Mdthbs

$ ssh mykey.pem ubuntu@10.128.2.7 -v

OpenSSH_7.3p1, OpenSSL 1.0.2j  26 Sep 2016

debug1: Reading configuration data /c/Users/works/.ssh/config

debug1: Reading configuration data /etc/ssh/ssh_config

debug1: Connecting to 10.128.2.7 [10.128.2.7] port 22.

debug1: Connection established.

debug1: key_load_public: No such file or directory

debug1: identity file /c/Users/works/Documents/interface setup/ifx_key.pem type -1

debug1: key_load_public: No such file or directory

debug1: identity file /c/Users/works/Documents/interface setup/ifx_key.pem-cert type -1

debug1: Enabling compatibility mode for protocol 2.0

debug1: Local version string SSH-2.0-OpenSSH_7.3

debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.8

debug1: match: OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.8 pat OpenSSH_6.6.1* compat 0x04000000

debug1: Authenticating to 10.128.2.7:22 as 'ubuntu'

debug1: SSH2_MSG_KEXINIT sent

debug1: SSH2_MSG_KEXINIT received

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

debug1: expecting SSH2_MSG_KEX_ECDH_REPLY

debug1: Server host key: ecdsa-sha2-nistp256 SHA256:R+d2ELtCJyoeyHMfivCsGKk98GOIfxxsTEPAFmKkSOI

debug1: Host '10.128.2.7' is known and matches the ECDSA host key.

debug1: Found key in /c/Users/works/.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_SERVICE_ACCEPT received

debug1: Authentications that can continue: publickey

debug1: Next authentication method: publickey

debug1: Trying private key: /c/Users/works/Documents/interface setup/ifx_key.pem

debug1: Authentications that can continue: publickey

debug1: No more authentication methods to try.

Permission denied (publickey).

I used to be able to ssh into this machine until yesterday.
Is there a way to login into it?

Only if you have a private key that is reference to in the .ssh/authorized_keys on the server. Have you deleted that file or altered its contents?

If you deleted the information, you won't be available to log into the server again, if you don't have physical access to the disk.

This is basic ssh security, if you don't have the appropriate key which is mentioned in the .ssh/authorized_keys, you don't get access. That way you make sure that noone else can easily access your server.

$ ssh mykey.pem ubuntu@10.128.2.7 -v

...

debug1: key_load_public: No such file or directory

debug1: identity file /c/Users/works/Documents/interface setup/ifx_key.pem type -1

debug1: key_load_public: No such file or directory

debug1: identity file /c/Users/works/Documents/interface setup/ifx_key.pem-cert type -1

...

debug1: Next authentication method: publickey

debug1: Trying private key: /c/Users/works/Documents/interface setup/ifx_key.pem

debug1: Authentications that can continue: publickey

The only key which your client tried to use is ifx_key.pem. It looks like that file isn't actually present (the "type -1" line). If that's the key which ssh is supposed to authenticate with, make sure the file is actually present on your local system and that you have permission to read it.

$ ssh mykey.pem ubuntu@10.128.2.7 -v

This suggests that you want ssh to use a different key file named mykey.pem, but you didn't specify the command correctly. To specify a key on the command line, use the -i option:

$ ssh -i mykey.pem ubuntu@10.128.2.7 -v