On 7/17/11 9:18 PM, Always Learning wrote:
>
>>> Legitimate senders should not use fake, false, misleading credentials.
>
>> There is no requirement for the greeting name to match any IP, and isn't likely
>> to work for multi-homed and/or clustered machines.
>
> Which type of 'multi-homing' were you thinking about ?
>
> http://en.wikipedia.org/wiki/Multihoming
>
> * Single Link, Multiple IP address (Spaces)
> * Multiple Interfaces, Single IP address per interface
> * Multiple Links, Single IP address (Space)
> * Multiple Links, Multiple IP address (Spaces)
Multiple interfaces, multiple IP addresses. Sendmail isn't going to track which
interface it is sending on and adjust its greeting.
> Which type of 'cluster' were you thinking about ?
>
> http://en.wikipedia.org/wiki/Computer_cluster
>
> * High-availability (HA) clusters
> * Load-balancing clusters
> * Compute clusters
>
> If any of these share the same IP address, they can share the same host
> name.
There are any number of topologies that use multiple IP addresses for what
appears to be one name. A load balancer might be involved, they may or may not
accept on the same IP's as they use for outbound connections, they may or may
not know the outbound ip.
> I am not well acquainted with either of the above two methods,
> multi-homed and clusters, but I can not understand why any of them
> should resort to using fake identities when sending-out emails.
Just because it doesn't match the IP doesn't make it fake.
> Can you help me understand why bogus identities are necessary in these
> circumstances ?
You are the one defining it as bogus. Consider a system where one or more of
it's routes to the internet go through nat routers or the nat functionality of a
load balancer. The program sending the mail won't even know the IP you see.
--
Les Mikesell
lesmikesell@xxxxxxxxx
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