networking options中 [*] network firewalls [*] ip: advanced router [*] ip: firewalling [*] ip: firewall packet netlink device [*] ip: transparent proxy support [*] ip: masquerading [*] ip: icmp masquerading [*] ip: masquerading special modules support ip: ipautofw masq support (experimental) ip: ipportfw masq support (experimental) ip: ip fwmark masq-forwarding support (experimental) [*] ip: masquerading virtual server support (experimental) (12) ip masquerading vs table size (the nth power of 2)