Linux – Unable to login to ec2 instance after running “sudo chmod 2770 /”

amazon ec2amazon-web-serviceslinux

I am new to linux and AWS.

I ran sudo chmod 2770 / command on my ec2 instance and after that

I was getting Permission denied on everything I was doing(even using
ls or cd)

So I exited my connection(using cygwin) and tried to re-connect but now I get

Permission denied (publickey,gssapi-keyex,gssapi-with-mic)

I tried setting chmod 400 my.pem , chmod 600 my.pem, chmod 777 my.pem but nothing worked.
I am trying to connect using ssh -i my.pem ec2-user@xx.xx.xx.x which was working fine earlier.
What is the solution?

Best Answer

Solution is to start a new instance and never do what you did again. It would be too complicated to try to properly recover all the permissions that you reset to 2770.

If you have any valuable files on the broken instance you can stop it, mount its root volume to the new instance and copy the files from there.

Update: as @GeraldSchneider points out you may be lucky if you didn't recursively change all the permissions everywhere. You'll have to start a new instance and use it to fix the root permissions back to 0755. Follow for example the instructions here: Changed AWS EC2 firewall rule and locked out of ssh (instead of Fix the firewall do sudo chmod 755 /mnt or wherever you mount the other disk).

Hope that helps :)

Related Topic