[plug] Dumb questino on networking

John Summerfield summer at os2.ami.com.au
Fri Jul 10 03:56:24 WST 1998

On Thu, 9 Jul 1998, Shackleton, Kevin wrote:

> Aren't we both saying the same thing here?  I didn't point out that
> 192.168. is the "public LAN" range, but the fact remains that the LAN IP
> addresses have to be mapped to internet addresses in this scenario which
> is why masq or proxy is required, whereas in my case the router only
> needs to determine what to pass through.
> Have I missed your point or did I not put mine clearly enough?
Either my english comprehension has finally broken down, or yes.

Th selection of IP addresses is an important matter and there must not be
any confusion about it.

If the public internet is the one we can all join, then 192.168.*.*
addresses are for private LANs that will not be (directly) connected to
the public internet.

It is perfectly possible to have a private allocation of, um, public IP
addresses (all IAPs, for example, do), and subject to physical connexions,
firewalls and routing these are accessible to all. 

The IP address is assigned to someone else and it would be a
bad thing for someone else to use it (or any addresses from the network and leak traffic onto the public internet because any
responses will head off to Japan and potentially cause mischief there.
However, I could get a range of IP addresses from my IAP from his
allocation and use them at home. We could then establish routing so that
my home LAN could be directly accessed by all & sundry whenever I'm

However, I use IP addresses 192.168.0.* and 192.168.1.* and these are not
accessible from anywhere except though my dialup machine. To clarify, you
can probably access my internal machines' web servers by using the proxy
server on my dialup machine. Connecting by telnet to my internal is not
possible unless you first telnet to the computer with the modem. 

I have no doubt that Kevin and others understand all this. However, I
believe that Kevin's use of the term "public" is likely to confuse any who
are new to networking.

John Summerfield
http://os2.ami.com.au/os2/ for OS/2 support.
Configuration, networking, combined IBM ftpsites index.

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