Concealing short disconnects

[Dan Nelson]

In the last episode (Feb 12), Andrew P. said:
> Dan Nelson wrote:
> >In the last episode (Feb 12), Andrew P. said:
> >>I have a few machines behind my FreeBSD box. The box connects to
> >>ISP via ppp (PPPoE protocol). It's all working very nicely, but the
> >>ISP is a pain - it disconnects every 24 hours. I can reconnect in
> >>just a moment - so the diconnect is usually less than a second
> >>long, but many applications, like ICQ/MSN and games "feel" the
> >>disconnect. The matter is that these applications can handle fairly
> >>large packet loss (e.g. Counter-Strike can cope with at least
> >>15-second long 100% packet loss), but AFAIK it's in the nature of
> >>the TCP/UDP that a disconnect is a disconnect.
> >>
> >>As I know that FreeBSD is full of magic, is there any way to
> >>conceal these reconnects as short moments of 100% packet loss? I am
> >>ashamed to know very little about protocols' technicalities, but
> >>I'll look into any sources you advise.
> >
> >Check to see if your IP number changes when you reconnect.  If it
> >does, there's nothing you really can do; the remote system you were
> >talking to knew you only by your old IP, and those packets coming to
> >them from this other IP are unrelated.
> 
> It changes only once in about a week. Let's say it doesn't change
> at all. What then?

I'm still suspicious :)  The two most common causes for connection
resets are IP address changes and NAT resets.  /usr/sbin/ppp keeps its
NAT table across disconnects as long as the process itself stays
running, so I don't think that's the cause.  If you have root access to
a remote system, try running tcpdump on it and your local machine while
running something like top over ssh, and watch what happens when your
connection drops and reconnects.

-- 
	Dan Nelson
	dnelson at allantgroup.com