Verifying username and password....but no go



Hello everyone. I have exhausted my avenues for trying to resolve an issue
that I have been having for one year now. I am hoping you guys might be able
to help me out with this one. We are having problems creating VPN
connections to our servers. I have two servers which both allow for RAS
connections through PPTP. These servers only have one NIC each. The NIC is
configured for the lan and uses a Netopia router for it's gateway. The
Netopia router is forwarding PPTP connections through using NAT to the
servers. I have used pptpclint.exe and pptpsrv.exe to make sure that my
servers are receiving packets tcp 1723 and IP 47 (GRE) from remote
connections. I have verified this both ways, to the server and from the
server and everything checks out fine. So routing is functioning as should.

The Problem:

It can take up 6 retries for any user to successfully created a remote PPTP
connection to our servers. Whenever we try to connect it display the
following message:

Verifying username and password...

And it sit there displaying this message for about 30-40 seconds, then it
says: "error: 721 The remote computer did not respond."

We retry and retry and usually within 6 tries we can successfully tunnel
into the server. From within our network, it is instant and without any
hiccups. Remotely, it is a different story. I have emailed Netopia several
times on this issues thinking it might be their routers. They assure me they
do not have any issues with this matter. I have since upgraded both servers
from NT 4.0 to Windows 2000 and I even bought the more expensive 3com NICs
for them hoping this problem would disappear which it didn't.

Just to clarify. We have two netopia routers on our network. They both have
their own separate WAN connection (we use a lot of bandwidth, hence the need
for two WAN connections). One server is configured to use one router as it's
gateway, and the other server uses the second router as it's gateway. When
PPTP connections are made, the connection comes in and back out the same
router (this I made sure). Like I said, it all works perfectly except for
the fact that it can take up to 6 retries to successfully connect.

Can someone shed any light on this? What can I try ? Many thanks in advance
to any suggestions.


Carl DaVault [MSFT]

If you are familiar with netmon, one way to find out what is happening is to
use netmon to compare the successful calls to the failing ones. When dealing
with fast, busy connections, it's best to increase the capture buffer size
or set up specific filters to reduce the amount of traffic captured.

(Sometimes you need to sniff both sides of a connection if you are going
across a router or NAT.)

You're probably looking at packet loss or problematic NAT behavior (the
classic 721 is caused by dropped/mangled GRE packets).

Jack Seredyniecki

Verifying username and password message comes up as soon as the connection
to port 1723 is made (basically if the port is open). It doesn't mean that
anything is actually being negotiated. For all you know there could be a
web server or FTP server running on that port.

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