), 255.255.255.0 for a dotted

triple, 255.255.0.0 for a dotted pair, or 255.0.0.0 for a single number.

An IPv6 network number must be written out fully; the netmask is

ff:ff:ff:ff:ff:ff:ff:ff, so IPv6 "network" matches are really always

host matches, and a network match requires a netmask length.

.IP "\fBsrc net \fInet\fR"

True if the IPv4/v6 source address of the packet has a network

number of \fInet\fP.

.IP "\fBnet \fInet\fR"

True if either the IPv4/v6 source or destination address of the packet has a network

number of \fInet\fP.

.IP "\fBnet \fInet\fR \fBmask \fInetmask\fR"

True if the IPv4 address matches \fInet\fR with the specific \fInetmask\fR.

May be qualified with \fBsrc\fR or \fBdst\fR.

Note that this syntax is not valid for IPv6 \fInet\fR.

.IP "\fBnet \fInet\fR/\fIlen\fR"

True if the IPv4/v6 address matches \fInet\fR with a netmask \fIlen\fR

bits wide.

May be qualified with \fBsrc\fR or \fBdst\fR.

.IP "\fBdst port \fIport\fR"

True if the packet is ip/tcp, ip/udp, ip6/tcp or ip6/udp and has a

destination port value of \fIport\fP.

The \fIport\fP can be a number or a name used in /etc/services (see

.IR tcp (4P)

and

.IR udp (4P)).

If a name is used, both the port

number and protocol are checked.

If a number or ambiguous name is used,

only the port number is checked (e.g., \fBdst port 513\fR will print both

tcp/login traffic and udp/who traffic, and \fBport domain\fR will print

both tcp/domain and udp/domain traffic).

.IP "\fBsrc port \fIport\fR"

True if the packet has a source port value of \fIport\fP.

.IP "\fBport \fIport\fR"

True if either the source or destination port of the packet is \fIport\fP.

.IP "\fBdst portrange \fIport1\fB-\fIport2\fR"

True if the packet is ip/tcp, ip/udp, ip6/tcp or ip6/udp and has a

destination port value between \fIport1\fP and \fIport2\fP.

.I port1

and

.I port2

are interpreted in the same fashion as the

.I port

parameter for

.BR port .

.IP "\fBsrc portrange \fIport1\fB-\fIport2\fR"

True if the packet has a source port value between \fIport1\fP and

\fIport2\fP.

.IP "\fBportrange \fIport1\fB-\fIport2\fR"

True if either the source or destination port of the packet is between

\fIport1\fP and \fIport2\fP.

.IP

Any of the above port or port range expressions can be prepended with

the keywords, \fBtcp\fP or \fBudp\fP, as in:

.in +.5i

.nf

\fBtcp src port \fIport\fR

.fi

.in -.5i

which matches only tcp packets whose source port is \fIport\fP.

.IP "\fBless \fIlength\fR"

True if the packet has a length less than or equal to \fIlength\fP.

This is equivalent to:

.in +.5i

.nf

\fBlen <= \fIlength\fP.

.fi

.in -.5i

.IP "\fBgreater \fIlength\fR"

True if the packet has a length greater than or equal to \fIlength\fP.

This is equivalent to:

.in +.5i

.nf

\fBlen >= \fIlength\fP.

.fi

.in -.5i

.IP "\fBip proto \fIprotocol\fR"

True if the packet is an IPv4 packet (see

.IR ip (4P))

of protocol type \fIprotocol\fP.

\fIProtocol\fP can be a number or one of the names

\fBicmp\fP, \fBicmp6\fP, \fBigmp\fP, \fBigrp\fP, \fBpim\fP, \fBah\fP,

\fBesp\fP, \fBvrrp\fP, \fBudp\fP, or \fBtcp\fP.

Note that the identifiers \fBtcp\fP, \fBudp\fP, and \fBicmp\fP are also

keywords and must be escaped via backslash (\\).

Note that this primitive does not chase the protocol header chain.

