Asci file: ip.html

Subject: Re: IP Address
Subject: Re: Static address and domain name: What joins them together?



Newsgroups: alt.unix.wizards
Subject: Re: IP Address
From: henke@kharendaen.krall.org
Lines: 52
Date: 28 Mar 1999 10:48:41 -0600

"tiger22" <air_jordan22@yahoo.com> writes:
> How can I find an IP Address?  Is there a special program or any
> certain way of accomplishing this task?

Pick four numbers, in the range 0 to 255 inclusive. Arrange them in
any order, delimited by dots. There, you've found an IP address.

I have a feeling that the question you asked was not the question you
meant to ask.

Do you mean "an interface on my computer already has an IP address and
I want to know what that address is" ? If so, try ifconfig.

Do you mean "I know the hostname of a computer and I want to find the
IP address" ? If so, try nslookup, dnsquery or dig.

Do you mean "I want to know the address of the machine on the other
end of a TCP/IP connection involving my machine" ? If so, try netstat.

Do you mean "I want to add a new device to an existing private network
and I need an IP address for it" ? If so, ask your network
administrator to provide one.

Do you mean "I want to add a new device to an existing private network
where addresses are doled out automatically via DHCP or BOOTP, and I
want to find out how to get an address" ? If so, RTFM "dhclient" or
have a look at http://www.isc.org/ .

Do you mean "My ISP dynamically assigns me an address each time I
connect and I want to know what that address is" ? See the manual for
pppd, or do an ifconfig while connected.

Do you mean "My ISP has given me a static address (or block) and I
want to know what it is" or "I have a dynamic address right now but I
want a static one" ? If so, ask your ISP for help and be prepared to
pay money in the latter case.

Do you mean "I have a private IP network which is not connected to the
Internet (or is, but using NAT or masquerading or VPN), and I want to
know what addresses to use" ? Use addresses in the 10.0.0.0/8,
172.16.0.0/16 or 192.168.0.0/16 blocks, which are reserved for such
use.

Do you mean "I run a very large network or a company that provides
network service to others, and I want to grab a big block of IPs to
use" ? No, you don't mean this. Forget I asked.

Do you mean something else that isn't any of the above? Try asking a
more specific question, maybe with an example.

-- 
Mail to henke at phoenix dot net.

-- 


From: wclark_xoom@my-dejanews.com
Newsgroups: comp.os.linux.networking
Subject: Re: Static address and domain name: What joins them together?
Date: Fri, 26 Mar 1999 02:02:16 GMT
Lines: 62

In article <36f835b2.0@news2.info2000.net>,
  billc@mail.info2000.net (Bill Cripe) wrote:

> First, I can hardly believe that I have to ask this question, but I just
> can't quite be sure I've got it right.

Better to ask and possibly look stupid than continue in ignorance.  I don't
think a failure to understand the DNS qualifies as "stupid", though. :)

>    I have a registered domain name and a static IP address on a DSL line.
> What is it exactly that tells the world that that domain and address are
> intended to go together?

That is the main purpose of the (D)omain (N)ame (S)ystem.

More information can be found in RFC1033, RFC1034, and RFC1035.  These RFC's
(or [R]equest [F]or [C]omments) can be found at http://www.faqs.org.

>    Having read the DNS-HOWTO it appears that correctly configuring named
> should do the trick, but is that really it?

Mostly.  You also need to notify the Internic what the _two_ DNS servers for
your domain are.  Only one is required to run DNS, but the Internic requires
you to register a secondary DNS server (which never actually has to be in
working order after the initial registration).

> If it is, then it would sure be easy for someone to "piss in the routing
> pool", so to speak. What prevents another site from snatching your domainname,
> address, etc.?

Addresses are handled seperately from names.  There is actually nothing
preventing somebody from "stealing" your IP address, but it's unlikely that
any traffic will get routed to it.  Advertising a route is a very public
thing, and anyone trying to steal an address in this matter would be ignored
if unsuccessful and caught very quickly if successful.	In other words, don't
worry about that part.

Theft of domain names is prevented by the Internic registration I mentioned
above.  A properly configured DNS server will check with the Internic to find
out what the "Authoritative" server for a given domain is.  So long as that's
your server, you'll be fine.

> I need to tell the Internet that my domain has a new address, and to stop
> using the old one.

What you mean is that your domain's primary DNS server has a new address --
the Internic has absolutely no idea what the IP address of any of your
servers are. Your DNS server(s) can be in a completely different domain, in a
completely different IP block from the rest of your machines, if you wanted. 
The sole purpose of Internic registration is to identify what DNS server is
"Authoritative" for a given domain.  Whatever IP addresses the DNS server
spits out in response to name queries at that point is entirely up to whoever
is running the machine.

There's a simple OnLine form at the Internic that will allow you to change
your primary and secondary DNS entries.  The internic can be found at
http://www.internic.net/

-Bill Clark

-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/       Search, Read, Discuss, or Start Your Own    

--
Hosted by: