Problem with Controlling a Mac From a Windows PC With TightVNC

Thank you for the nice comments about my article. I am glad to try to help. OK, the network administrator in me feels the need to start by saying that having a computer directly connected to the internet without a router is never a good idea. Even if you had a router, you would not want to open ports that allow direct access from the internet to remotely control a computer on your network.

Ideally for any remote access across the internet you would both have routers on your networks and you would set up a VPN connection to his network first. That way all your communication with his network is encrypted and there's a lot less risk of attack. Obviously you have some knowledge of routers and were probably already aware of that, but for the sake of others who may read this post, I felt the need to point that out.

OK, that being said... let's get to the question you asked. To be honest, if he can access his Mac from XP, and your setup is the same as his, and there are no firewalls between you and him... then there is no reason that it should not work. However, the fact that you cannot ping him is making me think that there is some kind of firewall in between. Let's start by eliminating some things.

1. Your router is not the issue (unless it's a $3000 pro router that controls outgoing and incoming traffic) Consumer routers by default are only concerned with incoming traffic. The few consumer routers that do block outgoing traffic are very general in their controls, and if that was the issue you would probably not be able to connect to the internet at all. Putting your PC in a DMZ only impacts how the internet see's you, and not how you see him. So we can eliminate that.

2. His software firewall settings on his Mac. As long as you are using the same credentials as he is, and he can connect with no problem, then it's definitely not his Mac's firewall. So we can eliminate that.

So, let's double check some things to troubleshoot:
1. Re-check his public IP address. Have him go to www.whatismyip.com and it will tell him his public IP address. Try to ping it and see what happens. Does it still time out? Note that if he does not have a static IP service through his ISP, his public IP will change from time to time.

2. What is his setup? Is he using DSL or Cable? Who is his service provider? Is his Mac hardwired directly to a modem? Is he wireless? Is he using an Airport base station? These are important questions because depending on his service provider or his modem type sometimes ISPs block ports and sometimes modems actually have routers and firewalls built into them. Also, if he is using an Airport or other wireless base station, they're really routers in disguise.

3. The fact that you cannot ping him is what makes me think that either the public IP is wrong, or he actually does have a router. Note: that by default a Mac will not refuse ping requests. Normally only routers with "block WAN request" are enabled do that. Your last thing to check, if you still can't ping him and you've confirmed the above, is to do a port scan of his public IP. This is advanced stuff, but if you want to give it a try do a search for superscan or angryip. It might provide some more clues.

That's about all I can think of to try. Hopefully it's just something simple that got overlooked.

Forgot to Ask: Does OS X respond to an http: request with a blank screen by default?

Thanks,
Paul

Great! I'm glad everything's working now.