Built-in Firewall blocking VNC connections

Question

Level 1

44 points

Built-in Firewall blocking VNC connections

Running 10.8.5 fully updated on a Mini. In System Preferences/Sharing, Screen Sharing is turned on. In System Preferences/Security, the Firewall is turned on. Clicking on options shows that Screen Sharing access is allowed, right at the top. (A few other apps are listed below it, all set to allow, there are no blocks.) Signed software is automatically allowed to receive connections, and stealth mode is disabled.

I try to connect via screen sharing from another computer. It fails, it just keeps trying and trying but never gets to the login prompt. Eventually I give up and hit Stop.

Go back to the mini, disable the firewall. Screen Sharing now works, logs in very quickly, as expected. If I reenable the firewall, an existiing screen sharing connection continues to work, but if I disconnect, I can't reconnect. (Until I disable the firewall again)

So why is the firewall blocking screen sharing from working, when Screen Sharing is explicly enabled in the firewall...? I would like to have the firewall turned on for security, but I need screen sharing allowed. Is there any way to do this?

This is a recent problem, just the last couple of days. It worked fine with the firewall turned on before. So maybe there's just some new trick that's needed?

Posted on Oct 29, 2013 12:41 PM

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Answer 1

Lanny

Level 6

13,183 points

Oct 29, 2013 12:55 PM in response to anothersmurf

I would like to have the firewall turned on for security,

If you're connected to the Internet using a router, you don't need to have the built-in firewall on. The router is firewall enough.

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Answer 2

anothersmurf Author

Level 1

44 points

Oct 29, 2013 1:12 PM in response to Lanny

Does VNC even work through a router?

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Answer 3

pwb503

Level 1

6 points

Oct 29, 2013 9:19 PM in response to anothersmurf

I had the same problem and just fixed it.

Here's my fix:

System Preferences -> Security & Privacy -> Firewall

Click on Firewall Options (you may need to click on the lock and type in your password to do this...)

Scroll down and see if you have the app "screensharingd" listed

If so click on it and click the minus button to delete it from the list

Hit OK

System Preferences -> Sharing

Turn off all sharing options

Restart the computer

Once restarted...

System Preferences -> Sharing

Turn on the sharing options you want, specifically either Remote Management or Screen Sharing

Click "yes" or "ok" or "allow" in the dialog box that asks if you should allow incoming connections

That should do it!

I know that a router should provide a firewall so you could turn the OS firewall off, but the problem is that it used to work with the firewall on, (before this fix) it did work with the firewall turned off, and it SHOULD work with the firewall on, regardless of if it's necessary or not...

This fix allows you to keep your firewall on just as it was before.

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Answer 4

pwb503

Level 1

6 points

Oct 29, 2013 9:20 PM in response to anothersmurf

I had the same problem and just fixed it.

Here's my fix:

System Preferences -> Security & Privacy -> Firewall

Click on Firewall Options (you may need to click on the lock and type in your password to do this...)

Scroll down and see if you have the app "screensharingd" listed

If so click on it and click the minus button to delete it from the list

Hit OK

System Preferences -> Sharing

Turn off all sharing options

Restart the computer

Once restarted...

System Preferences -> Sharing

Turn on the sharing options you want, specifically either Remote Management or Screen Sharing

Click "yes" or "ok" or "allow" in the dialog box that asks if you should allow incoming connections

That should do it!

I know that a router should provide a firewall so you could turn the OS firewall off, but the problem is that it used to work with the firewall on, (before this fix) it did work with the firewall turned off, and it SHOULD work with the firewall on, regardless of if it's necessary or not...

This fix allows you to keep your firewall on just as it was before.

Reply

Answer 5

BobHarris

Level 9

52,907 points

Oct 30, 2013 6:27 AM in response to anothersmurf

Does VNC even work through a router?

It can if you wish to configure your router to pass port 5900 from the internet to your Mac, but by default, No VNC clients out-side your home cannot connect to your Mac's VNC server through your home router.

Out bound VNC connects to an external VNC server that is visible on the internet can be done through your router, only in-bound connections need special router configuration.

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Answer 6

anothersmurf Author

Level 1

44 points

Oct 30, 2013 1:52 PM in response to pwb503

That works, but only temporarily. If after doing that, you restart the computer (some days later, say), VPN will go back to not working until the fix is reapplied.

What seems to happen is, on restart, if the firewall is enabled, remote access is changed to deny. Bizarrely, even if you open up Firewall and change it to Allow, the change doesn't take. That's got to be a bug (and not an attempt by Apple to make people go out and buy routers). So hopefully it'll get fixed someday...

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Answer 7

Mandesk

Level 1

0 points

Nov 17, 2013 6:57 AM in response to anothersmurf

I have been having the same issues, after I updated remote services to 3.7, only way to mange remote Mac from Windows was by turning off Firewall. This had worked fine up to then.

Now that I have finally been able to update to Mavericks, it is all working fine again....but I would like to reboot and try again. Will post back here one way or another....

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Answer 8

Mandesk

Level 1

0 points

Nov 17, 2013 7:35 AM in response to Mandesk

Yes after a reboot the Connection from my Windows 8 Desktop via realVNC is still working, connecting to my Mid 2011 Mac Mini....

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Answer 9

pwb503

Level 1

6 points

Nov 17, 2013 10:37 PM in response to anothersmurf

Anothersmurfis correct. I just restarted my computer and yes the "fix" is broken after a restart and you need to do the same thing over again to get it to work... Bogus! I didn't want to upgrade to Mavericks but I might have to just to see if this is fixed there....

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Answer 10

Davidy1

Level 1

0 points

Jan 23, 2014 8:06 AM in response to pwb503

I just upgraded to Remote services 3.7.1 which fixed the firewall problem, even after restart, it still works. Mavericks update was available but I thought I'd try 3.7.1 which also came up on available updates.

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Answer 11

pwb503

Level 1

6 points

Jan 23, 2014 2:58 PM in response to Davidy1

Were you already running Mavericks or were you on an older version of the OS? I haven't yet upgraded to Mavericks and would like to fix this problem without having to...

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