some Qs on IP addresses

thomo

does a pc have a constant ip address or an identification number like a mobile phones imei? does your ip address change when you change isp or does it remain constant? does your ip address change everytime you access mobile broadband?

hobochris

that depends on a few things if your pc & router are setup for dhcp then our ip will change. if your changing isp then they will likely issue you with a new router. so there is a good chance that your pc ip will change unless you configure your pc's ip as static on both the pc and router.

Edit: sorry misread the question. all network cards and devices have a mac address(this doesn't change) which is a unique address that each interface has(wireless or lan).

thomo

"Edit: sorry misread the question. all network cards and devices have a mac address(this doesn't change) which is a unique address that each interface has(wireless or lan)." thanks for reply but please explain. does this number show up whenever you access the net

seamus

The short answer is no. All phones have a specific IMEI which is tied that phone and stays with that phone.

There is no such identifier on PCs which cannot be changed or removed during the PC's lifetime.

hobochris is right on the various identifiers which are available. If you're using a network, there are two primary pieces of identifiers:

1. A MAC. This is an ID which is attached to every network device. It is not necessarily PC-specific. The MAC is attached to the piece of hardware which connects to the network - so in the case of a PC, this MAC is attached to the network card. This network card can be changed and some network cards allow you to change their MAC. So in effect you can change your PC's MAC if you want to.
For other devices such as routers, laptops and phones which have integrated network devices, it's tougher to change your MAC but not always impossible.

2. IP Address. This is an address assigned to your PC to identify it as part of a specific network (as opposed to a network device). This is non-permanent and non-specific. Your machine or router can get a different IP whenever it connects to a network. The simplest way of thinking of it is like those ticket machines you get in the tax office. You simply are assigned the next available number when you ask for one. In reality it's smarter and more complex than that, but that's it in very basic terms.

thanks for reply but please explain. does this number show up whenever you access the net

No. Not really. It's not possible for someone on the internet to see your MAC.

FruitLover

If you change ISP, your internet-routable IP address will change (private DHCP-assigned IPs are pretty much irrelevant past the internal network).

MAC addresses can be changed, and aren't readable past the ISP.

What do you mean by 'mobile' broadband? A phone? Or a PC using a 3G modem? Either way, your IP address will most likely change between connections. But this depends on various things, e.g. your ISP's policy, the way the ISP's IP-assigning server is set up, etc.

thomo

thanks thats very helpful. i have two more Qs. if i use an unregistered phone as a modem with my pc/laptop can the phones number and imei be identified. if i use an unregistered PAYG broadband modem in a pc that has a known mac or ip address is it possible to determine what the sim number is. i just want to keep my internet usage private and dont like the idea of everything you do being traced so im trying to find out whats the best way of doing it. thats the reason for all the questions

seamus

Ultimately it is always possible to identify who you are and often where you are when you're using a mobile device. That's the price you pay for using the device in the first place.

However this information is not publically available. Someone could get about as far as identifying your IP address and finding out that you're using a mobile ISP, but that's as far as they can get. In order to identify your mobile number or your IMEI, a person would need to obtain a court order (which in turn requires a very good reason) which would compel your mobile ISP to go through their logs and pull out that data.

If you're trying to stay private, simply install a good firewall and don't give out much personal information on the internet. No other information can be obtained. Your ISP will always have access to certain kinds of information and they know what you're doing, but ultimately they don't care beyond charging you for it.

Saruman

thomo sounds like he is up to something