Quickie: ipfw setup for redirecting SMTP

[Bill Eccles]

Y’all,

I have a MacOS X box that is running WebSTAR, which (in this version, at least) has a problem where the server attempts to bounce, via SMTP, E-mails directly to the mail exchanger of the destination domain instead of via the upstream SMTP relay host (aa.bb.cc.dd). (I don’t know why and our support agreement with 4D has run out. Yes, I’m moving my services to a MacOSXS box, but in the meantime, this is a puzzle I can’t refuse.)

So what I figure I can do is redirect port 25 of me to any to port 25 of the upstream server. That makes sense, right? So I’d probably use:

ipfw add 8000 divert 25 all from me to aa.bb.cc.dd via en0

(8000 is OK because the only other rule in there right now is the default at 65535.)

Well, that’s what I tried and it looks like Web* is still trying and failing to contact the servers directly. A “telnet somehost.net 25” fails, too.

So have I goofed the rule? (Yes.)

OK, then how have I goofed it?

Thanks,
Bill

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