AuthorizedKeysFile line commented out but still seems to work

Question

I'm setting up a server on Linode and following their Securing Your Server guide.

They recommend setting up ssh key pair authentication. I have already uploaded my public key to server and the key pair authentication seems to work fine, but how does it work if the following line is commented out in sshd_config:

#AuthorizedKeysFile     %h/.ssh/authorized_keys

Solution

That is the default location. You can use AuthorizedKeysFile to change to a different location, but if you don't specify it, then it will look in ~/.ssh/authorized_keys

From the man page (e.g., https://www.freebsd.org/cgi/man.cgi?query=sshd_config&sektion=5):

AuthorizedKeysFile

   Specifies the file that contains the public keys that can be used
   for user authentication.  The format is described in the AUTHO-
   RIZED_KEYS FILE FORMAT section of sshd(8).  AuthorizedKeysFile
   may contain tokens of the form %T which are substituted during
   connection setup.  The following tokens are defined: %% is
   replaced by a literal '%', %h is replaced by the home directory
   of the user being authenticated, and %u is replaced by the user-
   name of that user.  After expansion, AuthorizedKeysFile is taken
   to be an absolute path or one relative to the user's home direc-
   tory.  Multiple files may be listed, separated by whitespace.
   The default is ``.ssh/authorized_keys .ssh/authorized_keys2''.

Comments

[dmourati]

And further, if you want the key not to work, delete the file, the relevant line, or comment it out.

[The_Pingu]

you can also set it to "none" .