Hope anyone can help me with this. I have set up Suse 6.2 to act as our gateway to the internet for email and web access. I have enable IP_Masq and I have also closed of most ports (only 515 & 22 are currenlty open) any way if no other services are running on any other ports is it necessary to enable IP Chains.
From reading IP_Chains, IP_Masq and Firewall howto's there is usually only mention (that I can recall) of using IP_Chains to restrict access to certain ports.
Now if I don't have any ports open is it necessary to run IP_Chains, as from my understanding (or maybe lack of) if the service isn't running then you can't connect to it anyway. Is my thinking correct? Also on another note will I encounter any problems retrieving email using Exchange 5.5 (on NT 4.0) through the gateway. As what I understand is that SMTP works by 'forwarding' email to the recipient - how will the gateway be able to determine where to send it. (ATM using Sendmail or other derivative is not possible) I apologise if I haven't made a lot of sense or omitted anything, just trying to implement a better system as well as learn different (if not better) ways of doing things. Thanks, Mark