[Dshield] SMTP server banner?

Schneelocke schneelocke at gmail.com
Thu Oct 28 21:20:22 GMT 2004


Hi,

> When configuring an SMTP MTA for an external mail gateway, are there
> any best practices in terms of what the banner should display?  For
> example sendmail by default tells you sendmail is running and the
> version.  I don't like that.
> 
> So my initial thought is maybe just the machine name they connected to
> (our public mx record).  But are there any RFC or general requirements
> that we display anything in particular?

I personally think that it's best to give out as much information as
necessary but, at the same time, as little as possible, so I'd suggest
something like this:

220 host.domain.tld ESMTP

and nothing else (assuming your mail server does ESMTP). In
particular, I'd advise against putting in the mail server software's
name or version, since that makes scanning for vulnerable versions
when a new hole is found much easier.

-- 
schnee



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