GitLab SSH Keys - Permission denied (publickey) - ssh

Question

I followed this document to setup my SSH authentication https://kgcoe-git.rit.edu/help/ssh/README#generating-a-new-ssh-key-pair
It has worked before but this time on a new setup I get Permission denied (publickey) error
Below is the debug output from the ssh command
ankushko#node-0:~/Code$ sudo ssh -vT git#pc3.instageni.utc.edu
OpenSSH_7.2p2 Ubuntu-4ubuntu2.4, OpenSSL 1.0.2g 1 Mar 2016
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to pc3.instageni.utc.edu [150.182.135.23] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_rsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.4
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.4
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.4 pat OpenSSH* compat 0x04000000
debug1: Authenticating to pc3.instageni.utc.edu:22 as 'git'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256#libssh.org
debug1: kex: host key algorithm: rsa-sha2-512
debug1: kex: server->client cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ssh-rsa SHA256:BUPmhA1nWbH8Zq0cg4uohS3L/Vo4uOZ8PLrdUYf3ano
debug1: Host 'pc3.instageni.utc.edu' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/id_rsa
debug1: Trying private key: /root/.ssh/id_dsa
debug1: Trying private key: /root/.ssh/id_ecdsa
debug1: Trying private key: /root/.ssh/id_ed25519
debug1: No more authentication methods to try.
Permission denied (publickey).
Keys
ankushko#node-0:~$ sudo ls ~/.ssh/
authorized_keys id_rsa id_rsa.pub known_hosts
Update: Tried without sudo
ankushko#node-0:~$ ssh -vT git#pc3.instageni.utc.edu
OpenSSH_7.2p2 Ubuntu-4ubuntu2.4, OpenSSL 1.0.2g 1 Mar 2016
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to pc3.instageni.utc.edu [150.182.135.23] port 22.
debug1: Connection established.
debug1: identity file /users/ankushko/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /users/ankushko/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /users/ankushko/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /users/ankushko/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /users/ankushko/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /users/ankushko/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /users/ankushko/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /users/ankushko/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.4
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.4
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.4 pat OpenSSH* compat 0x04000000
debug1: Authenticating to pc3.instageni.utc.edu:22 as 'git'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256#libssh.org
debug1: kex: host key algorithm: rsa-sha2-512
debug1: kex: server->client cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ssh-rsa SHA256:BUPmhA1nWbH8Zq0cg4uohS3L/Vo4uOZ8PLrdUYf3ano
debug1: Host 'pc3.instageni.utc.edu' is known and matches the RSA host key.
debug1: Found key in /users/ankushko/.ssh/known_hosts:1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /users/ankushko/.ssh/id_rsa
debug1: Authentications that can continue: publickey
debug1: Trying private key: /users/ankushko/.ssh/id_dsa
debug1: Trying private key: /users/ankushko/.ssh/id_ecdsa
debug1: Trying private key: /users/ankushko/.ssh/id_ed25519
debug1: No more authentication methods to try.
Permission denied (publickey).
Thanks in advance.

Answer 1

I solved git#gitlab.com: Permission denied (publickey) issue by following these steps:
RUN cat ~/.ssh/id_rsa.pub
Copy id_rsa.pub (public key) to your getlab `Setting -> SSH Keys
RUN cat ~/.ssh/id_rsa
Copy id_rsa (private key) to `Code_repo->git_auth->id_rsa (private keys local file)
NOTE: Take care of the machine user if you are using root user in your DockerFile or anywhere else then use sudo su before running the above commands to get root user public and private keys.

Answer 2

The command:
sudo ssh -vT git#pc3.instageni.utc.edu
is running as root and will use /root/.ssh/config and a private ssh key from that same directory, e.g. /root/.ssh/id_rsa. In the command:
sudo ls ~/.ssh/
the shell, probably bash, will expand ~ to your home directory before it even calls sudo (prove this with sudo echo ~), so it will display files from your home directory, probably /home/ankushko.
Can I ask why you are running these command with sudo? Would it work to just connect as a normal user? That would be more secure, but sometimes there is a need to run things as root.
Either way, you need to make sure the private ssh key that you are actually using matches the public ssh key on the server.