RE: [ILUG] Dynamically choosing smtp server

From: Kenn Humborg (kenn at domain bluetree.ie)
Date: Tue 17 Sep 2002 - 12:02:01 IST


> On Tue, Sep 17, 2002 at 09:56:24AM +0100 or thereabouts, Kenn
> Humborg wrote:
> >
> > Are you running a DNS server on the dialup box? If so, create
> > a zone file for some fake domain (say conor-daly.). Then
> > put a single CNAME record in this zone for outgoing-smtp.conor-daly.
> > Your ip-up.local script then rewrites this zone file to bump up
> > the zone serial number and point this CNAME to the correct SMTP
> > server name. Then it does "service named reload".
>
> Do I need to have the smtp servers explicitly numbered in the zone file or
> can I have a
>
> smtphost CNAME smtp.iol.ie
>
> in the zone file instead?

You don't need the A. Just the CNAME is fine.

> > Mind you, a simple perl one-liner (which someone else can provide)
> > that modified sendmail.cf in-place it probably the simplest.
> > Note that, in a lot of cases, you don't need to restart sendmail
> > to pick up changes to the .cf file. But to be safe, stick a
> > "service sendmail reload" in your ip-up.local after modifying
> > sendmail.cf.
>
> or a
>
> sed -e 's/DSsmtp:.*$/DSsmtp:<current.smtp.server>/' sendmail.cf >
> send.cf &&
> mv send.cf sendmail.cf
>
> looks like working. Mind you, I thought I could have sed modify
> the file in
> place also...

Nope - you need perl -i (or something like that) for that.

> Since I'm queuing mail and flushing with
>
> sendmail -q
>
> rather than running in daemon mode, I shouldn't need to
>
> service sendmail reload
>
> though I am running sendmail on my internal smtp server but in
> queuing mode
> only. Arrgh, I'm getting confused now!

Yes. You don't need the service sendmail restart.

Later,
Kenn



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