Issue
I am trying to set up an ssh key on my github account, but it is continually rejected by the github server. My client is an Ubuntu based system.
On Ubuntu, I created a public and private key, stored in ~/.ssh/id_rsa and ~/.ssh/id_rsa.pub. Permissions for ~/.ssh are 700, for id_rsa are 600, and for id_rsa.pub are 644.
When I created the key (on Ubuntu, with ssh-keygen) the sha256 fingerprint computed and displayed by ssh-keygen matches exactly the fingerprint displayed in my github account (settings > account settings > SSH and GPG keys) for that key after I've pasted it into github and clicked on [Save]. Therefore, I am certain the public key I stored in github was correctly pasted and stored in my github account.
Nevertheless, when I attempt to ssh to github I get permission denied. So I increased the logging level from the client ssh application and have pasted the output below.
The command I issued was...
ssh -vvv -T [email protected]
Looking through the debug output, I see two clues ...
debug1: Remote protocol version 2.0, remote software version babeld-0843ac0d
debug1: no match: babeld-0843ac0d
... which seems to be telling me that the ssh daemon on github is not one that my Ubuntu ssh client knows about. I am not sure how much of an issue this is. My guess is that it is merely a warning. FWIW, it does report ssh protocol 2.0 - which is the same protocol version being used by my Ubuntu client.
A much more significant log entry is this...
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
... packet type '51' is defined as SSH_MSG_USERAUTH_FAILURE (per IANA SSH List).
That is certainly significant! However, it only tells us that github did not like our key for some reason. It does NOT explain why it did not like our key.
I've been unable to progress any further. I keep hitting a brick was at this point. I cannot understand why github is rejecting this key. It's fingerprint matches exactly the value displayed by ssh-keygen.
So that's where I'm at. I've seen similar questions here ... but no solutions. My hope is that by supplying the debug output someone might have a clue.
Here is the complete debug output...
% ssh -vvvT [email protected]
OpenSSH_8.2p1 Ubuntu-4ubuntu0.2, OpenSSL 1.1.1f 31 Mar 2020
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug2: resolving "github.com" port 22
debug2: ssh_connect_direct
debug1: Connecting to github.com [140.82.113.3] port 22.
debug1: Connection established.
debug1: identity file /home/zzzzz60/.ssh/id_rsa type 0
debug1: identity file /home/zzzzz60/.ssh/id_rsa-cert type -1
debug1: identity file /home/zzzzz60/.ssh/id_dsa type -1
debug1: identity file /home/zzzzz60/.ssh/id_dsa-cert type -1
debug1: identity file /home/zzzzz60/.ssh/id_ecdsa type -1
debug1: identity file /home/zzzzz60/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/zzzzz60/.ssh/id_ecdsa_sk type -1
debug1: identity file /home/zzzzz60/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /home/zzzzz60/.ssh/id_ed25519 type -1
debug1: identity file /home/zzzzz60/.ssh/id_ed25519-cert type -1
debug1: identity file /home/zzzzz60/.ssh/id_ed25519_sk type -1
debug1: identity file /home/zzzzz60/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /home/zzzzz60/.ssh/id_xmss type -1
debug1: identity file /home/zzzzz60/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.2p1 Ubuntu-4ubuntu0.2
debug1: Remote protocol version 2.0, remote software version babeld-0843ac0d
debug1: no match: babeld-0843ac0d
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to github.com:22 as 'zzzzz60'
debug3: hostkeys_foreach: reading file "/home/zzzzz60/.ssh/known_hosts"
debug3: record_hostkey: found key type RSA in file /home/zzzzz60/.ssh/known_hosts:4
debug3: load_hostkeys: loaded 1 keys from github.com
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],[email protected],rsa-sha2-512,rsa-sha2-256,ssh-rsa
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,[email protected],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,ext-info-c
debug2: host key algorithms: [email protected],[email protected],[email protected],rsa-sha2-512,rsa-sha2-256,ssh-rsa,[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],ssh-ed25519,[email protected]
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected],zlib
debug2: compression stoc: none,[email protected],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,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256
debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ssh-dss
debug2: ciphers ctos: [email protected],[email protected],[email protected],aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc
debug2: ciphers stoc: [email protected],[email protected],[email protected],aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc
debug2: MACs ctos: [email protected],[email protected],hmac-sha2-512,hmac-sha2-256,[email protected],hmac-sha1
debug2: MACs stoc: [email protected],[email protected],hmac-sha2-512,hmac-sha2-256,[email protected],hmac-sha1
debug2: compression ctos: none
debug2: compression stoc: none
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: rsa-sha2-512
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] 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: ssh-rsa SHA256:nThbg6kXUpJWGl7E1IGOCspRomTxdCARLviKw6E5SY8
debug3: hostkeys_foreach: reading file "/home/zzzzz60/.ssh/known_hosts"
debug3: record_hostkey: found key type RSA in file /home/zzzzz60/.ssh/known_hosts:4
debug3: load_hostkeys: loaded 1 keys from github.com
debug3: hostkeys_foreach: reading file "/home/zzzzz60/.ssh/known_hosts"
debug1: Host 'github.com' is known and matches the RSA host key.
