How do I identify which open ports are actually needed?

[mickeemuse]

I'm trying to reduce the attack surface of my network by closing as many ports as possible, I'm wondering how to identify the bare minimum amount of ports necessary so as to not disrupt the flow of network traffic.

 

[SkyNetRising]

It depends on software you're using, services provided to outside world.
If you don't know, what ports you need open, then you don't need any.

 

[nigelivey]

I wouldn't suggest closing 80 and 443!

 

[The Paladin]

to find out what ports are open on your router, check out this web site and run the scan on it.
http://www.ipfingerprints.com/portscan.php

 

[SkyNetRising]

I wouldn't suggest closing 80 and 443!

If you're not hosting a web server, then there's no need to have these ports open.
If those ports are forwarded to router itself, then this gives access to router configuration page for all the outside world.

 

[nigelivey]

I wouldn't suggest closing 80 and 443!

If you're not hosting a web server, then there's no need to have these ports open.
If those ports are forwarded to router itself, then this gives access to router configuration page for all the outside world.

Also depends on the level of your firewall, closing outbound ports??