Re: [exim] How to have port 80 open, along with a website?

On 2008-01-15 at 03:22 +0000, W B Hacker wrote:
> Though I agree (from actual testing) that use of port 80 is a bad idea,
> for smtp - the above does not apply in practice.

It does when you want to provide _both_ SMTP and HTTP on the same IP on
the same port, concurrently.

There are other sets of protocols where you can run a daemon service
which supports more than one protocol and dispatches accordingly; the
cases I know of all rely upon the client sending first. Where the
server sends first, it theoretically would be possible, if you can come
up with a greeting banner which is compliant to both protocols.
Probably just about possible in some cases.

None of which helps when SMTP sends the banner first and the client is
supposed to wait for the banner first, whilst HTTP speaks first and
there are then inherent race conditions. A multi-second timeout for
waiting for an HTTP request would be possible but would be far too
fragile for use in a production environment with paying customers.

-Phil