How to disable sendmail listening on port 25

May 21, 2014 5.1k views
jason.chancellor
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jason.chancellor
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
asb MOD May 21, 2014
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:

https://www.digitalocean.com/community/articles/how-to-setup-a-firewall-with-ufw-on-an-ubuntu-and-debian-cloud-server
How To Setup a Firewall with UFW on an Ubuntu and Debian Cloud Server
by Shaun Lewis
Learn how to setup a firewall with UFW on an Ubuntu / Debian cloud server.
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jason.chancellor May 21, 2014
This is exactly what I needed. Thank you!
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