man/man8/tc-flow.8

   1 .TH "Flow filter in tc" 8 "20 Oct 2015" "iproute2" "Linux"
   2
   3 .SH NAME
   4 flow \- flow based traffic control filter
   5 .SH SYNOPSIS
   6 .TP
   7 Mapping mode:
   8
   9 .RS
  10 .in +8
  11 .ti -8
  12 .BR tc " " filter " ... " "flow map key "
  13 .IR KEY " [ " OPS " ] [ " OPTIONS " ] "
  14 .RE
  15 .TP
  16 Hashing mode:
  17
  18 .RS
  19 .in +8
  20 .ti -8
  21 .BR tc " " filter " ... " "flow hash keys "
  22 .IR KEY_LIST " [ "
  23 .B perturb
  24 .IR secs " ] [ " OPTIONS " ] "
  25 .RE
  26
  27 .in +8
  28 .ti -8
  29 .IR OPS " := [ " OPS " ] " OP
  30
  31 .ti -8
  32 .IR OPTIONS " := [ "
  33 .B divisor
  34 .IR NUM " ] [ "
  35 .B baseclass
  36 .IR ID " ] [ "
  37 .B match
  38 .IR EMATCH_TREE " ] [ "
  39 .B action
  40 .IR ACTION_SPEC " ]"
  41
  42 .ti -8
  43 .IR KEY_LIST " := [ " KEY_LIST " ] " KEY
  44
  45 .ti -8
  46 .IR OP " := { "
  47 .BR or " | " and " | " xor " | " rshift " | " addend " } "
  48 .I NUM
  49
  50 .ti -8
  51 .IR ID " := " X : Y
  52
  53 .ti -8
  54 .IR KEY " := { "
  55 .BR src " | " dst " | " proto " | " proto-src " | " proto-dst " | " iif " | "
  56 .BR priority " | " mark " | " nfct " | " nfct-src " | " nfct-dst " | "
  57 .BR nfct-proto-src " | " nfct-proto-dst " | " rt-classid " | " sk-uid " | "
  58 .BR sk-gid " | " vlan-tag " | " rxhash " }"
  59 .SH DESCRIPTION
  60 The
  61 .B flow
  62 classifier is meant to extend the
  63 .B SFQ
  64 hashing capabilities without hard-coding new hash functions. It also allows
  65 deterministic mappings of keys to classes.
  66 .SH OPTIONS
  67 .TP
  68 .BI action " ACTION_SPEC"
  69 Apply an action from the generic actions framework on matching packets.
  70 .TP
  71 .BI baseclass " ID"
  72 An offset for the resulting class ID.
  73 .I ID
  74 may be
  75 .BR root ", " none
  76 or a hexadecimal class ID in the form [\fIX\fB:\fR]\fIY\fR. \fIX\fR must
  77 match qdisc's/class's major handle (if omitted, the correct value is chosen
  78 automatically). If the whole \fBbaseclass\fR is omitted, \fIY\fR defaults
  79 to 1.
  80 .TP
  81 .BI divisor " NUM"
  82 Number of buckets to use for sorting into. Keys are calculated modulo
  83 .IR NUM .
  84 .TP
  85 .BI "hash keys " KEY-LIST
  86 Perform a
  87 .B jhash2
  88 operation over the keys in
  89 .IR KEY-LIST ,
  90 the result (modulo the
  91 .B divisor
  92 if given) is taken as class ID, optionally offset by the value of
  93 .BR baseclass .
  94 It is possible to specify an interval (in seconds) after which
  95 .BR jhash2 's
  96 entropy source is recreated using the
  97 .B perturb
  98 parameter.
  99 .TP
 100 .BI "map key " KEY
 101 Packet data identified by
 102 .I KEY
 103 is translated into class IDs to push the packet into. The value may be mangled by
 104 .I OPS
 105 before using it for the mapping. They are applied in the order listed here:
 106 .RS
 107 .TP 4
 108 .BI and " NUM"
 109 Perform bitwise
 110 .B AND
 111 operation with numeric value
 112 .IR NUM .
 113 .TP
 114 .BI or " NUM"
 115 Perform bitwise
 116 .B OR
 117 operation with numeric value
 118 .IR NUM .
 119 .TP
 120 .BI xor " NUM"
 121 Perform bitwise
 122 .B XOR
 123 operation with numeric value
 124 .IR NUM .
 125 .TP
 126 .BI rshift " NUM"
 127 Shift the value of
 128 .I KEY
 129 to the right by
 130 .I NUM
 131 bits.
 132 .TP
 133 .BI addend " NUM"
 134 Add
 135 .I NUM
 136 to the value of
 137 .IR KEY .
