[pptp-server] Trouble using mppe-128

[Stefan Tomanek]

I am trying to use pptp with 128bit encryption, and applied the
corresponding patches to pppd as well as to the kernel.
The ppp_mppe module is loaded, and if I only activate mppe-40, I can
connect flawlessly.
But if I try to use 128bit encryption and put mppe-128 in the
pptpd-option file of client and server, strange things happen:
These are the options on the server:
auth
deflate 0
nobsdcomp
+chapms-v2
mppe-40
mppe-128
mppe-stateless
debug
###

Now I try to connect using the pptp linuxclient (I applied the same
patches to the client):
/usr/local/sbin/pptp 212.23.134.13 user stefan mppe-128 mppe-stateless

The log on the server shows the following:

Jun  8 08:12:11 kabel2 pppd[18526]: sent [CHAP Success id=0x1 "Welcome
to kabel2
."]
Jun  8 08:12:11 kabel2 pppd[18526]: sent [IPCP ConfReq id=0x1 <addr
192.168.192.
253> <compress VJ 0f 01>]
Jun  8 08:12:11 kabel2 pppd[18526]: sent [CCP ConfReq id=0x1 <mppe 1 0 0
60>]
Jun  8 08:12:11 kabel2 pppd[18526]: rcvd [IPCP ConfReq id=0x1 <addr
212.23.134.1
34> <compress VJ 0f 01>]
Jun  8 08:12:11 kabel2 pppd[18526]: sent [IPCP ConfNak id=0x1 <addr
192.168.192.
192>]
Jun  8 08:12:11 kabel2 pppd[18526]: rcvd [CCP ConfReq id=0x1 <mppe 1 0 0
40>]
Jun  8 08:12:11 kabel2 pppd[18526]: sent [CCP ConfRej id=0x1 <mppe 1 0 0
40>]
Jun  8 08:12:11 kabel2 pppd[18526]: rcvd [IPCP ConfAck id=0x1 <addr
192.168.192.
253> <compress VJ 0f 01>]
Jun  8 08:12:11 kabel2 pppd[18526]: rcvd [CCP ConfNak id=0x1 <mppe 1 0 0
40>]
Jun  8 08:12:11 kabel2 pppd[18526]: sent [CCP ConfReq id=0x2]
Jun  8 08:12:11 kabel2 pppd[18526]: rcvd [IPCP ConfReq id=0x2 <addr
192.168.192.
192> <compress VJ 0f 01>]
Jun  8 08:12:11 kabel2 pppd[18526]: sent [IPCP ConfAck id=0x2 <addr
192.168.192.
192> <compress VJ 0f 01>]
Jun  8 08:12:11 kabel2 pppd[18526]: Script /etc/ppp/ip-up started (pid
18528)
Jun  8 08:12:11 kabel2 pppd[18526]: rcvd [CCP ConfReq id=0x2]
Jun  8 08:12:11 kabel2 pppd[18526]: sent [CCP ConfAck id=0x2]
Jun  8 08:12:11 kabel2 pppd[18526]: rcvd [CCP ConfAck id=0x2]
Jun  8 08:12:11 kabel2 pppd[18526]: Script /etc/ppp/ip-up finished (pid
18528),
status = 0x0
Jun  8 08:12:14 kabel2 pppd[18526]: sent [CCP ConfReq id=0x2]
Jun  8 08:12:14 kabel2 pppd[18526]: rcvd [CCP ConfReq id=0x3 <mppe 1 0 0
40>]
Jun  8 08:12:14 kabel2 pppd[18526]: sent [CCP ConfRej id=0x3 <mppe 1 0 0
40>]
Jun  8 08:12:14 kabel2 pppd[18526]: rcvd [CCP ConfAck id=0x2]
Jun  8 08:12:14 kabel2 pppd[18526]: rcvd [CCP ConfReq id=0x4]
Jun  8 08:12:14 kabel2 pppd[18526]: sent [CCP ConfAck id=0x4]
Jun  8 08:12:17 kabel2 pppd[18526]: sent [CCP ConfReq id=0x2]
Jun  8 08:12:17 kabel2 pppd[18526]: rcvd [CCP ConfReq id=0x5 <mppe 1 0 0
40>]
Jun  8 08:12:17 kabel2 pppd[18526]: sent [CCP ConfRej id=0x5 <mppe 1 0 0
40>]
Jun  8 08:12:17 kabel2 pppd[18526]: rcvd [CCP ConfAck id=0x2]
Jun  8 08:12:17 kabel2 pppd[18526]: rcvd [CCP ConfReq id=0x6]

So in fact, no encryption is enabled and server and client continue to
negotiate abount <mppe 1 0 0 40>.
How can I get it working?
What is the differenz between <mppe 1 0 0 40>,<mppe 1 0 0 60> and <mppe 1 0 0 20>?

Thank for your help.
-- 
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