Question

Cannot connect with public key

I have been combing through stack exchange, ubuntu’s forums, and digital ocean, but I can’t seem to find out why I cannot connect to my server.

It’s been almost a year since I’ve been on it, I never had any problems until yesterday. I tried to connect via ssh and it didn’t work, so I decided to generate a new ssh key and add it in the security section.

After failing again with the newly generated key, I went to the web console and looked in authorized_keys, only to find that it hadn’t updated. I was able to copy about half my public key into the authorized_keys file and then I had to do it by hand because the characters began changing.

This Failed once again, below is the output of ssh -vvv user@IP

OpenSSH_7.6p1, LibreSSL 2.6.2 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 48: Applying options for * debug1: /etc/ssh/ssh_config line 52: Applying options for * debug2: ssh_connect_direct: needpriv 0 debug1: Connecting to 45.55.137.106 port 22. debug1: Connection established. debug1: identity file /Users/brendan/.ssh/id_rsa type 0 debug1: key_load_public: No such file or directory debug1: identity file /Users/brendan/.ssh/id_rsa-cert type -1 debug1: key_load_public: No such file or directory debug1: identity file /Users/brendan/.ssh/id_dsa type -1 debug1: key_load_public: No such file or directory debug1: identity file /Users/brendan/.ssh/id_dsa-cert type -1 debug1: key_load_public: No such file or directory debug1: identity file /Users/brendan/.ssh/id_ecdsa type -1 debug1: key_load_public: No such file or directory debug1: identity file /Users/brendan/.ssh/id_ecdsa-cert type -1 debug1: key_load_public: No such file or directory debug1: identity file /Users/brendan/.ssh/id_ed25519 type -1 debug1: key_load_public: No such file or directory debug1: identity file /Users/brendan/.ssh/id_ed25519-cert type -1 debug1: Local version string SSH-2.0-OpenSSH_7.6 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 debug3: fd 5 is O_NONBLOCK debug1: Authenticating to 45.55.137.106:22 as ‘root’ debug3: hostkeys_foreach: reading file “/Users/brendan/.ssh/known_hosts” debug3: record_hostkey: found key type ECDSA in file /Users/brendan/.ssh/known_hosts:4 debug3: load_hostkeys: loaded 1 keys from 45.55.137.106 debug3: order_hostkeyalgs: prefer hostkeyalgs: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521 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: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,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@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-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@libssh.org 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:CEfnZqyzQNOLTJXYcAeA+HnbiAeEKuVxn2iwW395O10 debug3: hostkeys_foreach: reading file “/Users/brendan/.ssh/known_hosts” debug3: record_hostkey: found key type ECDSA in file /Users/brendan/.ssh/known_hosts:4 debug3: load_hostkeys: loaded 1 keys from 45.55.137.106 debug1: Host ‘45.55.137.106’ is known and matches the ECDSA host key. debug1: Found key in /Users/brendan/.ssh/known_hosts:4 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: /Users/brendan/.ssh/id_rsa (0x7f8c226015d0) debug2: key: /Users/brendan/.ssh/id_dsa (0x0) debug2: key: /Users/brendan/.ssh/id_ecdsa (0x0) debug2: key: /Users/brendan/.ssh/id_ed25519 (0x0) debug3: send packet: type 5 debug3: receive packet: type 7 debug1: SSH2_MSG_EXT_INFO received debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512> 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: RSA SHA256:ho8g2Zv19llDRt8FMoR96YyncSO521zKT7bEvaNlP4k /Users/brendan/.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: /Users/brendan/.ssh/id_dsa debug3: no such identity: /Users/brendan/.ssh/id_dsa: No such file or directory debug1: Trying private key: /Users/brendan/.ssh/id_ecdsa debug3: no such identity: /Users/brendan/.ssh/id_ecdsa: No such file or directory debug1: Trying private key: /Users/brendan/.ssh/id_ed25519 debug3: no such identity: /Users/brendan/.ssh/id_ed25519: No such file or directory debug2: we did not send a packet, disable method debug1: No more authentication methods to try. root@45.55.137.106: Permission denied (publickey).

Can someone please help me parse through this error so we can at least get a little closer to a solution?

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Same Error, it looks like they remove the underscores from the post by the way.

Hey friend!

While there are other things that can cause this, the most likely is just that your private key is not a matching pair with anything in authorized_keys for the user/server you are attempting to log in to. Given that you just created new keys and manually entered the public key from the console, I would suggest a typo is far easier to make than see afterward. I could be wrong, I’m just trying to deal in most likely given the variables.

It’s interesting that characters kept changing for you. That was when you were pasting in our console? Paste is a new feature there, so I’m on the lookout for any situations to look over.

In the meantime I would perhaps enable password login to SSH via the console, restart the SSH server, then log in and paste in your public key to authorized_keys from your SSH client. If it still occurs, then we know the problem is related to keys but unlikely to be a case of mismatched pair.

Jarland