\label{Guts_Authentication}

On the library servers, it is a routine in \texttt{lond} that does
the authentication. It checks if this is the user's homeserver, checks
the password, and answers with {}``unknown\_user'', {}``authorized''
or {}``non\_authorized''.

Determination if this is the user's homeserver is done by the presence
of his or her password file in

\texttt{/home/httpd/lonUsers/domain/1.char/2.char/3.char/username/passwd}

for example

\texttt{/home/httpd/lonUsers/msu/s/m/i/smith/passwd}

The password is stored in the format \texttt{mechanism:info}, where
mechanism can currently be unix, krb4 or internal. For krb4, the info
is the Kerberos domain, for internal it is the crypt password itself.
unix simply authenticates against /etc/passwd.