Gaining legitimate, secure access to your other computers when you're away from them ranks high among the needs of people who have two or...

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Gaining legitimate, secure access to your other computers when you’re away from them ranks high among the needs of people who have two or more computers.

Apple played to this need by including Back to My Mac in its Mac OS X 10.5 Leopard release last year, pairing it with what’s now known as MobileMe.

Any two Leopard computers with Back to My Mac activated and logged in to the same MobileMe account can connect for file sharing, remote screen sharing and any other Mac service that can advertise its ability over a local network using Apple’s Bonjour.

After nearly a year of using Back to My Mac, writing and revising a long electronic book on the topic, and answering several hundred e-mails about the service from readers of this newspaper and my book, I have to conclude Back to My Mac isn’t a solution for most users.

I don’t have a single colleague who uses it to reach any of their machines remotely.

Part of this problem is Apple plays nice with networks. Other services, like Skype, that can reach through a broadband modem and a network gateway to communicate with computers on a local network that are otherwise unreachable from the outside world use a whole basket of tricks to make their operations work.

Apple chose to use standards without any tricks — and that leaves them at a disadvantage.

Back to My Mac requires that your broadband modem assigns a network gateway — a Wi-Fi base station such as Apple’s AirPort Extreme, a publicly reachable Internet address. Some Internet service providers — Qwest is one — do this as a routine matter; others require you pay extra; some, for apparent security reasons, don’t offer it at all.

A publicly reachable address, as opposed to one the ISP assigns out and acts as a shield for, prevents some undesirable attacks, but also disables the end-to-end principle of the Internet, which allows connections between any two computers with public addresses.

Back to My Mac also requires that a network gateway has one of two protocols available and turned on that lets Mac OS X ask the router to open up access to the outside world.

The router, if it’s set up right, responds to Leopard with information about how it opened itself up. Leopard then passes that information on to your MobileMe account, allowing other computers under your control to find that machine.

This request requires that a gateway is either an Apple base station released in 2003 or later, all of which offers the mouthful that is NAT-PMP (Network Address Translation Port Mapping Protocol), or is from most other firms, such as NetGear or Linksys with UPnP (Universal Plug and Play) available.

It turns out that Qwest (along with most other telephone companies) prefers to offer you a modem that doesn’t have UPnP as an option.

I have Qwest DSL with a 2Wire wireless modem; when I queried 2Wire about UPnP, a spokesperson explained that its customers (the telephone companies) preferred to leave UPnP out due to security concerns.

Some of these concerns are valid.

If you have neither a public IP address nor NAT-PMP or UPnP available, Back to My Mac simply won’t work.

For people who need remote access in these cases — including yours truly — I recommend LogMeIn Free for Mac. A no-cost product, as you can tell by its name, LogMeIn offers browser-based remote screen control.

You set up an account on, then install its small software packages on Macs and Windows systems you want to access remotely.

The free version doesn’t include file transfer, but you can use an intermediate — such as MobileMe’s iDisk — to copy files to and from.

There’s one trick I’ve found to make LogMeIn work best. When you connect to a remote system, before clicking a Remote Control link, click the Preferences link, then Remote Control Settings. From the Default Remote Control pop-up menu, choose Java.

I found that changing this setting creating fast and reliable connections.

I have confidence in what I know about Apple’s commitment to Back to My Mac that it should improve over time. A year into this effort, I’m optimistically underwhelmed.

Sometimes bad Is bad: You may recall when Apple introduced its updated iPhone 3G model, I raved about the subcompact USB power adapter that came with the version shipped in the U.S.

I’d never seen anything quite so small and useful — barely more than the plastic covering a USB jack and two AC outlet prongs.

Turns out I may have been a little overenthusiastic. Last week, Apple started up an “exchange” program — a good step below a government-coordinated recall — because of reports of electric shock resulting from prongs disattaching themselves when the adapter was removed from an outlet.

Although Apple says there were no injuries, and this apparently happened in a small number of cases, the company is offering a no-charge exchange for every adapter it bundled with the iPhone 3G in the U.S., Canada and several other countries.

You can sign up for an exchange at, starting Oct. 10, you can visit an Apple Store in person with your iPhone 3G and the power adapter and receive an exchange.

Apple recommends not using this adapter, only its replacement, which will be marked with a green dot near the prongs to avoid future confusion. The iPhone 3G can be charged through its USB cable safely plugged into a computer or another USB power adapter, such as those that ship with iPods.

Glenn Fleishman writes the Practical Mac column for Personal Technology and about technology in general for The Seattle Times and other publications. Send questions to More columns at