Screen sharing over the Internet?

Hi everyone,

I’ve been trying to set up screen sharing via Mac OS X under Mojave on one of my parents laptops. Normally, if they needed help, I’d just take a run over since they live five minutes away. That isn’t an option right bow.

I had my dad activate screen sharing on his laptop and he texted me the VNC IP address it said to use to access and control the machine. I plugged it into “Connect to Server”. It didn’t work. My machine couldn’t find the office machine.

I looked for basic step by step instructions to get this working but so far haven’t found anything of value. I’m guess I’m missing a setting that I must change on his machine or their router or there is a step that I’m missing that will make this workable.

Any help would be greatly appreciated.

Worst case, I’ll purchase Apple Remote Access and try using it. Again, though, I’d need step-by-step to get it running. Teamviewer is an option, too. Might be my best bet.

Same goes for an alternative to Teamviewer. Anything that is free or low-cost is preferable.

Thanks,

Robert

Quote
Robert M
he texted me the VNC IP address it said to use to access and control the machine.

Did the IP address that he provided look like
192.168.x.x
or
10.x.x.x
or
even 172.16.x.x to 172.31.x.x
?

If so, those are local network addresses that are not directly reachable on the Internet.
You can reach those addresses if you configure his router to have "port forwarding" to his computer or a "DMZ" to his computer.

Both options will necessarily compromise the security of his computer since it will let a computer on the Internet (yours or anyone else's) directly connect to his computer with only a username/password. If there is a bug in the protocol that can be exploited, the user/pass is not necessary.

I have regularly used TeamViewer for years and it does exactly what I need very simply.

Paul

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If you can FaceTime (which handles all of the protected connection and firewall stuff automatically), you may be able to turn on the Mac Screen Share feature using that connection.

Tom,

Yups. Just saw the local IP address. Would using the external IP address of the computer work? I can tell him how to get it.

The security risk is an issue but, in this case, it may prove necessary. Need the easiest solution out there. Might end up going with Teamviewer or something similar.

Thanks for the help!

Robert

Quote
Robert M
Yups. Just saw the local IP address. Would using the external IP address of the computer work? I can tell him how to get it.

Yes, providing the external IP address of the computer would be necessary (but not sufficient) to connecting to his Shared screen.

The device that is translating the external network address to the local address (Network Address Translation - NAT) needs to be told that connections to that external address are to be forwarded to the local address of the machine, e.g. "port forwarding" for a specific port or DMZ for all ports.
His router has a firewall that is blocking unsolicited connections from the outside world from reaching is local address (a good thing). He needs to set up port forwarding (if you know the ports needed for the VNC screen sharing) or enable forwarding of all ports (DMZ) so that your external connection can actually reach his computer in the LAN.

Tom,

We have port forwarding set up in his router for his home's surveillance system. I bet I can duplicate that configuration and change the address from his surveillance system to his Mac.

I'm trying to avoid Teamviewer since they charge for commercial usage and, in this case, he and I are going to be doing work related screen sharing. I know other people have been informed by Teamviewer that all of a sudden their screen sharing was determined to be commercial and they had to pay for the software and service. Teamviewer is too costly. I can't risk that right now.

Robert

Quote
Robert M
We have port forwarding set up in his router for his home's surveillance system. I bet I can duplicate that configuration and change the address from his surveillance system to his Mac.

That sounds promising.
The only tricky bit would be to forward the right port(s).
[support.apple.com] details what ports Apple software uses.
It looks like ports 88 and 5900 are used for Screen Sharing.

As long as the home surveillance system doesn't use the same ports as Screen Sharing, you can leave the port forwarding to the surveillance system intact and just add to the router the new port forwarding rules for his Mac.



Edited 1 time(s). Last edit at 03/20/2020 10:22AM by TheTominator.

Some TeamViewer Alternatives:

[anydesk.com] (free for personal use) - almost ready to pull the trigger on this one for myself

[www.remotepc.com] (no longer a free option but still pretty cheap) $6.95 for the first year using [www.remotepc.com]

[remotedesktop.google.com] (free)

[www.zoho.com] (free option)

TeamViewer is free for non-comm porpoises and works great.
Owen the cat set it up.
I've used it longer than Voodoo.
nudge, nudge, wink, wink

---

!#$@@$#!

If there are spelling issues, please pardon, Owen the cat is sitting on my keyboard.

TeamvVewer is great but I had issues when one computer was running Mavericks and was stuck at TeamViewer v12 and the other computer (the one I had to access) was newer and was at V14 or 15. I could not connect. I had to scramble to find a newer computer here to install TV.

Then for some reason the V14 or 15 over there is now too old.

I am going to try to see if Facetime has screen sharing or try to use Zoom.

Tom,

Just opened up the necessary port based on the info you've provided. Will test it shortly. Would prefer to use the existing software that is built into the OS and hardware I have on hand and in place instead of a 3rd party solution.

Thanks again to everyone with your help!

Robert

Blog from our sponsor

Screen Sharing Link

YMMV

Steve

Quote
kurtzie
Blog from our sponsor

Screen Sharing Link

That's a very helpful writeup on this. Thank you for sharing it. And thank you to our sponsors for providing it.

In particular I like the details about how to use the built-in Messages app to handle making the connection to screen sharing to avoid needing to set up the firewall on the shared computer.

Kurtzie,

Thank you for the link. Much appreciated! And, thank you to OWC for the info!

Robert