Date: Mon, 23 Nov 1998 23:25:29 +0100 (MET) From: Sascha Schumann <sas@schell.de> To: Malte Lance <malte.lance@gmx.net> Cc: van.woerkom@netcologne.de, marc@netcologne.de, G.Sittig@abo.FreiePresse.DE, freebsd-isdn@FreeBSD.ORG Subject: Re: isppp + dynamic IP Message-ID: <Pine.LNX.4.05.9811232316110.1352-100000@guerilla.foo.bar> In-Reply-To: <199811231546.QAA00687@neuron.webmore.prv>
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On Mon, 23 Nov 1998, Malte Lance wrote:
> On 22 Nov, Marc van Woerkom wrote:
> >
> > My guess is that this is some sort of control packet, by an older
> > request of mine, that has not been completed (e.g. a lame ftp transfer),
> > and that is now fooled because the IP at time of the request
> > is different from the present IP now due to a hang up in between.
These are sockets in WAIT state - somewhen timing out and sending one more
packet.
> Try this with telnet on linux. Does it work ?
Yes.
> As i said, there is much more than this.
Not really.
> Read the discussion i mentioned above. It also gives the reason,
> why this solution only works for some clients.
It works for Linux.
Excerpt from linux/Documentation/network/ip_dynaddr.txt
(s/diald/everything-with-non-static-IP/)
-------
This stuff allows diald ONESHOT connections to get established by
dynamically changing packet source address (and socket's if local procs).
It is implemented for TCP diald-box connections(1) and IP_MASQuerading(2).
If enabled[*] and forwarding interface address has changed:
1) Socket (and packet) source address is rewritten ON RETRANSMISSIONS
while in SYN_SENT state (diald-box processes).
2) Out-bounded MASQueraded source address changes ON OUTPUT (when
internal host does retransmission) until a packet from outside is
received by the tunnel.
This is specially helpful for auto dialup links (diald), where the
``actual'' outgoing address is unknown at the moment the link is
going up. So, the *same* (local AND masqueraded) connections requests that
bring the link up will be able to get established.
[...]
--------
Sascha
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