Vlad Ghitulescu

Q: 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

Close

Q: Which ports must be open für ScreenSharing?

  • All replies
  • Helpful answers

Page 1 of 3 last Next
  • by Mark Jalbert,

    Mark Jalbert Mark Jalbert Feb 16, 2015 6:29 AM in response to Vlad Ghitulescu
    Level 5 (4,649 points)
    Feb 16, 2015 6:29 AM in response to Vlad Ghitulescu
  • by rccharles,

    rccharles rccharles Feb 16, 2015 12:41 PM in response to Vlad Ghitulescu
    Level 6 (8,496 points)
    Classic Mac OS
    Feb 16, 2015 12:41 PM in response to Vlad Ghitulescu
  • by Vlad Ghitulescu,

    Vlad Ghitulescu Vlad Ghitulescu Feb 16, 2015 11:53 PM in response to Mark Jalbert
    Level 1 (11 points)
    Feb 16, 2015 11:53 PM in response to Mark Jalbert

    Hi, Mark!

     

     

    I've opened the port 5900, tried to connect to other Mac using vnc://192.168.1.2/ according to System Preferences - Sharing

     

       "(…) Other users can access your computer's screen at vnc://192.168.1.2/ (…)"

     

    and received the same old error message.

     

    What do I do wrong? :-(

     

     

    Regards,

    Vlad

  • by Vlad Ghitulescu,

    Vlad Ghitulescu Vlad Ghitulescu Feb 16, 2015 11:55 PM in response to rccharles
    Level 1 (11 points)
    Feb 16, 2015 11:55 PM in response to rccharles

    Hi, rccharles!

     

     

    What do you mean exactly with the servers?

    Should I use one of this addresses instead of the one suggested by System Preferences - Sharing?

     

     

    Thanks!

    Vlad

  • by Vlad Ghitulescu,

    Vlad Ghitulescu Vlad Ghitulescu Feb 17, 2015 12:08 AM in response to Vlad Ghitulescu
    Level 1 (11 points)
    Feb 17, 2015 12:08 AM in response to Vlad Ghitulescu

    Here is the error message I get:

     

    Bildschirmfoto 2015-02-17 um 09.03.08.png

    It says something like :"Connection failed with 109.168.1.2. Please check that screensharing (in system preferences - sharing) is active on the computer you want to connect. Check also that your internet connection is working properly."

  • by Vlad Ghitulescu,

    Vlad Ghitulescu Vlad Ghitulescu Feb 17, 2015 12:12 AM in response to Vlad Ghitulescu
    Level 1 (11 points)
    Feb 17, 2015 12:12 AM in response to Vlad Ghitulescu

    Apropos which address exactly: I've tried this combinations after CMD+K

     

    1.- vnc://<address_from_system_prefs_sharing>/

     

    2.- <address_from_system_prefs_sharing>

     

    3.- vnc://<ip_address>/

     

    4.- <ip_address>

     

    and all of them also whitout /  at the end.

     

    Nothing worked.

  • by Camelot,

    Camelot Camelot Feb 17, 2015 12:58 AM in response to Vlad Ghitulescu
    Level 8 (47,290 points)
    Mac OS X
    Feb 17, 2015 12:58 AM in response to Vlad Ghitulescu

    Are all these hosts on the same local network?

     

    if these hosts are disparate (e.g. in different locations) then the 192.168.x.x address won't be valid. That's a local area network address that will never work over the internet. Your router translates this (via NAT) to a publicly-routable IP address provided by your ISP. It is this public address that the remote user would need to connect to (in addition to the router being configured to route incoming connections on port 5900 to the relevant host).

     

    Note that if you do configure your router to permit incoming connections, you're leaving yourself open to random users hitting your system, and VNC is not considered secure. A better solution would be to implement a VPN which provides a secure connection between the remote locations - then you would be able to use the 192.168.x.x address since the VPN would make them seem like they are on the same network.

