Is 172.18 a private IP?

Is 172.31 public or private?

The title says it all.

Do the "normal" IPs use 172.31 as an alternate for public IPs or is it a subnet of the standard public subnets (192.168. Is it publicly addressable? And how much different can it be from an internal private address (eg 192.10.

It is part of the private block. It is used by routers that don't know about the private address ranges, and doesn't mean much more than that.

0/16 is not part of the public internet. The public internet is defined by the IANA Registry for Address Assignment Numbers. There are two groups of numbers: private address range and public address range. The private range is from 172.0 to 172.255. The public range is from 172.

There is a third range used by routers in private networks which is from 172.127. This is used by routers who don't have NAT capabilities and are still able to route IP traffic to their connected clients. This range does not mean anything outside of their own network. It could just as well be a random number generated by their router.

When discussing the difference between public and private addresses, we are only talking about end hosts and NAT devices. When you refer to an external host (client, web server, etc.) they have no way to differentiate between these three ranges.

Is 172.24 a private IP?

I have an IP with 172.

24.x. It's been owned by a client for a while. We used it for a few things and just recently switched ISPs. They gave it to us to put into a firewall. Now they won't let use it and we're wondering if that was a mistake? I need it to be able to do some things and would like to move it to a private IP. I've seen it's possible to set up a private IP but our ISP is blocking all our attempts to do so.

X is indeed a private address, it's a private address because it's not assigned to any IP network range which means it's unused. And in the IPv4 standards, private addresses are not guaranteed to be NAT-capable.

But it's still possible for you to configure your router to translate this address to a public address, check this tutorial about how to setup a VPN or how to configure IPSec to accomplish the same thing.