[pptp-server] GRE and traceroute - reliable?

[G. Georgiev]

	Hello,

	My pptp link came to live this morning, but it may be seen that my
ISP (for whatever reason) did change the routing - the third hop is now
10.154.0.35, yesterday was 10.154.0.34. Quite sure I may argue to
Videotron that .0.34 blocks the GRE traffic, but... I DID THE TRACEROUTE
WITH -G OPTION - GRE packets yesterday, and they went beyond the router in
question.

	In reality, if I am not mistaken, tracroute should use ICMP
packets - full imitation of GRE in traceroute it probably
impossible? And if that's the case is there any reasonable way to check if
a router blocks IP protocol 47 (GRE)?

	Thanks, George.

P.S. It may be usefull to have a 'public' pptp server running somewhere
to which everyone may try to connect - this way we may test if the problem
is close to our side or is on the other end.


         ---- Routing from this morning - VPN works ---------
 1  10.48.160.1 (10.48.160.1)  9.429 ms  8.989 ms  9.662 ms
 2  modemcable090.241-200-24.mtl.mc.videotron.ca (24.200.241.90)  8.101 ms
 3  10.154.0.35 (10.154.0.35)  8.106 ms  11.335 ms  7.884 ms
 4  * ia-cduc-bb02-ge3-0.videotron.net (207.96.163.9)  122.174 ms  123.818
 5  * if-7-3.core2.Montreal.Teleglobe.net (207.45.204.41)  128.289 ms *
 ..... (other lines equal with example below)



        -------- Routing from yesterday - no VPN -----------
 1  10.48.160.1 (10.48.160.1)  9.067 ms  9.352 ms  11.871 ms
 2  modemcable090.241-200-24.mtl.mc.videotron.ca (24.200.241.90)  7.826 ms
 3  10.154.0.34 (10.154.0.34)  9.283 ms  8.997 ms  13.797 ms
 4  ia-cduc-bb02-ge3-0.videotron.net (207.96.163.9)  7.583 ms  8.673 ms
 5  if-7-3.core2.Montreal.Teleglobe.net (207.45.204.41)  15.974 ms  45.709