ematch(8)			     Linux			     ematch(8)



NAME
       ematch - extended matches for use with "basic" or "flow" filters

SYNOPSIS
       tc filter add .. basic match EXPR .. flowid ..


       EXPR := TERM [ { and | or } EXPR ]

       TERM := [ not ] { MATCH | '(' EXPR ')' }

       MATCH := module '(' ARGS ')'

       ARGS := ARG1 ARG2 ..


MATCHES
   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, outgo-
       ing interface) or "src,src" (source ip address, incoming interface)
       syntax.


CAVEATS
       The ematch syntax uses '(' and ')' to group expressions. All braces
       need to be escaped properly to prevent shell commandline from inter-
       preting 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
       # 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)'


AUTHOR
       The extended match infrastructure was added by Thomas Graf.



iproute2			 6 August 2012			     ematch(8)