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VPN problem: Windows XP -> Windows 2000

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mmez

IS-IT--Management
Sep 18, 2002
3
IT
My problem is very simple to explain: I cannot make a VPN connection (native Windows PPTP connection) between my home PC and my office Server working.

Now, the details

Home PC: Windows XP Pro Service Pack 1.
Home router: Cisco 827-4V (IOS 12.2(8)T4) which connects to an ADSL line, act as a DHCP server and performs NAT.
Office server: Windows 2000 Server Service Pack 3.

When I try to connect to the server, the connection says "Verifying Username and Password" for 40~ seconds and then I receive error 721 (the remote computer is not responding).

The very strange thing is that, if I try again and again (50, 60, 70 times) finally I succeed in connecting.

Ok, let's go on with some more info

1) I tried to substitute the Cisco router with a ZyXel 645R: with the new router Windows XP is able to establish the connection every time.
2) I tried to substitute my home PC OS (I installed Windows 98 and Windows 2000): I can establish the connection every time also using the Cisco router.
3) I tried with a clean installation of Windows XP: again, it works with the ZyXel router, but it doesn't work with the Cisco one.
4) I tried to change (to lower) MTU in Windows XP: again, it works with the ZyXel router, but it doesn't work with the Cisco one.
5) I tried to sniff packets on the client side: the connection on port 1723 works fine (I see some handshaking packets running) but when my PC sends the first "protocol 47" packet it doesn't receive any answer.

These are my conclusions

1) It doesn't seem to be a Cisco problem: Windows 98 and Windows 2000 can connect.
2) It doesn't seem to be an ISP problem: Windows 98 and Windows 2000 can connect.
3) It doesn't seem to be a server problem: Windows 98 and Windows 2000 can connect.

BUT...

4) I doesn't seem to be a Windows XP problem: changing the router it can connect.

So, I really don't know what to do. Can you help me?

Thx.

My Cisco router configuration

service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
hostname mmerouter
!
enable secret 5 <password>
!
clock timezone CET 1
clock summer-time CEST recurring last Sun Mar 2:00 last Sun Oct 3:00
!
ip domain-name virgilio.it
ip name-server 212.216.112.112
ip name-server 212.216.172.62
ip dhcp excluded-address 192.168.30.1
!
ip dhcp pool Client
network 192.168.30.0 255.255.255.0
dns-server 212.216.112.112 212.216.172.62
default-router 192.168.30.1
domain-name virgilio.it
!
vpdn enable
!
vpdn-group pppoe
request-dialin
protocol pppoe
!
interface Ethernet0
ip address 192.168.30.1 255.255.255.0
ip nat inside
ip tcp adjust-mss 1452
!
interface ATM0
no ip address
pvc 8/35
pppoe-client dial-pool-number 1
!
interface Dialer0
ip address negotiated
ip nat outside
encapsulation ppp
dialer pool 1
dialer-group 1
ppp pap sent-username <username> password 7 <password>
!
ip nat inside source list 101 interface Dialer0 overload
!
ip route 0.0.0.0 0.0.0.0 Dialer0
!
access-list 101 permit ip 192.168.30.0 0.0.0.255 any
dialer-list 1 protocol ip list 101
!
line vty 0 4
access-class 101 in
password 7 <password>
login
!
sntp server 192.43.244.18
!
end
 
Hi Mmex,

I came accross the article while troubleshooting an ipsec problem with another router. I was unable to use the patch as I have the latest SP1 on my XP machine. But it is desinged specifically for PPTP connections for all windows operating systems.

&quot;
Good Luck

Deano
 
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