.IP "\fBip6 proto \fIprotocol\fR"

True if the packet is an IPv6 packet of protocol type \fIprotocol\fP.

Note that this primitive does not chase the protocol header chain.

.IP "\fBproto \fIprotocol\fR"

True if the packet is an IPv4 or IPv6 packet of protocol type

\fIprotocol\fP.  Note that this primitive does not chase the protocol

header chain.

.IP  "\fBtcp\fR, \fBudp\fR, \fBicmp\fR"

Abbreviations for:

.in +.5i

.nf

\fBproto \fIp\fR\fB

.fi

.in -.5i

where \fIp\fR is one of the above protocols.

.IP "\fBip6 protochain \fIprotocol\fR"

True if the packet is IPv6 packet,

and contains protocol header with type \fIprotocol\fR

in its protocol header chain.

For example,

.in +.5i

.nf

\fBip6 protochain 6\fR

.fi

.in -.5i

matches any IPv6 packet with TCP protocol header in the protocol header chain.

The packet may contain, for example,

authentication header, routing header, or hop-by-hop option header,

between IPv6 header and TCP header.

The BPF code emitted by this primitive is complex and

cannot be optimized by the BPF optimizer code, and is not supported by

filter engines in the kernel, so this can be somewhat slow, and may

cause more packets to be dropped.

.IP "\fBip protochain \fIprotocol\fR"

Equivalent to \fBip6 protochain \fIprotocol\fR, but this is for IPv4.

.IP "\fBprotochain \fIprotocol\fR"

True if the packet is an IPv4 or IPv6 packet of protocol type

\fIprotocol\fP.  Note that this primitive chases the protocol

header chain.

.IP "\fBether broadcast\fR"

True if the packet is an Ethernet broadcast packet.

The \fIether\fP

keyword is optional.

.IP "\fBip broadcast\fR"

True if the packet is an IPv4 broadcast packet.

It checks for both the all-zeroes and all-ones broadcast conventions,

and looks up the subnet mask on the interface on which the capture is

being done.

.IP

If the subnet mask of the interface on which the capture is being done

is not available, either because the interface on which capture is being

done has no netmask or because the capture is being done on the Linux

"any" interface, which can capture on more than one interface, this

check will not work correctly.

.IP "\fBether multicast\fR"

True if the packet is an Ethernet multicast packet.

The \fBether\fP

keyword is optional.

This is shorthand for `\fBether[0] & 1 != 0\fP'.

.IP "\fBip multicast\fR"

True if the packet is an IPv4 multicast packet.

.IP "\fBip6 multicast\fR"

True if the packet is an IPv6 multicast packet.

.IP  "\fBether proto \fIprotocol\fR"

True if the packet is of ether type \fIprotocol\fR.

\fIProtocol\fP can be a number or one of the names

\fBip\fP, \fBip6\fP, \fBarp\fP, \fBrarp\fP, \fBatalk\fP, \fBaarp\fP,

\fBdecnet\fP, \fBsca\fP, \fBlat\fP, \fBmopdl\fP, \fBmoprc\fP,

\fBiso\fP, \fBstp\fP, \fBipx\fP, or \fBnetbeui\fP.

Note these identifiers are also keywords

and must be escaped via backslash (\\).

.IP

[In the case of FDDI (e.g., `\fBfddi proto arp\fR'), Token Ring

(e.g., `\fBtr proto arp\fR'), and IEEE 802.11 wireless LANS (e.g.,

`\fBwlan proto arp\fR'), for most of those protocols, the

protocol identification comes from the 802.2 Logical Link Control (LLC)

header, which is usually layered on top of the FDDI, Token Ring, or

802.11 header.

.IP

When filtering for most protocol identifiers on FDDI, Token Ring, or

802.11, the filter checks only the protocol ID field of an LLC header

in so-called SNAP format with an Organizational Unit Identifier (OUI) of

0x000000, for encapsulated Ethernet; it doesn't check whether the packet

is in SNAP format with an OUI of 0x000000.

