Getting Back to my Mac working

Like others, I was having mucho trouble getting Back to my Mac working. I’m happy to say that now it works pretty reliably on many networks that I’ve tried to connect from.

I should start by saying that I do have one of the Apple-recommended routers at home… to be more specific, I have an Apple Airport Extreme 802.11n.

Since I have this router and it supports the NAT-UPnP that is needed for my home tower to open the ports, I didn’t have to do any specific forwarding. However, I did have something going on that was foiling it quite well. I had port 443 opened and forwarding to a Linux server on the local network. Turns out, that’s one of the ports that BtmM wants to use – 443/tcp and 4500/udp, to be specific. I took off the specific port mapping for 443 and it was all about the authentication at that point.

That did get me thinking though. For some multitudes of broadband users, BtmM probably won’t function. Apparently, BtmM uses 443/tcp to handshake and then negotiate the connections with your .Mac password. That’s fine, but what about all of those ISPs that block well-known web ports like 80 and 443?

That’ll pose a problem. So if you’re on an ISP that likes to do something like that, there’s a good chance that BtmM will not work for you. If you’re not in that boat, try the following:

– Make sure you have an Apple-branded router (or Apple recommended)

– Make sure you’re not using port 443 for something on your home network (or 4500/udp for that matter)

– Make sure UPnP is enabled on your router

– Make sure all computers involved are on OS X 10.5.2 or higher

– Make sure all routers are on the latest firmware

– Make sure your authentication is set up properly. On my laptop, my username is different than what I use on the tower at home. Therefore, initial connections fail because after using .Mac to authenticate, then it wants to use the local username of the machine you’re connecting to. Make sure your keychain agrees with that.

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