One of the main reasons for building a network is sharing files between computers. You might even want to set up a server, which is a computer with shared files that are always available to anyone on the network. Think of a server as a common file storage area for the rest of the network. Really, any computer that shares files is technically a server because it's serving, so to speak. But most people use the word server only to mean a computer that's dedicated solely to serving files, printers, and so on for the rest of the network.

Creating an account

Sharing files on your MacBook with other Mac users is a piece of cake. Remember, however, that you need to create an account for anyone whom you want to have access to your files. The accounts that you create can access only three folders, as shown in Figure 2-1:

Figure 2.1. The location of user folders and the Shared folder on your hard drive.

• The account's Home folder: That specific account's Home folder carries a short version of the username that's in the Users folder on your hard drive. Figure 2-1 shows the Home folder, which is noted with an icon that looks like a house, for the mark account (where mark is the short account name for Mark Chambers). The Home folder icon always bears the short account name for the user who's currently logged in.

• The account's Public folder: Each user account you create also has a Public folder located within its Home folder. Any files you place in the Public folder can be accessed by any user on your Mac.

• The Shared folder: This folder is also in the Users folder on your hard drive. Anyone with an account on your Mac can access the Shared folder, so it's a great place to keep common files that everyone wants to copy or use.

To create an account, you need to be logged in as an Admin user. Follow these steps:

1. Open System Preferences from the Apple menu (

   

2. Click the Accounts icon.

3. Click the New Account button, which carries a plus sign.

4. Fill in the appropriate information, including the name for the account and a password.

   Note that the name that appears as the short name determines the name of that user's Home folder.

5. Click Create Account.

6. Press

   

I cover creating accounts in greater detail in Book III, Chapter 5, but that's the short version.

Connecting to a shared resource

At the top of the Sharing pane, you can see that other Macintosh users can access your laptop at afp://<ip address>, where ip address is the IP address for your specific computer. When another Mac user wants to connect to your shared files, that person can do the following:

1. Choose Go

   

2. After the Connect to Server dialog opens, other Mac users can type afp://<ip address> (where ip address is the IP address of your MacBook) and then click the Connect button.

Tip

You can also browse for a shared resource in the Connect to Server dialog. Choose Go

Give the username and password that you created to the person using the other Mac, and he or she can now access files in that account's Home folder as well as any other Public folders on your computer.

The sidebar that appears in Finder windows offers a Shared heading. Click the arrow next to Shared to display other shared resources on your network, just as if you had clicked Browse from the Connect to Server dialog. (I'm starting to think Snow Leopard might be a synonym for convenience.)

Sharing your printer for others to use is one of the best reasons to have a network. Setting up your MacBook to share your printer is very easy under Mac OS X. Here's a quick rundown of what you need to do:

After Printer Sharing is enabled, follow these steps to connect to that printer from other computers on your network:

If you've deigned to allow PCs running Windows on your network (a generous gesture), you'll probably want to also share files with those computers. Sharing files with a Windows PC — actually a Windows user — is very similar to sharing files with other Mac users.

To allow file sharing with Windows computers, follow these steps:

If you allow a Windows PC to access your files, you'll also probably want to putter around with files on a Windows PC. Easy!

Accessing files on Windows computers relies on the Samba component (a part of the UNIX foundation of Mac OS X). Follow these steps:

After you mount the shared drive, you'll see it appear on your Desktop, just as you see a Mac volume. You can use this drive just as you do any other drive on your system. To disconnect from the Windows share, you can

FTP is part of the TCP/IP protocol suite ( the hoary acronym FTP stands for File Transfer Protocol. FTP is one of the oldest methods for sharing files between computers; however, because it's part of the TCP/IP protocol suite, it can be used on many different kinds of computers, including those running just about any type of strange and arcane operating system. You can still manage to exchange files regardless of whether you're using Mac OS X, Windows, Linux, or UNIX. (Heck, even dinosaurs like DOS can join the party.)

