[vpn-help] Problem using VPN client on two machines at same time

[Kevin VPN]

On 03/15/2012 09:54 PM, Curt Broyles wrote:
> Problem:
>
> We provide medical billing for a doctors office across the state.  In order
> to access his patient medical system, his IT company installed Shrew Soft on
> all our PC's.  We connect to their office via Access Manager, and once
> connected we open their patient medical software with a client they also
> installed on our PC's.  For some time all was working find then suddenly we
> started having the following problem.
>
> The first person can connect and work fine.  Once a second person makes a
> VPN connection from our office the first person's connection will freeze up
> and the only way the PC can recover is to reboot.  Even if the second person
> closes the VPN connection, the first person to make the connection cannot
> recover.
>
> To Reproduce:
>
> VPN Client Version = 2.1.7
> Windows OS Version = Windows XP SP Latest Updates
>
> Gateway:  Sonicwall TZ180
> Gateway OS:  Sonicwall Standard 3.8.0.1-27s
>

Hi Curt,

You mention that it was working for a while, then the problems began. 
That obviously suggests something changed on the path.  I'd first look 
to firewalls/gateways in the path.

What about at your local site?  Do you have a firewall protecting the 
office?  Has it recently had an upgrade or changes made to it?  Perhaps 
it needs IPsec passthrough re-enabled to handle multiple IPsec clients 
behind it.

The symptom of Shrew locking up the PC sounds a little like a condition 
I've seen where one of the Shrew processes (iked.exe or ipsecx.exe) take 
full control of the CPU and very reluctantly releases it.  For me this 
has happened when I've briefly lost my wifi connection.  My guess is 
that Shrew gets some unexpected packets and get horribly confused.

If this is what's happening with you, then I'd look for a local problem, 
like your firewall is mixing up or dropping some of the ipsec packets 
for your multiple Shrew clients.