SSH Agent Forwarding not working

Question

I'm having an hard time trying to configure Capistrano 3.1 to deploy an app hosted on Github.

I'm following Capistrano Documentation and I have successfully completed the first step (SSH keys from workstation to servers) and on the second one (From our servers to the repository host) I'm able to successfully run ssh -A [email protected] 'git ls-remote [email protected]:my_user/my_repo.git':

18f38afz261df35d462f7f4e2ca847d22f148a06    HEAD 18f38afz261df35d462f7f4e2ca847d22f148a06    refs/heads/master 

however, ssh [email protected] 'git ls-remote [email protected]:my_user/my_repo.git' fails:

Permission denied (publickey). 

Capistrano docs suggests

If you get the error "host key verification failed." log in into your server and run as the deploy user the command ssh [email protected] to add github.com to the list of known hosts.

SO, I tried so but I get

ssh [email protected] Warning: Permanently added the RSA host key for IP address '192.30.252.131' to the list of known hosts. Permission denied (publickey). 

And I'm basically not able to successfully access the Github repo.

SSH documentation states:

-A      Enables forwarding of the authentication agent connection.  This          can also be specified on a per-host basis in a configuration          file. 

How can I specified on a per-host basis in a configuration file?

My local machine runs Mac OSX Mavericks. The VPS runs Ubuntu 12.04

Thanks.

Answer 1

Do you have your ssh key added to the list of agent identites ?

You can check with ssh-add -L , you should see the key your are using to connect to github :

$ ssh-add -L ssh-rsa AAAAB3N.....0VmSiRvTzBrbU0ww== /Users/youruser/.ssh/id_rsa 

If you don't see the ssh key you use for github or a message like

The agent has no identities.

Then you should add your key with :

ssh-add ~/.ssh/id_rsa 

(replace with the path to the key you use for github)

See the ssh-add doc for more info