Hello Noman, Friday, December 23, 2005, 9:56:34 AM, you wrote: NL> [root@mail iptables-1.3.4]# iptables -A INPUT -p tcp NL> -m string --string "/bin/sh" -j DROP iptables v1.3.4: NL> STRING match: You must specify `--algo' NL> Try `iptables -h' or 'iptables --help' for more NL> information. You can use --algo bm for Boyer-Moore algorithm, or --algo kmp for Knuth-Pratt-Morris algorithm. -- Best regards, Oleg mailto:sysoleg@xxxxxxxxxxx