Git over ssh: Permission denied public key

Question

I have a problem with cloning public git repositories. My .ssh folder looks like this:

XXXXXX@XXXXXXXX:~/.ssh$ ls -ll
-rw------- 1 XXXXX XXXXX  398 Mar 17 10:03 authorized_keys
-rw-rw-r-- 1 XXXXX XXXXX  182 Mar 21 12:06 config
-rw------- 1 XXXXX XXXXX 3243 Mar 21 10:42 id_rsa
-rw-r--r-- 1 XXXXX XXXXX  745 Mar 21 10:42 id_rsa.pub
-rw------- 1 XXXXX XXXXX 1376 Mar 19 12:21 known_hosts

The output of the ssh connection test looks like this:

XXXXXXXX@XXXXXXXXXXXXx:~/.ssh$ ssh -Tvvvv git@github.com
OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n  7 Dec 2017
debug1: Reading configuration data /home/XXXXXXXX/.ssh/config
debug1: /home/XXXXXXXX/.ssh/config line 2: Applying options for *
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Executing proxy command: exec connect -H XX.X.XX.XX:8080 github.com 22
debug1: permanently_drop_suid: 1000
debug1: identity file /home/XXXXXXXX/.ssh/id_rsa type 0
debug1: key_load_public: No such file or directory
debug1: identity file /home/XXXXXXXX/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/XXXXXXXX/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/XXXXXXXX/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/XXXXXXXX/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/XXXXXXXX/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/XXXXXXXX/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/XXXXXXXX/.ssh/id_ed25519-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
debug1: Remote protocol version 2.0, remote software version babeld-d48c3acd
debug1: no match: babeld-d48c3acd
debug2: fd 5 setting O_NONBLOCK
debug2: fd 4 setting O_NONBLOCK
debug1: Authenticating to github.com:22 as 'git'
debug3: hostkeys_foreach: reading file "/home/XXXXXXXX/.ssh/known_hosts"
debug3: record_hostkey: found key type RSA in file /home/XXXXXXXX/.ssh/known_hosts:2
debug3: load_hostkeys: loaded 1 keys from github.com
debug3: order_hostkeyalgs: prefer hostkeyalgs: ssh-rsa-cert-v01@openssh.com,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,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-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: ssh-rsa-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-256,ssh-rsa,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,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,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,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
debug2: host key algorithms: ssh-dss,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc
debug2: MACs ctos: hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib,zlib@openssh.com
debug2: compression stoc: none,zlib,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: 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
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ssh-rsa SHA256:nThbk6kXUpJWGl7E1IUOCspRomTxdCARLwiKw6E5SY8
debug3: hostkeys_foreach: reading file "/home/XXXXXXXX/.ssh/known_hosts"
debug3: record_hostkey: found key type RSA in file /home/XXXXXXXX/.ssh/known_hosts:2
debug3: load_hostkeys: loaded 1 keys from github.com
debug1: Host 'github.com' is known and matches the RSA host key.
debug1: Found key in /home/XXXXXXXX/.ssh/known_hosts:2
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
debug2: key: /home/XXXXXXXX/.ssh/id_rsa (0x5627d1404e70), agent
debug2: key: /home/XXXXXXXX/.ssh/id_dsa ((nil))
debug2: key: /home/XXXXXXXX/.ssh/id_ecdsa ((nil))
debug2: key: /home/XXXXXXXX/.ssh/id_ed25519 ((nil))
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,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-rsa,rsa-sha2-512,rsa-sha2-256,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-keyex,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: RSA SHA256:fqtAIC3IejKfEAqUy34hBKy0EnLOnMxQ/5wbGgqFGOk /home/XXXXXXXX/.ssh/id_rsa
debug3: send_pubkey_test
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/XXXXXXXX/.ssh/id_dsa
debug3: no such identity: /home/XXXXXXXX/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/XXXXXXXX/.ssh/id_ecdsa
debug3: no such identity: /home/XXXXXXXX/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/XXXXXXXX/.ssh/id_ed25519
debug3: no such identity: /home/XXXXXXXX/.ssh/id_ed25519: No such file or directory
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
git@github.com: Permission denied (publickey).

The keys were generated using:

ssh-keygen -t rsa -b 4096 -C "XXXX@XXXX.com"

I also walked through this github help page ( https://help.github.com/en/github/authenticating-to-github/error-permission-denied-publickey ):

XXXXX@XXXXXX:~/.ssh$ eval $(ssh-agent -s)
Agent pid 21483
XXXXX@XXXXXX:~/.ssh$ ssh-add -l
The agent has no identities.
XXXXX@XXXXXX:~/.ssh$ ssh-add id_rsa
Identity added: id_rsa (id_rsa)
XXXXX@XXXXXX:~/.ssh$ ssh-add -l
4096 SHA256:fqtCIk3IDjkOEBqUp34hsKy0EnLOnNZQ/5wMXjqFgOk id_rsa (RSA)

I also tried https://stackoverflow.com/a/38144090/6228450 (restart ssh afterwards). Does not work either.

Anybody have another idea what the issue is?

Answer 1

Tty and recreate one:

• with the old format
• without passphrase (for at least testing)

That is:

ssh-keygen -t rsa -m PEM -P "" -C "XXXX@XXXX.com"

Do copy the ~/.ssh/id_rsa.pub public key to your GitHub SSH keys setting page.