Ubuntu 16.04 ssh: sign_and_send_pubkey: signing failed: agent refused operation
Solution 1:
Looks like an ssh-agent is running already but it can not find any keys attached. To solve this add the private key identities to the authentication agent like so:
ssh-add
Then you can ssh into your server.
in addition, you can see the list of fingerprints of all identities currently added by:
ssh-add -l
Solution 2:
Simple Solution
I had the same problem on Ubuntu 18.04. That's all about client-side private key permissions.
$ ssh [email protected]
sign_and_send_pubkey: signing failed: agent refused operation
The file permissions were too open (0644).
The following command solved it:
chmod 600 ~/.ssh/id_rsa
Solution 3:
I had the same problem (same symptoms)
sam@xxxxx:~/.ssh$ ssh [email protected]
sign_and_send_pubkey: signing failed: agent refused operation
Permission denied (publickey,gssapi-keyex,gssapi-with-mic).
... but the solution was different.
The problem was coming from the use of GNOME-KEYRING. The post referring to the solution may be read here.
In short:
- Detect the problem by adding SSH_AUTH_SOCK=0 in front of the ssh command. sam@xxxxx:~/.ssh$ SSH_AUTH_SOCK=0 ssh [email protected]
- In case it succeed to connect. Open the application StartUp Application (by using the search function of the Desktop for example) and disable the use of gnome-keyring.
- Reboot
The page provide other details in case of similar problem with different solution.
Solution 4:
I was getting the sign_and_send_pubkey: signing failed: agent refused operation when logging into several servers and read VonC's answer on Stack Overflow for more information about related bugs. The solution for me was to remove gnome-keyring, delete identities from ssh-agent, and reboot.
sudo apt-get autoremove gnome-keyring
ssh-add -D
Then all my keys started to work perfectly.
Temporary solution without uninstalling keyring
If you want to keep the gnome-keyring on the local computer and you have the agent refused operation error, use:
eval `ssh-agent -s`
ssh-add
or use SSH_AUTH_SOCK=0 ssh your-server.
Permanent solution without uninstalling keyring
If you can, gnome-keyring is compatible with 4096 bit RSA key, so just generate a new key with:
ssh-keygen -t rsa -f ~/.ssh/your-key-name -b 4096 -v -C root
Upload public key to the server:
ssh-copy-id -i ~/.ssh/your-key-name.pub [email protected]
Add ssh key to the agent:
ssh-add ~/.ssh/your-key-name
This should work without any additional hacks and gnome-keyring can remain installed.
(The -C [username] is optional, but required by providers like Google Cloud.)
Solution 5:
After upgrading to Ubuntu 18.04 I got the same error sign_and_send_pubkey: signing failed: agent refused operation. Turns out it was caused by the permissions of the ssh key being too open.
The following command fixed the problem for me
chmod 600 .ssh/id_rsa