libxt_hashlimit.man revision 9b488b992872d4d2b7ebf7897d74d52f4fb59e1c 
1\fBhashlimit\fR uses hash buckets to express a rate limiting match (like the
2\fBlimit\fR match) for a group of connections using a \fBsingle\fR iptables
3rule. Grouping can be done per-hostgroup (source and/or destination address)
4and/or per-port. It gives you the ability to express "\fIN\fR packets per time
5quantum per group":
6.TP
7matching on source host
8"1000 packets per second for every host in 192.168.0.0/16"
9.TP
10matching on source prot
11"100 packets per second for every service of 192.168.1.1"
12.TP
13matching on subnet
14"10000 packets per minute for every /28 subnet in 10.0.0.0/8"
15.PP
16A hash limit option (\fB--hashlimit-upto\fR, \fB--hashlimit-above\fR) and
17\fB--hashlimit-name\fR are required.
18.TP
19\fB--hashlimit-upto\fR \fIamount\fR[\fB/second\fR|\fB/minute\fR|\fB/hour\fR|\fB/day\fR]
20Match if the rate is below or equal to \fIamount\fR/quantum. It is specified as
21a number, with an optional time quantum suffix; the default is 3/hour.
22.TP
23\fB--hashlimit-above\fR \fIamount\fR[\fB/second\fR|\fB/minute\fR|\fB/hour\fR|\fB/day\fR]
24Match if the rate is above \fIamount\fR/quantum.
25.TP
26\fB--hashlimit-burst\fR \fIamount\fR
27Maximum initial number of packets to match: this number gets recharged by one
28every time the limit specified above is not reached, up to this number; the
29default is 5.
30.TP
31\fB--hashlimit-mode\fR {\fBsrcip\fR|\fBsrcport\fR|\fBdstip\fR|\fBdstport\fR}\fB,\fP...
32A comma-separated list of objects to take into consideration. If no
33--hashlimit-mode option is given, hashlimit acts like limit, but at the
34expensive of doing the hash housekeeping.
35.TP
36\fB--hashlimit-srcmask\fR \fIprefix\fR
37When --hashlimit-mode srcip is used, all source addresses encountered will be
38grouped according to the given prefix length and the so-created subnet will be
39subject to hashlimit. \fIprefix\fR must be between (inclusive) 0 and 32. Note
40that --hashlimit-srcmask 0 is basically doing the same thing as not specifying
41srcip for --hashlimit-mode, but is technically more expensive.
42.TP
43\fB--hashlimit-dstmask\fR \fIprefix\fR
44Like --hashlimit-srcmask, but for destination addresses.
45.TP
46\fB--hashlimit-name\fR \fIfoo\fR
47The name for the /proc/net/ipt_hashlimit/foo entry.
48.TP
49\fB--hashlimit-htable-size\fR \fIbuckets\fR
50The number of buckets of the hash table
51.TP
52\fB--hashlimit-htable-max\fR \fIentries\fR
53Maximum entries in the hash.
54.TP
55\fB--hashlimit-htable-expire\fR \fImsec\fR
56After how many milliseconds do hash entries expire.
57.TP
58\fB--hashlimit-htable-gcinterval\fR \fImsec\fR
59How many milliseconds between garbage collection intervals.
60