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Setup Cable modem on 2nd NIC

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Setup Cable modem on 2nd NIC - 21.Aug.2009 5:20:07 PM   
hermanf72

 

Posts: 9
Joined: 12.Jan.2008
From: The Netherlands
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Good day,

Last week I received my new DOCSIS3 Cable Modem from my ISP. I would like to install the cable modem on the external NIC of My ISA2006 firewall. So far I did not manage to get it work. The problem is that the external NIC doesn't receive a public IP address from the ISP. I think this is a DHCP issue?!? All I see is 0.0.0.0.

Allready I added the external NIC in the DHCP secion (system policies). No result.

Connecting the modem 1 on 1 to my pc is working perfect. Putting a router between the PC and the cable modem is working also perfectly. As well on the server. But the cable modem directly connected to the external NIC is NOT working. Resetting and turning off and on everything doesn't help either :-(

Any solutions ?

Have a good day.
Herman
Post #: 1
RE: Setup Cable modem on 2nd NIC - 21.Aug.2009 7:25:16 PM   
aek033

 

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Are you allowing dhcp from external to local host?

(in reply to hermanf72)
Post #: 2
RE: Setup Cable modem on 2nd NIC - 22.Aug.2009 8:07:32 AM   
hermanf72

 

Posts: 9
Joined: 12.Jan.2008
From: The Netherlands
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Yes... Yes i have a rule to accept DHCP from everywhere to local Host.

(in reply to aek033)
Post #: 3
RE: Setup Cable modem on 2nd NIC - 24.Aug.2009 4:12:30 AM   
DEVLAVI

 

Posts: 115
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From: Bangalore, India
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If you Include DHCP request and DHCP reply in your rule it Should receive IP address from the server

HTH,
Dev

(in reply to hermanf72)
Post #: 4
RE: Setup Cable modem on 2nd NIC - 24.Aug.2009 5:10:05 AM   
hermanf72

 

Posts: 9
Joined: 12.Jan.2008
From: The Netherlands
Status: offline
Hi folks,

Finally I managed it to work! In the system policy I added the External network at the DHCP (From) section. After some discussions I decided to change that entry into "Everywhere". Next I disabled the public NIC en restarted the cable modem! After the modem booted up I enabled the NIC again. And voila! It works...

Next issue I struggle with is my Dual Home NIC configuration. My situation now is 1 private NIC (10.0.0.10) and the Public NIC (IP DHCP ISP). The W2K3 server has running it's own DNS server for internal use. So the DNS of the private NIC points to 10.0.0.10. My question is what to do with the DNS of the Public NIC. Should it point to its own DNS servers or should I change it to point to 10.0.0.10 ? What is your opinion here?

I also get an configuration error back from ISA. But right now i dont have it in the log. As soon I see the error again I wil let yah know.

(in reply to DEVLAVI)
Post #: 5
RE: Setup Cable modem on 2nd NIC - 24.Aug.2009 5:43:27 AM   
DEVLAVI

 

Posts: 115
Joined: 16.Jul.2009
From: Bangalore, India
Status: offline
Hi
Making change to the system policy is not recommended.Why do it when you can achieve the same with firewall policy.
Anyways good to hear you got it working.

For the next issue you need to start a new thread or it ll be moved to the appropriate sections by the moderators shortly.

Do not use DNS on both NIC's. Use your Internal DNS only and Configure forwarders on your DNS server to resolve external resources

Dev

(in reply to hermanf72)
Post #: 6
RE: Setup Cable modem on 2nd NIC - 24.Aug.2009 5:49:42 AM   
hermanf72

 

Posts: 9
Joined: 12.Jan.2008
From: The Netherlands
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Hello,

what do you mean exactly? Should i leave the DNS entries on the Public NIC empty?

No I have put the private DNS IP in both of the NIC's

In the local DNS Server I filled in the ISP DNS IP's at the forwarders.

So what is the right way to do here?

(in reply to DEVLAVI)
Post #: 7
RE: Setup Cable modem on 2nd NIC - 24.Aug.2009 6:03:58 AM   
DEVLAVI

 

Posts: 115
Joined: 16.Jul.2009
From: Bangalore, India
Status: offline
quote:

what do you mean exactly? Should i leave the DNS entries on the Public NIC empty?


Yes

quote:

No I have put the private DNS IP in both of the NIC's


Remove it from the External NIC

quote:

In the local DNS Server I filled in the ISP DNS IP's at the forwarder


Yes that's the way it should be

Finally create a rule to allow DNS traffic from your Internal DNS to External

This Config allows you to resolve both INTERNAL & EXTERNAL names with a single DNS server i.e your Internal DNS sever

(in reply to hermanf72)
Post #: 8
RE: Setup Cable modem on 2nd NIC - 24.Aug.2009 6:34:17 AM   
hermanf72

 

Posts: 9
Joined: 12.Jan.2008
From: The Netherlands
Status: offline
Thank you for this clear answer!

So the DNS on the Public NIC should be empty!? Or let it resolve its adressen via the external ISP DHCP.

When I understand yah correctly, I keep the DNS setting static and leave the entries empty....

Am I correct...

(in reply to DEVLAVI)
Post #: 9
RE: Setup Cable modem on 2nd NIC - 24.Aug.2009 6:57:49 AM   
DEVLAVI

 

Posts: 115
Joined: 16.Jul.2009
From: Bangalore, India
Status: offline
I prefer & recommend that you use static IP Addresses on all your ISA server's NIC's. However in certain scenario like yours its not entirely possible to use static addressing where you get a dynamically assigned IP from the ISP
There are workarounds to deal with this but it depends on what you really need on your Network

Check out this article by Mr.Harrison this help you better understand DNS scenarios with their pros & cons
http://www.isaserver.org/tutorials/DNS_for_ISA_Server.html

HTH
DEV

(in reply to hermanf72)
Post #: 10
RE: Setup Cable modem on 2nd NIC - 24.Aug.2009 7:06:57 AM   
hermanf72

 

Posts: 9
Joined: 12.Jan.2008
From: The Netherlands
Status: offline
Okay thanks...

Now I have configured the public nic to get its IP adresses Dynamicly (DHCP ISP). The DNS entry on the other hand I configured Static with the internal DNS address (10.0.0.10).

So far it works well. But it looks like this is not what you mean...

What would you do ?

< Message edited by hermanf72 -- 24.Aug.2009 7:08:18 AM >

(in reply to DEVLAVI)
Post #: 11
RE: Setup Cable modem on 2nd NIC - 24.Aug.2009 7:31:25 AM   
DEVLAVI

 

Posts: 115
Joined: 16.Jul.2009
From: Bangalore, India
Status: offline
Hi
It ll work but its not the best practice. If i were you i would get a Static IP from the ISP. Besides you need Static IP for Server publishing rules to work as expected

Dev

(in reply to hermanf72)
Post #: 12
RE: Setup Cable modem on 2nd NIC - 27.Aug.2009 7:27:34 AM   
hermanf72

 

Posts: 9
Joined: 12.Jan.2008
From: The Netherlands
Status: offline
All is still working well. I want to thank everybody for the help and thinking! Thank you!

(in reply to DEVLAVI)
Post #: 13
RE: Setup Cable modem on 2nd NIC - 27.Aug.2009 3:39:18 PM   
DEVLAVI

 

Posts: 115
Joined: 16.Jul.2009
From: Bangalore, India
Status: offline
Hi hermanf72,

Its always good to here that you got it to work.

Dev

(in reply to hermanf72)
Post #: 14

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