LAN only VNC setup

Question

GOAL:

I have 2 computers in a LAN environment (I will refer to them as [computer A] and [computer B]) and I want to log into [computer B] via [computer A].

I have a VNC client on [computer A] Remote Desktop Viewer and I have setup Desktop Sharing Preferences on [computer B], see screenshots below. The LAN IP address of [computer A] is 192.168.0.1 and the LAN IP address of [computer B] is 192.168.0.2.

Both computers have no problem pinging to each other!

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QUESTION:

My question is, how do I connect to [computer B] from [computer A]?

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ERROR MESSAGE:

I am currently getting the following error message when I try to connect:

connection to 192.168.0.2 was closed

192.168.0.2 is the IP address of [computer B].

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PORTS / FIREWALL:

I can't see the port 5900 listed when I run sudo lsof -i -P | grep -i listen. I don't have a firewall installed either. I've now installed Gufw on both [computer A] and [computer B]. I am not sure how to configure it. Do I set it up to allow incoming connections for vnc on [computer B] and allow outgoing connections for vnc on [computer A]?

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OTHER INFO:

Computer A = 192.168.0.1 = Ubuntu 12.04
Computer B = 192.168.0.2 = Debian Stable

Both are fully updated

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IPTABLES (same on server and client):

Chain INPUT (policy ACCEPT)
target - prot opt source - destination

Chain FORWARD (policy ACCEPT)
target - prot opt source - destination

Chain OUTPUT (policy ACCEPT)
target - prot opt source - destination

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LISTENING PORTS

sudo lsof -i -P | grep -i listen
rpcbind   1853        root    8u  IPv4   5755      0t0  TCP *:111 (LISTEN)
rpcbind   1853        root   11u  IPv6   5762      0t0  TCP *:111 (LISTEN)
rpc.statd 1884       statd    8u  IPv4   5818      0t0  TCP *:56428 (LISTEN)
rpc.statd 1884       statd   10u  IPv6   5826      0t0  TCP *:39576 (LISTEN)
cupsd     2615        root    6u  IPv6  17952      0t0  TCP localhost:631 (LISTEN)
cupsd     2615        root    8u  IPv4  17953      0t0  TCP localhost:631 (LISTEN)
mysqld    3042       mysql   10u  IPv4   7466      0t0  TCP localhost:3306 (LISTEN)
exim4     3855 Debian-exim    3u  IPv4   8075      0t0  TCP localhost:25 (LISTEN)

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SCREENSHOTS:

This is the client software I have on [computer A]:

This is the software (server software I guess) I have on [computer B]:

Solution

Method #1 - VNC from ComputerA -> B

where a user is already logged in on B

You don't specify what VNC client you're using but one of the more popular ones is Vinagre. It's typically included with GNOME desktop based distros, which should cover most of the larger distros.

Installation

First you'll want to make sure that you have GNOME's VNC client, vinagre installed as well as the VNC server, vino.

On my Fedora 19 system these packages required installation.

$ sudo yum install vinagre vino

On Ubuntu you'd install the same packages, using apt.

$ sudo apt-get install vinagre vino

Server setup

Once installed you'll want to make sure that the VNC server is running on computer B. You can do this either by navigating through Settings -> Sharing menu from where you can select to enable "Screen Sharing".

Fedora

     

Ubuntu

              

NOTE: You can invoke vino's preferences from the command line like so:

 $ vino-preferences

Client setup

Once the VNC server's been setup on computer B, you should now be able to connect to it from computer A, using vinagre, the VNC client. You can do this either from the command line like so:

$ vinagre vnc://greeneggs.bubba.net

Where the vnc://... is the server string provided by vino, as in the screenshot above.

Additional notes

• If you need to summon the VNC server's dialog directly from the command line it's called vino-preferences.
• vinagre is also a GUI that can be launched bare, and bookmarks can be maintained for VNC severs that you may frequent.To launch it use the command vinagre.

      

Method #2 - VNC from ComputerA -> B

where a user is not already logged in on B

Server setup

Ubuntu

1. Install x11vnc

   $ sudo apt-get install x11vnc
   

2. Create /etc/init/x11vnc.conf file.

   start on login-session-start
   script
   x11vnc -xkb -noxrecord -noxfixes -noxdamage -display :0 -auth /var/run/lightdm/root/:0 -forever -bg -o /var/log/x11vnc.log
   end script
   

3. After restarting (rebooting), x11vnc should be listening on the standard VNC port, 5900.

4. You can confirm

   $ sudo netstat -tapn | grep 5900
   tcp        0      0 0.0.0.0:5900            0.0.0.0:*               LISTEN      2379/x11vnc     
   tcp6       0      0 :::5900                 :::*                    LISTEN      2379/x11vnc     
   

NOTE: The script is based on an upstart event mechanism where Lightdm emits login-session-start events, x11vnc is then started.

References

• Remote VNC login to Ubuntu 11.10
• Remote VNC login to Ubuntu 12.04

Comments

[user80551]

Did you enable incoming connections in the firewall for computer B. You can do it using gufw

[oshirowanen]

I had to install and enable gufw to do that and it made no difference.

