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Nille-asFlag for United States of America asked on

How do I open for port 22 trough firewall.

I have a Cisco firewall, and using nat. I have an official internet adress on the outside interface, and a Ubuntu server on the inside interface. I have configured NAT and security rules.

Problem is. When I open port 80 I am able to connect to the Ubuntu machine from outside. However, when I try port 22 ( SSH ) it will not pass trough. If I move the Ubuntu machine to a DMZ all ports work. IT seems that the lower ports on the inside interface is blocked whatever I try to do.

Need help to enable port on port 22 on the inside interface.
Linux DistributionsCiscoSSH / Telnet Software

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8/22/2022 - Mon


read through the pages, it takes you step by step. Enjoy =)

Thanks for the reply. :)

I am not looking for how to enable ssh on the firewall itself. I am looking for a solution how to let the firewall open up for trafic on port 22 from outside to inside interface. I am able to open a lot of ports, but not port 22. It seems there is a default setting on the inside interface to make it more secure, and even if I open port 22 on the security rule, it will not let it trough to the server on the inside interface.

I want to use ssh from a outside computer to a Ubuntu server on the corp network. It is not an option to have the server on a DMZ.

For an even more secure solution, why not setup your own personal VPN connection, enable port 22 on the inside of the firewall, tunnel in and SSH from inside. A Much more secure Idea than opening up a server to brute force and the likes.
Your help has saved me hundreds of hours of internet surfing.

If you setup up an access-list and the according static, there shouldn't be a reason for it not to work.

While xxx.xxx.xxx.xxx is your outside ip and yyy.yyy.yyy.yyy is your inside hosts ip.

access-list from_outside extended permit tcp any host xxx.xxx.xxx.xxx eq ssh
access-group from_ouside in interface outside
static (inside,outside) tcp xxx.xxx.xxx.xxx ssh yyy.yyy.yyy.yyy ssh netmask

I would also check if there's any fixup configured...

Does your firewall allow UPnP?   This is how I made something similar work for me.  Just setting this option to true on the firewall.  As I understand it, it will open ports for services that are signaling that they are awaiting something from the internal side.  We used smoothwall at my former work.  It was a checkbox in there.

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