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Multiple IP-addresses on single adapter - 13.Dec.2006 5:31:32 AM

lex zwetsloot

Posts: 2
Joined: 19.Jul.2004
From: Netherlands
Status: offline

Hi,

I'm trying to figure out how to use a secondary IP-address on the Internet facing adapter as outgoing (or sending) IP-address. Here's the situation: An ISA 2000 server has two adapters. On the external side the adapter is configured with four public IP-addresses. Two for company A, two for company B, for their respective WWW and SMTP servers. Incoming mail, directed to the second and fourth IP-address is accepted normally. However, when either of the internal SMTP servers is sending mail through ISA server it is always the primary address configured on the external adapter that is used as sending IP-address, even though the server publishing rules use one of the secondary addresses. This of course raises conflicts on some receiving SMTP servers, as only the second and fourth addresses are registered as reverse DNS record for e-mail purposes. How can I force ISA to use one of the secondary IP addresses as outgoing (sending) address?

Thanks, Lex

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lzw

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RE: Multiple IP-addresses on single adapter - 14.Dec.2006 7:55:29 PM

Jason Jones

Posts: 2121
Joined: 30.Jul.2002
From: United Kingdom
Status: offline

This issue affects all versions of ISA even up to the latest, it is designed so that all outbound connections appear to come from the single external IP address bound to the external adapter and this cannot be changed.

The best apprach is to change all MX records to use the IP of ISA external and get ISA to use SMTP publishing for incoming email.

You can also use a workaround with a public addressed DMZ, but this may not be ideal for most people.

JJ

< Message edited by Jason Jones -- 14.Dec.2006 7:56:51 PM >

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(in reply to lex zwetsloot)