[pptp-server] PPTP w/data encryption: works w/W98, not NT

[Nathan Meyers]

Hi,

I'm a new PoPToP user. I've configured for support of MS 40-bit
encryption with the following setup:

Kernel 2.2.12 (RH6.1)
pptpd 1.0.0
ppp-2.3.8 with ppp-2.3.8-mppe patches
SSLeay 0.6.6b

I've configured PPP as follows:

name foo
auth
require-chap
proxyarp
+chap
+chapms
+chapms-v2
mppe-40
mppe-stateless

I've ended up with a PPTP setup that works flawlessly with Win98 and
WinNT clients *without* data encryption, and with a Win98 client using
data encryption (after applying the MS dun40.exe update). But I cannot
get encryption to work with the WinNT client.

I'm running NT workstation with the latest service pack (#6). The
following options are disabled in the dialup setup for the VPN
connection:

IP header compression
Default gateway on remote network
Software compression
PPP LCP extensions

The attempt to login succeeds to a certain point: user authentication
succeeds but then, during the "Registering your computer on the network"
step, NT displays a failure dialog with the message "Error 742: The
remote server does not support encryption".

Looking at the logfiles on the Linux side, I see a successful
authentication and loading of the MPPE module, and then NT apparently
just hangs up:

>Dec 19 22:39:16 vectra pppd[7845]: pppd 2.3.8 started by root, uid 0
>Dec 19 22:39:16 vectra pppd[7845]: Using interface ppp1
>Dec 19 22:39:16 vectra pppd[7845]: Connect: ppp1 <--> /dev/pts/2
>Dec 19 22:39:16 vectra pptpd[7844]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
>Dec 19 22:39:17 vectra kernel: PPP BSD Compression module registered
>Dec 19 22:39:17 vectra kernel: PPP MPPE compression module registered
>Dec 19 22:39:17 vectra pppd[7845]: MSCHAP peer authentication succeeded for ntvectra
>Dec 19 22:39:18 vectra pptpd[7844]: CTRL: Error with select(), quitting
>Dec 19 22:39:18 vectra pptpd[7844]: CTRL: Client 192.168.204.128 control connection finished
>Dec 19 22:39:18 vectra pppd[7845]: Modem hangup
>Dec 19 22:39:18 vectra pppd[7845]: Connection terminated.
>Dec 19 22:39:19 vectra pppd[7845]: Exit.

Does anyone recognize this problem?

Nathan Meyers
nmeyers at javalinux.net