A question about IP addresses 1

[ZK]

Hi there,

Any input much appreciated.

Up till now I've always thought that when you want to set up a company network, you go to your service provider, ask them nicely to give you an IP address block, then you go ahead and assign the IP addresses to your LAN machines.

Now I've heard of the terms "public and private IP addresses". Can anyone tell me what these are and how they fit into the scheme of things?

Cheers
ZK

 

[Visitor]

In a Novell-related nutshell, sure.... Since the number of public IP addresses has been declining, less of them can be issued for use. So now, ISP issue 1 (or a small amount) to a company to use as their "public" IP address to the internet. The company then usually some sort of Network Address Translation (NAT) in conjunction with their firewall to translate between the public address and the internal, "private" addresses. This way, the company can set up many IP addresses on the inside of the firewall that get translated to the 1 (or few) IPs for the outside. Just typing quickly here, hope that makes sense....

 

[wybnormal]

Private ranges are in 3 groups..

10.0.0.0 to 10.255.255.255

172.16.0.0 to 172.31.255.255

192.168.0.0 to 192.168.255.255

These ranges are not to be advertised on the public internet. Normally you would use NAT ( network address translation) to go between the "real" IP address and your private. You can *overload* a single public IP address with multiple private IPs. for example, I have a single public IP for my broaband connection. I share it among 20 private IP addresses on my home office network.

Mike S

 

[jguy]

The private IPs are known as "classless". Joe W. Guy
Network Admin
MIS Director