Wednesday, December 29, 2010

SMTP -- Configure a mail transfer agent (MTA) to accept inbound email from other systems

This is a simple one, by default postfix will accept only mail originating locally, and all it takes is updating a config file to change that.
  1. Install the necessary packages
    1. yum install postfix 
  2. Edit the /etc/postfix/main.cf file
    1. Find the line inet_interfaces = localhost and change it to inet_interfaces = all
  3. Restart the service
    1. service postfix restart
  4. Open the firewall
    1. iptables -I INPUT -p tcp --dport 25 -j ACCEPT
You should be able to test this by telnetting from a remote computer. If you receive a connection, your good to go.

3 comments:

Jk said...

Isn't it IPTABLES -A INPUT ....

Here you have not specified any line number!!!

Anonymous said...

@Jk

IPTABLES -A INPUT will place the rule at the bottom of the INPUT chain
whereas INPUT -I INPUT will place the rule at the top.

Anonymous said...

you are correct on iptables -I will place it at the top of the chain. However, it is recommended to set your policy to DROP [iptables -P INPUT DROP] and append (-A ) to that policy. By default iptables's policies are set to ACCEPT.