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Starting this week, I'm going to work on a rather big project, which requires me to connect temporarely via VPN tunnel to my clients' network.

Right now, the statement is: Its supposed to work with Windows, but Linux is still a try and fail.
I'm not a big crack with this, either.

FYI: I'm using (K)Ubuntu Linux 7.04 "Feisty Fawn", connected over two routers (Arcor Easybox A 600, Linksys WRT54GL) with ADSL+ uplink (6 MBit/s).

I've already tried using the usual suspects like Cisco-VPN and pure PPTP, but that always resulted in a "couldnt establish connection". I've also tried getting it to work using a VM, which theoretically should work (if I'm right), as QEMU basically offers the network connectivity, but Windows in the VM does the thinking (PPTP) ..

So any good suggestions on how to get a VPN connection / tunnel working in Linux would be very appreciated.

cu, w0lf.

Fuck off the 30 seconds posting limit!

Does a Windows-based client require any special software? If not, it's probably PPTP.

I don't have much experience with Linux VPNs, but in those cases I've seen that didn't work it usually was because of incompatible authentication/compression settings. I'd start by comparing the settings of a working Windows client to my ppp config.

Can you post any screenshots, config files or logs?

"God is dead." - Nietzsche, 1882 "Nietzsche is dead." - God, 1900

This post was edited by null on Mar 18, 2008.

Right now, I've got it working under WinXP.
It looks just like a standard PPTP connection.

Are there any tools for Windoze to derive what exact connection I'm using right now?

cu, w0lf.

Fuck off the 30 seconds posting limit!

None that I know of. Well, there's of course Wireshark to see the handshake, but I'm not sure how much of the data it gathers will be unencrypted.
The best source of information I know of is the Properties window of your VPN connection. You can learn quite a lot about the authentication methods and encryption used by clicking on everything there and taking screenshots.
Your best bet would then probably be to create a ppp config file that's as faithful to these screenshots as possible.

"God is dead." - Nietzsche, 1882 "Nietzsche is dead." - God, 1900

Right now I've found out the following:

a) its PPTP
b) both MS-CHAP and MS-CHAP v2 are involved.

cu, w0lf.

Fuck off the 30 seconds posting limit!

So if I understood it correctly:

All of this works thanks to TCP/IP.

So why cant I connect eg. using a VMware-based Windows install? If I try doing exactly that using my QEMU-Win2k-VM, I get a "port not found" / "remote does not reply"-message.

Is there any chance or does anybode in here have got a clue how to find out which port gets connected to, so that I could look into some port forwarding?

cu, w0lf.

Fuck off the 30 seconds posting limit!

PPTP traffic consists of TCP (port 1723) and GRE packets. I really have no idea how the virtual/physical network mapping is done in your case, but in theory it should world.
If playing with the configuration doesn't help I'd use Wireshark to sniff the handshake packets and see if there's something suspicious.
If you think it's of any help I can set you up an account on my VPN server so you can try and connect there to see if it works.

"God is dead." - Nietzsche, 1882 "Nietzsche is dead." - God, 1900