How can I open port 80

Question

I am using a 2wire modem/router. I was told by a tech at ATT that I can only click a button that allows ALL ports open, but not just port 80.
Does anyone know if there is a way to open port 80 ONLY? I'm next to done setting up a security CCTV system for my home, and this would allow me to use my computer to look at whats going on, rather than buying a new monitor.
Thanks for helping.

Answer 1

Thanks for the reply. You and X423424X are close. From the beginning. I bought a 4 camera DVR security surveillance system. Yesterday, we installed it. I was told by the place from which I bought it ( and subsequently from the manufacturer's tech guy)  that if I wanted to use my computer for a monitor for the security setup, that in the Router Firewall Settings I would have to identify the device, and then 'direct' the device "through" port 80 to be able to view the 'goings on outside' (the input from the cameras) from my computer monitor. Inclusive with this configuration via the iMac, is that the DVR is recording all the time, and I could download any portion of the recorded material from the DVR to the iMac and burn it to a disk, for example to give to the cops if there was a theft. AND, it was also mentioned that in order to remote view whats going on around the place from say, a laptop or pc when I'm out of town can also be done, but that would require opening another port, with 4 digits, like 3806, or similar. I will eventually get the port number for this operation later. So that is what I'm trying to do.
So far, the 'local tech' from the security store seems to have limited knowledge of the Mac, and of the 2Wire router/modem. So HE was on the phone with first the tech support from the security cam/DVR dealers, and then with an ATT tech. The ATT tech was the one that said, in the firewall settings on the modem, there is a button that opens ALL ports, and that was the only way to allow port 80 to be used for the DVR/security setup.
I think that he is incorrect. I think that there is a way to view the camera images on my Mac monitor, and that there is a way to configure the settings on the router to allow the camera images to  be seen on the computer screen, and that I could also download to the HD on the iMac any 3 or 4 minute portion of what is recorded on the DVR, in order to burn a copy. I have a co-worker that had a car taken, and her neighbor was there in an instant telling her thatt he had the whole thing on his video surveillance, and had a disc burnt in about 5 minutes, which went to the police. Her car was found, and the perp arrested within 2 hours.
THATS what I want to end up with (no, not a stolen car, but the configuration), and I'm hoping that I can find the way to get 'er done here. There is only one good Apple/OS X tech in this town, and he is on vacation for another week. AND, I'm not sure he is a 2wire expert.
So, again, thank you for any help or input.