ematch(8) Linux ematch(8)
NAME top
ematch – extended matches for use with “basic”, “cgroup” or
“flow” filters
SYNOPSIS top
tc filter add .. basic match EXPR .. flowid ..
EXPR := TERM [ { and | or } EXPR ]
TERM := [ not ] { MATCH | ‘(‘ EXPR ‘)’ }
MATCH := module ‘(‘ ARGS ‘)’
ARGS := ARG1 ARG2 ..
MATCHES top
cmp
Simple comparison ematch: arithmetic compare of packet data to a
given value.
cmp( ALIGN at OFFSET [ ATTRS ] { eq | lt | gt } VALUE )
ALIGN := { u8 | u16 | u32 }
ATTRS := [ layer LAYER ] [ mask MASK ] [ trans ]
LAYER := { link | network | transport | 0..2 }
meta
Metadata ematch
meta( OBJECT { eq | lt |gt } OBJECT )
OBJECT := { META_ID | VALUE }
META_ID := id [ shift SHIFT ] [ mask MASK ]
meta attributes:
random 32 bit random value
loadavg_1 Load average in last 5 minutes
nf_mark Netfilter mark
vlan Vlan tag
sk_rcvbuf Receive buffer size
sk_snd_queue Send queue length
A full list of meta attributes can be obtained via
# tc filter add dev eth1 basic match ‘meta(list)’
nbyte
match packet data byte sequence
nbyte( NEEDLE at OFFSET [ layer LAYER ] )
NEEDLE := { string | c-escape-sequence }
OFFSET := int
LAYER := { link | network | transport | 0..2 }
u32
u32 ematch
u32( ALIGN VALUE MASK at [ nexthdr+ ] OFFSET )
ALIGN := { u8 | u16 | u32 }
ipset
test packet against ipset membership
ipset( SETNAME FLAGS )
SETNAME := string
FLAGS := { FLAG [, FLAGS] }
The flag options are the same as those used by the iptables “set”
match.
When using the ipset ematch with the “ip_set_hash:net,iface” set
type, the interface can be queried using “src,dst (source ip
address, outgoing interface) or “src,src” (source ip address,
incoming interface) syntax.
ipt
test packet against xtables matches
ipt( [-6] -m MATCH_NAME FLAGS )
MATCH_NAME := string
FLAGS := { FLAG [, FLAGS] }
The flag options are the same as those used by the xtable match
used.
canid
ematch rule to match CAN frames
canid( IDLIST )
IDLIST := IDSPEC[IDLIST]
IDSPEC := { ’sff’ CANID | ’eff’ CANID }
CANID := ID[:MASK]
ID, MASK := hexadecimal number (i.e. 0x123)
CAVEATS top
The ematch syntax uses ‘(‘ and ‘)’ to group expressions. All
braces need to be escaped properly to prevent shell commandline
from interpreting these directly.
When using the ipset ematch with the “ifb” device, the outgoing
device will be the ifb device itself, e.g. “ifb0”. The original
interface (i.e. the device the packet arrived on) is treated as
the incoming interface.
EXAMPLE & USAGE top
# tc filter add .. basic match …
# ‘cmp(u16 at 3 layer 2 mask 0xff00 gt 20)’
# ‘meta(nfmark gt 24)’ and ‘meta(tcindex mask 0xf0 eq 0xf0)’
# ‘nbyte(“ababa” at 12 layer 1)’
# ‘u32(u16 0x1122 0xffff at nexthdr+4)’
Check if packet source ip address is member of set named bulk:
# ‘ipset(bulk src)’
Check if packet source ip and the interface the packet arrived on
is member of “hash:net,iface” set named interactive:
# ‘ipset(interactive src,src)’
Check if packet matches an IPSec state with reqid 1:
# ‘ipt(-m policy –dir in –pol ipsec –reqid 1)’
AUTHOR top
The extended match infrastructure was added by Thomas Graf.
COLOPHON top
This page is part of the iproute2 (utilities for controlling
TCP/IP networking and traffic) project. Information about the
project can be found at
⟨http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2⟩.
If you have a bug report for this manual page, send it to
[email protected], [email protected]. This page was
obtained from the project’s upstream Git repository
⟨https://git.kernel.org/pub/scm/network/iproute2/iproute2.git⟩ on
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-08.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to [email protected]
iproute2 6 August 2012 ematch(8)
Pages that refer to this page:
tc(8),
tc-basic(8),
tc-bpf(8),
tc-cgroup(8),
tc-flow(8)
