[pptp-server] Poptop and Linux Kernel 2.4.9

[Martin Feeney]

Thanks very much to those who replied - no joy yet though.

After much tcpdumping I know what's happening, but I still don't know
why.

It looks to be a timing/retry issue of sorts.

3 scenarios are important here:

1. Linux pptp client connecting to poptop on my 2.2 kernel.
2. Linux pptp-client connecting to poptop on my 2.4 kernel.
3. win2k connecting to poptop on my 2.4 kernel.

1.

Control connection established. Server tries to contact client via GRE
tunnel. Client doesn't have it open yet. Server retries and client does
have it open this time. Handshaking occurs everyone is happy. doesn't
matter if the client is running a 2.2 or 2.4 kernel.

2.

Control connection established. Server tries to contact client via GRE
tunnel. Client doesn't have it open yet. Server doesn't retry, aborts
connection. If the client is on a 2.2 kernel, it doesn't know that the
server has aborted and retries until it reaches it's limit (usually 10).
If the client is on a 2.4 kernel, it realises that the server has given up
and does the same.

3.

Control connection established. Server tries to contact client via GRE
tunnel. Client has gre protocol open and everything goes according to
plan.


Big question here is why does the kernel version seem to change the
behaviour of poptop (to retry or not) and pptp-client (to give up or not)?

Should poptop retry the gre exchange or should pptp-client open it at the
same time as it opens the control(1723) tcp connection?

Martin.