  • by Vlad Ghitulescu,

    Vlad Ghitulescu Vlad Ghitulescu Feb 17, 2015 1:54 AM in response to Camelot
    Level 1 (11 points)
    Feb 17, 2015 1:54 AM in response to Camelot

    Hi, Camelot!

     

     

    Thanks for the reply!

     

    > Are all these hosts on the same local network?

    No, not at all. I'm trying to connect to some Mac in another country right now.

     

    > if these hosts are disparate (e.g. in different locations) then the 192.168.x.x address won't be valid.

    > That's a local area network address that will never work over the internet.

    I also supposed something like this. That's why I posted also exactly what I did after CMD+K.

     

    > Your router translates this (via NAT) to a publicly-routable IP address provided by your ISP.

    > It is this public address that the remote user would need to connect to

    > (in addition to the router being configured to route incoming connections on port 5900 to the relevant host).

    That's why I also tried with the "real" IP address (as seen from "outside"), in the format "vnc://ip_address/", "ip_address/" (that was completed with "smb://") and the same whitout the final /. But none of this attempts worked!

    I am surprised because with my previous (DSL-)internet connection and OS X systems (Mavericks and older) I had no problems at all.

     

    > Note that if you do configure your router to permit incoming connections, you're leaving yourself open to random users hitting your system,

    > and VNC is not considered secure.

    Thanks for this information, I didn't know this.

    I have also opened a port in order to VPN to my company's server. This port is always opened as well :-(

     

    > A better solution would be to implement a VPN which provides a secure connection between the remote locations -

    > then you would be able to use the 192.168.x.x address since the VPN would make them seem like they are on the same network.

    This seams very reasonable - but right now I an not even able to get a proper (and insecure ;-) VNC-connection working again! :-/

    I would gladly consider to implement a VPN-solution (even when I'm not so sure HOW exactly to do this right now…) but I would like to solve first this annoying problem. I must be able to reach my mother's Mac Mini again (she is living in Romania, has no clue and need assistance - and I cannot deliver this anymore! :-((()

     

    Thanks again!

     

     

    Regards,

    Vlad

  • by BobHarris,

    BobHarris BobHarris Feb 17, 2015 8:31 AM in response to Vlad Ghitulescu
    Level 6 (19,521 points)
    Mac OS X
    Feb 17, 2015 8:31 AM in response to Vlad Ghitulescu

    Generally you do NOT need to configure your router for out-bound VNC connections to a remote system.  HOWEVER, the remote system needs to allow connections over port 5900 to the destination computer.  If that destination computer is not using a public IP address and is behind a router, then it will need that router to port forward port 5900 to the computer.

     

    But since you ONLY experienced this problem AFTER changing your home setup, I am assuming the remote destination system is already configured to work correctly.

     

    The only reason I can imagine your "VDSL-router from Telekom" not allowing you to VNC out is if it has a Firewall feature that blocks most out-bound TCP connections, except for maybe port 80 (web servers), and the various ports for email.  This is a "Wild Guess".  I do NOT know anything about the "VDSL-router from Telekom", so I could be guessing totally wrong.

     

    Can you VNC to another computer in your home?   Or is that also being blocked?

     

    Is the remote destination computer a Mac with System Preferences -> Sharing -> Screen Sharing enabled?  Or is it a Windows or Unix/Linux system?

     

    Is it essential that you use VNC, or can you use something like TeamViewer.com (free for personal use).

     

    Side note:  192.168.n.n, 10.n.n.n, and 172.16.n.n thru 172.31.n.n are non-routing IP addresses.  You can ONLY access system in your home LAN using them.  Your home router will NOT send any of these addresses to the public internet.  Which range of IP addresses are used on your home LAN is determined by your home router.