FTP is a client/server application. In plain English, this means that two pieces make things tick: the server (which hosts the connection, rather like a file server) and the client (which connects to the server). Mac OS X, thanks to its UNIX foundation, has both an FTP server and client built in. To use FTP, you need a computer running the FTP server software to give others access to files; then the other computer, or client, can connect to the FTP server. After the connection is made, the client can either send files to the server (uploading) or get files from the server (downloading). In this section, I cover how to use FTP to give others access to your files as well as talk about the FTP applications that come with Mac OS X.

Using FTP from Terminal to transfer files

You can use FTP to transfer files with an FTP server by using the command-line interface (CLI); to use the CLI, open a Terminal, or shell, session. To use a Terminal session, double-click the Terminal icon in the Utilities folder inside the Applications folder. When you open a Terminal session, you're presented with a window that accepts text commands. You'll see a prompt that consists of your computer's name and the folder that you're currently in, followed by your user ID. It's at this prompt where you type various FTP commands.

After you're in the Terminal session, you'll use a series of commands to connect to another computer, move in and out of folders, and transfer files. Following is a list of the basic commands that you need to use FTP as well as a brief description of what each command does.

• ftp: This command starts the FTP command-line interface session. You can tell that you're in the FTP client application when you see ftp> as your command prompt. This is where you type all other FTP commands to do things.

• open: This command is used to start your connection to another computer. Type this command followed by the IP address of the FTP server that you want to connect to.

• ls: Use this command to see a listing of all files and folders in the current folder on the FTP server.

• cd: This command allows you to change the folder that you're in. Type cd <folder> (where folder is a specific folder name) to move into a subfolder on the FTP server. Type cd .. (that's c, d, space, and two periods) to go back out a folder level.

• lcd: This command acts exactly like cd except that it changes the folder that you're currently in on your local system, not the FTP server. Use this command to put yourself in the folder on the local drive that you want to transfer files to and from.

• bin: Type this command to get in binary mode to transfer files that aren't plain-text files. (Always use binary mode unless you're specifically transferring plain-text files.)

• ascii: This command puts you in ASCII mode for transferring text files.

• get or mget: To retrieve a single file, use the get command followed by the filename of the file that you want to retrieve. If you want to get multiple files at one time, use the mget command followed by a filename, possibly containing * and/or ? as wildcards.

• put or mput: To send a single file, use the put command followed by the filename to send a file to the FTP server. To send multiple files, use the mput command followed by a filename, possibly containing * and/or ? as wildcards.

• quit: Use the quit command to end your FTP session.

To end a Terminal session and exit Terminal at any time, press

Tip

Many FTP servers will let you send files only to certain folders. Most times this folder is named Upload, Uploads, or something similar.

Using these commands will enable you to exchange files with an FTP server. Here's an example of how to use these commands within the Terminal window:

1. Type ftp to get into FTP mode.

2. Type open <ip address> (where ip address is the server's network IP address) to open your connection to the FTP server.

3. At this point, you're asked for a username and password.

   For many FTP servers, using the username anonymous and your e-mail address as the password is enough to get you logged in. Some sites even allow you to log in without any username or password at all. On secure sites, however, you must use an assigned username and password provided by the administrator of that particular server.

4. Type lcd <folder> (where folder is a specific folder name) to change into the folder on your local drive that you want files to come to or from.

5. Type the ls and cd commands to place yourself into the desired folder on the FTP server.

6. Type the ascii or bin command to set your file transfer mode to ASCII or binary, respectively.

   Warning

   This is important because choosing the wrong type will likely cause the transfer to fail. Unless it's a plain-text file, always use binary mode.

7. Type the get, mget, put, and mput commands to send or receive the desired files.

8. Type the quit command to close the connection and exit the FTP session.

A firewall watches all the network communications coming into your MacBook. It automatically plays the role of security guard, blocking or denying certain network traffic that you want to prevent from reaching your laptop. It acts as another layer of security to help keep you safe from unwanted attacks. That's all well and good, but you must be careful to set up your firewall correctly before you turn it on: A configuration mistake could make your MacBook inaccessible from the network.

