MacMost Now 345: Setting Up an Airport Extreme for Outside Access

You can use Airport Utility to configure your Airport Extreme so you can access your Macs for file sharing and screen sharing. It involves both DHCP reservations and Port Forwarding. It also helps if you have a static IP address for your home Internet access.

Video Transcript
Hi, this is Gary, with MacMost Now. On today's episode, let's look at setting up your airport extreme, so you can access your Macs from outside of the house.
OK. So, you are out of your house, and you want to access one of the Macs inside your house. You've got a DSL or cable modem router, and you've got your airport extreme. How do you get from outside your house, through those, to one of your Macs inside the house?
Well, you can set that up in the airport extreme Airport Utility. So, you can find the Airport Utility in your Utilities folder in your Applications folder. When you launch it, it should connect here, you see the little green light, to your Airport Extreme.
Click on manual set up to go to some of the more specific controls. So, once you are connected, you want to go to the internet section and then the DHCP section, which is the dynamic host configuration protocol. This is what assigns IP addresses to the Macs in your house.
So, there are two types of IP addresses. There's internet IP addresses, which are worldwide, and if you've got one, it's yours and assigned only to you in the entire world. Then you've your local IP address. That's the one inside your house. Think of it as, like, the apartment building address, and then the apartment number.
So, in order to get to your computer, you've got to first go to your house, which is your Internet IP address, and then you've got to go through that to your local IP address to the specific computer.
So, DHCP is what assigns local IP addresses to each of your Macs. Now, it'll assign these in the order that they come. So, as new Macs log on, it'll assign a new address here, according to some rules. But, you can tell it that you want each of your Macs to have a very specific local IP address no matter what. And you do that in the DHCP reservation section.
Press the plus button, create a name for a reservation, and then you're going to use Mac Access addresses to assign it. So every computer and every device has a unique Mac address number. For Mac, you can go into your network settings, and click on Ethernet or airport and go to advanced and you can find it there.
In the case of this computer, which is hooked up by Ethernet, I can find it here, Ethernet ID. It's usually called Airport ID, if you are hooked up by airport. And it is a set of numbers that looks like this.
So you can see here, I've set this machine, the MacPro, to be this IP address. If I edit it, and go in here, I can see I've entered in the Mac address here, and the IP address here.
And it knows, the airport extreme knows, to always match the computer with this Mac Address to this IP address. So now I always know what address this Mac is going to be on my local network.
Now, the next step is to map a port, which will map a service, like file sharing, to that Mac. Back in Airport Utility, you'll find this in Advanced Port Mapping. Now, here you've got a bunch of different port mappings that you can make.
So, let's add one here, and you can set up to choose a service, like, say, Personal File Sharing. And, here it automatically fills in the TCP Port, so you don't have to worry about port numbers, you just have to choose personal file sharing.
Now, you have to choose the private IP address. So, if you wanted to set it to, say, 214, we could.
And, if I were to continue with this, it would go ahead and set up a mapping of port 548 through the airport extreme to that specific computer.
So, the point is, if I try to connect from outside my house to the IP address inside my house, and used file sharing, it would immediately know to route file sharing to that single Mac.
And you could do the same thing for other services, like screen sharing. Better yet, you can set your own port numbers. So, you saw how 548 was set up to be filing sharing. Well, I can say, well 549 will be file sharing on my second Mac, and 550 will be file sharing on my third Mac.
So from outside my house on a Mac, I can do command K, do afp:// which says file sharing, the IP address of my house, and this will connect me via file sharing, to that Mac in my house.
Now, if I wanted to do :548, it would do exactly the same thing. But, it already knows that file sharing, the afp protocol, is for port 548. If I set up port 549 and 550, like I mentioned, I could do 549 and that should route to my second Mac. 550 should route to my third Mac.
Now, you can use VNC instead of AFP to do screen sharing and you can set up similar port mappings to set up the main screen sharing address to a single Mac and then come up with alternate ports for other Macs in your house, as well.
Now, if you are already using Back to My Mac, you don't need to do any of this. Back to My Mac will figure it all out. Another thing Back to My Mac will figure out is what your IP address is at home, because, [xx] a standard DSL or cable modem connection, your IP address is changing all the time, which means you don't know how to connect to your house, you don't know the IP address of your house.
Usually you can pay your Internet provider a few more dollars a month to give you a static IP address, and it's well worth it if you need this type of service.
Now, if you don't happen to have an Airport Extreme, and you have another router, well, you can still do the same thing. Almost all the routers have the same functionality, they are just called something different.
And you're going to have to know the port numbers used by Apple for different things like file sharing and screen sharing, because it's not going to have that little pop up menu that I showed you.
But, you can do it with almost any router setup. Of course, the modem or router provided by your internet service provider could also have a firewall built into it that's blocking these ports, so you may want to check into that, too, and see if there is any documentation that will help you set it up.
In general, I find that a third of the time, this stuff works right away. Another third of the time, it takes some fooling around with the modem that your internet service provider gave you, and another third of the time, it just doesn't seem to work no matter what you do.
Perhaps there is something going on at your ISP just preventing it from happening.
Hope you found this useful. 'Til next time, this is Gary Rosenzweig with MacMost Now.

