PHWinfo - Afficher un message - redundancy on multi-homed hosts for outgoing mail

11/03/2008, 12h49

Michael Grant <michael.grant@gmail.com> wrote:

> On Mar 11, 9:26 am, "D. Stussy" <s...@bde-arc.ampr.org> wrote:
>> "Michael Grant" <michael.gr...@gmail.com> wrote in message
>>
>> news:0d6c72d8-8bbb-49f9-8489-fe109e9b16e4@e60g2000hsh.googlegroups.com...
>>
>> > My server is multi-homed with two ip addresses on different
>> > interfaces.
>>
>> > Is it possible to set up things so that if an outgoing network
>> > connection fails (for example a timeout) on one interface that it
>> > automatically retries out the other with the other source address?
>>
>> > Incoming mail is working on both interfaces.
>>
>> > I am running sendmail version 8.14.1 on freebsd 6.3.
>>
>> I don't believe that's a sendmail issue - but a routing table issue within
>> your multi-homed host.
>
> No I disagree. I don't think this is a routing issue. I might be
> using the term multi-homed incorrectly. The two interfaces have
> different IP addresses on them. I cannot shove packets out one
> interface with the ip address of the other. The machine is not a
> router and there's no routing exchange between my machine and the
> network to get those packets back to me if I do.
>
> It's as if I need to specify multiple CLIENT_OPTIONS in my .mc file,
> but this doesn't work.
>
> What I'm looking for is a way to tell sendmail to first try with one
> source address and if that fails, try with a different one. This way,
> if one network is down, mail still goes out.
>
> Up to now, when this happens, I have been flipping things over
> manually. Fortunately this doesn't occur often, though it would be
> best if it were automatic.

You may consider using a monitoring script to switch between sendmail
two configurations (with different CLIENT_OPTIONS).
AFAIK other solutions would require source code changes in sendmail.cf
e.g. to handle situation in which both connections are up and running
nut only one of them has connectivity problem to *some* (but not all)
nets.

The "difference of opinions" between you two may be caused by using
different assumptions:
a) single address space with two Internet connections.
It is best handled at routing level by routers.
[It is proffered solution by medium+ ISP]
b) two *separate* address spaces - switching default route "breaks"
already established TCP connections.
[It seems to be quite common for small firms.]

--
[pl>en: Andrew] Andrzej Adam Filip : anfi@priv.onet.pl : anfi@xl.wp.pl
Open-Sendmail: http://open-sendmail.sourceforge.net/
Isn't it nice that people who prefer Los Angeles to San Francisco live there?
-- Herb Caen

11/03/2008, 12h49	#4
Andrzej Adam Filip Messages: n/a Hébergeur:	Re: redundancy on multi-homed hosts for outgoing mail Michael Grant <michael.grant@gmail.com> wrote: > On Mar 11, 9:26 am, "D. Stussy" <s...@bde-arc.ampr.org> wrote: >> "Michael Grant" <michael.gr...@gmail.com> wrote in message >> >> news:0d6c72d8-8bbb-49f9-8489-fe109e9b16e4@e60g2000hsh.googlegroups.com... >> >> > My server is multi-homed with two ip addresses on different >> > interfaces. >> >> > Is it possible to set up things so that if an outgoing network >> > connection fails (for example a timeout) on one interface that it >> > automatically retries out the other with the other source address? >> >> > Incoming mail is working on both interfaces. >> >> > I am running sendmail version 8.14.1 on freebsd 6.3. >> >> I don't believe that's a sendmail issue - but a routing table issue within >> your multi-homed host. > > No I disagree. I don't think this is a routing issue. I might be > using the term multi-homed incorrectly. The two interfaces have > different IP addresses on them. I cannot shove packets out one > interface with the ip address of the other. The machine is not a > router and there's no routing exchange between my machine and the > network to get those packets back to me if I do. > > It's as if I need to specify multiple CLIENT_OPTIONS in my .mc file, > but this doesn't work. > > What I'm looking for is a way to tell sendmail to first try with one > source address and if that fails, try with a different one. This way, > if one network is down, mail still goes out. > > Up to now, when this happens, I have been flipping things over > manually. Fortunately this doesn't occur often, though it would be > best if it were automatic. You may consider using a monitoring script to switch between sendmail two configurations (with different CLIENT_OPTIONS). AFAIK other solutions would require source code changes in sendmail.cf e.g. to handle situation in which both connections are up and running nut only one of them has connectivity problem to some (but not all) nets. The "difference of opinions" between you two may be caused by using different assumptions: a) single address space with two Internet connections. It is best handled at routing level by routers. [It is proffered solution by medium+ ISP] b) two separate address spaces - switching default route "breaks" already established TCP connections. [It seems to be quite common for small firms.] -- [pl>en: Andrew] Andrzej Adam Filip : anfi@priv.onet.pl : anfi@xl.wp.pl Open-Sendmail: http://open-sendmail.sourceforge.net/ Isn't it nice that people who prefer Los Angeles to San Francisco live there? -- Herb Caen