As it hasn't been explicitly mentioned, sshd is by default very strict on permissions on for the
authorized_keys files. So, if
authorized_keys is writable for anybody other than the user or can be made writable by anybody other than the user, it'll refuse to authenticate (unless sshd is configured with
What I mean by "can be made writable" is that if any of the parent directories are writable for anybody other than the user, users permitted to modify those directories can start modifying permissions in such a way that they can modify/replace authorized_keys.
Furthermore, if the
/home/username/.ssh directory is not owned by the user, and thus the user has no permissions to read the key you can run into problems:
drwxr-xr-x 7 jane jane 4096 Jan 22 02:10 /home/jane
drwx------ 2 root root 4096 Jan 22 03:28 /home/jane/.ssh
Note that jane does not own the
.ssh file. Fix this via
chown -R jane:jane /home/jane/.ssh
These sorts of filesystem permission issues will not show up with
ssh -v, and they won't even show up in the sshd logs (!) until you set the log level to DEBUG.
/etc/ssh/sshd_config. You want a line that reads
LogLevel DEBUG in there somewhere. Reload the SSH server using the mechanism provided by the distro. (
service sshd reload on RHEL/CentOS/Scientific.) A graceful reload will not drop existing sessions.
- Try authenticating again.
- Work out where your auth facility logs go and read them. (IIRC,
/var/log/auth.log on Debian-based distros;
/var/log/secure on RHEL/CentOS/Scientific.)
Much easier to work out what's going wrong with the debug output which includes filesystem permission errors. Remember to revert the change to
/etc/ssh/sshd_config when done!