If you plan to install PerformanceGuard agents on computers that connect to your network using a software VPN solution, you must know that PerformanceGuard and certain software VPN solutions can't coexist without problems.
The problems are:

• Network connectivity is lost
• Windows crashes (on older versions on windows)

The problems are usually due to a non-conforming implementation of the NDIS interface in the VPN low-level driver.

Software VPN Implementations that Are Known to Cause Problems

These software VPN clients are known to cause problems when used together with the PerformanceGuard agent:

• Check Point VPN-1 Secure Client (network interface name: cp_scvna Check Point Virtual Network Adapter)
• VPN solutions based on Microsoft Whale driver (network interface name: Whale Network Connector)
• Cisco VPN Client

When PerformanceGuard agents identify one of the listed adapters they will disable the driver that conflicts with the faulty NDIS implementation. This means that PerformanceGuard won't make any measurements that rely on passive network data capture, such as TCP and UDP statistics and HTTP transaction filters.

If You Suspect that There's a Software VPN Conflict

If you experience problems on a computer with a software VPN client running when you install the PerformanceGuard agent:

• Verify that the problem only occurs when the PerformanceGuard agent and the VPN solution run at the same time.
• Use the PerformanceGuard agent web interface to get the name of the network adapter: On the computer that has the agent installed, open a browser and connect to http://localhost:4007. In the agent information window that opens, select View > Adapters. Make sure that you do this with the VPN client connected to the VPN server.

• Check the PerformanceGuard agent error log (View > Errors), and pay special attention to information from the E2ETcp module.

• Collect the information from the two last steps and send it to CapaSystems support, together with details on the VPN solution.