| Jan Engelhardt | 21df4af | 2007-07-09 16:50:17 +0000 | [diff] [blame] | 1 | Allows you to restrict the number of parallel connections to a server per |
| 2 | client IP address (or client address block). |
| 3 | .TP |
| 4 | [\fB!\fR] \fB--connlimit-above \fIn\fR |
| 5 | Match if the number of existing connections is (not) above \fIn\fR. |
| 6 | .TP |
| 7 | \fB--connlimit-mask\fR \fIprefix_length\fR |
| 8 | Group hosts using the prefix length. For IPv4, this must be a number between |
| 9 | (including) 0 and 32. For IPv6, between 0 and 128. |
| 10 | .P |
| 11 | Examples: |
| 12 | .TP |
| 13 | # allow 2 telnet connections per client host |
| 14 | iptables -A INPUT -p tcp --syn --dport 23 -m connlimit --connlimit-above 2 -j REJECT |
| 15 | .TP |
| 16 | # you can also match the other way around: |
| 17 | iptables -A INPUT -p tcp --syn --dport 23 -m connlimit ! --connlimit-above 2 -j ACCEPT |
| 18 | .TP |
| 19 | # limit the number of parallel HTTP requests to 16 per class C sized \ |
| 20 | network (24 bit netmask) |
| 21 | iptables -p tcp --syn --dport 80 -m connlimit --connlimit-above 16 |
| 22 | --connlimit-mask 24 -j REJECT |
| 23 | .TP |
| 24 | # limit the number of parallel HTTP requests to 16 for the link local network \ |
| 25 | (ipv6) |
| 26 | ip6tables -p tcp --syn --dport 80 -s fe80::/64 -m connlimit --connlimit-above |
| 27 | 16 --connlimit-mask 64 -j REJECT |