 138
 139 .RE
 140 .RS
 141 For the
 142 .BR or ", " and ", " xor " and " rshift
 143 operations,
 144 .I NUM
 145 is assumed to be an unsigned, 32bit integer value. For the
 146 .B addend
 147 operation,
 148 .I NUM
 149 may be much more complex: It may be prefixed by a minus ('-') sign to cause
 150 subtraction instead of addition and for keys of
 151 .BR src ", " dst ", " nfct-src " and " nfct-dst
 152 it may be given in IP address notation. See below for an illustrating example.
 153 .RE
 154 .TP
 155 .BI match " EMATCH_TREE"
 156 Match packets using the extended match infrastructure. See
 157 .BR tc-ematch (8)
 158 for a detailed description of the allowed syntax in
 159 .IR EMATCH_TREE .
 160 .SH KEYS
 161 In mapping mode, a single key is used (after optional permutation) to build a
 162 class ID. The resulting ID is deducible in most cases. In hashing more, a number
 163 of keys may be specified which are then hashed and the output used as class ID.
 164 This ID is not deducible in beforehand, and may even change over time for a
 165 given flow if a
 166 .B perturb
 167 interval has been given.
 168
 169 The range of class IDs can be limited by the
 170 .B divisor
 171 option, which is used for a modulus.
 172 .TP
 173 .BR src ", " dst
 174 Use source or destination address as key. In case of IPv4 and TIPC, this is the
 175 actual address value. For IPv6, the 128bit address is folded into a 32bit value
 176 by XOR'ing the four 32bit words. In all other cases, the kernel-internal socket
 177 address is used (after folding into 32bits on 64bit systems).
 178 .TP
 179 .B proto
 180 Use the layer four protocol number as key.
 181 .TP
 182 .B proto-src
 183 Use the layer four source port as key. If not available, the kernel-internal
 184 socket address is used instead.
 185 .TP
 186 .B proto-dst
 187 Use the layer four destination port as key. If not available, the associated
 188 kernel-internal dst_entry address is used after XOR'ing with the packet's
 189 layer three protocol number.
 190 .TP
 191 .B iif
 192 Use the incoming interface index as key.
 193 .TP
 194 .B priority
 195 Use the packet's priority as key. Usually this is the IP header's DSCP/ECN
 196 value.
 197 .TP
 198 .B mark
 199 Use the netfilter
 200 .B fwmark
 201 as key.
 202 .TP
 203 .B nfct
 204 Use the associated conntrack entry address as key.
 205 .TP
 206 .BR nfct-src ", " nfct-dst ", " nfct-proto-src ", " nfct-proto-dst
 207 These are conntrack-aware variants of
 208 .BR src ", " dst ", " proto-src " and " proto-dst .
 209 In case of NAT, these are basically the packet header's values before NAT was
 210 applied.
 211 .TP
 212 .B rt-classid
 213 Use the packet's destination routing table entry's realm as key.
 214 .TP
 215 .B sk-uid
 216 .TQ
 217 .B sk-gid
 218 For locally generated packets, use the user or group ID the originating socket
 219 belongs to as key.
 220 .TP
 221 .B vlan-tag
 222 Use the packet's vlan ID as key.
 223 .TP
 224 .B rxhash
 225 Use the flow hash as key.
 226
 227 .SH EXAMPLES
 228 .TP
 229 Classic SFQ hash:
 230
 231 .EX
 232 tc filter add ... flow hash \\
 233         keys src,dst,proto,proto-src,proto-dst divisor 1024
 234 .EE
 235 .TP
 236 Classic SFQ hash, but using information from conntrack to work properly in combination with NAT:
 237
 238 .EX
 239 tc filter add ... flow hash \\
 240         keys nfct-src,nfct-dst,proto,nfct-proto-src,nfct-proto-dst \\
 241         divisor 1024
 242 .EE
 243 .TP
 244 Map destination IPs of 192.168.0.0/24 to classids 1-256:
 245
 246 .EX
 247 tc filter add ... flow map \\
 248         key dst addend -192.168.0.0 divisor 256
 249 .EE
 250 .TP
 251 Alternative to the above:
 252
 253 .EX
 254 tc filter add ... flow map \\
 255         key dst and 0xff
 256 .EE
 257 .TP
 258 The same, but in reverse order:
 259
 260 .EX
 261 tc filter add ... flow map \\
 262         key dst and 0xff xor 0xff
 263 .EE
 264 .SH SEE ALSO
 265 .BR tc (8),
 266 .BR tc-ematch (8),
 267 .BR tc-sfq (8)