Block connections from specific IP range

[sdotsen]

So we opened up port 25 for our mail server. I ran "lsof -i TCP:25 -n" and found atleast 60+ connections to other servers. Because of this, our mail server isn't able to send emails to external domains. I verify this by killing the PID of connection, but seconds later they reappear. During this 3-5 second span, my emails that were in queue were sent out. Anyways, I think there's a setting in the oracle install that will accommodate these additional connections but I would also like to know so that I can block them if possible. I have iptables enabled but the same IPs keep showing up!

essmo 7110 applmail 185u IPv4 410413 TCP 192.168.10.31:3030->168.95.5.44:smtp (SYN_SENT)
essmo 7110 applmail 186u IPv4 411288 TCP 192.168.10.31:3312->168.95.6.180:smtp (SYN_SENT)
essmo 7110 applmail 189u IPv4 410424 TCP 192.168.10.31:3033->168.95.5.28:smtp (SYN_SENT)

IPTABLES OUTPUT

-A OUTPUT -d 168.95.6.0/255.255.255.0 -j DROP
-A OUTPUT -d 168.95.5.0/255.255.255.0 -j DROP
-A OUTPUT -d 168.95.4.0/255.255.255.0 -j DROP

[spinnerdog]

try something like this from the command line. if it works then add it /etc/sysconfig/iptables
-A INPUT -s 168.95.5.0/255.255.255.0 -i eth0 -p tcp -m tcp --dport 25 -j REJECT --reject-with icmp-port-unreachable

[spinnerdog]

don't forget to call iptables when trying from the command line

/sbin/iptables -A INPUT -s 66.0.0.0/255.0.0.0 -i eth0 -p tcp -m tcp --dport 22 -j REJECT --reject-with icmp-port-unreachable