The exceptions are:

.RS

.TP

\fBiso\fP

the filter checks the DSAP (Destination Service Access Point) and

SSAP (Source Service Access Point) fields of the LLC header;

.TP

\fBstp\fP and \fBnetbeui\fP

the filter checks the DSAP of the LLC header;

.TP

\fBatalk\fP

the filter checks for a SNAP-format packet with an OUI of 0x080007

and the AppleTalk etype.

.RE

.IP

In the case of Ethernet, the filter checks the Ethernet type field

for most of those protocols.  The exceptions are:

.RS

.TP

\fBiso\fP, \fBstp\fP, and \fBnetbeui\fP

the filter checks for an 802.3 frame and then checks the LLC header as

it does for FDDI, Token Ring, and 802.11;

.TP

\fBatalk\fP

the filter checks both for the AppleTalk etype in an Ethernet frame and

for a SNAP-format packet as it does for FDDI, Token Ring, and 802.11;

.TP

\fBaarp\fP

the filter checks for the AppleTalk ARP etype in either an Ethernet

frame or an 802.2 SNAP frame with an OUI of 0x000000;

.TP

\fBipx\fP

the filter checks for the IPX etype in an Ethernet frame, the IPX

DSAP in the LLC header, the 802.3-with-no-LLC-header encapsulation of

IPX, and the IPX etype in a SNAP frame.

.RE

.IP "\fBip\fR, \fBip6\fR, \fBarp\fR, \fBrarp\fR, \fBatalk\fR, \fBaarp\fR, \fBdecnet\fR, \fBiso\fR, \fBstp\fR, \fBipx\fR, \fBnetbeui\fP"

Abbreviations for:

.in +.5i

.nf

\fBether proto \fIp\fR

.fi

.in -.5i

where \fIp\fR is one of the above protocols.

.IP "\fBlat\fR, \fBmoprc\fR, \fBmopdl\fR"

Abbreviations for:

.in +.5i

.nf

\fBether proto \fIp\fR

.fi

.in -.5i

where \fIp\fR is one of the above protocols.

Note that not all applications using

.BR pcap (3PCAP)

currently know how to parse these protocols.

.IP "\fBdecnet src \fIhost\fR"

True if the DECNET source address is

.IR host ,

which may be an address of the form ``10.123'', or a DECNET host

name.

[DECNET host name support is only available on ULTRIX systems

that are configured to run DECNET.]

.IP "\fBdecnet dst \fIhost\fR"

True if the DECNET destination address is

.IR host .

.IP "\fBdecnet host \fIhost\fR"

True if either the DECNET source or destination address is

.IR host .

.IP \fBllc\fP

True if the packet has an 802.2 LLC header.  This includes:

.IP

Ethernet packets with a length field rather than a type field that

aren't raw NetWare-over-802.3 packets;

.IP

IEEE 802.11 data packets;

.IP

Token Ring packets (no check is done for LLC frames);

.IP

FDDI packets (no check is done for LLC frames);

.IP

LLC-encapsulated ATM packets, for SunATM on Solaris.

.IP "\fBllc\fP \Fitype\fR"

True if the packet has an 802.2 LLC header and has the specified

.IR type .

.I type

can be one of:

.RS

.TP

\fBi\fR

Information (I) PDUs

.TP

\fBs\fR

Supervisory (S) PDUs

.TP

\fBu\fR

Unnumbered (U) PDUs

.TP

\fBrr\fR

Receiver Ready (RR) S PDUs

.TP

\fBrnr\fR

Receiver Not Ready (RNR) S PDUs

.TP

\fBrej\fR

Reject (REJ) S PDUs

.TP

\fBui\fR

Unnumbered Information (UI) U PDUs

.TP

\fBua\fR

Unnumbered Acknowledgment (UA) U PDUs

.TP

\fBdisc\fR

Disconnect (DISC) U PDUs

.TP

\fBsabme\fR

Set Asynchronous Balanced Mode Extended (SABME) U PDUs

.TP

\fBtest\fR

Test (TEST) U PDUs

.TP

\fBxid\fR

Exchange Identification (XID) U PDUs

.TP

\fBfrmr\fR

Frame Reject (FRMR) U PDUs

.RE

.IP \fBinbound\fP

Packet was received by the host performing the capture rather than being

sent by that host.  This is only supported for certain link-layer types,

such as SLIP and the ``cooked'' Linux capture mode

used for the ``any'' device and for some other device types.