  • by rccharles,

    rccharles rccharles Feb 17, 2015 12:48 PM in response to Vlad Ghitulescu
    Level 6 (8,496 points)
    Classic Mac OS
    Feb 17, 2015 12:48 PM in response to Vlad Ghitulescu

    1) I suggest you switch to a free screen sharing app.  It will do all the work for you.

     

    https://secure.logmein.com/

     

    or

    see suggestion in the second to last paragraph.

     

    2) What ip address were you using for your mother before? It should not have changed.  If your mother has a dynamic ip address,

    You need one of these free servers...

    http://www.noip.com/free

    http://www.changeip.com/services/free-dynamic-dns/

    https://www.dnsdynamic.org/

     

    3) You should use the ping command to see if you can reach your mother's computer still.

    me $ # ping google.com
    me $ ping -c4 173.194.123.110
    PING 173.194.123.110 (173.194.123.110) 56(84) bytes of data.
    64 bytes from 173.194.123.110: icmp_seq=1 ttl=56 time=53.7 ms
    64 bytes from 173.194.123.110: icmp_seq=2 ttl=56 time=53.9 ms
    64 bytes from 173.194.123.110: icmp_seq=3 ttl=56 time=55.8 ms
    64 bytes from 173.194.123.110: icmp_seq=4 ttl=56 time=54.9 ms
    
    --- 173.194.123.110 ping statistics ---
    4 packets transmitted, 4 received, 0% packet loss, time 3005ms
    rtt min/avg/max/mdev = 53.774/54.635/55.850/0.823 ms
    me $
    
    
    

     

    4) Oh, skype allows you to view the screen of remote computers. You mother will have to click the correct button to enable.

     

    Robert

  • by Vlad Ghitulescu,

    Vlad Ghitulescu Vlad Ghitulescu Feb 17, 2015 1:28 PM in response to BobHarris
    Level 1 (11 points)
    Feb 17, 2015 1:28 PM in response to BobHarris

    Hi, Bob!

     

    Thanks for the reply!

     

    > Generally you do NOT need to configure your router for out-bound VNC connections to a remote system. 

    > HOWEVER, the remote system needs to allow connections over port 5900 to the destination computer. 

    > If that destination computer is not using a public IP address and is behind a router, then it will need that router to port forward port 5900 to the computer.

    > But since you ONLY experienced this problem AFTER changing your home setup,

    > I am assuming the remote destination system is already configured to work correctly.

     

    That should be so, my mother didn't change anything for sure.

     

     

    > The only reason I can imagine your "VDSL-router from Telekom" not allowing you to VNC out is if it has a Firewall feature that blocks most out-bound TCP connections, except for maybe port 80 (web servers), and the various ports for email. 

    > This is a "Wild Guess".  I do NOT know anything about the "VDSL-router from Telekom", so I could be guessing totally wrong.

     

    This is correct!

     

     

    > Can you VNC to another computer in your home?   Or is that also being blocked?

     

    I don't have right now any other computer in my home, but I did this previously, so yes, it is possible.

    However, I wasn't able to connect to the very same computer after it wasn't in my network anymore.

     

     

    > Is the remote destination computer a Mac with System Preferences -> Sharing -> Screen Sharing enabled?


    Yes!



    > Or is it a Windows or Unix/Linux system?

     

    No, the 3 computer I tried are all Macs.

     

     

    > Is it essential that you use VNC,

     

    Not at all, I would use anything that is possible. I only used the OS X screensharing app before, that's the reason why I asked about it.

     

     

    > or can you use something like TeamViewer.com (free for personal use).

     

    As I said, I would use anything! The only constraint is my mother's Mac Mini: it's the first Mac Mini, Power PC, running 10.5.8

     

     

    > Side note:  192.168.n.n, 10.n.n.n, and 172.16.n.n thru 172.31.n.n are non-routing IP addresses.  You can ONLY access system in your home LAN using them.  Your home router will NOT send any of these addresses to the public internet.  Which range of IP addresses are used on your home LAN is determined by your home router.