For instance, if you want to enable FTP access on your MacBook but you also want to keep all other traffic from coming into your system, you can tell the built-in firewall to allow only FTP traffic. The firewall on the MacBook will block or allow only TCP/IP traffic — not Bonjour — so Bonjour traffic (which is always from your local network and not the Internet, anyway) can always get in.

When enabled, the firewall blocks all traffic that comes into your MacBook. By default, however, the firewall is turned off. So, your first job is to enable the firewall, which you can do by following these steps:

This enables the firewall. And, by default, virtually all incoming TCP/IP traffic is blocked. You must enable each sharing method that you want to be able to use. When you enable different sharing methods from the Sharing pane in System Preferences (such as File Sharing or FTP Access), you'll notice that those types of traffic now appear in the Firewall list. (In other words, when you turn on a sharing method, the firewall automatically allows traffic for that sharing method, which Snow Leopard calls a service. Most excellent.)

Sometimes, you might want to allow other traffic through your firewall that isn't on the firewall list of recognized services and applications. At that point, you can click the Add button (which bears a plus sign) to specify the application that your firewall should allow. Snow Leopard presents you with the familiar Add dialog, and you can choose the application that needs access.

Forgive me whilst I wax techno-nerd here: One of the coolest advantages to a network is the ability to take control of one computer from another computer. For example, sometimes you might need to access files on your Mac Pro desktop while you're on a trip, but you don't have File Sharing enabled. What can you do? You can remotely connect into your Mac Pro and then — just as if you were sitting in front of it — enable File Sharing (as I demonstrate earlier in the chapter). Perhaps you have a file on your computer with someone's phone number that you suddenly need on the road. With remote control, it's at your fingertips! (Sigh ...ah, technology.)

Using Screen Sharing

Snow Leopard's Screen Sharing feature, which is available from iChat, can be turned on for individual users from the Sharing pane in System Preferences. You can allow access for all user accounts on your MacBook or limit remote access to selected users. Screen Sharing is Apple's implementation of Virtual Network Computing (VNC) technology.

To set up Screen Sharing, follow these steps:

1. Click the System Preferences icon in the Dock.

2. Click the Sharing icon to open the Sharing Preferences pane.

3. Click the Screen Sharing check box to select it.

4. To limit remote access for specific accounts, click the Only these users radio button, and click the Add button (which bears a plus sign) to select a user.

5. Close the System Preferences window to save the change.

After you've enabled screen sharing, you can use the Buddies

How VNC works

In a nutshell, VNC takes the graphical interface on your monitor, turns it into data, and sends it to the computer that you're using to remotely control it. The computer that you're using sends keyboard presses, trackpad movements, and clicks to it, acting just the same way as it would if you were sitting right in front of it.

Tip

As I mention earlier, you can use Snow Leopard's Screen Sharing feature in iChat to make a remote connection from another Mac to your MacBook. However, you're not limited to using just another Mac using Snow Leopard and Screen Sharing in iChat — you can control your MacBook from a Windows PC, or from an older version of Mac OS X as well! If you've already enabled Screen Sharing (as I demonstrate earlier in this chapter), follow these steps to enable any VNC connection:

1. Click the System Preferences icon in the Dock.

2. Click the Sharing icon to open the Sharing Preferences pane.

3. Click the Screen Sharing entry.

4. Click the Computer Settings button.

5. Click the VNC Viewers May Control Screen with Password check box to select it.

6. Click within the password text box and enter a password for VNC applications.

7. Click OK to exit the Computer Settings sheet, and close the System Preferences window to save the changes.

Figure 2-3 shows a screenshot of a Mac running Mac OS X Tiger being remotely controlled from a computer running Windows 98. (Yes, I know, it's a travesty, but then again, sometimes you've just gotta use what you've got.)

Figure 2.3. Yes, bucko, that's Mac OS X accessed remotely via Windows!

Warning

Mr. Paranoia speaks again: Make doggone sure that you set up the password access correctly for VNC or don't run it! I can't stress enough how much fun a hacker would have with free remote control over your Mac OS X Desktop.