On 11/22/2010 10:43 AM, Les Mikesell wrote:
On 11/22/2010 9:11 AM, Robert Moskowitz wrote:
By default, sendmail only listens on the localloop:
DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl
But by default to allow sendmail to even work the iptables entry is:
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 25 -j ACCEPT
Without this, sendmail can't even connect to localloop. But should I handedit this line to something like:
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp -d 127.0.0.1 --dport 25 -j ACCEPT
And once you handedit iptables, you can't use the gnome firewall applet, I suspect...
Every security decision has its own tradeoffs, so first you need to consider what you are trying to protect against. If you don't have a program listening on a port, it doesn't matter whether it is explicitly firewalled or not. A program needs root access to listen on ports below 1024 - and anyone with root access can change the iptables settings too...
Ah, there is the combination I missed. I was concerned about sendmail doing what I thought it was suppose to do: only listen on loopback. If something could change that behaviour, it could also change any iptables settings.
I have 25 blocked on the firewall anyway. But just looking at the i(s) and t(s). (while trying not to stuff more angels on the pinhead or some such metaphor).