.IP \fBoutbound\fP

Packet was sent by the host performing the capture rather than being

received by that host.  This is only supported for certain link-layer types,

such as SLIP and the ``cooked'' Linux capture mode

used for the ``any'' device and for some other device types.

.IP "\fBifname \fIinterface\fR"

True if the packet was logged as coming from the specified interface (applies

only to packets logged by OpenBSD's or FreeBSD's

.BR pf (4)).

.IP "\fBon \fIinterface\fR"

Synonymous with the

.B ifname

modifier.

.IP "\fBrnr \fInum\fR"

True if the packet was logged as matching the specified PF rule number

(applies only to packets logged by OpenBSD's or FreeBSD's

.BR pf (4)).

.IP "\fBrulenum \fInum\fR"

Synonymous with the

.B rnr

modifier.

.IP "\fBreason \fIcode\fR"

True if the packet was logged with the specified PF reason code.  The known

codes are:

.BR match ,

.BR bad-offset ,

.BR fragment ,

.BR short ,

.BR normalize ,

and

.B memory

(applies only to packets logged by OpenBSD's or FreeBSD's

.BR pf (4)).

.IP "\fBrset \fIname\fR"

True if the packet was logged as matching the specified PF ruleset

name of an anchored ruleset (applies only to packets logged by OpenBSD's

or FreeBSD's

.BR pf (4)).

.IP "\fBruleset \fIname\fR"

Synonymous with the

.B rset

modifier.

.IP "\fBsrnr \fInum\fR"

True if the packet was logged as matching the specified PF rule number

of an anchored ruleset (applies only to packets logged by OpenBSD's or

FreeBSD's

.BR pf (4)).

.IP "\fBsubrulenum \fInum\fR"

Synonymous with the

.B srnr

modifier.

.IP "\fBaction \fIact\fR"

True if PF took the specified action when the packet was logged.  Known actions

are:

.B pass

and

.B block

and, with later versions of

.BR pf (4),

.BR nat ,

.BR rdr ,

.B binat

and

.B scrub

(applies only to packets logged by OpenBSD's or FreeBSD's

.BR pf (4)).

.IP "\fBwlan ra \fIehost\fR"

True if the IEEE 802.11 RA is

.IR ehost .

The RA field is used in all frames except for management frames.

.IP "\fBwlan ta \fIehost\fR"

True if the IEEE 802.11 TA is

.IR ehost .

The TA field is used in all frames except for management frames and

CTS (Clear To Send) and ACK (Acknowledgment) control frames.

.IP "\fBwlan addr1 \fIehost\fR"

True if the first IEEE 802.11 address is

.IR ehost .

.IP "\fBwlan addr2 \fIehost\fR"

True if the second IEEE 802.11 address, if present, is

.IR ehost .

The second address field is used in all frames except for CTS (Clear To

Send) and ACK (Acknowledgment) control frames.

.IP "\fBwlan addr3 \fIehost\fR"

True if the third IEEE 802.11 address, if present, is

.IR ehost .

The third address field is used in management and data frames, but not

in control frames.

.IP "\fBwlan addr4 \fIehost\fR"

True if the fourth IEEE 802.11 address, if present, is

.IR ehost .

The fourth address field is only used for

WDS (Wireless Distribution System) frames.

.IP "\fBtype \fIwlan_type\fR"

True if the IEEE 802.11 frame type matches the specified \fIwlan_type\fR.

