IPv4 Address

G

gordont8

New Member
As a matter of interest can someone please explain to me why my laptop seems to have two IPv4 addresses.
When I go on the web and ask what my IPv4 address is I get one answer starting 51. However, when I look on my network connection details on the laptop it shows a completely different number which starts 192. I assume only one can be right and would like to know which one.
 
The one you see on the website shows your external (public) IP, and the one you see on your network connection is your internal (private) IP. The 51. address you see is actually assigned to your modem, so everything on your home network will have that same public IP, while every device on your home network will have a different public 192. IP.
 
^ That.

Most ISP give you a single WAN address since the IP space is exhausted. Home routers by default will use PAT (Port Address Translation) to 'share' the single external address with your inside/private (192.168) network. As your packets leave the router they will source from your 51. address, and the router will forward return traffic on that originating port to your 192.168 address.

Therefore, both numbers are right but it depends on which network you are referencing.
 
Type in ipconfig /all under cmd prompt and be prepared to be blown away!

You'r router issues an IP address, your modem has one and then your ISP has one for your WAN (Wide Area Network.) That is your IP people on the net can see, the WAN IP.

Each device needs an address to communicate to.

Go here: http://whatismyipaddress.com/

That's the IP address people see you as.

To make matters worse, there is also X forwarded for as well. You have actual IP and X forwarded for. X forwarded for is an IP address in the header of a packet primarily used in proxies or people like me who know how to forge their own. :D This website sees your X forwarded for. Yours will be the same using the first website unless you use a proxy. https://www.dnsleaktest.com/

Don't worry about X forwarded for though. You're interested in actual IPs.
 
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Thank you all for the information you have provided. If I understand it correctly, for connection to the internet, via an internet service provider, a Modem is essential and has its unique public address. A Router, as well as giving a degree of security that a Modem alone does not, also provides a method of establishing a local area network and provides a separate private address to each computer on the LAN. Hope that's about right.
 
gordont8 said:
Thank you all for the information you have provided. If I understand it correctly, for connection to the internet, via an internet service provider, a Modem is essential and has its unique public address. A Router, as well as giving a degree of security that a Modem alone does not, also provides a method of establishing a local area network and provides a separate private address to each computer on the LAN. Hope that's about right.
Click to expand...
That is the jist of it!
 
beers said:
X forwarded for is a feature of http (layer 7) and only resides in the data/payload portion of a packet, not the header.
Click to expand...


Here's what Google says:

The X-Forwarded-For (XFF) HTTP header field is a common method for identifying the originating IP address of a client connecting to a web server through an HTTP proxy or load balancer.
Click to expand...
 
gordont8 said:
Thank you all for the information you have provided. If I understand it correctly, for connection to the internet, via an internet service provider, a Modem is essential and has its unique public address. A Router, as well as giving a degree of security that a Modem alone does not, also provides a method of establishing a local area network and provides a separate private address to each computer on the LAN. Hope that's about right.
Click to expand...


The IP addresses aren't used as a security thing. But, yes, a router offers SPI (Stateful Packet Inspection) as well as other things depending on type of router and firmware used does provide security. Some modems are router/modems combined. Like what Comcast offers.

Just think of an IP address as a home address. It's just a number that determines where to route data packets.
 
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