I tried to use github so I followed the help doc. But when I used this command : ssh -vT git@github.com I got error like this:

jacos@Jing:~/.ssh$ ssh -vT git@github.com
OpenSSH_5.8p1 Debian-7ubuntu1, OpenSSL 1.0.0e 6 Sep 2011
debug1: Reading configuration data /home/jacos/.ssh/config
debug1: Applying options for github.com
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to ssh.github.com [] port 443.
debug1: Connection established.
debug1: identity file /home/jacos/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/jacos/.ssh/id_rsa-cert type -1
debug1: identity file /home/jacos/.ssh/id_dsa type -1
debug1: identity file /home/jacos/.ssh/id_dsa-cert type -1
debug1: identity file /home/jacos/.ssh/id_ecdsa type -1
debug1: identity file /home/jacos/.ssh/id_ecdsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.1p1 Debian-5github2
debug1: match: OpenSSH_5.1p1 Debian-5github2 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.8p1 Debian-7ubuntu1
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Server host key: RSA 16:27:ac:a5:76:28:2d:36:63:1b:56:4d:eb:df:a6:48
debug1: Host '[ssh.github.com]:443' is known and matches the RSA host key.
debug1: Found key in /home/jacos/.ssh/known_hosts:4
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/jacos/.ssh/id_rsa
debug1: Remote: Forced command: gerve gnijuohz 54:da:c2:c1:ca:4a:b9:4d:21:10:5b:42:3f:5a:8e:f7
debug1: Remote: Port forwarding disabled.
debug1: Remote: X11 forwarding disabled.
debug1: Remote: Agent forwarding disabled.
debug1: Remote: Pty allocation disabled.
debug1: Server accepts key: pkalg ssh-rsa blen 279
Agent admitted failure to sign using the key.
debug1: Trying private key: /home/jacos/.ssh/id_dsa
debug1: Trying private key: /home/jacos/.ssh/id_ecdsa
debug1: No more authentication methods to try.
Permission denied (publickey).

Agent admitted to sign using the key? No more authentication methods to try?

Can someone explain what's wrong here?



Searching google for "Agent admitted failure to sign using the key." suggests that logging out of your current session and then back in, or using ssh-add should solve the problem

Rationale: Ubuntu uses ssh-agent program:

 ssh-agent is a program to hold private keys used for public key authentication (RSA, DSA, ECDSA).  The idea
 is that ssh-agent is started in the beginning of an X-session or a login session, and all other windows or
 programs are started as clients to the ssh-agent program.  Through use of environment variables the agent can
 be located and automatically used for authentication when logging in to other machines using ssh(1).

If you just generated a key, ssh-agent does not know about it so it can't sign using the key - exactly what the error message says.

To add the key, you either need to restart ssh-agent (i.e. log out and log back in) or to use ssh-add to re-scan the keys.

See man ssh-add and man ssh-agent for more info

  • It works as Sergey explains and both solution are good. Thanks.
    – grosshat
    Jun 18 '12 at 16:32
  • No, Ubuntu doesn't uses ssh-agent. Instead it uses an alternate implementation of the SSH agent feature: gnome-keyring-daemon (which has its own issues)
    – dolmen
    Feb 19 '15 at 8:40

Did you properly set up git and the ssh keys. If not see here.

Taken from github:

This problem can also be caused when ssh cannot find your keys. Make sure your key is in the default location, ~/.ssh. If you run ssh-keygen again and just press enter at all 3 prompts it will be placed here automatically. Then you can add the contents of id_rsa.pub to your account. If id_rsa.pub doesn’t work try id_dsa.pub. You might need to generate a new dsa key with ssh-keygen -t dsa if you just have an rsa key.

P.S. Also sometimes the URL is typed wrong. URLs are case sensitive. Make sure to type them properly.

See this also.

  • Suggesting to create an SSH key without password is a very bad security advice.
    – dolmen
    Feb 19 '15 at 8:41

Use github-keygen for your SSH setup for Github: easy, powerful, safe and secure (more secure than what the official documentation recommends).

Disclaimer: I'm the author of this tool.

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