ssh: no matching cipher found

After a recent Ubuntu upgrade on my home machine, ssh attempts to it from the VirtualBox instance at work stopped working.   Here’s what ssh spewed back at me:

  no matching cipher found: client blowfish-cbc,arcfour server aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com

Impatient, I just logged in from another machine.  The VM runs CentOS 5.10 so that its environment is comparable with what [used to be] present on the majority of our production servers.   I’m an anti-RedHat bigot in the first place, and didn’t want to hunt down repos and upgrade my ssh.

That was not necessary.  The problem was a “Ciphers” line I’d added to my ~/.ssh/config, intended to prefer  (“Googallegedly”) faster encryption methods.   Adding all but those that resemble email addresses seems to have fixed the issue.   My “Ciphers” line now looks like this:

  Host *
  Ciphers blowfish-cbc,arcfour,aes128-ctr,aes192-ctr,aes256-ctr

The ciphers may be defined in your system /etc/ssh/ssh_config.  Check around.  If you can’t find it anywhere, try this:

  sudo find  ~/.[a-z]* /etc -path '*ssh*' -type f | sudo xargs fgrep Cipher

Anyway, that was my fix.   Right on in, easy-peasy lemon-squeezy.