Setting up Screen Sharing (Mac to Mac, external network)

Discussion in 'Mac Apps and Mac App Store' started by ChocoboNL, Nov 18, 2013.

  1. ChocoboNL macrumors member

    Feb 20, 2008
    Dear All,

    I am currently trying to set up screen sharing for family abroad so I can be 'that guy' to help out with some computer problems. I have no problem sharing screens with another Mac on my LAN, but am getting confused setting it up for a computer on an external network (on the other side of the world).

    My MacBook is running OS X 10.9 (Mavericks), I'm not 100% sure about theirs but I believe it is OS X 10.6, 10.7 or 10.8 (Snow Leopard, Lion or Mountain Lion.

    I have had them enable 'screen sharing' in sys. pref. - sharing.

    I know their external IP address, but they are using a wifi router, so they have a different internal IP address. Simply pointing my Finder to connect to vnc://external_ip does not work.

    So I have been looking into setting up SSH connections and port forwarding but am not sure how to resolve this problem.
    Should I let my family log into their router and forward a random port (e.g. 5901 to internal_ip:5900, e.g. -> Or should I have them fiddle with terminal commands and ssh tunneling? Should I set up any ssh tunneling myself, is it at all involved in the equation?
    If possible I would prefer not to have them do anything but give me their IP addresses, user name and password but I could have them log in to their router to change settings.

    We're not dealing with top-secret information, but I would like to keep things reasonably secure. Also, I'm generally tech-savvy and like to learn but by no means a network administrator.
  2. maflynn Moderator


    Staff Member

    May 3, 2009
    Use logmein, teamviewer or gotomypc, they're generally easier to set up,, first two are free and I recommend any of them.

    I use gotomypc, for my work computer.
  3. Bruno09 macrumors 68020

    Aug 24, 2013
    Far from here
    For that very same purpose, I use iChat / Messages with AIM accounts.

    No need to know IP addresses or things like that : just a user name and go ahead.
  4. ChocoboNL thread starter macrumors member

    Feb 20, 2008
    Dear Mike,

    Thank you for the suggestions, I have heard of the first two, but I prefer not to install any additional applications. Especially on their side.
    As this screen sharing is already installed on all the macs I would prefer to try and get this working first. Also in no small part because I like to find out how it works.




    Dear Bruno,

    Thanks, but they don't have iMessages, nor AIM accounts. So I don't think this would work. Also, Skype is not working properly - one of the things I would like to help them fix - so screen sharing through Skype is not an option either.

  5. Bruno09, Nov 18, 2013
    Last edited: Nov 18, 2013

    Bruno09 macrumors 68020

    Aug 24, 2013
    Far from here
  6. ChocoboNL thread starter macrumors member

    Feb 20, 2008
    Thank you Bruno, but even if we both create AIM accounts, it will not allow me to control their computer, right? And we'd always have to launch iChat, log in etc. Whereas if I get screen sharing working properly I can just log in myself, take control, fix things by myself. They don't even need to be at their computer (with a 7-hours time difference it's not always easy to manage that).
  7. takeshi74 macrumors 601

    Feb 9, 2011
    I wouldn't consider the approach you're considering "reasonably secure". I'd also suggest one of the solutions suggested in the first reply.
  8. Bruno09 macrumors 68020

    Aug 24, 2013
    Far from here
    With iChat / Messages you can control your buddy's computer.

    You don't have to login : just launch iChat or Messages.

    You can do : text messaging, audio, video, screen sharing (with control).

    Sure, your buddy has to be at his computer for that, as the "auto login" feature has been removed since Lion I think.
  9. glenthompson macrumors 68000


    Apr 27, 2011
    Their router is probably blocking the VNC port. Yes you will have to get them to setup port forwarding on their router. If there are multiple machines to access you will need multiple incoming ports.

    On the security side, all their equipment needs to be locked down well or anyone can get into their system via the open ports.
  10. Brian33 macrumors 6502a

    Apr 30, 2008
    USA (Virginia)
    I like Bruno's suggestion, though I've never tried using iChat that way. OTOH, I really like the screen sharing feature which I've been using on my own local network.

    I think glenthompson is right. You just need to set up (once) the port forwarding rule on their router. From your original post it looks like you understand what that rule would be like.

    I don't recall if screen sharing does any encryption of the data stream. I'm pretty sure you don't have to use SSH tunneling to get screen sharing to work, but that might be an option if you want to secure the data stream (I don't personally know yet how that works).

    If I remember correctly, screen sharing asks for the user's password to log in. I guess this would be the only thing keeping "bad guys" from connecting to their screen sharing server. You'd want them to have a good long password which might be inconvenient for them.
  11. zookid80, Nov 20, 2013
    Last edited: Nov 20, 2013

    zookid80 macrumors newbie

    Nov 20, 2013
    You can share screens while using any account that iChat supports: iCloud or MobileMe ( or, AIM, Jabber, Google Talk. or Yahoo!. You can also share your screen with others on a local network using Bonjour.[​IMG]
    Screen sharing in iChat is independent of screen sharing settings in System Preferences. You can share screens using iChat even when Screen Sharing is deselected in the Sharing pane of System Preferences.

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