Port expression or the keyword 'any'. A port expressions is structured as 'port' (default), 'op port' or 'port1 op port2', where 'op' is a mathematical operator for: o equal (default) = o unequal != o less than < o less than or equal <= o greater than > o greater than or equal to >= o outside range <> o inside range >< The port must be specified as a decimal number or one of the aliases: o tcp/udp: echo (7) o tcp/udp: discard, sink, null (9) o tcp: ftp-data (20) o tcp: ftp (21) o tcp/udp: ssh (22) o tcp: telnet (23) o tcp/udp: domain, nameserver (53) o tcp/udp: bootps (67) o tcp/udp: bootpc (68) o udp: tftp (69) o tcp/udp: www, http (80) o tcp/udp: kerberos, krb5 (88) o tcp: sftp (115) o tcp/udp: ntp (123) o udp: snmp (161) o udp: snmp-trap, snmptrap (162) o tcp/udp: bgp (179) o tcp/udp: ldap (389) o tcp/udp: https (443) For ICMP only: ICMP type and code can be specified as: o 'type <i>' o 'type <i> code <j>' where <i> and <j> are decimal numbers (0..255).