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

       The extended match infrastructure was added by Thomas Graf.

iproute2                                          6 August 2012                                        ematch(8)

       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.

       # 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)'

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 := intLAYER := { link | network | transport | 0..2 }

   u32
       u32 ematch

       u32( ALIGNVALUEMASK at [ nexthdr+ ] OFFSET )

       ALIGN := { u8 | u16 | u32 }

   ipset
       test packet against ipset membership

       ipset( SETNAMEFLAGS )

       SETNAME := stringFLAGS := { 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]-mMATCH_NAMEFLAGS )

       MATCH_NAME := stringFLAGS := { 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)

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

tcfilteradd..basicmatch EXPR ..flowid..EXPR := TERM [ { and|or } EXPR ]

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

       MATCH := module '(' ARGS ')'

       ARGS := ARG1ARG2 ..