[user-name]@git.drupal.org: Permission denied (publickey)

Question

I am trying to use git.drupal.org without success...

• I have uploaded my public key in the SSH keystab under my profile
• I have checked that the fingerprint on Drupal match my fingerprint in .ssh/id_rsa
• I have Filled in the Git access tab under my profile=> I got a username and I accepted the agreement

But when I run: GIT_SSH_COMMAND="ssh -vvv -p 22 -i /home/myname/.ssh/id_rsa -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null" git clone my_user_name@git.drupal.org:project/a_project.git

I got the following error: my_user_name@git.drupal.org: Permission denied (publickey).

Here is the output: (to anonymize the following, I replaced my Git user name by "my_user_name" and my computer User name by "myname")

OpenSSH_7.9p1 Ubuntu-10, OpenSSL 1.1.1b  26 Feb 2019
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolving "git.drupal.org" port 22
debug2: ssh_connect_direct
debug1: Connecting to git.drupal.org [140.211.10.58] port 22.
debug1: Connection established.
debug1: identity file /home/myname/.ssh/id_rsa type 0
debug1: identity file /home/myname/.ssh/id_rsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.9p1 Ubuntu-10
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.4p1 Debian-10+deb9u6
debug1: match: OpenSSH_7.4p1 Debian-10+deb9u6 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to git.drupal.org:22 as 'my_user_name'
debug3: hostkeys_foreach: reading file "/dev/null"
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com,zlib
debug2: compression stoc: none,zlib@openssh.com,zlib
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1
debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com
debug2: compression stoc: none,zlib@openssh.com
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
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
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:FeJiekFTTnXWc1GDUfFVcRckyZkZfdmks1dSqtS6OVg
debug3: hostkeys_foreach: reading file "/dev/null"
debug3: hostkeys_foreach: reading file "/dev/null"
Warning: Permanently added 'git.drupal.org,140.211.10.58' (ECDSA) to the list of known hosts.
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug1: Skipping ssh-dss key myname@mycomputer - not in PubkeyAcceptedKeyTypes
debug1: Will attempt key: /home/myname/.ssh/id_rsa RSA SHA256:J9ZRdKhvB9rfq/uchczwpi2CyvOqzktf9q+12AIetxE explicit agent
debug2: pubkey_prepare: done
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug3: start over, passed a different list publickey
debug3: preferred publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering public key: /home/myname/.ssh/id_rsa RSA SHA256:J9ZRdKhvB9rfq/uchczwpi2CyvOqzktf9q+12AIetxE explicit agent
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
my_user_name@git.drupal.org: Permission denied (publickey).
fatal: Could not read from remote repository.

Any hint?

`

Answer 1

Cloning a project as maintainer of that project is done using the following command.

git clone git@git.drupal.org:project/a_project.git

The username is always git.

As non-maintainer, the command to clone the project is the following.

git clone https://git.drupalcode.org/project/a_project.git

When I want to clone one of the projects hosted on drupal.org for which I am maintainer, I use the following command.

git clone drupal:project/a_project.git

In the .ssh/config file, I added the following lines.

Host drupal
   HostName git.drupal.org
   User git
   IdentityFile ~/.ssh/id_ed25519_drupal

In this way, the Git command is using the correct identity file, even if I have multiple identity files (for example, one for GitHub and one for Gitlab).

The Git command I reported to clone a project, as maintainer or not, is what the Version control tab of every project (for example https://www.drupal.org/project/drupal/git-instructions for Drupal, where you won't see the instructions for maintainers, if you aren't one of them).
What reported in Generating SSH keys (Linux) is outdated. Git Authentication for Drupal.org Projects has the most updated information. In particular, under Changing Git Remotes, it says:

If you are a maintainer who has an established Git remote in the format <username>@git.drupal.org:project/<yourproject>.git, the format should be changed to git@git.drupal.org:project/<yourproject>.git.