Valid \fIwlan_type\fRs are:

\fBmgt\fP,

\fBctl\fP

and \fBdata\fP.

.IP "\fBtype \fIwlan_type \fBsubtype \fIwlan_subtype\fR"

True if the IEEE 802.11 frame type matches the specified \fIwlan_type\fR

and frame subtype matches the specified \fIwlan_subtype\fR.

.IP

If the specified \fIwlan_type\fR is \fBmgt\fP,

then valid \fIwlan_subtype\fRs are:

\fBassoc-req\fP,

\fBassoc-resp\fP,

\fBreassoc-req\fP,

\fBreassoc-resp\fP,

\fBprobe-req\fP,

\fBprobe-resp\fP,

\fBbeacon\fP,

\fBatim\fP,

\fBdisassoc\fP,

\fBauth\fP and

\fBdeauth\fP.

.IP

If the specified \fIwlan_type\fR is \fBctl\fP,

then valid \fIwlan_subtype\fRs are:

\fBps-poll\fP,

\fBrts\fP,

\fBcts\fP,

\fBack\fP,

\fBcf-end\fP and

\fBcf-end-ack\fP.

.IP

If the specified \fIwlan_type\fR is \fBdata\fP,

then valid \fIwlan_subtype\fRs are:

\fBdata\fP,

\fBdata-cf-ack\fP,

\fBdata-cf-poll\fP,

\fBdata-cf-ack-poll\fP,

\fBnull\fP,

\fBcf-ack\fP,

\fBcf-poll\fP,

\fBcf-ack-poll\fP,

\fBqos-data\fP,

\fBqos-data-cf-ack\fP,

\fBqos-data-cf-poll\fP,

\fBqos-data-cf-ack-poll\fP,

\fBqos\fP,

\fBqos-cf-poll\fP and

\fBqos-cf-ack-poll\fP.

.IP "\fBsubtype \fIwlan_subtype\fR"

True if the IEEE 802.11 frame subtype matches the specified \fIwlan_subtype\fR

and frame has the type to which the specified \fIwlan_subtype\fR belongs.

.IP "\fBdir \fIdir\fR"

True if the IEEE 802.11 frame direction matches the specified

.IR dir .

Valid directions are:

.BR nods ,

.BR tods ,

.BR fromds ,

.BR dstods ,

or a numeric value.

.IP "\fBvlan \fI[vlan_id]\fR"

True if the packet is an IEEE 802.1Q VLAN packet.

If \fI[vlan_id]\fR is specified, only true if the packet has the specified

\fIvlan_id\fR.

Note that the first \fBvlan\fR keyword encountered in \fIexpression\fR

changes the decoding offsets for the remainder of \fIexpression\fR on

the assumption that the packet is a VLAN packet.  The \fBvlan

\fI[vlan_id]\fR expression may be used more than once, to filter on VLAN

hierarchies.  Each use of that expression increments the filter offsets

by 4.

.IP

For example:

.in +.5i

.nf

\fBvlan 100 && vlan 200\fR

.fi

.in -.5i

filters on VLAN 200 encapsulated within VLAN 100, and

.in +.5i

.nf

\fBvlan && vlan 300 && ip\fR

.fi

.in -.5i

filters IPv4 protocols encapsulated in VLAN 300 encapsulated within any

higher order VLAN.

.IP "\fBmpls \fI[label_num]\fR"

True if the packet is an MPLS packet.

If \fI[label_num]\fR is specified, only true is the packet has the specified

\fIlabel_num\fR.

Note that the first \fBmpls\fR keyword encountered in \fIexpression\fR

changes the decoding offsets for the remainder of \fIexpression\fR on

the assumption that the packet is a MPLS-encapsulated IP packet.  The

\fBmpls \fI[label_num]\fR expression may be used more than once, to

filter on MPLS hierarchies.  Each use of that expression increments the

filter offsets by 4.

