Can't connect to VPN (error 721)

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Guest

Hi folks,

I'm using XP Media Center, SP2 on a new laptop, from behind a Belkin N1
Wireless 180170 router, and I can't connect to the VPN at work. It gets to
the Verifying username / password stage, then times out with error 721. To
minimise interference with the problem, I've turned off the firewall, and set
the connection properties on the VPN to allow any security protocol
(obviously that will have to change, but I wanted to get it working first,
then tighten things back up.) The packet trace (AAA is my machine, BBB is
the VPN server) shows what looks like a healthy PPTP negotiation, followed by
a failure to negotiate a PPP connection across the link:

No. Time Source Destination Protocol Info
1 0.000000 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB TCP
1105 > pptp [SYN] Seq=0 Len=0 MSS=1460
2 0.186823 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA TCP
pptp > 1105 [SYN, ACK] Seq=0 Ack=1 Win=16352 Len=0 MSS=1460
3 0.186916 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPTP
Start-Control-Connection-Request
4 0.377000 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPTP
Start-Control-Connection-Reply
5 0.377110 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPTP
Outgoing-Call-Request
6 0.565987 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPTP
Outgoing-Call-Reply
7 0.573595 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPTP
Set-Link-Info
8 0.578747 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
9 0.777695 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA TCP
pptp > 1105 [ACK] Seq=189 Ack=349 Win=16328 Len=0
10 0.779526 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPTP
Set-Link-Info
11 0.890481 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB TCP
1105 > pptp [ACK] Seq=349 Ack=213 Win=17308 Len=0
12 2.578390 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
13 2.763129 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
14 2.763745 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack

17 5.578413 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
18 5.763058 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
19 5.995117 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
20 9.578431 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
21 9.764535 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
22 9.995098 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
23 13.579023 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
24 13.765316 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
25 13.994091 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
26 17.579168 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
27 17.765118 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
28 17.994231 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
29 21.579195 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
30 21.765782 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
31 21.994384 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
32 25.579213 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
33 25.765299 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
34 25.994147 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
35 29.579235 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
36 29.790609 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
37 29.993796 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
38 33.579259 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
39 33.766132 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
40 33.995014 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
41 37.579597 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPTP
Call-Clear-Request
42 37.785972 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA TCP
pptp > 1105 [ACK] Seq=213 Ack=365 Win=16336 Len=0
43 37.856126 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Termination Request
44 37.856369 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPTP
Call-Disconnect-Notify
45 38.006897 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB TCP
1105 > pptp [ACK] Seq=365 Ack=361 Win=17160 Len=0
46 38.579260 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPTP
Stop-Control-Connection-Request
47 38.785582 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA TCP
pptp > 1105 [ACK] Seq=361 Ack=381 Win=16352 Len=0
48 38.785687 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB TCP
1105 > pptp [FIN, ACK] Seq=381 Ack=361 Win=17160 Len=0
49 38.972232 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA TCP
pptp > 1105 [ACK] Seq=361 Ack=382 Win=16351 Len=0
50 38.972379 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB TCP
1105 > pptp [RST, ACK] Seq=382 Ack=361 Win=0 Len=0

.... for whatever reason, the VPN sends the Request and the Ack, by my
machine sends the Request only and refuses to acknowledge the one sent by the
VPN. But I can see it going by (the packet trace is from my machine).

I'm confused, and would greatly appreciate any advice. Thanks,
 
(Ug. Sorry about the formatting of the trace; the newsgroup interface
decided to rearrange things.)
 
sounds like GRE issue. Make sure the router/firewall is VPN pass though. these search results may help,

error 721 and error 800
I double checked the check list in server management and enabled VPN to the ... with an domain administrator account I still get those error:721,and 800 . ...
http://www.chicagotech.net/Q&A/vpn25.htm -

Case Studies - VPN error 721 and 800
Case 1: When a user attempts to access the Windows VPN server that is behind a Linksys WRT54G, he receives VPN Error 800 or 721. ...
http://www.chicagotech.net/VPN/vpncase800.htm -

cannot establish VPN with error 721 and 800
Cannot establish VPN with error 721 and 800. Situation: 1. The client setup VPN behind a Cisco 678 DMT. Whenever he tries to establish the VPN, ...
http://www.chicagotech.net/cisco/vpngre1.htm -

VPN Issues
Symptom: When attempting to connect to a VPN server on the outside of the PIX it returns error 721 or 800, the computer failed to respond. ....
http://www.chicagotech.net/vpn.htm


Bob Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN Troubleshooting on http://www.ChicagoTech.net
How to Setup Windows, Network, VPN & Remote Access on http://www.HowToNetworking.com
Hi folks,

