IP Address.

[shedhead]

Can anyone explain an IP address.
Does this address stay with you and not change ?
Does this address change each day ?
Is this address different with each PC you have running on the same broadband line.
Why do we need an IP address?

 

[TonyW]

An Internet Protocol address (IP) is a unique identifier for devices (including PC's, Printers, etc) on a computer network.

The IP address will stay with you while you are logged on to your ISP. If you disconnect you will most likely be issued a different IP.

I think the only time the address will change is when you disconnect or your ISP changes it.

The address has to be different for each PC on the same broadband line.

Without a unique address packets of information cannot be sent or received.

Hope that of some help and I have got my facts right

Cheers
Tony
Just typed this and found IP ADDRESS on Wikepedia. More info than you could want :shock:

 

[BradNaylor]

I am a complete numpty when it comes to computers; however my understanding is that the IP address is your internet connection. All computers on the same connection will have the same IP address.

The IP address stays with you unless you change your braodband supplier.

The IP address enables everyone to be traced if they get up to anything dodgy. It is not as easy as people think to be anonymous on t'internet.

I'm sure someone will come alomg with a better answer.

Dan

 

[Fecn]

Can anyone explain an IP address.

Yep. Sure can.

Does this address stay with you and not change ?

You can get static IP addresses which don't change. If you're a business customer you tend to want static IP addresses so you can host websites and run private networks. Most mom&dad home users have dynamic IP addresses which are handed out as and when needed and reclaimed after they haven't been used for a couple of days.

Does this address change each day ?

Totally depends on your service provider. Most of the ones in the UK seem to let you keep the same address as long as you keep the computer connected and switched on. If you leave the computer off for a couple of days then the IP address you were using might be given to someone else.

Is this address different with each PC you have running on the same broadband line.

There's only a fixed number of IP addresses that exist.. It's around 6 billion, but for all sorts of complicated reasons only a fraction of that number are actually useable. To work around the limited number that are useable, we use public (out on the internet) and private (on your own network cables) IP addresses. A company with a couple of hundred employees doesn't need each and every PC to be visible on the Internet. They'll use a Private IP address for the computers in their offices and then use a router/firewall to allow the PCs to talk to other systems on the Internet using a Public (Internet) address.

Why do we need an IP address?

Back in the old days, many PC networks ran the NetBIOS/IPX network protocol which allowed thousands of computers to talk to each other on company networks.. but that was before the days of the Internet. The Internet needed to allow millions of computers all over the world to talk to each other and that required a new protocol - IP - The Internet Protocol.

IP is actually a pretty nifty system for working out how to route information from one place to another - Hence the reason everyone now has a thing called a router. Your home router is a fairly simple machine which only knows one route (your ISP), but bigger routers talk to each other in order to work out the best way to get information from one place to another. IP addresses are handed out in large blocks (millions) by geographical region, and then in smaler sub-blocks (thousands) to orgnaisations within a country. The IP network 84.x.x.x contains 16M different addresses - This whole network is allocated to europe. A subnetwork of it, 84.92.x.x is assigned to my internet service provider, and an ever smaller subnet of a few tens of addresses is for me. When a router in the US wants to send to me, it doesn't need to know the intimate details of my ISP.. It just knows that 84.x.x.x is in europe and sends it on it's way.

I've oversimplified things somewhat there to try and get the point across - If you want to know everything I do, then read this extremely good paper by 3com... http://www.3com.com/other/pdfs/infra/co ... 501302.pdf

 

[shedhead]

Thanks all for your very informative replys.
I wanted to know about IP addresses as i was told that you could recognize people on the internet this way.
The reason i asked is that when using Ebay i often get the feeling that a seller has multiple user IDs and can bid on their own item to inflate the selling price.
In my experience when i have placed a bid on say a cordless drill with 2 24v batteries, and the starting bid is only.99p with no reserve, there is always someone with a small feedback score bidding in the last few days that stops this item from selling at a silly low price. It is like a built in protection to stop an item selling low. The small starting bid acts as bait, but it will never ever sell for this low price.
Does this make sense. It is hard to explain my thoughts, but it has happened to me quite a few times. I have never been able to beat this. Can companies get a program to run on their listings?

 

[oddsocks]

excellent explanation Fecn !

I'll add a few points hopefully not to confuse matters.....

