When you use SSH, you normally just want to connect securely to a host, and you don’t really care about what cipher to use. In other cases, however, you might want to use a specific cipher, perhaps for compliance reasons, or perhaps because you are paranoid and want to make sure that you are connecting using your favorite cipher. Both are perfectly good reasons :P

SSH allows you to use a specific cipher when you connect to a host. First of all, you need to see what ciphers are available on your operating system. This is the command to list them:

ssh -Q cipher

At this point, you can connect to a host via SSH specifying one of these ciphers in the following way:

ssh user@host -c cipher

So, if you want to connect using AES256, you would type this:

ssh user@host -c aes256-cbc