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 From:  Manuel Kasper <mk at neon1 dot net>
 To:  m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] how to set up a the PPTP server with firewall rules
 Date:  Mon, 7 Jul 2003 09:27:45 +0200 (CEST)
On Sun, 6 Jul 2003, Fred Wright wrote:

> Only the GRE traffic is a problem, since there's no conflict with the
> control connection (as long as you don't need simultaneous client and
> server operation with respect to a single remote system).  So the PPTP
> code should be able to use the local IP address of the already-established
> control connection socket to bind() the (presumably raw) GRE socket.  It
> could even bind to the remote IP by using connect(), which also improves
> efficiency.

Interestingly, the reason for the "Address already in use" message is not
GRE, but the TCP port 1723 server socket. I sent Michiel a slightly
modified version of m0n0wall where the PPTP server uses "set pptp self"
(to like the PPTP client does (which uses the pseudo WAN IP
address assigned on the WAN->PPTP setup page). Still - the same message...
Looking at MPD's source code, it's clear that the message originates from
the bind() on the TCP server socket. I don't quite understand why two
different processes cannot bind to the same port but on different IP
addresses... I thought that was possible. MPD even uses setsockopt(...
SO_REUSEADDR ...) before the bind() - don't know what effect that has,

Some more debugging may be in order, I guess. Maybe we have to check if
MPD really supplies the IP address given in "set pptp self" to bind().

- Manuel