[pptp-server] client pptp-linux-1.0.2 + pppd-mppe-2.3.11 CLP ProtRej problem

[schulz]

I think I have set up pptp and pppd following the directions by 
http://jefe.org/Newschool/Projects/PPTP/newHOWTO-PoPToP.html#3.0,
http://neurosis.hungry.com/~ben/software/pptp.html and
http://personal.rdu.bellsouth.net/rdu/t/a/tayljl/linux-pptp-client/linux-pptp-client-setup.html.

In the log I see a connection established and try a simple ping into the
target network.
Instead I receive a LCP ProtRej.

Here's the setup as seen by 'ip addr' and 'ip route':
(Note that the assigned addresses are part of the target network)

1: lo: <LOOPBACK,UP> mtu 3924 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
    link/ether 00:60:67:33:b6:e4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.100.100/24 brd 192.168.100.255 scope global eth0
11: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP> mtu 1492 qdisc pfifo_fast
qlen 10
    link/ppp
    inet 'my assigned address' peer 'remote tunnel address'/32 scope
global ppp0

'remote tunnel address' dev ppp0  proto kernel  scope link  src 'my
assigned address'
'vpn server' via 192.168.100.103 dev eth0
192.168.100.0/24 dev eth0  proto kernel  scope link  src 192.168.100.100
'remote network'/24 via 'remote tunnel address' dev ppp0
127.0.0.0/8 dev lo  scope link
default via 192.168.100.103 dev eth0

But what happens is (e.g. simple ping, kdebug 7 output):
Feb 16 22:10:26 minou kernel: ppp: write frame, count = 88
Feb 16 22:10:26 minou kernel: FF 03 00 21 45 00 00 54 ...!E..T
Feb 16 22:10:26 minou kernel: B2 6B 00 00 40 01 A7 FB .k.. at ...
...
Feb 16 22:10:26 minou kernel: 08 00 82 E6 1A 03 00 00 ........
Feb 16 22:10:26 minou kernel: A2 EB 8D 3A 38 ED 07 00 ...:8...
Feb 16 22:10:26 minou kernel: 08 09 0A 0B 0C 0D 0E 0F ........
Feb 16 22:10:26 minou kernel: 10 11 12 13 14 15 16 17 ........
Feb 16 22:10:26 minou kernel: 18 19 1A 1B 1C 1D 1E 1F ........
Feb 16 22:10:26 minou kernel: 20 21 22 23 24 25 26 27  !"#$%&'
Feb 16 22:10:26 minou kernel: 28 29 2A 2B 2C 2D 2E 2F ()*+,-./
Feb 16 22:10:26 minou kernel: 30 31 32 33 34 35 36 37 01234567  
...
Feb 16 22:10:30 minou pppd[786]: rcvd [LCP ProtRej id=0x7 c2 a3 d3 f5 38
d3 99 7
a ab c3 31 67 2e 20 8a 34 60 1c fc a9 56 88 ed 0b 0d d1 94 37 be df 9f
dd c6 9c
2e a0 c9 d7 96 12 b5 25 c7 7d 48 6f ef 4d e3 5a e4 46 5e 9b ca 91 c8 41
f6 53 e2
 9e 1c 11 bf 14 80 21 08 26 5b 77 a5 cf b1 ee b9
Feb 16 22:10:30 minou pppd[786]: Protocol-Reject for unsupported
protocol 0xc2a3

What's going on here?
Here are few more snippets from the preceding protocol exchange log:
...
Feb 16 22:10:17 minou kernel: ppp_proto_ccp rcvd=1 code=1 flags=f071043
Feb 16 22:10:17 minou kernel: ppp_proto_ccp rcvd=1 code=2 flags=f071043
Feb 16 22:10:17 minou kernel: ppp0: decomp running
Feb 16 22:10:17 minou pppd[786]: rcvd [IPCP ConfAck id=0x2 <addr
205.207.66.82>]
Feb 16 22:10:17 minou pppd[786]: ipcp: up
Feb 16 22:10:17 minou kernel: ppp_ioctl: set flags to f07304b
Feb 16 22:10:17 minou kernel: ppp: set np 0 to 0
Feb 16 22:10:17 minou pppd[786]: Cannot determine ethernet address for
proxy ARP
Feb 16 22:10:17 minou pppd[786]: local  IP address x.x.x.x
Feb 16 22:10:17 minou pppd[786]: remote IP address x.x.x.y
Feb 16 22:10:17 minou pppd[786]: Script /etc/ppp/ip-up started (pid 788)
Feb 16 22:10:17 minou pppd[786]: rcvd [CCP ConfReq id=0x6 <mppe 0 0 0
40>]
Feb 16 22:10:17 minou pppd[786]: sent [CCP ConfAck id=0x6 <mppe 0 0 0
40>]
Feb 16 22:10:17 minou kernel: ppp_proto_ccp rcvd=0 code=2 flags=f07204b
Feb 16 22:10:17 minou kernel: ppp0: comp running
Feb 16 22:10:17 minou pppd[786]: Untimeout 0x805096c:0x8079a20.
Feb 16 22:10:17 minou kernel: ppp_ioctl: set flags to f0730cb
Feb 16 22:10:17 minou pppd[786]: MPPE 128 bit, non-stateless compression
enabled
Feb 16 22:10:17 minou pppd[786]: Script /etc/ppp/ip-up finished (pid
788), status = 0x0
...