| This modules matches a given string by using some pattern matching strategy. It requires a linux kernel >= 2.6.14. |
| .TP |
| \fB\-\-algo\fP {\fBbm\fP|\fBkmp\fP} |
| Select the pattern matching strategy. (bm = Boyer-Moore, kmp = Knuth-Pratt-Morris) |
| .TP |
| \fB\-\-from\fP \fIoffset\fP |
| Set the offset from which it starts looking for any matching. If not passed, default is 0. |
| .TP |
| \fB\-\-to\fP \fIoffset\fP |
| Set the offset up to which should be scanned. That is, byte \fIoffset\fP-1 |
| (counting from 0) is the last one that is scanned. |
| If not passed, default is the packet size. |
| .TP |
| [\fB!\fP] \fB\-\-string\fP \fIpattern\fP |
| Matches the given pattern. |
| .TP |
| [\fB!\fP] \fB\-\-hex\-string\fP \fIpattern\fP |
| Matches the given pattern in hex notation. |
| .TP |
| Examples: |
| .IP |
| # The string pattern can be used for simple text characters. |
| .br |
| iptables \-A INPUT \-p tcp \-\-dport 80 \-m string \-\-algo bm \-\-string 'GET /index.html' \-j LOG |
| .IP |
| # The hex string pattern can be used for non-printable characters, like |0D 0A| or |0D0A|. |
| .br |
| iptables \-p udp \-\-dport 53 \-m string \-\-algo bm \-\-from 40 \-\-to 57 \-\-hex\-string '|03|www|09|netfilter|03|org|00|' |
