Finalmente sono riuscito a bloccare Msn Messenger sul firewall
Quel maledetto usa tutti i trucchi possibili per uscire, usando anche la porta 80 e bypassando ogni regola del firewall, ma io l'ho ammazzato il bastardo!
iptables -I OUTPUT -d messenger.hotmail.com -p tcp -j DROP
iptables -I OUTPUT -d webmessenger.msn.com -p tcp -j DROP
iptables -I OUTPUT -d hotmail.com -p tcp -j DROP
iptables -I OUTPUT -d msn.com -p tcp -j DROP
iptables -I FORWARD -p tcp --dport 1863 -j DROP
iptables -I INPUT -s 207.46.0.0/16 -j DROP
iptables -I INPUT -s 207.68.0.0/16 -j DROP
iptables -I INPUT -s 213.199.154.54 -j DROP
iptables -I INPUT -s 216.178.160.34 -j DROP
iptables -I INPUT -s 207.68.178.239 -j DROP
iptables -I INPUT -s 194.130.106.132 -j DROP
iptables -I INPUT -s 195.33.103.52 -j DROP
iptables -I INPUT -s 213.199.154.11 -j DROP
iptables -I INPUT -s 213.249.102.94 -j DROP
iptables -I FORWARD -s 207.46.0.0/16 -j DROP
iptables -I FORWARD -s 207.68.0.0/16 -j DROP
iptables -I FORWARD -d 64.4.13.0/18 -j DROP
iptables -I FORWARD -d 64.12.163.0/24 -j DROP
iptables -I FORWARD -d 65.54.0.0/16 -j DROP
iptables -I FORWARD -d 66.35.250.0/24 -j DROP