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SMTP & External IP question - 30.Mar.2006 1:41:21 PM

drog

Posts: 2
Joined: 30.Mar.2006
Status: offline

Hello !

Recently I've started to have problems with reverse DNS lookups. The reason is external IP that ISA uses for SMTP. Just like discribed in the article: http://www.isaserver.org/tutorials/You_Cannot_Control_the_Source_IP_Address_on_the_External_Interface_of_the_ISA_Server.html

The question is - is it true for ISA 2004 as well for 2000. I'm using ISA 2000 and wonder if this problem solved in 2004.

Thank you,
Dmitry

Post #: 1

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RE: SMTP & External IP question - 31.Mar.2006 5:05:44 PM

tshinder

Posts: 47663
Joined: 10.Jan.2001
From: Texas
Status: offline

Hi Dmitry,

Same problem.

Tom

_____________________________

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Prowess Consulting http://www.prowessconsulting.com/
Blog: http://blogs.isaserver.org/shinder/

GET THE NEW ISA 2006 Book!: http://tinyurl.com/2gpoo8

(in reply to drog)

Post #: 2

RE: SMTP & External IP question - 3.Apr.2006 8:20:06 AM

drog

Posts: 2
Joined: 30.Mar.2006
Status: offline

Hello, Tom!

I thought so... I've solved it by adding multiple A records for one FQDN (mail server FQDN) in ISP's DNS, so reverse DNS lookups work fine now.

Best regards,
Dmitry

(in reply to tshinder)

Post #: 3

RE: SMTP & External IP question - 5.Apr.2006 5:04:53 PM

tshinder

Posts: 47663
Joined: 10.Jan.2001
From: Texas
Status: offline

Hi Dmitry,

That's the way to do it!

Thanks!
Tom

_____________________________

Thomas W Shinder, M.D.
Sr. Consultant/Technical Writer
Prowess Consulting http://www.prowessconsulting.com/
Blog: http://blogs.isaserver.org/shinder/

GET THE NEW ISA 2006 Book!: http://tinyurl.com/2gpoo8

(in reply to drog)

Post #: 4

RE: SMTP & External IP question - 5.Apr.2006 8:40:26 PM

Ashokk001

Posts: 232
Joined: 6.Oct.2005
Status: offline

Hi Dmitry,

Can you please tell me how you went about this, i'm facing the same problem ad using isa 2004. If you could provide an example of this.

TIA,

Ashok.

(in reply to drog)

Post #: 5

RE: SMTP & External IP question - 9.Apr.2006 12:17:47 PM

H4ppyGilmore

Posts: 199
Joined: 8.Apr.2006
Status: offline

I am of the opinion that the next release of ISA server MUST have the one to one NATing feature. You can avoid these mess with 1-to-1 nating. Why the ISA development team is not implementing this feature is beyond me.

To answer your question, add the primary IP number of ISA's external interface to the MX record.

DNS record:

yourcompany.com     10 MX mail.yourcompany.com

mail.yourcompany.com   A   4.2.2.1
mail.yourcompany.com   A   4.2.2.2

Assuming the primary IP number is 4.2.2.1.

Just in case, you may want to have another rule for incoming SMTP traffic in ISA.

(in reply to Ashokk001)

Post #: 6

RE: SMTP & External IP question - 9.Apr.2006 5:47:17 PM

Ashokk001

Posts: 232
Joined: 6.Oct.2005
Status: offline

Hi H4appyGilmore,

Thanks for the explanation, i'll give this a go. Aparently the 1:1 NAT will NOT be available with the next release (2006) as well, so i don't know if the ISA development team are listening or not.

Ashok.

(in reply to H4ppyGilmore)

Post #: 7

RE: SMTP & External IP question - 16.Apr.2006 4:09:00 PM

tshinder

Posts: 47663
Joined: 10.Jan.2001
From: Texas
Status: offline

Hey guys,

They are listening.

Tom

_____________________________

Thomas W Shinder, M.D.
Sr. Consultant/Technical Writer
Prowess Consulting http://www.prowessconsulting.com/
Blog: http://blogs.isaserver.org/shinder/

GET THE NEW ISA 2006 Book!: http://tinyurl.com/2gpoo8

(in reply to Ashokk001)

Post #: 8