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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

Feb 23, 2015 9:50 AM in response to Drew Reece

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

That was pinging google.com. I was waiting for some form of summary, just like in the posting from rccharles from Feb 17, 2015 9:48 PM .

But the other ping attempt (see my message from Feb 20, 2015 3:53 PM) was saying:

Vlads-iMac:~ Vlad$ ping -c4 109.100.181.55

PING 109.100.181.55 (109.100.181.55): 56 data bytes

Request timeout for icmp_seq 0

Request timeout for icmp_seq 1

Request timeout for icmp_seq 2

--- 109.100.181.55 ping statistics ---

4 packets transmitted, 0 packets received, 100.0% packet loss

Vlads-iMac:~ Vlad$

There were 0 packets from 4 that were received, so I suppose that this means "ping failure again".

Wrong?

Drew Reece

Level 6

10,660 points

Feb 23, 2015 10:48 AM in response to Vlad Ghitulescu

Ping on OS X will continue if it is getting replies so the google test would have gone on forever, giving you response times.

When failures occur they get averaged & eventually you get the failure indicating how many packets were lost.

Apple have the manuals on the developer site…

https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/ man8/ping.8.html

Or man ping in terminal, q to quit the man reader (man more).

ping -c10 google.com

…may be what you really want for a shortish test.

Devices like firewalls may block pings, even if they accept other services on open ports, you have to be careful with the results.

Feb 23, 2015 11:38 AM in response to Drew Reece

> Ping on OS X will continue if it is getting replies so the google test would have gone on forever, giving you response times.

Oh, I see now (reading through the man pages)! And I thought that even google is not responding! :-) Embarrassing!

The short test is then ok:

Last login: Sat Feb 21 10:40:14 on ttys000

Vlads-iMac:~ Vlad$ ping -c10 google.com

PING google.com (173.194.44.40): 56 data bytes

64 bytes from 173.194.44.40: icmp_seq=0 ttl=57 time=30.362 ms

64 bytes from 173.194.44.40: icmp_seq=1 ttl=57 time=30.379 ms

64 bytes from 173.194.44.40: icmp_seq=2 ttl=57 time=30.297 ms

64 bytes from 173.194.44.40: icmp_seq=3 ttl=57 time=30.465 ms

64 bytes from 173.194.44.40: icmp_seq=4 ttl=57 time=30.428 ms

64 bytes from 173.194.44.40: icmp_seq=5 ttl=57 time=30.183 ms

64 bytes from 173.194.44.40: icmp_seq=6 ttl=57 time=30.406 ms

64 bytes from 173.194.44.40: icmp_seq=7 ttl=57 time=30.576 ms

64 bytes from 173.194.44.40: icmp_seq=8 ttl=57 time=30.753 ms

64 bytes from 173.194.44.40: icmp_seq=9 ttl=57 time=30.507 ms

--- google.com ping statistics ---

10 packets transmitted, 10 packets received, 0.0% packet loss

round-trip min/avg/max/stddev = 30.183/30.436/30.753/0.148 ms

Vlads-iMac:~ Vlad$

That means also that both my mothers and my brothers routers blocks ping! :-( Does this say something about their ability to answer to VNC-attempts?

Thanks!

Regards,

Vlad

rccharles

Level 6

12,957 points

Feb 23, 2015 11:48 AM in response to Vlad Ghitulescu

That means also that both my mothers and my brothers routers blocks ping! :-( Does this say something about their ability to answer to VNC-attempts?

I haven't tried this, but you could forward all network traffic in your router to a computer. The computer should respond to the ping.

Drew Reece

Level 6

10,660 points

Feb 23, 2015 11:49 AM in response to Vlad Ghitulescu

Vlad Ghitulescu wrote:

That means also that both my mothers and my brothers routers blocks ping! :-( Does this say something about their ability to answer to VNC-attempts?

It only means they might be blocking pings from the outside. It says nothing about VNC.

Drew Reece

Level 6

10,660 points

Feb 23, 2015 11:56 AM in response to rccharles

rccharles wrote:

That means also that both my mothers and my brothers routers blocks ping! :-( Does this say something about their ability to answer to VNC-attempts?

I haven't tried this, but you could forward all network traffic in your router to a computer. The computer should respond to the ping.

The terms of use on this site suggest you try advice you give out.

What you are suggesting here is routing traffic from the internet to a computer like it is a 'DMZ'. This turns a computer into a 'public machine' with no external firewall. This machine will be attacked & could be swamped my malware, script kiddie attacks, botnets and other automated attacks.

DO NOT DO THIS!

Roote

Level 4

1,631 points

Feb 23, 2015 3:58 PM in response to Vlad Ghitulescu

From what I gather from reading a couple user manuals and forums, including German Telekom customer service forums:

The Speedport W 724V is designed for safety, security, and simplicity and not for advanced configuration by the user.
The router's integrated firewall/packet filters cannot be configured by the user.
Issues with pinging are known and are considered a feature, not a bug, to prevent Ausspähungen (reconnaissance).
Implements UPnP AV only, for use with a USB attached media server.

