Bug 52036 - Listen for incoming VNC server connection
Summary: Listen for incoming VNC server connection
Status: CONFIRMED
Alias: None
Product: krdc
Classification: Applications
Component: VNC (show other bugs)
Version: unspecified
Platform: Compiled Sources Linux
: NOR wishlist
Target Milestone: ---
Assignee: Urs Wolfer
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2002-12-17 22:18 UTC by Luke-Jr
Modified: 2024-11-21 22:21 UTC (History)
5 users (show)

See Also:
Latest Commit:
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Description Luke-Jr 2002-12-17 22:18:18 UTC
Version:            (using KDE KDE 3.0.9)
Installed from:    Compiled From Sources
Compiler:          GCC 3.2 
OS:          Linux

KRdc should allow the user to listen on a port for a reverse VNC connection (server connects to client).
Comment 1 Brad Hards 2006-07-31 14:10:15 UTC
Which clients and servers support this?
Comment 2 Luke-Jr 2006-07-31 18:28:32 UTC
Virtually all of them-- usually as vncviewer -listen
Comment 3 Marco Menardi 2007-04-10 03:28:06 UTC
Any news for this "60 votes" request? This mode is very useful when assisting people, since connection originates from them and so it can pass firewall and other settings on their side. For instance, for Windows people you can use UltraVNC "single click" and prepare a VNC server that connects to your client, if in "listen mode", passing easily through their router/firewall. If only KRdc could support listen mode... 
Comment 4 Adam Wood 2007-04-12 10:03:16 UTC
This could be very useful for remote technical support. I often have to help people out when they are working from home. NAT and Firewalls give me real headaches as you can imagine so being able to set up a small config file ahead of time so that when KRDC is fired up there is an option to connect to a predefined server.

Just a thought, but how would the listening "server" handle multiple incoming requests? Could we generate a SessionID? which is displayed on the initiators screen and once that number has been phoned/e-mailed through to tech support the SessionID can be picked off a list and connection established. This would make the job of linking incident reports to remote connections so much easier.
Comment 5 Charles 2007-09-08 16:29:29 UTC
I just voted for this bug since it is a very annoying issue for beginners, who may need help.
This bug seems quite old know will it have a chance to be implemented ?
Comment 6 Urs Wolfer 2007-09-08 18:16:17 UTC
Yes, this feature is planned. I will have a look at libVNCclient if it is already implemented there.
Comment 7 carthexis 2008-06-27 17:44:18 UTC
Any news on this one?
This feature would really make my life easier as I quite often have to help people over the net (through NATs and Firewalls, of course).
Comment 8 Urs Wolfer 2008-06-27 22:10:08 UTC
Nope, still nothing available. LibVNCclient, which is the base for KRDC does not support that IIRC.
Do you know an open source VNC client, which does support that?
Comment 9 GCN 2008-06-27 22:14:37 UTC
@Urs Wolfer:
Tightvnc does this.

From the (vncviewer man page):
-listen
       Make the viewer listen on port 5500+display for reverse connections  from  a  server.
       WinVNC  supports  reverse  connections using the "Add New Client" menu option, or the
       -connect command line option. Xvnc requires the use of the helper program vncconnect.
Comment 10 Dennis Jansen 2008-08-14 21:47:01 UTC
@Marco:
You need special parameters for tightvnc in order to connect to SingleClick clients. Here's a description of how to use tightvnc to listen for ultravnc's single click connections:
http://linux-tipps.blogspot.com/2008/08/ultravnc-single-click-and-linux.html
Comment 11 Marcel Partap 2009-11-05 19:38:19 UTC
Well this can't be too hard to implement in libvncclient, can it? All source for this piece of functionality is available:
http://www.tightvnc.com/download/1.3.10/tightvnc-1.3.10_unixsrc.tar.gz
just needs someone picking the task!
Comment 12 Paul Eggleton 2013-03-26 15:20:35 UTC
FWIW, it looks like the latest version of libvncclient supports listening for reverse connections (finally).
Comment 13 Marco Menardi 2014-10-04 16:04:34 UTC
Any news? 170 votes so far. Remmina does this but I would prefer use krdc of course
Comment 14 Rainer Meier 2024-11-21 21:35:04 UTC
Isn't this also reuiring reverse connection in krfb?
As of my knowledge krfb also does not yet support reverse connections. Typically VNC clients listen on port 5500 to allow a reverse connection. This is very useful if the server is behind NAT (mostly the case for desktop clients). I am personally using UltraVNC based solution very successful to support Windows systems. It offers reverse connection on server side. I am running a "repeater" component on a public internet host with public IP address which is allowing me then to connect from ma viewer to the repeater (typically port 5900) as well as the server connecting to the repeater (typically port 5500) to allow relayed connection even if both parties are behind NAT.
Comment 15 Luke-Jr 2024-11-21 22:08:33 UTC
(In reply to rainer.meier from comment #14)
> Isn't this also reuiring reverse connection in krfb?

The nice thing about standards is that there are multiple implementations. No, it doesn't require krfb to support it, since there are other VNC servers that do.
Comment 16 Rainer Meier 2024-11-21 22:10:21 UTC
(In reply to Luke-Jr from comment #15)
> The nice thing about standards is that there are multiple implementations.
> No, it doesn't require krfb to support it, since there are other VNC servers
> that do.

Good point. But the number of VNC servers supporting wayland sessions is pretty much limited too.
Comment 17 Luke-Jr 2024-11-21 22:11:14 UTC
(In reply to rainer.meier from comment #16)
> Good point. But the number of VNC servers supporting wayland sessions is
> pretty much limited too.

Thankfully, VNC is also not limited to Wayland.
Comment 18 Rainer Meier 2024-11-21 22:21:18 UTC
(In reply to Luke-Jr from comment #15)
> Thankfully, VNC is also not limited to Wayland.

I see your point. So perhaps I have to elaborate that my (yes my personal) use case is to support friends and family with almost zero computer knowledge. They might run a wayland-only desktop and ask for remote support.
This is why I was looking for a VNC serverr supporting waland and found krfb to be the promising but without reverse connection it's questionable if this can support this use case if developers don't see a benefit. I might just have to do some more research about alternative options then. What I need is an RFB server allowing reverse connection with either simple GUI or simple command-line which even my grandma would be able to launch. So thanks for your reply. Krfb/krdc might just not be the right tool for the job.