[pptp-server] Unsupported protocol 0x... received

[Rogelio J. Baucells]

Hello

I just installed a pptpd server in a linux machine running kernel 2.4.1,
ppp-2.4 and pptp-1.1.2. I am using Windows 2000 clients and I have no
problems with some of them (No high encryption pack installed), with a
couple of them (128 bits encryption installed) I can connect but nothing
comes thru the link. This is the log file for the last ones.

found interface eth0 for proxy arp
local  IP address X.Y.Z.W
remote IP address X1.Y1.Z1.W1
rcvd [CCP ConfAck id=0x2 <mppe 1 0 0 20>]
MPPE 40 bit, stateless compression enabled
rcvd [proto=0x1f76] bd 23 c9 1c 42 43 29 75 67 9c 1b 79 a6 76 be 6e fa d2 6d
02 15 b3 c6 24 b3 db 38 d2 3a b8 4d df ...
Unsupported protocol 0x1f76 received
sent [LCP ProtRej id=0x4 1f 76 bd 23 c9 1c 42 43 29 75 67 9c 1b 79 a6 76 be
6e fa d2 6d 02 15 b3 c6 24 b3 db 38 d2 3a b8 ...]
rcvd [proto=0xb7c4] fa 6e 9f 38 9b 4c 4d 2b 6b f6 62 b8 80 9c b4 12 a9 6c 49
bb f0 bc 57 42 1f 6e ff 70 f1 3f 5a b7 ...
Unsupported protocol 0xb7c4 received

and a lot of "Unsupported protocol XXXX received".
....

kernel-2.4.1 patched with linux-2.4.0-openssl-0.9.6-mppe.patch
ppp-2.4.1 patched with ppp-2.4.0-openssl-0.9.6-mppe.patch

-- /etc/ppp/options.pptp
lock
debug
auth
ktune
+chap
+chapms
+chapms-v2
mppe-40
mppe-stateless
proxyarp

-- /etc/pptpd.conf
debug
option          /etc/ppp/options.pptp
localip         X.Y.Z.W
remoteip     X.Y.Z.W1-W2
listen          X.Y.Z.W3

I tried using CHAP authentication with a computer (with 128 bits encryption)
and it worked fine, but if I use MS-CHAP or MS-CHAP v2 I got the errors
showed above.

How can I force mppe-40 to test if the problem persists?

Is there any thing I can do to resolve this problems?

Thanks

Rogelio J. Baucells
ATS