.IP

For example:

.in +.5i

.nf

\fBmpls 100000 && mpls 1024\fR

.fi

.in -.5i

filters packets with an outer label of 100000 and an inner label of

1024, and

.in +.5i

.nf

\fBmpls && mpls 1024 && host 192.9.200.1\fR

.fi

.in -.5i

filters packets to or from 192.9.200.1 with an inner label of 1024 and

any outer label.

.IP \fBpppoed\fP

True if the packet is a PPP-over-Ethernet Discovery packet (Ethernet

type 0x8863).

.IP "\fBpppoes \fI[session_id]\fR"

True if the packet is a PPP-over-Ethernet Session packet (Ethernet

type 0x8864).

If \fI[session_id]\fR is specified, only true if the packet has the specified

\fIsession_id\fR.

Note that the first \fBpppoes\fR keyword encountered in \fIexpression\fR

changes the decoding offsets for the remainder of \fIexpression\fR on

the assumption that the packet is a PPPoE session packet.

.IP

For example:

.in +.5i

.nf

\fBpppoes 0x27 && ip\fR

.fi

.in -.5i

filters IPv4 protocols encapsulated in PPPoE session id 0x27.

.IP "\fBgeneve \fI[vni]\fR"

True if the packet is a Geneve packet (UDP port 6081). If \fI[vni]\fR

is specified, only true if the packet has the specified \fIvni\fR.

Note that when the \fBgeneve\fR keyword is encountered in

\fIexpression\fR, it changes the decoding offsets for the remainder of

\fIexpression\fR on the assumption that the packet is a Geneve packet.

.IP

For example:

.in +.5i

.nf

\fBgeneve 0xb && ip\fR

.fi

.in -.5i

filters IPv4 protocols encapsulated in Geneve with VNI 0xb. This will

match both IP directly encapsulated in Geneve as well as IP contained

inside an Ethernet frame.

.IP "\fBiso proto \fIprotocol\fR"

True if the packet is an OSI packet of protocol type \fIprotocol\fP.

\fIProtocol\fP can be a number or one of the names

\fBclnp\fP, \fBesis\fP, or \fBisis\fP.

.IP "\fBclnp\fR, \fBesis\fR, \fBisis\fR"

Abbreviations for:

.in +.5i

.nf

\fBiso proto \fIp\fR

.fi

.in -.5i

where \fIp\fR is one of the above protocols.

.IP "\fBl1\fR, \fBl2\fR, \fBiih\fR, \fBlsp\fR, \fBsnp\fR, \fBcsnp\fR, \fBpsnp\fR"

Abbreviations for IS-IS PDU types.

.IP "\fBvpi\fP \fIn\fR"

True if the packet is an ATM packet, for SunATM on Solaris, with a

virtual path identifier of

.IR n .

.IP "\fBvci\fP \fIn\fR"

True if the packet is an ATM packet, for SunATM on Solaris, with a

virtual channel identifier of

.IR n .

.IP \fBlane\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

an ATM LANE packet.

Note that the first \fBlane\fR keyword encountered in \fIexpression\fR

changes the tests done in the remainder of \fIexpression\fR

on the assumption that the packet is either a LANE emulated Ethernet

packet or a LANE LE Control packet.  If \fBlane\fR isn't specified, the

tests are done under the assumption that the packet is an

LLC-encapsulated packet.

.IP \fBoamf4s\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

a segment OAM F4 flow cell (VPI=0 & VCI=3).

.IP \fBoamf4e\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

an end-to-end OAM F4 flow cell (VPI=0 & VCI=4).

.IP \fBoamf4\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

a segment or end-to-end OAM F4 flow cell (VPI=0 & (VCI=3 | VCI=4)).

.IP \fBoam\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

a segment or end-to-end OAM F4 flow cell (VPI=0 & (VCI=3 | VCI=4)).

.IP \fBmetac\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

on a meta signaling circuit (VPI=0 & VCI=1).

.IP \fBbcc\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

on a broadcast signaling circuit (VPI=0 & VCI=2).

