ERROR 721 VPN

[CluelessJon]

Hi,

Right I have a VPN server that I connect XP clients to.

I cannot for the life of me get past error 721. I had this on another laptop... so i rebuilt it and it connected ok.

I have just formatted this win2k machine and installed winXP and the VPN fails to get connected again
( error 721 )

My Ip Address is the same as it was before and I have no idea what is causing this.

I have had this a couple of times before and a rebuild seemed to solve the problem.

I cannot rebuild this machine.

Please bear in mind that it is not the router / firewall or anything like that. I have other XP machines here that connect with no problem.

The network cable and setup never left my machine during the re installation and all the setting are the same as before.

Please does anyone have a fix for this. I have gone through about 100 google news groups and there is no definative fix available.

I have however done this

1. Click "Start", and then click "Run".

2. In the "Open" box, type "regedit" (without the quotation marks)
and then press ENTER.

3. In Registry Editor, locate the following subkey in the registry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325
-11CE-BFC1-08002bE10318}\000x , where 000x represents the network
interface used to establish the VPN connection.

4. On the "Edit" menu, point to "New" and then click "DWORD Value".

5. Type "ValidateAddress" (without the quotation marks), and then
press ENTER.

6. Quit Registry Editor.

7. Restart your computer



PLEASE DOES ANYONE HAVE AN IDEA ??

Thanks

Regards

Jonno BrainDump Specialist
MCSE(NT) MCSA(2k) CCNA

 

[CluelessJon]

Anyone Please ???

Regards

Jonno BrainDump Specialist
MCSE(NT) MCSA(2k) CCNA

 

[bcastner]

Error 721 on a VPN connection has this text in Help and Support:
If you are trying to establish a virtual private network (VPN) connection, make sure that the host name or the IP address of your destination server is correct and try the connection again. To check this information, right-click
the connection, click Properties, and review the information on the General tab.
----------------------------------------------------

Here's one specific problem which your system probably evidences:

http://support.microsoft.com/default.aspx?scid=kb;en-us;329441

(this kb article gives a workaround, but a better choice is to reinstall the SP1.

Your mention of error 721 in relation to VPN brings me to a different post-sp1 issue, though, and it is one I don't feel I have a real strong technical description of--but let me give it a try--the test for this one would be that a gold XP would vpn into a given Windows 2000 server just
fine, whereas an SP1 XP would get error 721 on that same connection.
-----------------------------------------------
This one relates to VPN connections--there's a security fix in SP1 which breaks previously working connections to improperly configured vpn hosts, described thusly:

Why XP Pro worked versus XPSP1:
SP1 included a patch which provided a VPN security fix.
The fix was that the client will only accept replies from the initial server ip address that it was VPN'ing into. This was to prevent highjack of a TCP session from another machine other than the server.

Error 721 on attempting connection is a symptom

http://support.microsoft.com/default.aspx?scid=kb;en-us;271731

This needs to be fixed at the host.

What's confusing about my description of this issue above, is that 271731 a). doesn't mention XP at all--it is in relation to other clients, and b). doesn't mention error 721. However my understanding is that the description
under Resolution in this KB article is what you need to know in relation to the server end setup--and what has to change.

From a newsgroup note of Bill Sanderson, MVP

 

[CluelessJon]

Thanks Bcastner

Just reinstalled SP1 again Same problem.

This is a integrated XPSP1 install so I cant uninstall the SP Either.

I will ask the VPN server guy to make the other suggested fixes

"To resolve this problem, make sure that earlier version PPTP clients establish the connection to the first IP address that is bound to the server's network interface, and that the default gateway on the server is configured on the interface that receives the connection attempt"


Will report back tomorrow. I am amazed at how widespread and unsolved this problem is.

Thanks for help BC

Regards

Jonno BrainDump Specialist
MCSE(NT) MCSA(2k) CCNA