Feature that blocks outgoing port 25

[eduardosilva]

Hello,

I noticed that my server wasnt sending mails, and I started to check the possible causes.

I observed that there was a in the chain output from iptables blocking the destination port 25. I guess that this is part of something to avoid my server becoming a spammer, and probably this is an option that I enable and now it's not working fine.

For keep services working, i removed this rule from iptables, but I would like to know where should I fix it.

thanks.

[eth00]

Do you run a firewall script such as apf or csf?

Do you have the default redhat/centos firewall? (did you ever disable it?)

What datacenter are you in? There is a possibility they install a custom one on your server.

/etc/sysconfig/iptables

may give you some idea of what is going on and how you can fix it.

[eduardosilva]

Hello eth00, thanks for the input.

Answering your questions:
> I'm not running any custom firewall on this machine, just the default setup of cpanel.

> Centos firewall is disabled

> I'm on my own datacenter, the machines are provisioned by me.

My firewall device is over a separated hardware.

I think that after office hours, i will make a test and try a reboot to check if the rule will be on the firewall again.

Those where my only rules in the chain output:

pkts bytes target     prot opt in     out     source               destination         
ACCEPT     tcp  --  *      *       0.0.0.0/0            127.0.0.1           tcp dpt:25 
REJECT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0           tcp dpt:25 reject-with icmp-port-unreachable 
acctboth   all  --  *      *       0.0.0.0/0            0.0.0.0/0

(I removed the second line since i dont know what is it and was causing some problems)

Thanks