John Haxby said:
> Andrew Smith wrote:
>
>>I was wondering if anyone knows the answer to or could
>>direct me to the directives to determine the IP address
>>that sendmail uses when sending email.
>>
>>I have a server with a dozen IP addresses and it seems
>>to pick the last one as the IP addresses it uses to
>>send email.
>>
>>I have 3 MTA's listening:
>>DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTALocal')
>>DAEMON_OPTIONS(`Port=smtp,Addr=X.Y.A.B, Name=MTA')
>>DAEMON_OPTIONS(`Port=smtp,Addr=X.Y.C.D, Name=MTA2')
>>
>>
> The sending IP address depends upon IP routing -- you're trying to
> connect to some machine and you have to go via some interface which has
> a route to that machine and an IP address associated with it. The
> source IP address is necessarily the IP address associated with the
> outgoing interface.
An interface can have more than 1 IP address (eth0 eth0:0 etc.)
and if they are all in the same subnet then the source address
should be allowed to be set to any of them shouldn't it?
e.g. 'ping -I'
But I guess the reason why I get whichever IP it is using may be
a routing issue - I'll look into that.
Hmm - yep the table doesn't look very neat! I'll have to tidy
that up first.
One other point though - I only today noticed seeing
'${if_addr}X.Y.A.B' in the qf files (it may have been there
all along - but only just noticed it today) so I guess
there's another path I can follow up.
I only moved to this server a few weeks ago.
> On the other hand, the _name_ used for outgoing mail is defined by the
> "j" macro and defaults to the (fully-qualified) hostname for the machine
> (roughly speaking). You can change that. You can also masquerade
> domain names to hide internal names. I do a combination of these for my
> home server setup.
I use sendmail directly so yes the names are no problem -
it's the fact that the IP address reverse maps to only one
name (the people who supply my dedicated server supply an
interface that only allows 1 reverse map for each IP) so
when I send out the weekly >40,000 member opt-in newsletter
I get a few bounces saying it may be spam - probably due to
the reverse map - that's what lead me down this path :-)
> I'm curious -- why don't you just listen on the wildcard IP address?
> Do you actually make use of the distunction between all those possible
> listeners? If so, what?
I do not want it listening on any IP other that those that are
expecting to get incoming data
Its a small busy server (>600MB web traffic a day - kids site)
I don't want anything extra listening than is required.
Even my firewall ends with DENY everywhere - it's pretty
restrictive :-)
>>Also, the machine is actually running 7.3 not 9, but
>>that shouldn't make much of a difference.
>>
>>
> Glad you said. In this case it doesn't make any difference, you're
> right, but it's good to know.
>
> jch
Thanks for the hint re: routing ...
--
-Cheers
-Andrew
MS ... if only he hadn't been hang gliding!
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