iptables firewall

If someone has a minute and knows this stuff I could really use some help.

I am constructing a firewall and so far it seems perfectly fine with one exception: when it is up and running mail stops coming in or out.

Here is the firewall config, I know fancy fancy articles "have rules for in and out and forward chains redirecting to tables and blah blah blah / dam it has to be simplier", however for now i just want to make one using ony simple iptables config.

Code: 
*filter
:INPUT ACCEPT [3034524:360618404]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [5624541:7189514591]
-A INPUT -i eth0 -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 25 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 21 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 20 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 80 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 8080 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 53 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 110 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 143 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 443 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 10000 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 20000 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 5000:5050 -j ACCEPT
-A INPUT -i eth0 -p udp -m udp --dport 53 -j ACCEPT
-A INPUT -i eth0 -p udp -m udp --dport 25 -j ACCEPT
-A INPUT -i eth0 -p udp -m udp --dport 67 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp -j DROP
-A INPUT -i eth0 -p udp -m udp -j DROP
COMMIT
Additionally when this is running there seems to be a performance loss on the network itself. Like when I pop3 in it takes a while or ssh in it takes a while, to establish connections.

Its a redhat 9 box.

5000-5050 are for ftp passsive ports.

I just simply want to make all ports blocked except those I need.

Any internal lo -> lo traffic is good.

Any outgoing yes is fine. I want to keep them out but I don't want to keep me in iptables firewall

Any pointers?

Thank you very much in advance...

- R

 

 

 

 

Top