1This modules matches a given string by using some pattern matching strategy. It requires a linux kernel >= 2.6.14. 2.TP 3\fB\-\-algo\fP {\fBbm\fP|\fBkmp\fP} 4Select the pattern matching strategy. (bm = Boyer-Moore, kmp = Knuth-Pratt-Morris) 5.TP 6\fB\-\-from\fP \fIoffset\fP 7Set the offset from which it starts looking for any matching. If not passed, default is 0. 8.TP 9\fB\-\-to\fP \fIoffset\fP 10Set the offset up to which should be scanned. That is, byte \fIoffset\fP-1 11(counting from 0) is the last one that is scanned. 12If not passed, default is the packet size. 13.TP 14[\fB!\fP] \fB\-\-string\fP \fIpattern\fP 15Matches the given pattern. 16.TP 17[\fB!\fP] \fB\-\-hex\-string\fP \fIpattern\fP 18Matches the given pattern in hex notation. 19.TP 20\fB\-\-icase\fP 21Ignore case when searching. 22.TP 23Examples: 24.IP 25# The string pattern can be used for simple text characters. 26.br 27iptables \-A INPUT \-p tcp \-\-dport 80 \-m string \-\-algo bm \-\-string 'GET /index.html' \-j LOG 28.IP 29# The hex string pattern can be used for non-printable characters, like |0D 0A| or |0D0A|. 30.br 31iptables \-p udp \-\-dport 53 \-m string \-\-algo bm \-\-from 40 \-\-to 57 \-\-hex\-string '|03|www|09|netfilter|03|org|00|' 32