Re: Blocking SMB

[Medovarszky Zoltán <igor@prnt.hu>]

>     I am in trying to set up firewall on a machine running debian. What i
> want to do is to block people browsing smb shares on my network from
> outside. How can i do this? What ports does smb use?

Ports 137 - 139 tcp and udp,

It is safer to enable certain ports and disabling all other, than disabling
certain ports and enabling all oteher.

you also need to block smb going out from windoze machines:

iptables -A FORWARD -o externalinterface -p tcp --dport 137 -j REJECT
iptables -A FORWARD -o externalinterface -p tcp --dport 138 -j REJECT
iptables -A FORWARD -o externalinterface -p tcp --dport 139 -j REJECT

iptables -A FORWARD -o externalinterface -p udp --dport 137 -j REJECT
iptables -A FORWARD -o externalinterface -p udp --dport 138 -j REJECT
iptables -A FORWARD -o externalinterface -p udp --dport 139 -j REJECT


Medovarszky Zoltan