Debug ssh

LogLevel DEBUG3 in /etc/ssh/sshd_config via http://stackoverflow.com/questions/20864224/putty-getting-server-refused-our-key-error

• or ssh -vvv root@ip
• sometimes need to generate other key

up vote
8
down vote
Adding a few thoughts as other answers helped, but were not exact fit.

First of all, as mentioned in accepted answer, edit

/etc/ssh/sshd_config
and set log level:

LogLevel DEBUG3
Then try to authenticate, and when it fails, look for log file:

*or ssh -vvv root@ip from another machine

/var/log/secure
It will have errors you are looking for.

Could not open

• Check for debug1: Could not open authorized keys '/...../.permssion denied

selinux

• even permissions are ok, is selinux problem
• If the permissions are correct, SELinux might still be preventing sshd from opening the file. Try fixing the labels inside the .ssh directory (and maybe $HOME):

• • restorecon -FRvv ~/.ssh
  • (I'm intentionally not suggesting disabling SELinux or setting it to the permissive mode.)

• I had the same problem with the same cause, but restorecon didn't work. I had to change the SELinux type explicitly. chcon -Rv -t ssh_home_t ~/.ssh via http://stackoverflow.com/questions/20688844/sshd-gives-error-could-not-open-authorized-keys-although-permissions-seem-corre
  • for sftp user and also for root
  • Or chcon -Rv -t ssh_home_t .ssh ( for current directory)

[root@ssd176 ~]# chcon -Rv -t ssh_home_t .ssh
changing security context of ‘.ssh/authorized_keys’
changing security context of ‘.ssh’

Also, check /etc/ssh/ssd_config to ensure that RSAAuthentication and PubkeyAuthentication options aren't disabled. Default is yes so that shouldn't be a problem.