Lately my passwordless, SSH logins to all my servers have quit working, at least they seem to have stopped working from the only accessible “work” workstation that I have at the moment, MA7053. Since our enterprise malware mitigation agent, Traps, is blocking my access to my “real” workstation, MA8660, this has become more than just a nuisance.

So here’s what I came up with as a process to try and determine exactly where the problems are…

To Debug SSHD Issues with Key Logins

From a terminal opened in the target (CentOS 7 in this example) server:

sudo su
# stop the sshd service
systemctl stop sshd.service
# as root, restart the sshd service in DEBUG mode.  Note that your terminal will NOT return, it's spooling debug output
/usr/sbin/sshd -d
# attempt to connect again and look for DEBUG output in your terminal window
# once resolved, ctrl-c to kill the above process, then be sure to restart sshd like so:
systemctl start sshd.service

To Create and Engage a New SSH Key

  • On your local workstation open a terminal and enter the following with defaults and NO password or phrase:
    • ssh-keygen
  • Next, using the islandora user at dgdocker1.grinnell.edu as an example, enter the following to copy the key to the target server:

And that’s a wrap. Until next time…