It seems the helper match shouldn't succeed if the strings being compared aren't the same length. For example, both of these nat rules match the helper connections if I start an FTP session on master port 212 with FTP conntrack configured to support both ports: -A PREROUTING -p tcp -m state --state RELATED -m helper --helper "ftp-212" -A PREROUTING -p tcp -m state --state RELATED -m helper --helper "ftp-2122" because the strncmp is just using the length of the helper. Is this by design? Thanks Brian -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html