Red Hat Enterprise Linux 5 Administration Unleashed

Using IPTables Match Extensions 487markMatch the netfilter mark field of the packet.--mark /Define the mark value. The / is the option.mportMatch packets with specific source or destination ports. Must be used with the -ptcp or -p udp options. is a comma-separated list of port numbers.--source-ports Define source ports on which to match.--destination-ports Define destination ports on which to match.--ports Only match if source and destination ports match each other and are in thegiven list of ports.24nthMatch the nth packet.--every Match every nth packet.--counter Use specified counter. Must be from 0 to 15. Defaults to 0.--start Start counter at . Counter starts at 0 if not specified.--packet Match if packet number is .osfMatch data from SYN packet to OS fingerprints.--log If set to 0, log all determined entries. If set to 1, log only first determined entry.Logs are sent to syslog.--smartUse some smartness to determine remote OS. Use initial TTL only if connectionsource is in local network.--netlinkLog all events through netlink.--genre [!] stringMatch an OS genre by passive fingerprinting.