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Re: Strange LAN IP Address.

On Tue, 03 Jul 2018 10:53:27 +0100
Jeremy Nicoll <jn.ml.dbn.25@xxxxxxxxxxxxxxx> wrote:

> On Tue, 3 Jul 2018, at 07:19, john doe wrote:
> > 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!!! :)  
> I've a Virgin Media cable connection in the UK.  They supply a
> combined modem/router.    But the unit can be put into modem-only
> mode, and used with a different router.  
> So far as I remember the first of these combined things that I
> received came with only very basic instructions that did not mention
> the way to do this - it was Virgin's own technical support people who
> told me how to do it.    Subsequent improved models have come with
> instructions that mentioned the possibility.

In general, there is no need to switch to modem only, unless you
definitely want to handle the public address directly on your firewall.
Almost always, you can put your own NAT firewall behind an existing NAT
router without problems.

I say almost, because about ten years ago, a client of mine moved
premises and was given a new router which detected any such second NAT
stage and refused to function. Not a bug, a deliberate policy. Really
quite annoying, I needed to reconfigure several network machines to
work with this router, and lost my detailed firewall control.