UPDATE: I started with kernel 2.6.35.4 #2 and lsmod | grep ipt = ipt_LOG 5419 2. My service provider produced a replacement kernel 2.6.24-28-xen #1. Now lsmod | grep ipt reveals ...... ipt_LOG 8192 2 iptable_filter 4608 1 ip_tables 24232 1 iptable_filter x_tables 23432 5 xt_string,ipt_LOG,xt_state,xt_tcpudp,ip_tables and, to my personal joy and pleasure, iptables -A XXXX -p tcp -m string --algo bm --string 'login' -j DROP is accepted by IP Tables. Thank you to everyone who contributed to this thread. With best regards, Paul.