[Elliott Frisch]

Have you verified you can telnet to port "5900" on the server from the client?

[oshirowanen]

@ElliottFrisch, I can't telnet to 5900 to the server from the client. I get Unable to connectto remote host: Connection refused.

[Elliott Frisch]

@oshirowanen Then the server isn't allowing remote connections; do you have any "ipfw" rules? Also, you might consider trying PortForwarding.

[oshirowanen]

I've not touched the iptables at all, so whatever the default settings are on Debian is what my current iptables is set to on the server. I'll update the question with the output I get from the servers iptables in a moment.

[oshirowanen]

@ElliottFrisch, done.

[Elliott Frisch]

@oshirowanen which vnc server package did you install?

[oshirowanen]

@ElliottFrisch, vnc server is vino and vnc client is vinagre.

[Elliott Frisch]

And you're logged in to the server and you've started vino-server?

[oshirowanen]

So I need to install vinagre on computer A and vino on computer B?

[oshirowanen]

I've installed vinagre on computer A and vino on computer B. I then laungh vino-preferences and it looks totally different from your screenshot. On my computer, it has the title Desktop Sharing Preferences and it doesn't display a vnc type link/path. Anyway, I tried to continue and tried connecting to the server, but it can't connect. connection to 192.168.0.2 was closed.

[oshirowanen]

I can't see the port 5900 listed when I run that command. I don't have a firewall installed either. I've now installed Gufw on both [computer A] and [computer B]. I am not sure how to configure it. Do I set it up to allow incoming connections for vnc on [computer B] and allow outgoing connections for vnc on [computer A]?

[Ben Lin]

If you don't have port 5900 opened for listening in [Computer B], that is not a good sign. sounds like the VNC server (desktop sharing server) is not running well in this server. Please give out the result of the command sudo lsof -i -P | grep -i listen It's better if you DON'T have firewall :)

[slm]

@oshirowanen - what happens when you run this command from computerA? telnet 192.168.0.2 5900? If this doesn't work then you have 1 of 2 problems. Routing b/w A & B isn't correct, or the VNC server on B isn't running or accepting connections on port 5900. Also when replying to me do an at sign @ + slm, otherwise I won't see your comments. I hadn't see the above ones until today, just by accident.

[oshirowanen]

Yes, when I try to VNC from A -> B, I login as a user on B.

[slm]

@oshirowanen - OK, that's b/c it's my A, so those do get through. Oddly I do not remember seeing any comments from this on Dec 28th, no matter. The telnet is telling you that there is no VNC server running on computer B!

[slm]

@oshirowanen - what I mean when I say "logged in already" is that userX is already logged into computer B and you're running VNC client from computer B, logging in as userX. The method discussed with vino requires the user is already logged into the desktop on computer B.

[oshirowanen]

But I installed vino and set it as shown in my screenshot, which seems to mirror your screenshot?

[slm]

@oshirowanen - and you're logged into B, can you check the box to always show the vnc icon in the tool bar?

[oshirowanen]

Done, but I can't see a vnc icon in the notification area.

[oshirowanen]

what I mean when I say "logged in already" is that userX is already logged into computer B and you're running VNC client from computer A, logging in as userX, or did you really mean what I mean when I say "logged in already" is that userX is already logged into computer B and you're running VNC client from computer B, logging in as userX?

[slm]

No what I said is what I meant. It's confusing but you can only establish a connection using VNC if the user you're logging in as, is already logged in on computer B. This is b/c vino will not run until userX has logged into the desktop.

[oshirowanen]

So that means I need to use your Method 2? But I think I need to get the server listening to port 5900 first? Or does Method 2 correct that problem too? I've updated my question to include further port details, I see port 5900 nowhere...

[slm]

Method #2 will take care of starting the server. A reboot is required. Only 1 time to trigger the starting of X11Vnc as part of the starting of lightdm (Ubutnu's login manager).

[oshirowanen]

Thanks, I'll try that and get back to you as soon as possible.

[slm]

@oshirowanen - take your time and good luck. I'll be here if you need help and/or have questions.

[oshirowanen]

Thanks! Got another question (already). My server is a Debian server and I have XFCE installed with GDM as the display manager. Your method 2 instructions are based on Ubuntu. I'm assuming those instructions are to be executed on the server and not on the client? Just wanted to make sure because with me having Ubuntu as the client and your instructions being based on Ubuntu, it's getting confusing. I've sure those instructions are for the server, but as I have GDM instead of lightdm, that .conf file probably needs to be a little different?

[slm]

Yes the directions for the setup are meant for the servers. Given you're using Debian your directions will be slightly different (I would expect) though I do not have access to Debian to confirm this for a fact. So you're going to have to experiment. I'll try and get a Debian system setup if possible.

[slm]

@oshirowanen - this thread might be of help: forums.debian.net/viewtopic.php?f=5&t=55327. Also running x11vnc manually on computer B will likely prove this approach is correct. Making it part of computer B's startup can be dealt with afterwards. Also this URL might be helpful: wiki.archlinux.org/index.php/X11vnc