There appears to be a problem with Dial-up Networking on NT 4.0 with the
maximum size of a packet that can be transmitted (called MTU).
The problem is that the Microsoft software fails to ask for the MTU and
must therefore be assuming a constant. This works without SKIP encryption but
fails when encryption is enabled because SKIP adds some headers increasing
the size of the packet beyond the Adapter's MTU.
What is supposed to happen is that when IP asks for the MTU, SKIP intercepts
the reply and subtracts the size of the additional headers from the MTU
returned to IP.
Since IP doesn't appear to be asking for the MTU, SKIP does not get a chance
to reduce the MTU.
There is a workaround that requires setting the MTU in the registry.
I've found some information in the April '98 MSDN library.
The Title is "TCP/IP and NBT Configuration Parameters for Windows NT".
The registry value that needs to be set to specify the MTU is called "MTU" in
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NdisWan<n>\Paramters\Tcpip
MTU DWORD <value>
<n> is a number, e.g. NdisWan7
<value> is the Adapter's MTU - 134, e.g. 1500 - 134 = 1366.
This _should_ fix the problem.
jp
