The keys work from config but not from ssh-add

Question

Ssh keys work fine, if indicated in ./ssh/config but if i try
$ssh-add mykey
Could not open a connection to your authentication agent even with ssh-add -l give the same result

Answer 1

ssh-add tries to add a key to the agent, but on your system no ssh-agent is running.

ssh has two different modes of working with keys. Either ssh is connecting to the agent and asking the agent to authenticate, or ssh is reading the key from disk.

As there is no agent running on your system the first mode is failing but the second one works, because there is no agent involved.

You can temporarily start an agent by ssh-agent bash. Afterwards ssh-add should work without problems.

Usually the agent is started with your desktop environment. If you are not using a desktop environment you have to make sure by yourself that an agent is running if you need it.

If you are connected to a remote host by ssh. Then you might want to transfer your local agent to the remote host. Use ssh -A if that is what you want.