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Which ports must be open für ScreenSharing?

Hello!

Since my ISP-change a couple of months before I am not able to use the screensharing-app anymore.

I try to connect (via CMD+K from Finder and then "vnc://îp_number") but after trying a couple of minutes I get an error message from the screen-sharing-app saying that the connection wasn't possible.

I've tried to connect to different Macs using different versions of OS X (Yosemite, Mavericks and even a PowerPC - Mac Mini running 10.5.8), all of them set to enable screen-sharing-connections - with no success! :-(

So I came to the conclusion that my router (a VDSL-router from Telekom) must block the ports necessary for screen-sharing, because it did something similar blocking the ports for VPN - normally open on an Airport Extreme!

Sadly I cannot use the Airport Extreme with VDSL, so I am not even able to check if my presumption is true :-(

However I know how to switch the ports on and off, so now I "only" need to know WHITCH ports are needed for screensharing to work.

Could anybody help me with this information?

Thank you!

Regards,

Vlad

P.S. I am using a late 2012 27" iMac (3,4 GHz Intel Core i7) running OS X Yosemite 10.10.2

iMac (27-inch, Late 2012), OS X Yosemite (10.10.2)

Posted on Feb 16, 2015 3:53 AM

43 replies

Roote

Level 4

1,631 points

Feb 20, 2015 7:14 PM in response to Vlad Ghitulescu

Disclaimer: I know nothing about your particular router model.

Two suggestions:

1. Many routers allow you to set it to Bridge Mode. Your modem will will stop acting as a wireless modem and router and instead it will act as a pass-through modem. This will allow you to use Airport Extreme for wireless. If this is possible at all, it may require the assistance of your Internet provider to set up.

2. In some troublesome configurations, on both ends of a connection, I've had success with a free Nat-PMP and UPNP app called Port Map by TheCodingMonkeys.

Feb 21, 2015 12:32 AM in response to rccharles

ok, than only TeamViewer and no LogMeIn

BUT: it looks like I have general problems (see my ping-results) I have to solve first :-(

Feb 21, 2015 12:35 AM in response to BobHarris

Yes, my mother still has this IP.

Ok, than her router is also something to be solved… :-( this will be the worst part :-((

Feb 21, 2015 12:38 AM in response to BobHarris

I got the same ping-response with my brother, also in Romania.

He's running Mavericks on a Mac Mini (not the current model but the previous one).

Both of them are changed to Telekom and received a modem-router-combo, so it is possible that both of them has the same problem (regarding to no response to ping AND my screen sharing attempts)

Feb 21, 2015 1:16 AM in response to Roote

Thanks for the idea with PortMap.

I've send it to my mother and brother with the instructions how to use it and asked for screenshots.

Meanwhile I started PortMap myself and voila:

I myself am a Telekom (Germany) client and connect to internet through a VDSL-router (named Speedport W 724V) from Telekom (that's the only alternative if I want to use VDSL).

(I put my AirPortExtreme in Bridge mode and connect the iOS-devices wireless to his WLAN in order to enjoy at least for them the easy Apple configuration! :-)

I will google a bit in order to find how to enable NAT-PMP on my Speedport W 724V from Telekom… it can be the same problem my mother and brother have with their router!

Thanks again!

Regards,

Vlad

P.S. My IP address is 93.213.68.226. Previously I opened the port 5900 as suggested. I've just opened the screensharing settings:

Could please somebody try

a) ping me and

b) request screensharing?

Thank you!

Feb 21, 2015 1:17 AM in response to Vlad Ghitulescu

What's about the endless list as response to ping google.com?

Feb 21, 2015 1:26 AM in response to Vlad Ghitulescu

ok, now I know: there's no way to enable UPNP on my Speedport W 724V router, I must switch every port on manually :-/

Feb 21, 2015 1:38 AM in response to Vlad Ghitulescu

and this is the answer my mother become from PortMap:

rccharles

Level 6

12,957 points

Feb 21, 2015 12:46 PM in response to Vlad Ghitulescu

I think you should try out TeamViewer. I suspect it will avoid all the hassles of worrying about internet address and router configuration. Logmein was no sweet to set up and use. I think Logmein did all its communication via http or https to avoid all configuration hassles.

These internet fraudsters were using Logmein to "fix"(mess up) your pc. They must know something about accessing the widest set of pc's with the fewest hassles.