debug1: Found key in /home/zzzzz60/.ssh/known_hosts:4
Warning: Permanently added the RSA host key for IP address '140.82.113.3' to the list of known hosts.
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey out 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 in after 134217728 blocks
debug1: Will attempt key: /home/zzzzz60/.ssh/id_rsa RSA SHA256:zj5+CcvII4ZfOQhehs+eVrAI6bO19QBOYUKpnJteanM agent
debug1: Will attempt key: /home/zzzzz60/.ssh/id_dsa
debug1: Will attempt key: /home/zzzzz60/.ssh/id_ecdsa
debug1: Will attempt key: /home/zzzzz60/.ssh/id_ecdsa_sk
debug1: Will attempt key: /home/zzzzz60/.ssh/id_ed25519
debug1: Will attempt key: /home/zzzzz60/.ssh/id_ed25519_sk
debug1: Will attempt key: /home/zzzzz60/.ssh/id_xmss
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=<[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],ssh-ed25519,ecdsa-sha2-nistp521,ecdsa-sha2-nistp384,ecdsa-sha2-nistp256,rsa-sha2-512,rsa-sha2-256,ssh-rsa,ssh-dss>
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 gssapi-with-mic,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/zzzzz60/.ssh/id_rsa RSA SHA256:zj5+CcvII4ZfOQhehs+eVrAI6bO19QBOYUKpnJteanM 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
debug1: Trying private key: /home/zzzzz60/.ssh/id_dsa
debug3: no such identity: /home/zzzzz60/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/zzzzz60/.ssh/id_ecdsa
debug3: no such identity: /home/zzzzz60/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/zzzzz60/.ssh/id_ecdsa_sk
debug3: no such identity: /home/zzzzz60/.ssh/id_ecdsa_sk: No such file or directory
debug1: Trying private key: /home/zzzzz60/.ssh/id_ed25519
debug3: no such identity: /home/zzzzz60/.ssh/id_ed25519: No such file or directory
debug1: Trying private key: /home/zzzzz60/.ssh/id_ed25519_sk
debug3: no such identity: /home/zzzzz60/.ssh/id_ed25519_sk: No such file or directory
debug1: Trying private key: /home/zzzzz60/.ssh/id_xmss
debug3: no such identity: /home/zzzzz60/.ssh/id_xmss: No such file or directory
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
[email protected]: Permission denied (publickey).
Solution
The problem is the username. For GitHub, all SSH operations work over the git username and you're identified solely by your key. So you'd need to do ssh -vvv -T [email protected].
It is the case that OpenSSH doesn't know specifically about babeld, the SSH service on GitHub, but it should work fine nevertheless. OpenSSH knows about some particular SSH servers in order to apply workarounds for broken behavior (such as an incompatible implementation of [email protected] in some older OpenSSH versions), but babeld doesn't have those problems, so that means it should work just fine.
Answered By - bk2204 Answer Checked By - Senaida (WPSolving Volunteer)