VNC without SSH tunnel?

notooth · 08-25-2020, 07:42 PM

Hello,

Can anyone tell me how to make a VNC connection without SSH tunnel?

berndbausch · 08-25-2020, 07:46 PM

Ensure that no firewall blocks VNC ports on the VNC server. By default, the Centos firewall blocks the ports.
Run vncserver on the VNC server. It will tell you the port number or display number, e.g. :1.
Run a VNC client like tightvnc on the client. Provide the server's IP address followed by the port number.

EDIT: Here is one of the millions of tutorials that cover the subject: https://wiki.centos.org/HowTos/VNC-Server. It uses iptables to unblock ports, but on Centos 7 and later, firewall-cmd is an easier solution. I think you can use a command like firewall-cmd --add-service vnc or so.

notooth · 08-25-2020, 08:09 PM

I followed the tutorial and failed to make a connection:

Code:

$ sudo systemctl stop firewalld

$ vncserver

New 'localhost.localdomain:1 (notooth)' desktop is localhost.localdomain:1

Starting applications specified in /home/notooth/.vnc/xstartup
Log file is /home/notooth/.vnc/localhost.localdomain:1.log

$ vncviewer localhost.localdomain:1
...
CConn:       unable connect to socket: Connection refused (111)

michaelk · 08-25-2020, 08:17 PM

Are you running the viewer on a different machine? Try using its ip address instead

notooth · 08-25-2020, 08:19 PM

No, I run the server and the viewer on the same machine.

michaelk · 08-25-2020, 09:30 PM

Here is another guide for CentOS 7

https://www.tecmint.com/install-and-...r-in-centos-7/

Since you are running the viewer on the same machine the firewall does not matter since you are using internal networking.

berndbausch · 08-25-2020, 10:14 PM

Quote:

Originally Posted by notooth

I followed the tutorial and failed to make a connection:

Code:

$ sudo systemctl stop firewalld

$ vncserver

New 'localhost.localdomain:1 (notooth)' desktop is localhost.localdomain:1

Starting applications specified in /home/notooth/.vnc/xstartup
Log file is /home/notooth/.vnc/localhost.localdomain:1.log

$ vncviewer localhost.localdomain:1
...
CConn:       unable connect to socket: Connection refused (111)

Connection refused means that there is no listener. List all listeners with sudo ss -lntp, and check the above log file.

notooth · 08-26-2020, 05:47 AM

Quote:

Originally Posted by berndbausch

Connection refused means that there is no listener. List all listeners with sudo ss -lntp, and check the above log file.

I listed all listeners, but I don't know how to check:

Code:

$ sudo ss -lntp
State           Recv-Q          Send-Q                   Local Address:Port                    Peer Address:Port                                                                               
LISTEN          0               128                            0.0.0.0:111                          0.0.0.0:*              users:(("rpcbind",pid=1170,fd=4),("systemd",pid=1,fd=240))          
LISTEN          0               32                       192.168.122.1:53                           0.0.0.0:*              users:(("dnsmasq",pid=1887,fd=6))                                   
LISTEN          0               128                            0.0.0.0:22                           0.0.0.0:*              users:(("sshd",pid=1402,fd=5))                                      
LISTEN          0               5                            127.0.0.1:631                          0.0.0.0:*              users:(("cupsd",pid=1403,fd=10))                                    
LISTEN          0               128                            0.0.0.0:3580                         0.0.0.0:*              users:(("nisvcloc",pid=39619,fd=5))                                 
LISTEN          0               128                            0.0.0.0:5355                         0.0.0.0:*              users:(("systemd-resolve",pid=1607,fd=13))                          
LISTEN          0               128                               [::]:111                             [::]:*              users:(("rpcbind",pid=1170,fd=6),("systemd",pid=1,fd=242))          
LISTEN          0               128                               [::]:22                              [::]:*              users:(("sshd",pid=1402,fd=7))                                      
LISTEN          0               5                                [::1]:631                             [::]:*              users:(("cupsd",pid=1403,fd=9))                                     
LISTEN          0               128                               [::]:5355                            [::]:*              users:(("systemd-resolve",pid=1607,fd=15))

berndbausch · 08-26-2020, 06:02 AM

Quote:

Originally Posted by notooth

I listed all listeners, but I don't know how to check:

Well, none of the listeners here is vncserver, which probably means that vncserver doesn't run at all. Thus the "connection refused" error.

Also, if it were running, it should normally be listening at an address/port combination of 127.0.0.1:5901.

The next step is finding out why it is not running or listening. The best bet for information about this problem is the log file.

notooth · 08-26-2020, 06:10 AM

Here is the log file:

Quote:

Xvnc TigerVNC 1.9.0 - built Apr 23 2020 14:52:39
Copyright (C) 1999-2018 TigerVNC Team and many others (see README.rst)
See http://www.tigervnc.org for information on TigerVNC.
Underlying X server release 12003000, The X.Org Foundation

Wed Aug 26 18:06:05 2020
vncext: VNC extension running!
vncext: Listening for VNC connections on all interface(s), port 5901
vncext: created VNC server for screen 0
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Internal error: Could not resolve keysym XF86MonBrightnessCycle
> Internal error: Could not resolve keysym XF86RotationLockToggle
Errors from xkbcomp are not fatal to the X server
Killing Xvnc process ID 135195

Wed Aug 26 18:06:09 2020
ComparingUpdateTracker: 0 pixels in / 0 pixels out
ComparingUpdateTracker: (1:-nan ratio)

berndbausch · 08-26-2020, 06:48 AM

This is beyond my area of competency, but you are a step closer to the solution now. I suggest you try to find information about this error on the internet or create a new question.