Error 781

  • Thread starter Thread starter Walt Smith
  • Start date Start date
W

Walt Smith

The encryption attempt failed because no valid
certificate was found.

Just setup on WIN2K3 server simple VPN, allow DIal-in
access for account, and got this message from Win XP pro
system.

What is wrong?

Thanks
 
quoted form http://www.ChicagoTech.net
Error 781 - Encryption Failed

Symptom: When connecting to a VPN server, you may receive this Error 781:
The encryption attempt failed because no valid certificate was found.

Resolution: If your VPN client is trying to use L2TP/IPSec for the VPN
connection, you may receive above message. What you need to do is switching
to a PPTP VPN connection, which doesn't need a certificate. To do this,
open the properties of the VPN connection, choose the Networking tab, and
change the "Type of VPN" to PPTP VPN (default is Automatic). Also make sure
you have good connection. Sometimes, poor connection can cause this issue
too.
--
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Posting on MS newsgroup will benefit all readers and you may get more help.

Robert Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN, Anti-Virus, Tips & Troubleshooting on
http://www.ChicagoTech.net
This posting is provided "AS IS" with no warranties.
 
Robert and others,

I changed it to PPTP, now I am getting error 628.

Something is wrong with the setup. In the past I had a server with two dual
Ethernet cards, one local and one ISP. Now my server is on an internal
network, an duse a DSL router. Thus I have only one Ethernet card.

Whenever I install the VPN RAS, my clients can access the server anymore.
Must be a routing issue!

With NT and WIN2K (now I am using WIN2K3), I remember I ahd to install the
VPN RAS manualy as the wizard had problems. Or else...I forgot.

It is very simple to run through the questions of the wizard -- not too many
questions!

Any ideas will be helpful!
 
In another thread, I read teh following:

Are the clients going through a firewall or router to get to the VPN server?
If so does the router/firewall allow TCP port 1723 and IP Protocol 47 (GRE)?
Can a client on the same subnet as the VPN server connect?


Thus, I tried from a local XP client , and I got connected!

The other WIN 2K client access goes through a DSL router, and dails with
error 628, and re-tries -- I checked, and I have 1723 and 47 forwarded!

Any suggestions! Thanks
 
It probably has nothing to do with this problem, but you misread the
posting. GRE is not a port!

GRE is an IP protocol, just like TCP. If it is blocked, PPTP will fail,
because the encrypted data is carried as the payload of an IP packet with a
GRE header.
 
Bill,

I understand what you reply -- my dsl router manulka indicated VPN will work
when specifying to forword these two ports.
 
Yes, it is a commonly held view that PPTP needs tcp port 47. Even router
manufacturers (who should kow better) include it in their instructions. But
it is not required. What you must have is GRE.
 
Both D_LINK DSL router and DELL router claims it supports GRE on port 47.

I have e-mailed D-LINK tech support to see what we need to do to make MS VPN
work. PPTP should work!

Anyone know how, let me know!

Thanks
 
Regardless of how many people say it, GRE is not a port! It is a protocol.

If the router/firewall does not mention GRE by name or by its protocol
number, look for things like PPTP pass-through or even VPN pass-through
mode. Both of these are used by router makers to indicate allowing GRE.
 
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