Fixing SSH after upgrading to macOS 10.13.2

I recently upgraded to macOS 10.13.2 and tried to SSH into a project I’ve been working on to check on the logs. The error read:

Unable to negotiate with XX.XX.XXX.XX port 22: no matching cipher found. Their offer: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se

I’m not precisely sure what changed, but thankfully the fix turned out to be relatively simple. In your /etc/ssh/ssh_config file you should see many lines that have been commented out.

Find the one that looks like this and uncomment it:

Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc

It should work as it did before.

Apple’s had a slew of rough updates lately, between the strange bug where you couldn’t type the letter “i” on iOS and the inexcusable root login bug. Upgrading to 10.13 a couple weeks ago froze my computer and forced me to restart the computer in recovery mode, which I’ve pretty much never had to do. Hopefully this isn’t a trend that continues.