Tell me more ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.
up vote -5 down vote favorite

I have noticed that ipconfig and a website that tells you what your ip is, are different.

Two cases:

  1. E.g. I rdp from my laptop to my PC via an IP on that is always in the same network ID (so first 3 parts of the IP - can't remember exact term - do not change). A website gives a different IP, often starting with 80.

  2. I run my own servers on the cloud. They have static, private IPs, thus only accessible via a VPN. I can map public IPs to the servers via NAT. However, an app I use (mobilepcmonitor) which allows me to control my servers from my phone, reports another IP.

Why are there differences?

share|improve this question
1  
May I suggest that you work on your accept rate and voting patterns. 29% accepted of 91 questions is quite poor, and only 6 votes is even worse. If an answer has helped you, give it +1 vote (click the up-arrow button next to the post). If it has helped you and answered your question (such as the one below), give it an up-vote and click the tick icon next to their post. – Mark Henderson♦ May 24 '12 at 21:39
2  
Working on it, I am retrospectively approving questions! :) – dotnetdev May 24 '12 at 21:41
Good stuff :) Glad to hear it. – Mark Henderson♦ May 24 '12 at 21:41

closed as not a real question by Ward, Khaled, WesleyDavid, mdpc, John Gardeniers Dec 15 '12 at 10:09

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, see the FAQ.

1 Answer

up vote 5 down vote accepted

You used the keyword - NAT (Network address translation).

Usually (in home networks and most corporate networks), users are assigned private IP addresses (ie 10.x.x.x, 172.16.x.x,... 192.168.x.x). When they connect to the internet, their router translates those addresses to one (or more) external IP(s). (for example the one starting with 80.), but their "ipconfig" still shows their internal (private) IP.

If any of the IPs you see are from the private range (mentioned above), it is perfectly normal that the external IP is different from internal one (that's why we have NAT, so we can put many computers in a network, and connect them all to the internet, using just one external IP).

share|improve this answer
I see. So if I was to rdp to my machine from outside its network, which would I use? – dotnetdev May 24 '12 at 21:40
If you want to RDP from outside, you first need to set port forwarding on your router, so your router will forward connections (to rdp port) from your public ip, to your internal ip). So you would add a rule to forward port 3389 (RDP) to your internal ip (you have that setting somewhere on your router), and then connect to your external (80.some.thi.ng) IP when outside your network. – mulaz May 24 '12 at 21:44
The public one obviously, as the private address is, well... private. But it's not going to work unless the router is configured to do port-forwarding. Consider this: The router has 1 public ip with multiple private ip's behind it. If it receives incoming rdp it has no way of telling which internal private ip must receive the traffic. It needs to be configured to forward incoming rdp to the correct private ip. That's what is called port-forwarding. I suggest you read up on NAT and port-forwarding. Wikipedia is a good starting point. – Tonny May 24 '12 at 21:48

Not the answer you're looking for? Browse other questions tagged or ask your own question.