What is an IP packet?

Computers are not only an integral part of today’s world, they have also become a passion. Hotels, cafes and even neighborhoods have made Internet access available, meeting the demand for connectivity. But how does information travel across cyberspace from one computer to another? Like the Star Trek transporter, information is disassembled into small blocks of data, sent independently to the destination address, then reassembled at the receiving end. Each block of data is known as an IP packet.

Internet service providers assign a numeric address to each computer.

Whenever you connect to the Internet, your ISP assigns your computer a unique numeric address. This unique address identifies your computer on the network so that you can request and receive information. The address is known as an Internet Protocol (IP) address. When you initiate a request, such as clicking a link in your web browser, the request travels across the Internet in the form of packets of data stamped with your IP address. Hence the term IP packets.

Due to the structure of networks, small IP packets work more efficiently than large packets. Not only would a single large IP packet take longer to transmit, but high traffic conditions would quickly clog the network. Sending smaller packets (up to about 1500 bytes) has the advantage of moving more traffic along the available routes at a faster rate with less chance of creating bottlenecks. Consequently, each IP packet travels through the Internet independently, guided by routers that read the destination address and forward the packet along the fastest available route. At the destination address, the packets are reassembled.

The protocol responsible for orchestrating the movement of IP packets in cyberspace is the Transfer Control Protocol, better known as TCP. TCP is “layered” on top of the addressing protocol (IP) to break requests into small packets, monitor the arrival of each IP packet at the destination address, request retransmission of missing packets, and reassemble packets in the original format. This suite of protocols is known as TCP/IP, a term likely familiar to anyone who has set up an Internet connection.

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Each IP packet carries vital information that allows it to be properly handled by TCP. The “DNA” of an IP packet includes, among other things, the size of the IP packet, the sender and destination addresses, and the payload itself or the data being sent. Packet numbering, error reporting and fragmentation are also included, with an end-of-life seal to prevent lost packets from bouncing around in cyberspace indefinitely as junk traffic. Packets that do not reach their destination in time are simply discarded.

A successful transmission is processed by a web server which responds by sending the requested web page, which in turn is split into IP packets for the trip back to the computer screen. These hurried packets of data constitute “The Information Superhighway”.

While TCP/IP may seem involved, it operates faster than the Star Trek transporter under normal conditions. So what’s up with those occasional slow page loads? Assuming your computer is capable of quickly processing page content, a slow load could be caused by third-party ad servers or a busy website that is processing more requests than your hardware can comfortably handle.

Despite the robust nature of TCP/IP, there is a downside to the protocol. Anyone can “hear” what is being transmitted between your computer and the Internet without your knowledge. How is this possible?

A typical IP packet might pass though several routers and servers before reaching its destination. At any point along the way, specialized software or hardware can “trap” the data packet, taking a snapshot before forwarding it along. The interloper’s stolen copy can be analyzed and read at will, as IP packet payloads are felt as plain text, sometimes referred to as “in the clear.” Tools that trap IP packets are known as “packet sniffers.”

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Network administrators legitimately use packet sniffers to troubleshoot local area networks (LANs) and to filter unwanted traffic coming in from the Internet. Law enforcement can plant packet sniffers on an Internet Service Provider to monitor some or all of its traffic, if the provider agrees or is compelled by law to comply. But packet sniffers can also be used by virtually anyone to simply eavesdrop, or worse, steal sensitive information like passwords and usernames sent over unencrypted channels.

With identity theft on the rise and concern for privacy at an all time high, the best way to protect yourself from packet sniffers is to use encryption for all transmissions that contain personal information. Encrypted packets are unreadable en route, and are only decrypted at the destination address.

Online retailers already provide secure, encrypted connections for passing data between your computer and the website. To check for encryption, look for https in the Web browser’s address field. That extra “s” stands for security, and indicates all traffic between your computer and the Web server is encrypted. Your computer will still generate IP packets, but the payload portion of the IP packet will be in unreadable cipher, protecting credit cards, bank accounts, and other highly sensitive information from prying eyes.

Since the IP packet is also used for email, file transfers, telnet, and other networking services, you might also choose to encrypt other transmissions. Pretty Good Privacy (PGP), a military grade encryption program, can automatically encrypt mail in several popular email programs. GNU Privacy Guard (GPG), based on the same source code but part of the Free Software Foundation, is another encryption program. GPG used with the Enigma plugin provides Mozilla™ Thunderbird™ with fully automated, easy to use encryption.

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Web surfing can be encrypted through online security services, though it might slow surfing and is probably overkill for the average person. Surfing by using anonymous proxy servers that sit between your computer and the Internet is a more common alternative for those who wish to surf anonymously.

Additional protocols can be bundled with TCP/IP to form other “suites” that accommodate different types of networking environments and hardware. In special situations the User Datagram Protocol (UDP) is sometimes substituted for TCP, but provides no mechanism for IP packet loss, lacking TCPs ability to call for retransmissions. Network host computers might use several additional protocols for exchanging router information, such as Internet Control Message Protocol (ICMP), the Interior and Exterior Gateway Protocols (IGP/EGP), and the Border Gateway Protocol (BGP).

Using the Internet from the familiar settings of home or school causes many people, especially children, to feel a false sense of security and privacy. A basic understanding of the “vulnerability” of the IP packet and the ubiquitous availability of packet sniffers drives home the point that one should always check for a secure, encrypted connection (https) before sharing sensitive information online. The rule is, anything that travels unencrypted should be considered public and not private.

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