Once upon a time, Erik Laxdal elaxdal@ece.uvic.ca said:
The supported KexAlgorithms, Ciphers, and MACs are generally listed in the sshd_config man page. So 'man sshd_config' then look for the section of the item of interest.
Note that the man page does not always match the actual compiled binary (the build process does not update the man page to match configuration). The best way is to run "ssh -Q cipher" (as mentioned in the ssh_config and sshd_config man pages under Ciphers).