NAME

       IFE - encapsulate/decapsulate metadata

SYNOPSIS

       tc  ...  action ife DIRECTION [ ACTION ] [ dst DMAC ] [ src SMAC ] [ type TYPE ] [ CONTROL
               ] [ index INDEX ]

       DIRECTION := { decode | encode }

       ACTION := { allow ATTR | use ATTR value }

       ATTR := { mark | prio | tcindex }

       CONTROL := { reclassify | use | pipe | drop | continue | ok | goto chain CHAIN_INDEX }

DESCRIPTION

       The ife action allows for a sending side to encapsulate arbitrary metadata, which is  then
       decapsulated  by  the  receiving end. The sender runs in encoding mode and the receiver in
       decode mode. Both sender and receiver must specify the same ethertype. In  the  future,  a
       registered ethertype may be available as a default.

OPTIONS

       decode For the receiving side; decode the metadata if the packet matches.

       encode For the sending side. Encode the specified metadata if the packet matches.

       allow  Encode direction only. Allows encoding specified metadata.

       use    Encode direction only. Enforce static encoding of specified metadata.

       mark [ u32_value  ] The value to set for the skb mark. The u32 value is required only when
              use is specified.  If  mark  value  is  zero,  it  will  not  be  encoded,  instead
              "overlimits" statistics increment and CONTROL action is taken.

       prio [ u32_value  ]  The  value to set for priority in the skb structure. The u32 value is
              required only when use is specified.

       tcindex [
              u16_value ] Value to set for the traffic control index in the  skb  structure.  The
              u16 value is required only when use is specified.

       dmac DMAC
       smac SMAC
              Optional six byte destination or source MAC address to encode.

       type TYPE
              Optional 16-bit ethertype to encode. If not specified value of 0xED3E will be used.

       CONTROL
              Action to take following an encode/decode.

       index INDEX
              Assign  a  unique  ID  to  this  action  instead  of  letting the kernel choose one
              automatically.  INDEX is a 32bit unsigned integer greater than zero.

EXAMPLES

       On the receiving side, match packets with ethertype 0xdead and restart  classification  so
       that it will match ICMP on the next rule, at prio 3:
              # tc qdisc add dev eth0 handle ffff: ingress
              # tc filter add dev eth0 parent ffff: prio 2 protocol 0xdead \
                   u32 match u32 0 0 flowid 1:1 \
                   action ife decode reclassify
              # tc filter add dev eth0 parent ffff: prio 3 protocol ip \
                   u32 match ip protocol 0xff flowid 1:1 \
                   action continue

       Match with skb mark of 17:

              # tc filter add dev eth0 parent ffff: prio 4 protocol ip \
                   handle 0x11 fw flowid 1:1 \
                   action ok

       Configure  the  sending side to encode for the filters above. Use a destination IP address
       of 192.168.122.237/24, then tag with skb mark of  decimal  17.  Encode  the  packaet  with
       ethertype  0xdead,  add  skb->mark  to  whitelist  of  metadatum  to send, and rewrite the
       destination MAC address to 02:15:15:15:15:15.

              # tc qdisc add dev eth0 root handle 1: prio
              # tc filter add dev eth0 parent 1: protocol ip prio 10 u32 \
                   match ip dst 192.168.122.237/24 \
                   match ip protocol 1 0xff \
                   flowid 1:2 \
                   action skbedit mark 17 \
                   action ife encode \
                   type 0xDEAD \
                   allow mark \
                   dst 02:15:15:15:15:15

SEE ALSO

       tc(8), tc-u32(8)