[pptp-server] pppd Unsupported Protocol errors when using pptp connection

[Andy Grundman]

I am trying to get PoPToP up and running and I am testing between 2 machines on the same subnet.  I can connect from my NT box to
the Linux server using PPTP.  But when I try to ping the PPTP server IP address from the NT client, my pptp log file spits out:

Nov 16 11:54:37 demo pppd[770]: Unsupported protocol (0x8d57) received
Nov 16 11:54:37 demo pppd[770]: sent [LCP ProtRej id=0x8 8d 57 0d 3a 1d a1 78 54 3d c4 e6 4b 9b 18 c0 b0 c5 2c 2a 73 08 43 87 ff e3
af e2 44 23 7e 4d d9 8b 88 8d 08 ea ea 2d 7c 7e 69 a5 55 f8 05 93 67 61 75 ce 1a 51 d6 fc 78 90 ef 30 21 bb b7]
Nov 16 11:56:04 demo pppd[770]: rcvd [proto=0xd6d2] b2 89 98 20 93 7c 51 58 69 5c be 39 1f 9b a5 ee d0 45 86 c6 66 34 e2 5d d7 dd d7
54 fc e8 ed 4b ...

for each ping request.  The NT box gets no ping response, but traffic is coming back to the NT box from the server over the PPTP
connection.

I figured it was maybe just ICMP that wasn't working, so I set up the default gw on my NT to be the VPN adapter, and tried HTTP.  I
got the same result, with an unsupported protocol message.  I can't ping in either direction across the pptp connection... I don't
get those error messages when I ping from the server to the client though.  Does anyone know what the problem is here?  I think I
must have compiled my ppp wrong or forgot something in the options file.

/etc/ppp/options:
lock
debug
name demo
auth
require-chap
+chap
+chapms
+chapms-v2
mppe-40
mppe-128
mppe-stateless

(I had proxyarp in there but it didn't make any difference.)

ifconfig on linux server:
eth0      Link encap:Ethernet  HWaddr 00:A0:C9:32:16:01
          inet addr:193.9.211.65  Bcast:193.9.211.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:15448 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2704 errors:0 dropped:0 overruns:0 carrier:0
          collisions:126 txqueuelen:100
          Interrupt:11 Base address:0x1000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:3924  Metric:1
          RX packets:2 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0

ppp0      Link encap:Point-to-Point Protocol
          inet addr:10.0.0.1  P-t-P:10.0.0.11  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:17 errors:0 dropped:0 overruns:0 frame:0
          TX packets:18 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:10

route on server:
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.0.0.11       *               255.255.255.255 UH    0      0        0 ppp0
193.9.211.65    *               255.255.255.255 UH    0      0        0 eth0
193.9.211.0     *               255.255.255.0   U     0      0        0 eth0
127.0.0.0       *               255.0.0.0       U     0      0        0 lo
default         193.9.211.1     0.0.0.0         UG    0      0        0 eth0

-Andy