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Can I run PPTP VPN ISA Server Behind a NAT Router?

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Can I run PPTP VPN ISA Server Behind a NAT Router? - 28.Jul.2011 2:18:47 PM   
Rexkh

 

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I come across a lot of problems configuring VPN on ISA Server 2004. But now I want to start my first question. Can I run PPTP VPN ISA Server Behind a NAT Router?
Post #: 1
RE: Can I run PPTP VPN ISA Server Behind a NAT Router? - 29.Jul.2011 9:51:13 AM   
paulo.oliveira

 

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Hi,

yes, make sure to forward the traffic to ISA firewall.

Regards,
Paulo Oliveira.

_____________________________

Microsoft Premier Field Engineer (PFE)
Blog: http://poliveirasilva.wordpress.com/
Twitter: https://twitter.com/poliveirasilva

(in reply to Rexkh)
Post #: 2
RE: Can I run PPTP VPN ISA Server Behind a NAT Router? - 29.Jul.2011 1:10:49 PM   
Rexkh

 

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Thanks paulo.oliveira for your reply.I'm glad to hear it is possible but I have problem connecting PPTP VPN from outside network using public IP Address. Authentication was successful but the connection immediately terminated. I'm not sure why but some message tell about PPP protocol error. I have tested connect VPN in local network and it was successful. And I also configure port forwarding 1723 for PPTP VPN. I'm so frustrated! I'm so glad if you have a clue to solve my problem. Please get back to me soon.

(in reply to paulo.oliveira)
Post #: 3
RE: Can I run PPTP VPN ISA Server Behind a NAT Router? - 29.Jul.2011 2:09:25 PM   
paulo.oliveira

 

Posts: 3472
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Hi,

PPTP also uses GRE protocol, have you allowed it?

Regards,
Paulo Oliveira.

_____________________________

Microsoft Premier Field Engineer (PFE)
Blog: http://poliveirasilva.wordpress.com/
Twitter: https://twitter.com/poliveirasilva

(in reply to Rexkh)
Post #: 4
RE: Can I run PPTP VPN ISA Server Behind a NAT Router? - 29.Jul.2011 9:23:28 PM   
Rexkh

 

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What is port number of GRE Protocol? Anyways, I have config DMZ, I think it should forward all ports. but still get error. If you don't mind, I can allow you to remote to my server.

(in reply to paulo.oliveira)
Post #: 5
RE: Can I run PPTP VPN ISA Server Behind a NAT Router? - 30.Jul.2011 9:42:57 AM   
paulo.oliveira

 

Posts: 3472
Joined: 3.Jan.2008
From: Amazon, Brazil
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Hi,

GRE is not a port, it is an IP level protocol!

http://www.ietf.org/assignments/protocol-numbers/protocol-numbers.xml

Here is an article about ISA behind a firewall and handling VPN connection:
http://www.isaserver.org/articles/2004pubvpn.html

Regards,
Paulo Oliveira.

_____________________________

Microsoft Premier Field Engineer (PFE)
Blog: http://poliveirasilva.wordpress.com/
Twitter: https://twitter.com/poliveirasilva

(in reply to Rexkh)
Post #: 6
RE: Can I run PPTP VPN ISA Server Behind a NAT Router? - 30.Jul.2011 12:41:58 PM   
Rexkh

 

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Joined: 1.Mar.2010
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I have read a whole tutorial and got much understand about VPN. I have some questions regard to the tutorial.

1. Do I need to configure NAT-T on front-end ISA if I need to connect only PPTP VPN?
2. Do I need to install any NAT-T VPN Client if I need to use only PPTP VPN?
3. Is it enough for just using default Windows XP VPN Client for just connecting to PPTP VPN?

I think this tutorial is a little different from my case because in the tutorial; NAT device is ISA Server; not a Hardware Router.
I'm not sure if my problem connecting using PPTP VPN is because of my Hardware Router does not has enough features which ISA has.

Can I have you IM for a little chat? I promise to use it to solve this case only.

(in reply to paulo.oliveira)
Post #: 7
RE: Can I run PPTP VPN ISA Server Behind a NAT Router? - 30.Jul.2011 6:20:45 PM   
paulo.oliveira

 

Posts: 3472
Joined: 3.Jan.2008
From: Amazon, Brazil
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Hi,

first and second questions: No, NAT-T is only for IPSec.
Third question: Yes, it is.

I'm sure the article differes from you scenario. Have you tried to get wireless router out of the way?

It is better we continue from here, so anyone can benefit from your problem.

Regards,
Paulo Oliveira.

_____________________________

Microsoft Premier Field Engineer (PFE)
Blog: http://poliveirasilva.wordpress.com/
Twitter: https://twitter.com/poliveirasilva

(in reply to Rexkh)
Post #: 8
RE: Can I run PPTP VPN ISA Server Behind a NAT Router? - 31.Jul.2011 1:07:52 AM   
Rexkh

 

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Joined: 1.Mar.2010
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So in my case, As usually, I shouldn't have any problem connecting PPTP VPN but I do have. What did you mean about getting wireless router out of the way?

Can you tell me what time you are available at the forum? So I can send you my VPN login. If you see the message yourself, you might be able to determine the problem. I think the problem is at the point of my router. Is there a router which does not support VPN?

(in reply to paulo.oliveira)
Post #: 9
RE: Can I run PPTP VPN ISA Server Behind a NAT Router? - 31.Jul.2011 6:07:13 PM   
paulo.oliveira

 

Posts: 3472
Joined: 3.Jan.2008
From: Amazon, Brazil
Status: offline
Hi,

I meant to configure ISA as your network's edge device and not wireless router.

There are some problems with PPTP VPN NAT editor on some devices. That's the reason I suggested you to configure ISA as edge device.

Regards,
Paulo Oliveira.

_____________________________

Microsoft Premier Field Engineer (PFE)
Blog: http://poliveirasilva.wordpress.com/
Twitter: https://twitter.com/poliveirasilva

(in reply to Rexkh)
Post #: 10
RE: Can I run PPTP VPN ISA Server Behind a NAT Router? - 2.Aug.2011 12:25:52 PM   
Rexkh

 

Posts: 10
Joined: 1.Mar.2010
Status: offline
The Router from ISP has multi functions as a PPPoE modem and a Router. Can you tell me how to configure it as a modem only whereas ISA work as a Router?

(in reply to paulo.oliveira)
Post #: 11

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