     

    Aha! Thanks!

     

     

     

    Regards,

    Vlad

  • by Vlad Ghitulescu,

    Vlad Ghitulescu Vlad Ghitulescu Feb 17, 2015 1:38 PM in response to rccharles
    Level 1 (11 points)
    Feb 17, 2015 1:38 PM in response to rccharles

    Hi, Robert!

     

     

    Thanks for the reply!

     

    > 1) I suggest you switch to a free screen sharing app.  It will do all the work for you.

    > https://secure.logmein.com/

    > or

    > see BobHarris suggestion in the second to last paragraph.

     

    Ok, I'll take a look at logmein and TeamViewer (I didn't use them before).

    As I wrote in the answer to Bob, the only problem is the very old Mac Mini of my mother. I am curious if it's possible to install the client of logmein or TeamViewer on an old Mac like this.

     

    > 2) What ip address were you using for your mother before? It should not have changed.

     

    I don't know, because I didn't need it with the screensharing app. Unfortunately iChat is not supported anymore on her Mac, so now I need a substitute.

     

    > If your mother has a dynamic ip address,

    > You need one of these free servers...

    > http://www.noip.com/free

    > http://www.changeip.com/services/free-dynamic-dns/

    > https://www.dnsdynamic.org/

     

    I will, if she has a dynamic ip address.

     

     

    > 3) You should use the ping command to see if you can reach your mother's computer still.

     

    I will try, thanks! I totally forgot about it! :-/

     

     

    > 4) Oh, skype allows you to view the screen of remote computers. You mother will have to click the correct button to enable.

     

    There is a problem with Skype. Microsoft doesn't support Skype anymore for Macs with operating systems older than Snow Leopard. I've found a workaround but implies some work in Terminal, so this is something I have to do remotely… after connecting via VNC to her Mac Mini! :-)

    So one after the other…

     

    I will try the ping AND LogMeIn AND TeamViewer and report the results

    Thanks again!

     

     

    > Robert

     

    Regards,

    Vlad

  • by Vlad Ghitulescu,

    Vlad Ghitulescu Vlad Ghitulescu Feb 20, 2015 6:53 AM in response to rccharles
    Level 1 (11 points)
    Feb 20, 2015 6:53 AM in response to rccharles

    Hello again!

     

     

    Sorry for the delay, is not easy to co-ordinate with elder parents! ;-)

     

    What have I done?

     

    1.- My mother went to http://www.whatismyip.com and found out that she have the IP 109.100.181.55

     

    2.- Armed with this information I went to the Terminal.app and ping-ed her. Here is the result:

     

    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$

     

    3.- A little disappointed :-) I ping-ed google.com (see attached screenshot). It is still running…

    Bildschirmfoto 2015-02-20 um 15.38.00.png

    Something is wrong here, but I'm not sure if only with my mother's Mac Mini :-/

     

    What do you think?

     

     

    Regards,

    Vlad

  • by rccharles,

    rccharles rccharles Feb 20, 2015 12:12 PM in response to Vlad Ghitulescu
    Level 6 (8,496 points)
    Classic Mac OS
    Feb 20, 2015 12:12 PM in response to Vlad Ghitulescu

    quick scan of TeamViewer indicates it supports older version of TeamVIewer, so I'd guess you could find a version for your Mother.

     

    So much for the free logmein account.

    "After ten years, LogMeIn’s free remote access product, LogMeIn Free, is going away."

     

    I had logmein.com working about a year ago on my iMac g3 600 running Tiger 10.4.11 to Windows xp.  I think the oldest OS to run on the Mini is Tiger.

     

    Apple Macintosh OS X 10.9 (Mavericks), 10.4 (Tiger), 10.5 (Leopard), 10.6 (SnowLeopard), 10.7 (Lion) and 10.8 (MountainLion)

    https://secure.logmeinrescue.com/helpdesk/features.aspx

Page 1 of 3 last Next