ssh_exchange_identification: Connection closed by remote host. This is the message I kept getting when I attempted to login to my web server a few days ago. Maybe you noticed the outage too. At first, a number of thoughts crossed my mind. Maybe the server is under such heavy loads that it’s stopped accepting any new network connections. Maybe it’s been hacked. Maybe it just wants a cookie. Googling for the error message also brought up similar suggestions.
Not having any other option, I asked for the server to be rebooted. It came back up within minutes, but still remained inaccessible to me and it took another reboot before I could login to see what was wrong. The hard disk had suddenly started showing signs of imminent death and some of the data had already been lost. dmesg showed a number of bus error messages and I knew I had to act fast.
A brief exchange of messages with the Cari.net support guys and soon, the server was up with a new hard disk and the previous one connected as a secondary drive. I copied over all the configuration and whatever data I could and presto. Everything was back to normal. It’s a good thing I keep regular backups which allowed me to restore whatever was lost.
So now you know a couple of things. Namely that if you get the above error message, it could mean your system is in grave danger. Cari.net is an excellent host (thanks a lot guys. Hope you don’t charge me for the hard drive). And lastly and most importantly, always keep backups.