Question about sendmail...

[Philip Prindeville]

Craig White wrote:

>On Fri, 2005-10-28 at 06:18 +0200, Alexander Dalloz wrote:
>  
>
>>Am Fr, den 28.10.2005 schrieb Philip Prindeville um 4:26:
>>
>>    
>>
>>>I'm running FC3 (updated) on a handful of machines.
>>>
>>>I have a single IP address, with a NATing router set to that
>>>address.  I have a domain, and an MX which points through
>>>the router at my mail server (or rather, the router is configured
>>>to port-forward 25, 143, etc to the mail server).
>>>
>>>I also have several mail clients on my 192.168.1.x network.
>>>
>>>The issues are the following:
>>>
>>>* the clients have a smart host (DS) defined as the mail relay,
>>>   but they canonical its name and then look it up in the DNS,
>>>   trying to contact it on the external IP address (and not its
>>>   internal 192.168.1.x address in the /etc/hosts file).  My
>>>   /etc/nsswitch.conf file is unmodified.
>>>
>>>* the clients then try to relay the email with a sender's envelope
>>>   address as user at host.my-domain, which the relay rejects
>>>   because "host.my-domain" doesn't resolve in the DNS.
>>>
>>>* I should probably have define(`LOCAL_RELAY', `:$S') to
>>>   handle forwarding everything to the mail server.
>>>
>>>I used to know all of this stuff once upon a time...
>>>      
>>>
>>>-Philip
>>>      
>>>
>>Reading this I have the strong feeling it was you I was talking to in
>>#sendmail on freenode this evening (night) :)
>>
>>I would vote for running a local DNS (bind) service, in conjunction with
>>DHCP and dynamic zone updates. That would be ideal. And for unqualified
>>sender addresses use the masquerading features of Sendmail.
>>
>>On the other hand you may go this route: do not run local Sendmail
>>daemons, but use the submission process to directly feed outgoing mail
>>from inner clients to the central mail hub. Have a look at
>>/etc/mail/submit.mc. Comment out (remove the leading "dnl") for
>>
>>define(`confDIRECT_SUBMISSION_MODIFIERS',`C')
>>
>>and even add a line
>>
>>FEATURE(`nocanonify', `canonify_hosts')
>>
>>and finally change the IP in
>>
>>FEATURE(`msp', `[127.0.0.1]')dnl
>>
>>to the one of the central mail hub.
>>
>>Please see http://www.sendmail.org/m4/msp.html or better the current
>>cf/README coming with your Sendmail on Fedora. Many discussion about
>>this topic to be found through
>>
>>http://groups.google.com/groups?hl=en&lr=&c2coff=1&sa=X&oi=groupst&q=Sendmail+confDIRECT_SUBMISSION_MODIFIERS
>>
>>Hope it helps.
>>    
>>
>----
>the alternative to running local dns is to use /etc/hosts to define a
>locally available name that doesn't resolve properly via dns isn't it?
>It would strike me as simpler to add the name to /etc/hosts but I still
>prefer just using the ip address in sendmail.mc
>
>Craig
>
>
>  
>

That's what I thought too, but it turns out you can't have "name"
in the /etc/hosts file...  Or rather, you need both "name" and "name."
in there, since sendmail likes to put a "rooting" dot on the end of
domain names.

-Philip