Ubuntu 14.04 SSH bug for “Agent admitted failure to sign using the key”

For the past few weeks I’ve had problems logging into servers using my SSH keys from Ubuntu desktops. The following would happen each time:

[chris@work ~] sshserverAgentadmittedfailuretosignusingthekey.Permissiondenied(publickey).[chris@work ]
Oddly, this only happened from my Ubuntu desktop systems. My Ubuntu servers had no issue connecting.

After some digging, I found out that issues with the gnome-keyring were at fault. gnome-keyring doesn’t always handle specific formats of SSH keys correctly. Unfortunately, gnome-keyring was trying to handle all SSH key usage, preventing the keys from working.

If you are having this issue, you can confirm that gnome-keyring is at fault on your system by added SSH_AUTH_SOCK=0 in front of the ssh command as follows:

[chris@work ~]$ SSH_AUTH_SOCK=0 ssh server
Welcome to Ubuntu 14.10 (GNU/Linux 3.13.0-37-generic x86_64)

• Documentation: https://help.ubuntu.com/

0 packages can be updated.
0 updates are security updates.

Last login: Wed Mar 11 11:49:50 2015 from host
[chris@work ~]$
If the connection works, then you likely have the same problem that I had. If the connection does not work, please read the Fixing other sources of agent failure section below for further ideas to fix your problem.