I'm using XP Media Center, SP2 on a new laptop, from behind a Belkin N1
Wireless 180170 router, and I can't connect to the VPN at work. It gets to
the Verifying username / password stage, then times out with error 721. To
minimise interference with the problem, I've turned off the firewall, and set
the connection properties on the VPN to allow any security protocol
(obviously that will have to change, but I wanted to get it working first,
then tighten things back up.) The packet trace (AAA is my machine, BBB is
the VPN server) shows what looks like a healthy PPTP negotiation, followed by
a failure to negotiate a PPP connection across the link:

No. Time Source Destination Protocol Info
1 0.000000 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB TCP
1105 > pptp [SYN] Seq=0 Len=0 MSS=1460
2 0.186823 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA TCP
pptp > 1105 [SYN, ACK] Seq=0 Ack=1 Win=16352 Len=0 MSS=1460
3 0.186916 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPTP
Start-Control-Connection-Request
4 0.377000 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPTP
Start-Control-Connection-Reply
5 0.377110 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPTP
Outgoing-Call-Request
6 0.565987 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPTP
Outgoing-Call-Reply
7 0.573595 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPTP
Set-Link-Info
8 0.578747 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
9 0.777695 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA TCP
pptp > 1105 [ACK] Seq=189 Ack=349 Win=16328 Len=0
10 0.779526 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPTP
Set-Link-Info
11 0.890481 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB TCP
1105 > pptp [ACK] Seq=349 Ack=213 Win=17308 Len=0
12 2.578390 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
13 2.763129 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
14 2.763745 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack

17 5.578413 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
18 5.763058 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
19 5.995117 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
20 9.578431 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
21 9.764535 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
22 9.995098 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
23 13.579023 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
24 13.765316 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
25 13.994091 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
26 17.579168 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
27 17.765118 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
28 17.994231 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
29 21.579195 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
30 21.765782 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
31 21.994384 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
32 25.579213 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
33 25.765299 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
34 25.994147 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
35 29.579235 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
36 29.790609 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
37 29.993796 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
38 33.579259 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPP LCP
Configuration Request
39 33.766132 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Ack
40 33.995014 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Configuration Request
41 37.579597 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPTP
Call-Clear-Request
42 37.785972 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA TCP
pptp > 1105 [ACK] Seq=213 Ack=365 Win=16336 Len=0
43 37.856126 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPP LCP
Termination Request
44 37.856369 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA PPTP
Call-Disconnect-Notify
45 38.006897 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB TCP
1105 > pptp [ACK] Seq=365 Ack=361 Win=17160 Len=0
46 38.579260 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB PPTP
Stop-Control-Connection-Request
47 38.785582 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA TCP
pptp > 1105 [ACK] Seq=361 Ack=381 Win=16352 Len=0
48 38.785687 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB TCP
1105 > pptp [FIN, ACK] Seq=381 Ack=361 Win=17160 Len=0
49 38.972232 BBB.BBB.BBB.BBB AAA.AAA.AAA.AAA TCP
pptp > 1105 [ACK] Seq=361 Ack=382 Win=16351 Len=0
50 38.972379 AAA.AAA.AAA.AAA BBB.BBB.BBB.BBB TCP
1105 > pptp [RST, ACK] Seq=382 Ack=361 Win=0 Len=0

... for whatever reason, the VPN sends the Request and the Ack, by my
machine sends the Request only and refuses to acknowledge the one sent by the
VPN. But I can see it going by (the packet trace is from my machine).

I'm confused, and would greatly appreciate any advice. Thanks,
 
Robert L said:
sounds like GRE issue. Make sure the router/firewall is VPN pass though. these search results may help,
Click to expand...

Thanks for the reply Robert,

The router does claim to be VPN pass-through, but more importantly, I can
see the PPP LCP Requests and Acks from a (non-promiscuous mode) packet
sniffer on my notebook. Those PPP LC packets are coming across the
established GRE link. Surely the fact that I can see them means that they're
making it through the router? (he asks hopefully, being fairly ignorant of
how wireless works?) Or am I somehow seeing them as they hit the router, but
they're making it no further? Its almost as if the incoming (only; the
outgoing ones must be making it through to the VPN server because I'm
receiving Acks for them) GRE packets are making it through the router to my
network interface and then being blocked by some sort of firewall - but I've
tried turning off both Windows and Norton Firewalls to no avail.
 
The plot thickens...

Just to ensure that it wasn't the router, I tried connecting to the same VPN
from the other wireless machine (XP home edition, SP2) sitting right next to
the notebook - works fine.
 
Hmmm.

Doesn't seem to be a firewall thing either. I completely uninstalled all of
the Norton products, and configured the windows Firewall exactly the same on
the notebook (which doesn't work) as on the second machine (which does.) As
well as turning it off, of course.

There isn't some subtle difference between XP Media Center and XP Home
Edition that could effect this, is there? Seems to be the main difference
left between the two machines...
 
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