Not sure if anyone can shed any light on my situation, but I'll give it a try...

I've been very frustrated with my inability to do a screen share with my Mother (who lives 3,000 miles away). The button is to do so is grayed out. For a while it occurred to me that the issue was one of bandwidth-- but we are able to video chat, and that requires more, right?

I had her go to system prefs/sharing, and check the appropriate box for screen sharing, but it is still no go.

I know that the problem isn't on my end because I am able to pull the task off with other Mac users on iChat. Is there anything else I should think about to resolve the issue?

Someone else would be more helpful but here some thoughts . I have not tried screen sharing "you mean" that is you can take control on your moms mac right ?

Anyway

1 - Check your moms firewall , we had problems with that turned on.

2 - If you have other computers check to see whats running ? Example I would be on iChat and the connection seems bad so I check my daughters iMac and sure enough she has FF running with 10 open windows , iTunes , Vue , PS , Illustrator and some other stuff - hogging bandwidth

3 - If wireless check to see if your feeding the whole neighborhood

4 - Check to see what version of iChat and version of OS ? Somebody mentioned that before

What is the first set of digits of her IP address, for example, 75.x.x.x or 222.x.x.x.

If it's something like 192.x.x.x or 10.x.x.x the that would mean she's behind a router or airport base so you would have to use back to my Mac to do it, or have the firewall in the router set up to forward the outside IP address (not the internal 192 or 10) request to her computer.

Edit - If you're doing it via iChat not sure why it's not working then, seems iChat is flaky for that for some reason.

This may help.

http://www.macfixit.com/article.php?story=20071102122311545

Thanks for the reply...

She does employ the use of an Airport base station (Time Capsule, actually), but so does my father for that matter-- and I never have any trouble screen sharing with him.

Edit: the whole IP address issue is confusing to me. When I do a speed test reading my IP address is 74.79.XXX.XXX, but when I look at my network prefs it reads 10.0.1.XXX. Which is it? Hell, I don't know enough about this stuff myself-- to say nothing of my ability to help another!

IP in a nutshell, I'll try anyway. When you type in a website name, for example MacTech.com, the web browser sends the request to what is called a Domain Name Server, (DNS) that translates the real name into a number, the IP address, also referred to as an external or WAN IP address, of the server that the website is coming from. Every device connected directly to the Internet gets a unique WAN IP address, but every WAN IP address doesn't have a real name unless one wants to register the IP address to a name with a Domain Registrar.

There are internal and external IP's. Your modem will hand out one or more external or WAN IP's, all depending on your Internet Service Provider's plan that you have. If you have your computers connected through an ethernet switch or hub they will get the external IP's from the modem. A switch/hub doesn't do anything fancy, just connects all the cables together. The advantage to a router (base station) over a switch/hub besides the router having a built in firewall, is that with the switch/hub you only get the number of IP addresses your ISP allots. If you have more computers than IP's alloted then you need a router. If you have a router instead of a switch/hub connected to the modem the router will grab one WAN IP address from the modem, hand out many internal or LAN IP's, 254 theoretically but not all routers will hand out that many, and route the incoming and outgoing traffic accordingly from each computer while using the one WAN IP. Certain IP ranges are reserved for LAN IP's only, most commonly in the form of 192.x.x.x for most off the shelf home routers, Apple base stations use 10.0.1.x by default. So the 10.0.1.xxx in your networks prefs is the LAN IP coming from the base station, either wireless or ethernet, to that particular computer. The 74.79.x.x is the address of the base station, which is coming straight from the modem and connected to outside world directly as opposed to the computer being "buffered" we could say, by the base station.

Many modems nowadays also have a router built in so you may see computers connected directly to a modem getting a LAN IP of 192.x.x.x instead of external IP's.

For the Screen Sharing problem, if you're using iChat for Screen Sharing the IP addresses won't matter as it's using the unique username that iChat is broadcasting to resolve the WAN IP address of the modem and the LAN IP address of the computer. Make sure the built in Firewall is off in OS X if you're using a base station or router, you don't need it and it can complicate things since there is already a firewall in the base or router.

You are using iChat to connect with Screen Sharing on both machines, right? Make sure all version of iChat are the same if so.

If you're not using it on both, then it gets much more complicated to use Screen Sharing unless you use Back to My Mac or something.

Much more detailed and informative than I would have been.

One of the first things I did with my router was to change its default IP to something non-standard - just makes it a little more difficult to discover.

Screen sharing in OSX sounded like a really cool and useful feature. Unfortunately, they made a complete mess out of it and I've yet to find more than a small handful of people that actually got it to work.

I had it set up on my parent's computer so I could log in and do things. It worked once, and hasn't worked since. I made no configuration changes, etc.

The article Reboot linked to is a great resource, but have you seen the size of it? It's a long-arse article. It just shouldn't be so difficult.