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
       netdev@vger.kernel.org, shemminger@osdl.org.  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 man-pages@man7.org

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)