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Filter expression syntax

Valid fields

  • tcp: bool
  • udp: bool
  • vlan: bool
  • arp: bool
  • eth.addr: byte-string | regex
  • eth.dst: byte-string | regex
  • eth.src: byte-string | regex
  • ip.addr: ip | net | list(ip | net)
  • ip.dst: ip | net | list(ip | net)
  • ip.src: ip | net | list(ip | net)
  • vlan.id: number | list(number)
  • port: number | list(number)
  • srcport: number | list(number)
  • dstport: number | list(number)
  • payload: byte-string | regex
  • payload.len: number | list(number)

Type explanation

bool

use the fields name with or without logical operations.

Example:

  • 'tcp'
  • 'not udp'
  • '!arp'

byte-string

hexadecimal numbers separated by ':'.

Example:

  • 'eth.src contains db:03 || eth.dst contains 00:55'
  • 'payload contains 00:aa:bb:cc'

list (of anything)

space separated types between curly braces.

Example:

  • 'srcport in {80, 443}'
  • 'srcport not in {80, 443}'
  • 'eth.dst in {00.11.22.44:55, 55:44:33:22:11:00}'

ip

An ip.

Example:

  • 'ip.dst == 1.1.1.1'
  • 'ip.dst == 2606:4700:4700::1111',
  • 'ip.dst >= 173.245.48.0 && ip.dst < 173.245.49.0',
  • 'ip.src != 192.168.0.1'

net

An ip network in prefix notation. Example:

  • 'ip.addr in {192.168.1.0/24}'
  • 'ip.dst in {192.168.3.1, 10.0.0.0/8}'

mac-address

A Mac address. Separated by either of ':', '-', '.' or continuous.

Example:

  • eth.addr == 11:22:33:44:55:66
  • eth.src == 11-22-33-44-55-66
  • eth.dst == 112.233.445.566
  • eth.src == 112233445566

number

A whole non-negative number without fractions

Example:

  • 'srcport in {22, 80}'
  • 'srcport < 1024'
  • 'payload.len > 50 and payload.len < 500'

regex

A double quoted ascii string with Rust regex support.

(See here for details: https://docs.rs/regex/1.9.1/regex/#syntax)

Example:

  • 'payload matches "GET /secret"'
  • 'payload ~ "\r\n\x45\xdb"'
  • 'payload ~ "GET /(secret|password)"'
  • 'payload ~ "[[:ascii:]]{100}"' // matches any payload that has a 100 ascii characters in a row
  • 'payload ~ "^\x00BOOM\x00"' // matches any payload that starts with null followed by BOOM followed by null

Operations

Logical

  • and ('and', '&&')
  • or ('or', '||')
  • not ('not', '!')
  • grouping using parentheses ().
  • Comparison: '==', '!=', '>', '>=', '<', '<='
  • In (bytes): 'contains'
  • In (list): 'in'
  • Not in (list): 'not in'
  • Regex: 'matches', '~'

Examples:

  • 'ip.src == 192.168.1.7 || ip.dst == 1.2.3.4 && (srcport == 9 || dstport == 9)'
  • 'eth.src == 3f:43:9a:2c:00:00 or eth.dst contains 2c:9a:bb'
  • 'srcport in {80, 443}'
  • 'srcport not in {80, 443}'
  • 'payload contains "something"'
  • 'payload.len > 50'
  • 'payload ~ "(ASCII|\x22\x12)"'
  • 'payload ~ "(?i)CaSeInSeNsItIvE"' # case insensitive match