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How to block port 25

If you are not sending email from your VPS, you may want to block access to port 25. This can help prevent spam from being sent from your server.

The steps may very slightly depending on the Linux type that you are using, however the general steps will be the same. In this example we will use CentOS.

Step 1: Add iptables rules to Drop port 25

iptables -A INPUT -p tcp --dport 25 -j DROP
iptables -A OUTPUT -p tcp --dport 25 -j DROP

Step 2: Save iptables rules

service iptables save

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