Robert

Feb 21, 2015 11:28 PM in response to rccharles

Ok, I'll try TeamViewer then and report my success :-)

Thanks again!

Regards,

Vlad

Drew Reece

Level 6

10,660 points

Feb 22, 2015 1:12 AM in response to Vlad Ghitulescu

Has your 'remote end' got a Gmail/ AIM/ Jabber account and do you have one too?

It may be possible to use the "share screen" feature of Messages app assuming your can talk someone through a few account setup steps via telephone etc.

That may allow you enough access to setup the remote end correctly. If you know the router password you can probably login via Safari at that end & configure that is required (Teamviewer may need to create port rules dynamically, which is the reason for the UPnP/PMP error).

Messages screen sharing works with AIM, Jabber, Google Talk and Bonjour (local network) accounts.

The requirements don't mention UPnP/PMP.

Messages (Mountain Lion): Requirements for audio chats, video chats, and screen sharing

P.S.

As Camelot mentioned already, opening port 5900 to the internet is not a great idea, are you certain the remote end at the company has strong passwords on ALL enabled user accounts? VNC may allow any botnet or script kiddie to attempt to brute force the passwords & usernames. Personally I would run ssh & avoid opening access to any other service, but that involves a lot more manual setup than Teamviewer or any other remote access service, (ssh can be setup to ignore username/ password requests, so only users with pre setup ssh keys can access the server).

Feb 22, 2015 4:55 AM in response to Drew Reece

> Has your 'remote end' got a Gmail/ AIM/ Jabber account and do you have one too?

Yes, Gmail & AIM.

> It may be possible to use the "share screen" feature of Messages app assuming your can talk someone through a few account setup steps via telephone etc.

That would be ok for me (Yosemite), but not for my mother (who uses a Power Pc Mac Mini running Mac OS X 10.5.8 - where iChat & Skype is not supported anymore) :-(

> As Camelot mentioned already, opening port 5900 to the internet is not a great idea, are you certain the remote end at the company has strong passwords on ALL enabled user accounts? VNC may allow any botnet or script kiddie to attempt to brute force the passwords & usernames. Personally I would run ssh & avoid opening access to any other service, but that involves a lot more manual setup than Teamviewer or any other remote access service, (ssh can be setup to ignore username/ password requests, so only users with pre setup ssh keys can access the server).

Thanks for the warnings! I'll close than the port.

All I wanted was to be able to:

1.- access my mother's Mac Mini via a VNC (in order to help her with the admin-part of it)

and

2.- masquerade the Skype-Version of 10.5.8 in order to work again.

Drew Reece

Level 6

10,660 points

Feb 22, 2015 1:31 PM in response to Vlad Ghitulescu

Apologies I missed that the remote was a PPC Mac. I don't think screen sharing was an option back then.

Feb 22, 2015 10:27 PM in response to Drew Reece

Hi, Drew!

> Apologies I missed that the remote was a PPC Mac.

Oh, no problem, it's already a long thread and it's easy to overlook some details.

That's why I stated again what I was looking for.

> I don't think screen sharing was an option back then.

Actually it was and it worked very well until the ISP and router change.

Right now it doesn't work with her anymore but it also doesn't work with my brother either, and he has a "modern" Mac Mini (the model before the current one) with a "modern" OS X (Mavericks).

Strange / Funny enough, my mother & my brother (both located in Romania) on the one hand and me (in Germany) on the other all changed to Telekom, so all of us have now the same type of router and a similar response from PortMap (see the screenshot I sent on Feb 21, 2015 10:38 AM).

I'm also not able to ping anyone of them (and not even google.com!) - so it seems that the router it's pretty "impermeable" :-/

Regards,

Vlad

Drew Reece

Level 6

10,660 points

Feb 23, 2015 8:14 AM in response to Vlad Ghitulescu

Vlad Ghitulescu wrote:

I'm also not able to ping anyone of them (and not even google.com!) - so it seems that the router it's pretty "impermeable" :-/

That blue/ green screenshot of Ping running is actually showing SUCESS not failure. You can ping that address.

It doesn't help your situation at all because it is not relevant to what you are trying to do.

Sorry, I think you are just confusing various tests & mixing things up.

I'm not sure what the answer is beyond enabling UPnP on both ends & use Teamviewer or any other similar service. The router at the destination end must allow ports to be dynamically opened or it will probably continue to fail.

You need UPnP or NAT/PMP active on the router.

Which ports must be open für ScreenSharing?