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Re: Strange LAN IP Address.




On 7/3/2018 2:42 AM, David Wright wrote:
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 162.237.98.238!!?????  The LAN modem employs DCHP
set with allowed IP range as 192.168.1.64 through 192.168.1.253,
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=162.237.98.238

is this your public IP (IP assigned by your ISP)?

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

  Received: from 162-237-98-238.lightspeed.clmboh.sbcglobal.net (EHLO
  [192.168.1.123]) ([162.237.98.238]) by smtp431.mail.bf1.yahoo.com
  (Oath Hermes SMTP Server) with ESMTPA ID
  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 162.237.98.238 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.


You are correct in the case of an ADSL "router".

Sadly, in the case of my European ISP I'm stuck with what they give me!
I must say that I've never investigated how I could use my own cable modem and understand the kind of restriction they're using to prevent me from doing that!!! :)


An alternative to DDWRT is OpenWrt.

If your willing to fealed that security gap it clearly make sence to check the list of compatible device (OpenWrt DDWrt ...) so if you don't like the stock firmware you can change it!


A fanless server solution could be:
https://www.pcengines.ch/

On that box yu could install pfsense, Debian, IPFire...

If your stuck with your ISP "router" you could try:
- Add your own router in the DMZ (you only use the ISP router for the modem part) - Set your ISP modem in "bridge mode" or what ever it's called to turn everything off but the modem


The idea here is to have one way or an other your own "firewall" behind a modem.

--
John Doe