There may be a way (refers to W723V) to disable the router's firewall to assess whether this is indeed the issue. Not recommended except for testing temporarily. Make sure your computer's software firewall is active and filter appropriately. However, I think you can assume that the router's firewall is the issue without testing.

You would think that having port-forwarded the desired service appropriately, and other computer sharing and firewall options set correctly, that everything should function. (You might try deleting all the port-forwarding and set it up again.) Or that setting the Speedport W 724v to modem only mode (if possible, depends upon firmware; page 191 in User's Manual) and using the Airport Extreme as the router would work.

If you've tried all suggestions, and I don't know if it is possible or desirable for you, but I'm coming closer to the conclusion that a different modem/router is a more viable solution.

Telekom Speedport W 724v User Manuals in German:

Type A (Huawei)

Type B (Arcadyan)

Type C (SerComm)

Speedport Wikipedia:

Wikipedia Speedport in German

Wikipedia Speedport English translation

Universal Plug and Play (UPnP) Wikipedia

Forum examples in German:

https://telekomhilft.telekom.de/t5/Frage-stellen/Speedport-724v-Firewall-ausscha lten/qaq-p/202949

http://www.computerbase.de/forum/showthread.php?t=1322053

Forums examples English translation:

http://translate.google.ca/translate?hl=en&sl=de&u=https://telekomhilft.telekom. de/t5/Frage-stellen/Speedport-724v-Firewall-ausschalten/qaq-p/202949&prev=search

http://translate.google.ca/translate?hl=en&sl=de&u=http://www.computerbase.de/fo rum/showthread.php%3Ft%3D1322053&prev=search

Feb 23, 2015 9:49 PM in response to Roote

>(…) I'm coming closer to the conclusion that a different modem/router is a more viable solution.

I would so gladly use another router, but this is unfortunately not possible with VDSL.

I have searched for "VDSL through something else than Speedport" ;-) immediately after having the initial problems with VPN and my company's server (I couldn't reach the server anymore after switching ISP & router due to the fact that the port vor VPN was closed by default).

That's why I put my AirPort Extreme in bridge-mode and not completely replaced with it the Speedport.

Roote

Level 4

1,631 points

Feb 23, 2015 11:15 PM in response to Vlad Ghitulescu

I would so gladly use another router, but this is unfortunately not possible with VDSL.

Did you look at the VDSL Fritz!Box range of products? Models 7490, 7390, 7360, 3390, and 3370 in particular.

FRITZ!Box service info that may be of interest:

Configuring port forwarding for incoming Internet connections

Configuring automatic port forwarding via UPnP

Configuring static port forwarding

Feb 23, 2015 11:49 PM in response to Roote

>> I would so gladly use another router, but this is unfortunately not possible with VDSL.

> Did you look at the VDSL Fritz!Box range of products? Models 7490, 7390, 7360, 3390, and 3370 in particular.

> FRITZ!Box service info that may be of interest:

> Configuring port forwarding for incoming Internet connections

> Configuring automatic port forwarding via UPnP

> Configuring static port forwarding

No, I haven't! Perhaps my fault: I wanted so badly to use my AirPort Express! :-) so I searched only for "VDSL AirPort Express" :-(

I will read immediately everything about Fritz!Box. Thanks!

However this will solve the problem on this end only.

For my mother (in Romania) I still have to go with Team Viewer.

Roote

Level 4

1,631 points

Feb 24, 2015 12:32 AM in response to Vlad Ghitulescu

You're welcome, I hope you find a solution.

Two relevant Fritz!Box product pages I missed:

FRITZ!Box 3490

Comparing AVM products

Mar 1, 2015 9:46 AM in response to Vlad Ghitulescu

Hello again!

Sorry for the delay, it took me a while to co-ordinate a test of TeamViewer with my mother :-/

It was almost a success!

Almost.

I managed to get her install TeamViewer version 7 (current version is 10) and also to get the screensharing working. I'm not sure that we can do it again, but let's hope! :-)

What I couldn't do in almost 2 hours trying was a video-chat.

I could establish the connection and accept her invitation to a meeting (using TeamViewer Join version 7 - she couldn't accept my invitation, due to the fact that TeamViewer Join version 10 - what I'm running - cannot be installed on her Mac Mini running Mac OS X 10.5.8), I could also see a video of her (ca. one inch big and in green - no kidding!) but whitout any sound!

Strange enough, the VoIP-LED on her router - HUAWEI HG658 - doesn't light, so it seems that the sound-feature are somehow disturbed.

I managed to log in into the router-settings - via screensharing - but unfortunately I couldn't find the setting to switch this on and test again :-(

So: screensharing ok, but video-chat still not!

I'll try again and keep you updated.

Thanks again for all your help!

Regards,

Vlad

rccharles

Level 6

12,957 points

Mar 1, 2015 1:44 PM in response to Vlad Ghitulescu

That's good to hear. Keep trying! Perhaps some other video app would be available.

Which ports must be open für ScreenSharing?