é bom acrescentar essa regra

#Portas netbios
iptables -A FORWARD -p tcp --dport 135 -j DROP
iptables -A FORWARD -p udp --dport 135 -j DROP
iptables -A FORWARD -p udp --dport 137 -j DROP
iptables -A FORWARD -p udp --dport 138 -j DROP
iptables -A FORWARD -p tcp --dport 139 -j DROP
iptables -A FORWARD -p udp --dport 445 -j DROP
iptables -A FORWARD -p tcp --dport 445 -j DROP
iptables -A FORWARD -p tcp --dport 593 -j DROP

Abraços

Muganga
MSN: mugangalinux@hotmail.com
ICQ: 314528019