D-Link NetDefendOS User Manual page 738

• Password - Specifies the password for the interface.
Security
• IPsecInterface - Optionally specify an IPsecTunnel object to use. The tunnel should not have
the Dynamically add route to remote network option enabled since this can cause
problems.
• Authentication - These choices specify which authentication protocol to use.
• MPPE - Specifies if Microsoft Point-to-Point Encryption is used and which level to use.
If Dial On Demand is enabled then the PPTP/L2TP tunnel will not be set up until traffic is sent on
the interface. The parameters for this option are:
• Activity Sense - Specifies if dial-on-demand should trigger on Send or Recv or both.
• Idle Timeout - The time of inactivity in seconds to wait before disconnection.
Using the PPTP Client Feature
One usage of the PPTP client feature is shown in the scenario depicted below.
Here a number of clients are being NATed through NetDefendOS before being connected to a
PPTP server on the other side of the NetDefend Firewall. If more that one of the clients is acting
as a PPTP client which is trying to connect to the PPTP server then this will not work because of
the NATing.
One way of achieving multiple PPTP clients being NATed like this is to use the PPTP ALG (see
Section 6.2.8, "The PPTP ALG"). Another way is for the NetDefend Firewall to act as a PPTP client
when it connects to the PPTP server and the setup for this requires the following:
• A PPTP tunnel is defined between NetDefendOS and the server.
• A route is added to the routing table in NetDefendOS which specifies that traffic for the
server should be routed through the PPTP tunnel.
Using this client approach is suitable for situations where an ISP requires PPTP for authentication.
738
Chapter 9: VPN