Hi Bennett,

I patched your smtpprox 1.2 in order to access mailservers that require
SMTP_AUTH in form of "AUTH LOGIN" (but it might easily be extended to
handle other authorization methods). I needed it because my ISP has
blocked all outgoing TCP connections to the port 25, and at the same time
only accepts SMTP_AUTH sessions on its own mail relay (even for
connections originating by hosts in its IP address space). As my Linux box
still runs an old version of sendmail unable to handle SMTP_AUTH, all its
outgoing mail was blocked. Now I may point sendmail to the proxy on
localhost as smarthost, and the latter can use the ISP's mail relay by
handling the authentication.

The implementation is very simplistic, and relies upon server and client
for spotting abnormal conditions and aborting the session. The SMTP_AUTH
dialogue is triggered by a "HELO" from the client; if the latter issues a
EHLO, the authentication is supposed to be handled by the client and the
proxy behaves like before.

Username and password may be passed as command-line options, but the move
is not very smart because other shell users can see them by doing
"ps -efl". For security, it is better to edit the default initial values
of $username and $password in the source code, or to modify the code to
use configuration files.

I'm attaching the replacement for smtpproxy, named smtpauthproxy, and a
diff file from the original.

Cheers --

Enzo