.IP \fBsc\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

on a signaling circuit (VPI=0 & VCI=5).

.IP \fBilmic\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

on an ILMI circuit (VPI=0 & VCI=16).

.IP \fBconnectmsg\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

on a signaling circuit and is a Q.2931 Setup, Call Proceeding, Connect,

Connect Ack, Release, or Release Done message.

.IP \fBmetaconnect\fP

True if the packet is an ATM packet, for SunATM on Solaris, and is

on a meta signaling circuit and is a Q.2931 Setup, Call Proceeding, Connect,

Release, or Release Done message.

.IP  "\fIexpr relop expr\fR"

True if the relation holds, where \fIrelop\fR is one of >, <, >=, <=, =,

!=, and \fIexpr\fR is an arithmetic expression composed of integer

constants (expressed in standard C syntax), the normal binary operators

[+, -, *, /, %, &, |, ^, <<, >>], a length operator, and special packet data

accessors.  Note that all comparisons are unsigned, so that, for example,

0x80000000 and 0xffffffff are > 0.

.IP

The % and ^ operators are currently only supported for filtering in the

kernel on Linux with 3.7 and later kernels; on all other systems, if

those operators are used, filtering will be done in user mode, which

will increase the overhead of capturing packets and may cause more

packets to be dropped.

.IP

To access data inside the packet, use the following syntax:

.in +.5i

.nf

\fIproto\fB [ \fIexpr\fB : \fIsize\fB ]\fR

.fi

.in -.5i

\fIProto\fR is one of \fBether, fddi, tr, wlan, ppp, slip, link,

ip, arp, rarp, tcp, udp, icmp, ip6\fR or \fBradio\fR, and

indicates the protocol layer for the index operation.

(\fBether, fddi, wlan, tr, ppp, slip\fR and \fBlink\fR all refer to the

link layer. \fBradio\fR refers to the "radio header" added to some

802.11 captures.)

Note that \fItcp, udp\fR and other upper-layer protocol types only

apply to IPv4, not IPv6 (this will be fixed in the future).

The byte offset, relative to the indicated protocol layer, is

given by \fIexpr\fR.

\fISize\fR is optional and indicates the number of bytes in the

field of interest; it can be either one, two, or four, and defaults to one.

The length operator, indicated by the keyword \fBlen\fP, gives the

length of the packet.

For example, `\fBether[0] & 1 != 0\fP' catches all multicast traffic.

The expression `\fBip[0] & 0xf != 5\fP'

catches all IPv4 packets with options.

The expression

`\fBip[6:2] & 0x1fff = 0\fP'

catches only unfragmented IPv4 datagrams and frag zero of fragmented

IPv4 datagrams.

This check is implicitly applied to the \fBtcp\fP and \fBudp\fP

index operations.

For instance, \fBtcp[0]\fP always means the first

byte of the TCP \fIheader\fP, and never means the first byte of an

intervening fragment.

Some offsets and field values may be expressed as names rather than

as numeric values.

The following protocol header field offsets are

available: \fBicmptype\fP (ICMP type field), \fBicmp6type (ICMP v6 type field)

\fBicmpcode\fP (ICMP code field), \fBicmp6code\fP (ICMP v6 code field), and

\fBtcpflags\fP (TCP flags field).

The following ICMP type field values are available: \fBicmp-echoreply\fP,

\fBicmp-unreach\fP, \fBicmp-sourcequench\fP, \fBicmp-redirect\fP,

\fBicmp-echo\fP, \fBicmp-routeradvert\fP, \fBicmp-routersolicit\fP,

\fBicmp-timxceed\fP, \fBicmp-paramprob\fP, \fBicmp-tstamp\fP,

\fBicmp-tstampreply\fP, \fBicmp-ireq\fP, \fBicmp-ireqreply\fP,

\fBicmp-maskreq\fP, \fBicmp-maskreply\fP.

The following ICMPv6 type fields are available: \fBicmp6-echo\fP,