Bosco’s Screen Share: Router Setup Guide

Grab your hard hat and a screwdriver.

Time to make some adjustments. We’re about to adjust your router and firewall so your friends can call you. Technically speaking, you’re about to make the adjustments. We’re just going to sit back and snicker.

But seriously... If you don’t know a router from a fuel injector (which is perfectly OK so long as your mechanic doesn’t find out), you might want to have a smart friend help you. We also offer basic router and computer configuration assistance over the phone for a fee.

Scroll down to learn how to configure your router.

Bosco is ready — screwdriver in hand — to configure your router.

Overview
Many computers connect to the Internet through a device called a router. Routers are often used to allow several computers to share a single Internet address. They may also be used to provide wireless Internet access, e.g. Apple's Airport. The router usually has an external address on the Internet and a private range of internal addresses for computers connected to the router. If you want to accept calls from people on the Internet, you need to set up your router to direct incoming calls to your computer.

With the plague of viruses, worms, spyware, etc., many computers use a built-in firewall to prevent unauthorized software from connecting to the computer. Both Mac OS X and Windows XP have built-in firewall software that can be configured by administrator-level users.

Note: If you just want to dial out with Bosco’s Screen Share, you do not need to worry about configuring your router or firewall. However, you’ll have a lot more fun if your friends can call you too!

Table of Contents


						1. What Bosco’s Screen Share needs
						

						2. Are you really behind a router?
						

						3. Set your computer’s fixed address on your LAN.
						

						4. Configure your router.
						

						5. Configure your personal firewall.
						

						6. Test your setup.

Don’t get frustrated. We’re here to help.

1. What Bosco's Screen Share needs
To call Bosco's Screen Share on your computer from a computer on the Internet, your router must be configured to forward port 20229 requests to your computer and your firewall must be configured to accept connections on port 20229.

If port 20229 is inconvenient or someone else on your local network wants to receive calls to Bosco's Screen Share, you can change the port in the Preferences window. This document assumes you're using port 20229.

If you have someone who supports your network and computer, you should tell them the following:

You need to have TCP sockets on port 20229 forwarded from the router to your computer.
You probably need a static local address so as not to confuse the router.
Your computer needs to accept port 20229.
You will buy them lunch for their efforts.

If someone else is setting things up for you, you're done with this document!

Figure 1: What Bosco’s Screen Share needs

2. Are you really behind a router?
Bosco’s Screen Share has an easy built-in way for you to figure out if you are behind a router. On the Interactive panel, at the top of the Addresses and Links section, you’ll find a note telling you whether you are behind a router.

If you don’t see the Addresses and Links section, turn off Expert Interface (uncheck it) by choosing it in the Edit menu.

If you are not behind a router, the only thing you should have to do is configure your personal firewall. You should skip steps 3 and 4.

Figure 2: Behind a router

3. Set your computer’s fixed address on your LAN.
If you are behind a router, then you (usually) need to ensure that you have a fixed local address. This way, the router will know where to forward port 20229. If you have a dynamic local address, the router probably won’t know which computer is yours.

You definitely need to get assistance from whoever manages the router. That person will need to assign you a fixed local address for use with the router which will not be used by anyone else. She can probably also help you configure the networking on your computer to use a fixed local address rather than DHCP (dynamic). Here are some hints:

Airport users with Mac OS X... Make a new location just for this network and have a more general Airport location that retains DHCP for local address configuration. You'll need to switch locations when you go on the road and you probably will not be able to answer calls at other locations.
Windows users... We need some hints for you, don't we?

Figure 3: Setting a fixed local address in Mac OS X System Preferences

4. Configure your router.
Now that you have given your computer a fixed local address, you’re ready to configure your router to forward TCP sockets on port 20229 to your computer. You will typically have a fixed local address similar to “192.168.x.x” or “10.x.x.x”, where the x’s depend on the subnet used by your router (that makes tremendous sense, right?).

Routers designed for home use are usually configured by either an application that runs on your computer (e.g. Apple’s AirPort) or through your web browser (e.g. LinkSys routers). If you run a special application to configure your router, the application should automatically find your router for you. If you connect through a browser, you usually will connect to the router’s local address on your LAN. For LinkSys and other popular routers, this address is usually 192.168.1.1.

Once you have connected to your router, you need to find the setting that lets you specify port forwarding. This is usually considered an “advanced” feature. We have seen it called “forwarding” and “applications”. Your router may have a different name for it. Some routers support something called a “DMZ Host”. This will work, but is inherintly insecure and we recommend against using it.

Figure 4: Configuring port forwarding on a LinkSys router

5. Configure your personal firewall.
If you are running a personal firewall on your computer to protect it from nefarious (that means “bad”) outside connections, you will need to open port 20229.

On Mac OS X, open the System Preferences and click the Sharing icon. Click the Firewall tab. If the Firewall is on, you will need to add a new “allowed” port. Click the New button. Select Other from popup menu, enter 20229 for the port, and name it “Bosco's Screen Share”.
On Windows XP, if you have upgraded to XP Service Pack 2, you already have a built-in firewall that is very easy to configure. When you run Bosco’s Screen Share and your firewall does not have port 20229 open, you will be asked by Windows whether you would like to open the port. Respond affirmatively and you are good to go.

Figure 5: Opening port 20229 in Mac OS X System Preferences

6. Test your setup.
Choose Check Router/Firewall... from the File menu. Bosco’s Screen Share will attempt to call itself through your router’s external Internet address. If it succeeds, you are good to go. If it fails, you need to make more adjustments. Sorry!!

We have encountered some routers that fail the test despite being configured correctly. The ultimate test is whether a friend can call you.

Figure 6: Testing your router and firewall

Figure 7: Hopefully, the test succeeded.