How to disable sendmail listening on port 25

Posted May 21, 2014 6.6k views
I only use my LAMP based setup to send outbound mail and have another mail server to handle inbound mail. I wanted to understand (for security reasons) how I could disable sendmail listening on port 25. I'm running the LAMP image: Ubuntu Sendmail 8.14

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2 answers
Hey Jason,

You could setup default firewall rules that allow outgoing connections, but not incoming ones. Assuming you need ports 22 and 80 open, it's as simple as:

ufw default deny incoming
ufw default allow outgoing
ufw allow ssh
ufw allow http
ufw enable

Check out this article for more info on using ufw to setup firewall rules:
by Shaun Lewis
Learn how to setup a firewall with UFW on an Ubuntu / Debian cloud server.
This is exactly what I needed. Thank you!