tc-flow(8) - phpMan

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Flow filter in tc(8)                 Linux                Flow filter in tc(8)



NAME
       flow - flow based traffic control filter

SYNOPSIS
       Mapping mode:

              tc filter ... flow map key KEY [ OPS ] [ OPTIONS ]

       Hashing mode:

              tc filter ... flow hash keys KEY_LIST [ perturb secs ] [ OPTIONS ]

       OPS := [ OPS ] OP

       OPTIONS  :=  [  divisor  NUM  ]  [  baseclass  ID  ] [ match EMATCH_TREE ] [ action
               ACTION_SPEC ]

       KEY_LIST := [ KEY_LIST ] KEY

       OP := { or | and | xor | rshift | addend } NUM

       ID := X:Y

       KEY := { src | dst | proto | proto-src | proto-dst | iif | priority | mark | nfct |
               nfct-src | nfct-dst | nfct-proto-src | nfct-proto-dst | rt-classid | sk-uid
               | sk-gid | vlan-tag | rxhash }

DESCRIPTION
       The flow classifier is meant to extend the SFQ hashing capabilities  without  hard-
       coding  new  hash  functions.  It  also  allows  deterministic  mappings of keys to
       classes.

OPTIONS
       action ACTION_SPEC
              Apply an action from the generic actions framework on matching packets.

       baseclass ID
              An offset for the resulting class ID.  ID may be root, none or a hexadecimal
              class ID in the form [X:]Y. If X is omitted, it is assumed to be zero.

       divisor NUM
              Number of buckets to use for sorting into. Keys are calculated modulo NUM.

       hash keys KEY-LIST
              Perform a jhash2 operation over the keys in KEY-LIST, the result (modulo the
              divisor if given) is taken as class ID, optionally offset by  the  value  of
              baseclass.   It  is possible to specify an interval (in seconds) after which
              jhash2's entropy source is recreated using the perturb parameter.

       map key KEY
              Packet data identified by KEY is translated  into  class  IDs  to  push  the
              packet  into.  The  value may be mangled by OPS before using it for the map-
              ping. They are applied in the order listed here:

              and NUM
                  Perform bitwise AND operation with numeric value NUM.

              or NUM
                  Perform bitwise OR operation with numeric value NUM.

              xor NUM
                  Perform bitwise XOR operation with numeric value NUM.

              rshift NUM
                  Shift the value of KEY to the right by NUM bits.

              addend NUM
                  Add NUM to the value of KEY.

              For the or, and, xor  and  rshift  operations,  NUM  is  assumed  to  be  an
              unsigned,  32bit  integer  value.  For the addend operation, NUM may be much
              more complex: It may be prefixed by a minus ('-') sign to cause  subtraction
              instead  of  addition and for keys of src, dst, nfct-src and nfct-dst it may
              be given in IP address notation. See below for an illustrating example.

       match EMATCH_TREE
              Match packets using the extended match infrastructure. See tc-ematch(8)  for
              a detailed description of the allowed syntax in EMATCH_TREE.

KEYS
       In mapping mode, a single key is used (after optional permutation) to build a class
       ID. The resulting ID is deducible in most cases. In hashing more, a number of  keys
       may be specified which are then hashed and the output used as class ID.  This ID is
       not deducible in beforehand, and may even change over time for a given  flow  if  a
       perturb interval has been given.

       The  range  of  class IDs can be limited by the divisor option, which is used for a
       modulus.

       src, dst
              Use source or destination address as key. In case of IPv4 and TIPC, this  is
              the  actual  address  value.  For  IPv6, the 128bit address is folded into a
              32bit value by XOR'ing the four 32bit words. In all other cases, the kernel-
              internal  socket  address  is  used (after folding into 32bits on 64bit sys-
              tems).

       proto  Use the layer four protocol number as key.

       proto-src
              Use the layer four source port as key. If not available, the kernel-internal
              socket address is used instead.

       proto-dst
              Use the layer four destination port as key. If not available, the associated
              kernel-internal dst_entry address is used after XOR'ing  with  the  packet's
              layer three protocol number.

       iif    Use the incoming interface index as key.

       priority
              Use  the  packet's priority as key. Usually this is the IP header's DSCP/ECN
              value.

       mark   Use the netfilter fwmark as key.

       nfct   Use the associated conntrack entry address as key.

       nfct-src, nfct-dst, nfct-proto-src, nfct-proto-dst
              These are conntrack-aware variants of src, dst, proto-src and proto-dst.  In
              case  of  NAT, these are basically the packet header's values before NAT was
              applied.

       rt-classid
              Use the packet's destination routing table entry's realm as key.

       sk-uid sk-gid For locally generated packets, use the user or group ID the originat-
              ing socket belongs to as key.

       vlan-tag
              Use the packet's vlan ID as key.

       rxhash Use the flow hash as key.


EXAMPLES
       Classic SFQ hash:

              tc  filter  add  ... flow hash \      keys src,dst,proto,proto-src,proto-dst
              divisor 1024

       Classic SFQ hash, but using information from conntrack to work properly in combina-
       tion with NAT:

              tc filter add ... flow hash \      keys  nfct-src,nfct-dst,proto,nfct-proto-
              src,nfct-proto-dst \      divisor 1024

       Map destination IPs of 192.168.0.0/24 to classids 1-257:

              tc filter add ... flow map \      key dst addend -192.168.0.0 divisor 256

       Alternative to the above:

              tc filter add ... flow map \      key dst and 0xff

       The same, but in reverse order:

              tc filter add ... flow map \      key dst and 0xff xor 0xff

SEE ALSO
       tc(8), tc-ematch(8), tc-sfq(8)



iproute2                          20 Oct 2015             Flow filter in tc(8)

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