Ssh – Can’t SSH into remote server after changing password

sshubuntu-16.04

I previously followed this guide to add SSH keys to my remote server(I didn't hide or remove the keys from anywhere, just to be sure I don't lose access). It was passphrase protected. However I changed the passphrase to something else, and changed it back to the old one but now I can't login to it using another terminal session. Only my current terminal session is logged on, and unfortunately this is all as the root user. I generated new SSH key and added it to the server as well as my machine too but I still can't logon on it from another terminal session. How can I fix this?!

I fear I'd get locked out if I can't find a solution in time, that is, if my internet disconnects..

Best Answer

Check the logs on the server. If a login is failed, usually something is written to the logs.

According to your comment, you can't su with an ordinary user. This suggests you trying to supply a wrong password, otherwise su would work.

Try changing the root password to something simple which cannot possibly be mistyped. If the server isn't behid a firewall, just be sure to change to something long, that will do for the short time you're experimenting. Be sure to actually type the password, do not copy and paste it.

If you have public/private keys, be sure that only the owner has read/write access the .ssh directory, as well as to the keys. The ssh server won't authorize a key which is accessible to anyone but the owner.

If you still can't login, run the ssh server in debug mode on an other port like this:

/usr/sbin/sshd -d -d -d -p 10022

Then try connecting to the port 10022. The debug sshd process will log everything to the screen, so you may be able to spot any errors or anomalies preventing you from logging in.

Related Solutions

Ssh – How to automate SSH login with password

Don't use a password. Generate a passphrase-less SSH key and push it to your VM.

If you already have an SSH key, you can skip this step… Just hit Enter for the key and both passphrases:

$ ssh-keygen -t rsa -b 2048
Generating public/private rsa key pair.
Enter file in which to save the key (/home/username/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/username/.ssh/id_rsa.
Your public key has been saved in /home/username/.ssh/id_rsa.pub.

Copy your keys to the target server:

$ ssh-copy-id id@server
id@server's password:

Now try logging into the machine, with ssh 'id@server', and check-in:

.ssh/authorized_keys

Note: If you don't have .ssh dir and authorized_keys file, you need to create it first

to make sure we haven’t added extra keys that you weren’t expecting.

Finally, check to log in…

$ ssh id@server

id@server:~$

You may also want to look into using ssh-agent if you want to try keeping your keys protected with a passphrase.

Ubuntu – SSH connection lost during server upgrade – How to reconnect to process

The process actually runs in a screen or byobu session as the root user. reconnect to the server with putty on port 22 or the failsafe 1022. sudo su - or su - into your root account and resume the screen with byobu or a screen -r and resume where you left.

oh and yes i found out the hard way ;-)

Best Answer

Related Solutions

Ssh – How to automate SSH login with password

Ubuntu – SSH connection lost during server upgrade – How to reconnect to process

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