[pptp-server] Traceroute for GRE packets ??

[G. Georgiev]

        Hello,

        A problem with pptp client - the GRE tunnel does not
build over my cable modem link. The control channel, which is
a pure TCP link start fine, but it looks like some router on
my ISP network blocks GRE traffic. 

        Is there some tool which may like traceroute check
what's happening with GRE packets? This way I may find the
offending router and may be convince my ISP to correct it?

	

        Thanks, George.