[Winpcap-users] Using winpcap on a VPN

Gaming Mouse gaming_mouse at yahoo.com
Wed Mar 14 14:53:45 GMT 2007

> If you are using the vanilla VPN stuff from microsoft, it's most 
> probably PPTP. In that case WinPcap should work without any problem.
> Before the connection is established, at all times, you can see a fake 
> adapter called "generic dialup adapter". You can use that adapter to 
> capture all the management frames used to establish the connection. 
> After the connection is established, a new adapter appears, as well, 
> usually called PPP/SLIP connection or similar. You can basically 
> capture the same identical packets on the two adapters. All the frames 
> will be encapsulated into a (fake) ethernet packet. The first thing i 
> would try to do to check that everything works is trying windump (or 
> wireshark) and see if wireshark captures on those adapters. If it 
> works, I kinda have a suspect as to the source of the issue with jpcap 
> (and it's related to COM). Which OS are you using?
> Have a nice day
> GV

Again, thanks very much for your help.  I installed wireshark and was 
able to capture packets both on my wirless card (without the VPN), and 
using the WAN (PPP/SLIP) adapter after my VPN was connected.  In both 
cases, however, it was raw packet information, rather than the plaintext 
html (or other plaintext traffic) that I am able to output with my 
sample program.  However, I assume this is just default behavior and is 
to be expected. 

To answer your other question, I am using WinXP Pro, though I've also 
tested on  WinXP Home and had the same issue.

What exactly is the problem with jpcap?  Is there a way to fix it?

Thanks again,

Get your own web address.  
Have a HUGE year through Yahoo! Small Business.

More information about the Winpcap-users mailing list