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Re: [Openvpn-users] OPENVPN GUI - display for Revoked certs? anyone?


  • Subject: Re: [Openvpn-users] OPENVPN GUI - display for Revoked certs? anyone?
  • From: James Yonan <jim@xxxxxxxxx>
  • Date: Thu, 2 Sep 2004 20:37:29 -0600 (MDT)


On Thu, 2 Sep 2004, Mathias Sundman wrote:

> On Wed, 25 Aug 2004, hallian hallian wrote:
> 
> > I have seen the popup windows for "connect" and "disconnect."
> > 
> > But when I revoke a certificate for a user on the server, the server log 
> > display "user cert has been revoked" but how can we display a similar 
> > message as "PLease contact your Administrator" on the OPENVPN GUI.  I 
> > have noticed it keeps going and trying in an infinite loop.  Are we 
> > suppose to see a unsuccessful pop window?  Just wondering a road warrior 
> > could be staring at the screen for some time...... without seeing any 
> > error messages.
> 
> I took a closer look at this. And it's just like you say. The OpenVPN 
> server logs that the certificate is revoked, but the client don't seem to 
> be notified of this. Atleast nothing is logged about this.
> 
> James, would it be possible for the server to notify the client that the 
> certificate has been revoked, so a log message can be printed on the 
> client?

Right now, OpenVPN doesn't have any authentication-failed handshake.  When
one side of the connection is unable to authenticate the other side, it
resets its state, essentially dropping the TLS handshake.  This behavior
ensures security, as there is no failure handshake for an attacker to
exploit.  The downside, of course, is that there is no positive indication
of authentication failure from the server which is rejecting the 
certificate to the client which presented it -- only a repeating loop of 
authentication attempts which never succeed.  

The best solution would be if there was a way for side A (client) of the
connection to determine that side B (server) has reset its state due to
the authentication failure of A without requiring any specific message
from B to A.

James


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