If you're at home with an ADSL modem (speed touch or similar) then the ip address of the PC is the public internet facing one which is unique to your connection at that time- much more vulnerable to attacks hence the need for personal firewalls etc.. You can only have 1 PC connected. Example IP addresses are in the 81.x.x.x - to 84.x.x.x depending on provider

If you have a broadband router (wired or wireless) then the router has the single public facing IP address and provides a private network to all the local connected PCs. In this case each PC has a unique IP address (typically in 192.168.x.x range) and that IP address is never seen by the internet. The router manages the internet flows from multiple local PCs to the internet by using Address Translation and session management so it appears to be coming from the public address . Routers typically include firewalls and by default block most 'dodgy' probes for your PC. You should still run a personal firewall if only to protect yourself from others in the household! With a home router you can (in most) connect up to 254 devices - the maximum the subnet will support

If you have a wireless router you can also limit connection to specific MAC addresses (more later).

You can tell your IP address by:

from the start menu select RUN and enter CMD... a black window appears.
in the window type IPCONFIG ....what gets displayed depends on your PC -but look for the line that says IP Address - if its 192.168.x.x then its in the private range and you are connected to a router.

MY example (vista so it shows IPv4 - the 'old' system and ipv6 the new standard to allow for more PCs and many other improvements).

Connection-specific DNS Suffix . :
Link-local IPv6 Address . . . . . : fe80::dd7d:5771:bb6cxxxxx
IPv4 Address. . . . . . . . . . . : 192.168.0.13
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.0.1
Note when I did this my internet IP declared by the router was 81.83.n.n (not giving the full value here), which is in the Pipex range.

The default gateway is normally the address of your local router - the 'letterbox' that all messages have to go via.

Whether you have an ADSL modem or Router the ISP still knows who has what public IP address at anytime - hence they can trace data back to you if necessary. Once in your private network (with a router) it is the registered person with the ISP that is responsible for traffic from any private network connected device.....e.g illegal downloads


MAC addresses...

Every single network device that is manufactured has a unique MAC address - its assigned to the hardware at manufacture (i'll ignore the fact that with the right software you can change it in some cases). The network devices send data between themselves using an Address Resolution Protocol - a dynamic list that discovers and then maps each MAC address to an assigned IP address - remember the MAC address is fixed, whereas the IP address gets assigned or refreshed every time you switch on.

In a wireless router you can (in most versions) further protect your privacy from others using your wireless connection by restricting access to approved MAC addresses - i.e the physical unique interface in a PC. In my netgear this is the 'wireless station access list' - if you turn that on even a PC that finds your signal and knows your security (if you have it enabled - make sure you do) it still won't connect unless you add the specific MAC.

finally....if you stilll have a broadband modem get onto ebuyer or down the high street and buy a router - wired or wireless. It will give you better protection and free up CPU power as the router manages the internet facing modem and data processing

 

[tnimble]

Just a few side notes.

The speedtouch like modems have actually already a full functional router, only the router functionality is not enabled per default. Whith the default configuration only one PC can be connected and special software has to be present on the PC. Some ISPs provide these modem configured router with the configuration hidden to cheap connections and with the configuration not hidden to the more expensive connections.

With the router functionally enabled on a ASDL modems the router part of the modem uses the public IP address and the PCs connected use private IP addresses. Theoretically when using the 10.x.x.x or 192.168.x.x private subnet upto 64512 can be connected. However to the memory limitations of the modem and available bandwidth the amount is far less to about a couple of dozen at most.

The number of IP addresses available are very limit due to the way static IP addresses were assigned in the ealy years far before the Internet came available to the public. Back then it was very normal to assign a thousands of IP addresses a library or even millions to a university. The thought was that only these organisations would ever be connected to the internet.

Later on it was realised that soon every home would be connected to the internet and they started to create a newer version of the IP protocol using wider addresses in the form of xxxx:xxxx:xxxx:xxxx:xxxx:xxxx However the way IP addresses are assigned nowadays and the extra manageability and provided secutrity by using private addresses has already solved this addressing problem. At current with the old IP addressing using xxx.xxx.xxx.xxx notation about 180.000.000.000.000 (180.000 billion) computers can be connected to the internet. Thats about 27.000 computers per person including 3th world countries that have no electricity at all.

Although the new version of the IP protocol already exists for 12 years only a slim amount of hard and software has support for it.

 

[shedhead]

WOOW!!!
I did not think this thread was so big. Thank you ALL for your input into this. I am amazed at the depth of knowledge you have. Thanks again.