G
Guest
I am trying to connect to a customer's network via Microsoft PPTP VPN. The
symptom of the problem is the logon process hanging on "Verifying username
and password" and then timing out with Error 721 (The remote computer did not
respond.) By now I have tried everything anyone had recommended but I still
can't get to the bottom of it. What freaks me out is that it used to work
fine until about a month ago.
The client I am trying to connect from is Windows XP Pro SP2. It is behind
a firewall (linux iptables also doing NAT) on my home network. I have been
able to connect to the server from both my linux machine as well as my wife's
Windows XP Home SP2 machine so I know the problem does not lie with my linux
firewall.
In one of the other posts someone else reported exactly the same problem and
managed to fix it by applying the ValidateAddress=0 registry fix that turns
off a check in one of the XP patches that prevents connection to a server
where the reply does not originate from the same IP address. Still the same
problem.
The Windows firewall is disabled and although I am running McAfee Personal
Firewall, it used to work with this installed and even when I uninstalled my
entire McAfee suite I still had the same problem.
Btw, I have already re-installed Windows XP Sp2. Also reset the TCP stack
as suggested elsewhere in this forum.
Using Ethereal I sniffed the packets and came up with the following:
Protocol Info
TCP 1092 > pptp [SYN] Seq=0 Ack=0 Win=65535 Len=0 MSS=1460
TCP pptp > 1092 [SYN, ACK] Seq=0 Ack=1 Win=16352 Len=0 MSS=1436
PPTP Start-Control-Connection-Request
PPTP Start-Control-Connection-Reply
PPTP Outgoing-Call-Request
PPTP Outgoing-Call-Reply
PPTP Set-Link-Info
PPP LCP Configuration Request
TCP pptp > 1092 [ACK] Seq=189 Ack=349 Win=16328 Len=0
PPTP Set-Link-Info
TCP 1092 > pptp [ACK] Seq=349 Ack=213 Win=65323 Len=0
PPTP [TCP Out-Of-Order] Set-Link-Info
TCP [TCP Dup ACK 11#1] 1092 > pptp [ACK] Seq=349 Ack=213 Win=65323 Len=0
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPTP Call-Clear-Request
TCP pptp > 1092 [ACK] Seq=213 Ack=365 Win=16336 Len=0
PPTP Call-Disconnect-Notify
TCP 1092 > pptp [ACK] Seq=365 Ack=361 Win=65175 Len=0
PPTP Stop-Control-Connection-Request
TCP pptp > 1092 [ACK] Seq=361 Ack=381 Win=16352 Len=0
TCP 1092 > pptp [FIN, ACK] Seq=381 Ack=361 Win=65175 Len=0
TCP pptp > 1092 [ACK] Seq=361 Ack=382 Win=16351 Len=0
TCP 1092 > pptp [RST, ACK] Seq=382 Ack=361 Win=0 Len=0
Now, unfortunately I don't know enough about LCP but from what I have read
there should be one of three responses from the server - ACK, NAK or REJ -
and the server is not responding.
Can anyone shed some light or suggest anything I can try to get this sorted
out?
Thanks in advance.
symptom of the problem is the logon process hanging on "Verifying username
and password" and then timing out with Error 721 (The remote computer did not
respond.) By now I have tried everything anyone had recommended but I still
can't get to the bottom of it. What freaks me out is that it used to work
fine until about a month ago.
The client I am trying to connect from is Windows XP Pro SP2. It is behind
a firewall (linux iptables also doing NAT) on my home network. I have been
able to connect to the server from both my linux machine as well as my wife's
Windows XP Home SP2 machine so I know the problem does not lie with my linux
firewall.
In one of the other posts someone else reported exactly the same problem and
managed to fix it by applying the ValidateAddress=0 registry fix that turns
off a check in one of the XP patches that prevents connection to a server
where the reply does not originate from the same IP address. Still the same
problem.
The Windows firewall is disabled and although I am running McAfee Personal
Firewall, it used to work with this installed and even when I uninstalled my
entire McAfee suite I still had the same problem.
Btw, I have already re-installed Windows XP Sp2. Also reset the TCP stack
as suggested elsewhere in this forum.
Using Ethereal I sniffed the packets and came up with the following:
Protocol Info
TCP 1092 > pptp [SYN] Seq=0 Ack=0 Win=65535 Len=0 MSS=1460
TCP pptp > 1092 [SYN, ACK] Seq=0 Ack=1 Win=16352 Len=0 MSS=1436
PPTP Start-Control-Connection-Request
PPTP Start-Control-Connection-Reply
PPTP Outgoing-Call-Request
PPTP Outgoing-Call-Reply
PPTP Set-Link-Info
PPP LCP Configuration Request
TCP pptp > 1092 [ACK] Seq=189 Ack=349 Win=16328 Len=0
PPTP Set-Link-Info
TCP 1092 > pptp [ACK] Seq=349 Ack=213 Win=65323 Len=0
PPTP [TCP Out-Of-Order] Set-Link-Info
TCP [TCP Dup ACK 11#1] 1092 > pptp [ACK] Seq=349 Ack=213 Win=65323 Len=0
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPP LCP Configuration Request
PPTP Call-Clear-Request
TCP pptp > 1092 [ACK] Seq=213 Ack=365 Win=16336 Len=0
PPTP Call-Disconnect-Notify
TCP 1092 > pptp [ACK] Seq=365 Ack=361 Win=65175 Len=0
PPTP Stop-Control-Connection-Request
TCP pptp > 1092 [ACK] Seq=361 Ack=381 Win=16352 Len=0
TCP 1092 > pptp [FIN, ACK] Seq=381 Ack=361 Win=65175 Len=0
TCP pptp > 1092 [ACK] Seq=361 Ack=382 Win=16351 Len=0
TCP 1092 > pptp [RST, ACK] Seq=382 Ack=361 Win=0 Len=0
Now, unfortunately I don't know enough about LCP but from what I have read
there should be one of three responses from the server - ACK, NAK or REJ -
and the server is not responding.
Can anyone shed some light or suggest anything I can try to get this sorted
out?
Thanks in advance.