Comments: 18 Responses to “MacMost Now 345: Setting Up an Airport Extreme for Outside Access”

    Sam Gregory
    3/2/10 @ 4:22 am

    I’m trying to set this up in Snow Leopard but the first problem I’ve encountered is that under the internet tab in Airport Utility I don’t have a DHCP tab. How do i do this in Snow Leopard, and what other differences will i encounter?

      3/2/10 @ 7:04 am

      This tutorial IS in Snow Leopard. Not sure why you are not seeing a DHCP tab. Perhaps that is dependent on another setting. Play around with it and check the Help.

    Matt Hughes
    4/2/10 @ 7:26 pm

    I’ve been trying to set this up with my Airport Express, but have no place to “add” a dhcp reservation. Is this a limitation of the Express model?

      4/2/10 @ 10:19 pm

      Could be. I don’t have a Airport Express to test.

    Jonathan Sullivan
    4/14/10 @ 4:41 am

    Gary – how is this handled while the the AE is in bridge mode, meaning that the DHCP is handled via the modem?

      4/14/10 @ 6:58 am

      I’d imagine then you’d have to set up everything in the modem. Which means doing all the setting manually.

    Wilson
    8/1/10 @ 7:52 pm

    why when you set your private IP address your continue button does not lit up? my does not either unless I change the public tcp port number with you said I don’t have to worry about. there is something wrong here. yes I am using snow leopard too.

      8/1/10 @ 8:02 pm

      I’m not really sure which part of the process you are talking about. But I’m sure if you look into all the settings you will figure it out.

      Jamie
      10/20/10 @ 5:05 pm

      Just add a 1 to the TCP number. It just says that port is reserved. Make sure to change both the public and the private one to match.

    Steven Tiggemann
    8/8/11 @ 5:52 pm

    Gary, When you were doing this video there was a yellow exclamation mark when entering port 548 on the airport extreme. I get the same thing saying that this pors is being used by the base station so I can’t choose that number.

      8/8/11 @ 6:08 pm

      Right. If you have file sharing turned on with your Extreme, it uses 548. O you can’t share a drive hooked up to your Extreme at the same time as forward sharing to a Mac. It would be like two houses having the same address — the post office wouldn’t know where to delivery the mail. :)

    Steven Tiggemann
    8/9/11 @ 10:19 pm

    Gary, I turned off file sharing on the Airport Extreme and that allowed me to choose port 548. However, I’m not able to connect via afp or ftp through connect to server. I connect right away with screen sharing through connect to my server if I put vnc://ipaddress. I have file sharing turned on my G5 running Leopard.

      8/10/11 @ 5:00 am

      Hard for me to tell what might be wrong. You have File Sharing turned on right? Reviewed the settings? Do you have a router above your AirPort Extreme (DSL or Cable Modem?) There are so many settings to review.

    Steven Tiggemann
    8/15/11 @ 9:26 pm

    Gary, Can you contact me at my email address to discuss. Thanks

      8/15/11 @ 9:38 pm

      If you need one-on-one support it is best to call Apple or stop by the Genius Bar.

    Steven Tiggemann
    8/16/11 @ 11:33 am

    My afp and vnc (screensharing) work. Just can’t get ftp to work. Have port 21 forwarded to the same ip as the afp and vnc on the Aiport Extreme and file sharing and ftp afp support turned on in file sharing. Just can’t get it to connect.

    DANIEL CODIANNI
    3/7/12 @ 7:23 am

    Listening to you wonderful talk I was not able to get the name of the program that one could purchase, ” Match my Mac”?

    Thanks

    dc

      3/7/12 @ 7:42 am

      There is a transcript under the video. But I don’t think I mention any program that you can purchase in this one. Perhaps you mean “Back To My Mac” — that is part of iCloud (MobileMe).

Comments Closed.