ssh port forwarding suddenly stops working

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Environment

SUSE Linux Enterprise Server 12

SUSE Linux Enterprise Server 11

SUSE Linux Enterprise Desktop

Situation

ssh port forwarding has been working successfully for some time, with a command such as:

Executed on machine 10.1.2.99, by a process running as User1:

ssh -vvv -N -g -L 4001:10.1.2.3:2022 10.1.2.99

And is running as shown by:

# ps aux | grep ssh | grep User1

User1 9518 0.2 0.2 35044 2892 pts/3 S+ 14:25 0:00 ssh -vvv -N -g -L 4001:10.1.2.3:2022 10.1.2.99

This ssh session causes 10.1.2.99 port 4001 to be opened in listen mode, and any new traffic there will be forwarded to 10.1.2.3 port 2022.

This has been working for some time, yet now it fails. Within the debug logs for the ssh port forwarding session, the following is seen:

debug1: Connection to port 4001 forwarding to 10.1.2.3 port 2022 requested.
<snip>

channel 1: open failed: administratively prohibited: open failed

Resolution

User1's password had expired. Due to the way the processes were started, the port forwarding session was able to start and open port 4001, but no real use of the port forwarding could succeed.

Once the user account was reset and functional, and the ssh port forwarding session was killed and restarted, it worked again.

Disclaimer

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