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msm760 can not modify dhcp server dns settings

 
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Occasional Visitor

msm760 can not modify dhcp server dns settings

My msm760 is connected to a network without a dhcp server. So am using msm760's built in dhcp server. My problem is that because of some weird logic, if my msm760 is using a static IP address (which it is since there is no external dhcp server available) the msm760 dhcp dns setting will only show the ip of the msm760. Thus all clients receiving the dns settings from the msm760 dhcp server think the msm760 is the dns server and I can't override so they point to the real dns server available. Ideas? Help!

 

P.S. This thread has been moved from Communications, Wireless (Legacy ITRC forum) to MSM Series. -HP Forum Moderator

3 REPLIES 3
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Trusted Contributor

Re: msm760 can not modify dhcp server dns settings

This is due to the fact that the DHCP server embedded in the MSM controller is not meant to serve your network, but rather to provide addresses to the wireless clients primarily in access control scenarios.

When using access control, you want the clients to point everything to the MSM controller so that their traffic can be analysed and controlled. The MSM controller replaces your DNS by iteself, because it wants the DNS requests to go by it first. It will then do some logic to intercept and proxy the DNS request to the "real" DNS server that is located on the Internet/WAN port of the MSM controller.

Anyway, what that means is that by default you cannot override this behavior. Now, the following is not necessarily documented and I haven't tried it to make sure it is working, but there might be a way to address this by directly editing your configuration.

I can't imagine that this is supported by the HP support organization. So be aware that you are on your own here, but that it might be worth a try!

Backup your configuration and use a classic text editor (that maintains the encoding, windows tools have a tendency to force the encoding of the file, which migh screw up the restore configuration process of the controller). Linux traditional editors are generally fine/safe to edit the configuration file.

A good idea would be to store an unmodified version of your config somewhere so that if your controller's configuration resets or if the trick does not work or your editor screw up the encoding of the file you can always restore your original configuration.

Locate the following configuration block (or similar in your own configuration)


state = ENABLED
interface = PORT-LAN
domain-name-servers = 192.168.1.1
range-begin = 192.168.1.2
range-end = 192.168.1.254
routers = 192.168.1.1
subnet = 192.168.1.0
netmask = 255.255.255.0

The DHCP-SERVER-SUBNET-1 tag is what you want to locate. Inside that block, what do you see? YES, that's right! 'domain-name-servers'!

Well there you go ;P Change the address next to the 'domain-name-servers = ' token to your DNS, save that new config, restore it on the controller and reply to this thread to let me know if that worked!

You have the right to get me 10,000 points if it does :-)))))))))
Highlighted
Occasional Visitor

Re: msm760 can not modify dhcp server dns settings

This workaround does not work (tested with FW 6.3 on MSM720). VSC simply gets disable as the setting is incorrect after restore and restart.

 

HP, fix this nuisance please!

 

There are many reasons to assign different DNS servers to different VSCs, especially when AD authentication is used. Last thing I need is for my Guest VSC users to be able to resolve intranet names to their IP addresses.

Regular Advisor

Re: msm760 can not modify dhcp server dns settings

If your VSC is access controller/tunneled through the controller you have to use the MSM as the DNS server, and that makes complete sense IMHO. You don't want your guest users on the access controlled/tunneled VSC using an internal DNS server, otherwise you are no longer provided a secure guest wireless network that is isolated from your production network.

For NON-access controlled/tunneled VSCs, then I'd suggest using an external DHCP server for those VSCs/networks then you can use whatever DNS server(s) you want. Having an external DHCP server shouldn't be a problem pretty much every network has a DHCP server or can have one very easily.
Jesse R
Source One Technology, Inc.
HP Partner


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