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Re: Strange LAN IP Address.

On Mon 02 Jul 2018 at 21:58:15 (+0200), john doe wrote:
> On 7/2/2018 9:17 PM, Stephen P. Molnar wrote:
> >I have my principle Debian Stretch platform on the LAN in our
> >home. Two towers (both Linux platforms) and a HP Printer have
> >wired connections, my Win 10 Laptop and two Android smartphones
> >use WiFi connections.
> >
> >This morning when I
> >
> >When I tried using WinSCP on the Laptop to transfer a file from
> >the principle Linux platform the connection attempt failed!
> >
> >When I ran ifconfig on the Linux platform it showed the unet
> >connection to be!!?????  The LAN modem employs DCHP
> >set with allowed IP range as through,
> >which was set by the T&T installer when we switched to a fiber
> >optic network.
> >
> >Further examination of the modem settings showed IP Passthrough
> >status as on (Public IP Address), which was, in fact the IP.
> >
> >I spent 40 minutes, on hold for 28 of those minutes, with an AT&T
> >UVVerse technical (????) person without hearing any reasons why
> >the IP was what it was.
> >
> >Note the tense at the end of the above sentence, because
> >subsequent rebooting the modem restored the IP address to the
> >correct DHCP range. I suppose the moral of this - first reboot the
> >modem.
> >
> >The question that I have, however, is how did this happen in the
> >first place? Or is the reason lost in the black hole of the
> >Internet?
> >
> >Is this indicative of a hardware problem?
> >
> Could be hardware failure or could also be an software bug!
> While searching for that IP I get:
> https://www.ipligence.com/ip-address?ip=
> is this your public IP (IP assigned by your ISP)?

Looks like it. Here's the first hop of the OP's posting:

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 665b52fd3833c7e5d4ced5690502aed7 for <debian-user@xxxxxxxxxxxxxxxx>;
 Mon, 02 Jul 2018 19:17:29 +0000 (UTC)

> It could be that the ISP router went into "bridge mode" (router
> function was disabled).

Which is rather worrying as you are exposed to the Internet
without any security.

> Most of the time ISP router are not the best and I would suggest to
> anyone to not reley on that router for firewalling capability
> especially when ISPs can remotely control that thing!
> In the case of my ISP I need to reboot my ISP router every week or
> so to get stable services.

Sounds like you have a combined modem/router. My advice would be to
ditch it and get separate units. This means you can, if you like, use
the modem your line provider supplies (which means they can't blame
you for any incompatibilities with the wire), but you have full
control over the router. (It also gives you more flexibility with
their siting.)

It even means you can independently test the modem safely, by booting
a live system from a stick and connecting directly to the modem port.
(You will then see your address as for the right reason.)

My own experience is that an ADSL modem should be left running 24/7 as
that prevents it having to retrain. OTOH there's no harm in rebooting
a router whenever you think it might be misbehaving.