Chapter 22. SSH, FTP, VPN, and Web Sharing

Chapter 22. SSH, FTP, VPN, and Web Sharing Email and Web surfing may be the most popular Internet activities, but the worlds most gigantic network has many other uses.
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Chapter 22. SSH, FTP, VPN, and Web SharingChapter 22. SSH, FTP, VPN, and Web SharingEmail and Web surfing may be the most popular Internet activities, but the worlds mostgigantic network has many other uses. The general idea is always the same, though:letting one computer reach out and touch another.Mac OS X offers a few features that embrace the more literal aspects of that notion. Forexample, you can turn your Mac into a Web server—an actual living Web site thatanyone on the Internet can visit. This chapter also explores various advanced methods ofmanipulating your own Mac from the road, including remote access technologies likelong-distance file sharing, FTP, SSH, and virtual private networking (VPN).Note: Most of these technologies are designed for full-time Internet connections (cablemodem or DSL, for example). If you have a dial-up modem, these features work onlywhen youre actually online. Still, they may occasionally be useful anyway. You couldalways get online, call up a friend and say, Check out my Web site right now—heres thecurrent IP address or call someone back home to say, I have to grab a file off my harddrive. Could you make the Mac on my desk go online?22.1. Web SharingUsing the Sharing pane of System Preferences, you can turn your Mac into a Web site (orserver), accessible from the Web browsers of people on your office network, the Internetat large, or both.This feature assumes, of course, that youve already created some Web pages. For thispurpose, you can use Web design programs (Macromedia Dreamweaver, for example, orthe free Netscape Composer) or save documents out of TextEdit or Word as Web pages.Or you could let Mac OS X build Web pages for you using iPhoto or Image Capture.After you provide your friends and co-workers with your Macs Website address, theycan view your Web pages, graphics, and documents in their own Web browsers. Andwhenever youre online, your Web site is also available to any one on the Internet—butyou dont have to pay a penny to a Web-hosting company. UP TO SPEED The IP Address Mess: Port Forwarding There are so many ways to connect to your Mac from another computer. Youcan use Web sharing, SSH, file sharing, screen sharing, and so on. Theyre easyto use—when you want to connect across your home or office network.When you want to connect from across the Internet, though, things getcomplicated fast.In that case, you need to know your home Macs IP address. (It stands forInternet Protocol.) An IP address is always made up of four numbers separatedby periods, like 192.168.1.104. Every computer on earth thats directlyconnected to the Internet has its own unique IP address.Now, if you have only one Mac, and its connected directly to your broadbandmodem, no big deal. You can find out its IP address by opening SystemPreferences, clicking Sharing, and clicking File Sharing.Unfortunately, your Mac at home probably isnt connected directly to theInternet. If youre like most people, its connected to a router, or maybe anAirPort base station, so that several computers in your house can share the sameInternet connection. In this setup, the router (or base station) has a unique IPaddress—not the Macs connected to it.(The router doles out private IP addresses to each computer in your house oroffice, usually beginning with 192 or 10. If you check your Macs IP address inSystem Preferences, youll find out only its private address—not the public onethats accessible from the Internet. To find out that information, you have tocheck your router or base stations configuration screen; check the routersmanual for instructions.)All right: How are you supposed to connect to one particular Mac if itsconnected to a router and doesnt have a true, public IP address?One solution is Back to My Mac, the remote-access feature described on Section13.5.3.4. It solves the behind-the-router problem for you, but it requires a .Macaccount (Section 18.6).Otherwise, your only hope is to turn on a router feature called port forwarding.It makes the router pass signals intended for a specific port (Section 12.9) to oneparticular computer on the network. For example, you could direct all port-80communications to the Mac doing Web serving, for example, and all 548 trafficto a Mac doing file sharing.The point is that, even with port forwarding, you still cant access two differentmachines using the same port. (For some services, including ssh and Timbuktu, you can work around this limitation by logging into the machine specified for port forwarding, and then from that machine, log into the others on the rest of the network.) Turning on port forwarding doesnt require a programming degree, but its not simple by any means. For starters, the steps are different for every router model. Fortunately, you can find guided tutorials on the Web. You can use Google to search for your particular router model, or check, www.portforward.com which offers free step-by-steps for hundreds of router models, including Apples AirPort base stations. Even so, try to arrange the assistance of someone who knows networking. In this chapter, the term your IP address means your public IP address. If you have only one Mac, thats its IP address. If you have a router or wireless network, use that devices IP address—as passed along by port forwarding.Tip: Web sharing is also an easy and efficient way to share your Mac files with WindowsPCs, either those on your office network or those on the Internet. No special software ortranslation is required, and posting your files on the Web page avoids all the usualcomplexities of sending files by email.Mac OS Xs Web Sharing feature isnt some feeble junior version, either. Inside Mac OSX is Apache, one of the strongest and ...