I maintain a virtual machine (VM) of Slackware Current. I don’t use the system in production and maintain the system only as a way of following Current development.
I have SSH configured to allow access to the VM. Within the past several weeks the SSH login displayed gobbledygook squarish characters just after the
Last login: text.
The display was not disruptive, but after a few weeks I decided to investigate.
I started with backups of the VM. That soon revealed when the goobledygook appeared. Inconclusive because the change log did not reveal anything obvious.
Slowly I whittled my way around possible causes.
An obvious cause had not occurred to me immediately. Eventually I remembered that SSH can be configured to display a message of the day (motd) file. Somehow the contents of the
/etc/motd file was corrupted. The file itself contained the goobledygook. I don’t know how the file got corrupted.
Through many years I have had little reason to tinker with the local SSH configurations. Being unchanged for so long rendered those configurations more or less “forgotten.”
Sometimes years of experience with computers does not always reveal obvious root causes.