Chapter 1

Welcome to Networking

IN THIS CHAPTER

Getting a handle on networks

Considering why networking is useful (and is everywhere)

Telling the difference between servers and clients

Seeing how networks change computing life

Examining network topology

Identifying (and offering sympathy to) the network administrator

Computer networks get a bad rap in the movies. In the 1980s, the Terminator movies featured Skynet, a computer network that becomes self-aware (a computer network of the future), takes over the planet, builds deadly terminator robots, and sends them back through time to kill everyone unfortunate enough to have the name Sarah Connor. In the Matrix movies, a vast and powerful computer network enslaves humans and keeps them trapped in a simulation of the real world. And in the 2015 blockbuster Spectre, James Bond goes rogue (again) to prevent the Evil Genius Ernst Blofeld from taking over the world (again) by linking the computer systems of all the world's intelligence agencies together to form a single, all-powerful evil network that spies on everybody.

Fear not. These bad networks exist only in the dreams of science-fiction writers. Real-world networks are much more calm and predictable. Although sophisticated networks do seem to know a lot about you, they don't think for themselves and they don't evolve into self-awareness. And although they can gather a sometimes disturbing amount of information about you, they won't try to kill you, even if your name is Sarah Connor.

Now that you're over your fear of networks, you're ready to breeze through this chapter. It's a gentle, even superficial, introduction to computer networks, with a slant to the concepts that can help you use a computer that's attached to a network. This chapter goes easy on the details; the detailed stuff comes later.

Defining a Network

A network is nothing more than two or more computers connected by a cable or by a wireless radio connection so that they can exchange information.

You can create a simple computer network by using a device called a switch to connect all the computers in your network to each other. You do that by stringing a network cable from the switch to each computer. The cable plugs into a special jack on the back of each computer; this jack is connected to a network interface, which is an electronic circuit that resides inside your computer to facilitate networking. Voilà! You have a working network.

If you don't want to mess with cables, you can create a wireless network instead. In a wireless network, the computers use wireless network adapters that communicate via radio signals. All modern laptop computers have built-in wireless network adapters, as do most desktop computers. (If yours doesn't, you can purchase a separate wireless network adapter that plugs into one of the computer's USB ports.) You'll need a device called a wireless access point (WAP) to enable the computers to properly connect. In small office or home networks, the WAP is bundled with a device called a router, which lets you connect your network to the internet. The combination of a WAP and a router is called a wireless router.

Figure 1-1 shows a typical network with five computers. This network is a home network used by a family that bears only a totally coincidental similarity to a famous TV family you may or may not have heard of. You can see that each family member has a device that connects to the network - two of them wirelessly, two of them through cables. There's also a printer that connects wirelessly.

In this example, the wireless router also has a built-in switch that provides several jacks for connecting computers via cable. Most wireless routers include this feature, typically with three to five wired network ports.

Although the network is a small one, it has much in common with larger networks that contain dozens, hundreds, or even thousands of connected computers.

FIGURE 1-1: A typical network.

Here's the rundown for each of the devices connected to this network:

• Lisa has a laptop computer that connects wirelessly. She uses it mostly for school.
• Bart has a fancy gaming computer that's cabled directly to the router.
• Marge doesn't have a full-fledged computer, but she does use an iPad, which is connected wirelessly.
• Homer has an old computer he bought at a garage sale in 1989. He doesn't know how to use it, but he doesn't know that, so no one tells him. Lisa set it up for him and repairs it when Homer breaks it (which happens every few months); she gets repair parts from eBay.
• The printer connects wirelessly to the network and is set up so that any member of the family can print on it.
• The wireless router connects to the internet using the family's cable TV provider. This allows everyone in the family to access the internet.

Delving into Network Lingo

Computer networking has its own strange vocabulary. Although you don't have to know every esoteric networking term, it helps to be acquainted with a few of the basic buzzwords:

• Local area network (LAN): Networks are often called LANs, short for local area network.

  LAN is the first three-letter acronym (TLA) of this book. You don't really need to remember it or any of the many TLAs that follow. You may guess that the acronym for four-letter acronym is FLA. Wrong! A four-letter acronym is an ETLA, which stands for extended three-letter acronym. After all, it just wouldn't be right if the acronym for four-letter acronym had only three letters.

• On the network: Every computer connected to the network is said to be "on the network." The technical term (which you can forget) for a computer that's on the network is a node.
• Online, offline: When a computer is turned on and can access the network, the computer is online. When a computer can't access the network, it's offline. A computer can be offline for several reasons. The computer can be turned off, the user may have disabled the network connection, the computer may be broken, the cable that connects it to the network can be unplugged, or a wad of gum can be jammed into the disk drive.
• Up, down: When a computer is turned on and working properly, it's up. When a computer is turned off, broken, or being serviced, it's down. Turning off a computer is sometimes called taking it down. Turning it back on is sometimes called bringing it up.
• Local, remote: A resource such as a disk drive is local if it resides in your computer. It's remote if it resides in another computer somewhere else on your network.
• Internet: The internet is a huge amalgamation of computer networks strewn about the entire planet. Networking the computers in your home or office so that they can share information with one another and connecting your computer to the worldwide internet are two separate but related tasks.

Seeing What You Can Do with a Network

Frankly, computer networks are a bit of a pain to set up. So, why bother? Because the benefits of having a network outweigh the difficulties of setting one up.

You don't have to be a PhD to understand the benefits of networking. In fact, you learned everything you need to know in kindergarten: Networks are all about sharing. Specifically, networks are about sharing three things: files, resources, and programs.

Accessing the internet

Probably the main reason most small business and home networks exist is to allow everyone to access the internet through a single shared internet connection. In Figure 1-1, you can see that the wireless router is connected to the internet. By sharing this connection, all the computers on the network, whether connected wirelessly or via cables, can access the internet through the wireless router.

It's important to note that nearly all wireless routers also contain a built-in firewall. The firewall helps protect the computers on the network from the imminent dangers of the internet. The moment you connect a home or office network to the internet, cybercriminals will begin trying to break into your network and try to trick you into divulging sensitive information, such as the password to your bank account.

Never - and I mean never - allow any computer to connect directly to the internet without a firewall in place.

Sharing files

Networks enable you to share information with other computers on the network. Depending on how you set up your network, you can share files with your network friends in several different ways. You can send a file from your computer directly to a friend's computer by attaching the file to an email message and then mailing it. Or you can let your friend access your computer over the network so that your friend can retrieve the file directly from your hard drive. Yet another method is to copy the file to a disk on another computer and then tell your friend where you put the file so that your friend can...