Internet Protocol (IP) address is given to each device connected to the Net. IP addresses consist of four numbers and look something like 117.0.0.1. All these numbers are usually assigned to Internet Service Providers (ISPs) within the region-based blocks. An IP-address can be used to identify the country or region from which a device is connecting to the Internet.

Earlier, ISPs issues one IP-address to each user. These are called static IP addresses. ISPs now issue IP addresses in a dynamic fashion out of a pool of addresses (using DHCP). These are referred to as dynamic IP addresses. With virtual hosting, a single machine can act like multiple machines (with multiple domain names and protocol addresses).

IP Address reveals your...

Using an IP-address it is quite easy to identify the place including the country, state, city, using a few web applications. Finding IP-address of the Yahoo, Rediff, Hotmail, etc, email senders is easy. Google masks the outgoing IP-address of the sender who sends mails using the Gmail web interface.

Using IP-Tracker like software installed on remote devices, you can access the same from anywhere. IP-Tracker constantly monitors the dynamic IPaddress of the device and whenever the IPaddress changes, it sends a mail to your inbox notifying you of your new IPaddress.

How can I change my IP Address

• If you are using a dial-up connection, you can simply dialup through an alternate access number
• For cable/DSL with a router:

1. Open your router control panel
2. Increase your MAC address by one number
3. Then disconnect and reconnect your router. Now, after doing this, your ISP will give a new IP.
4. If you find any problem, switch back to previous MAC

You can hide your IPaddress using...

• IP changer software.
• anonymous software

Knowing your IPaddress can allow you to access

• services running on your machine (E.g., online games)
• servers (FTP, web, mail)
• remote access utilities (MS Remote Desktop, GoToMyPC, PCAnywhere).

Virtual hosting allows a single machine act like multiple machines (with multiple domain names and IP-addresses).

How can I know the IP-address of the person whom you have been chatting in your IM (Instant Messenger)

• If you want to know the IP, run a packet sniffer and initiate a file transfer.
• You will need to set up a file transfer in order to see the internet protocol address of the person you are communicating with; the transfer will go pretty much direct to the other person's computer. Otherwise you get the protocol address of the server.

If you run a packet sniffer, you need to send a request using ICMP, and then TCP with the SYN ACK flag set) and the target computer will respond. TCP SYN ACK packet gives you the target device's port number, IP-address, etc.

But there are exceptions. If the target device runs behind a router with a hardware firewall, you may not get the actual protocol address you are looking for; instead, a WAN IP of some sort usually the one from the ISP will be displayed.

In conclusion, since internet protocol addresses reveal your physical location and also gives more details to others; it is advisable not to display your protocol address except for essential and important communication. Mask the IP-address for you and your device's security sake.

Resources:
Hacking - What, When & How
Browsers - Gateway to the Internet
Strategies to Learn English Article

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