[SOLVED]Error with TigerVNC

arch_user_xric · 2021-12-13 11:16:16

I followed Wiki https://wiki.archlinux.org/title/TigerVNC, to set up my server on Arch Linux.
But failed when I try to connect it, the client shows an Error:

The port on which the computer is listening for a connection could not be contacted.

My /etc/tigervnc/vncserver.users file looks like this:

# TigerVNC User assignment
#
# This file assigns users to specific VNC display numbers.
# The syntax is <display>=<username>. E.g.:
#
# :2=andrew
# :3=lisa
  :2=lhqwd

And ~/.vnc/config file:

session=plasma
geometry=1920x1080
localhost
alwaysshared

I started the VNC by:

systemctl start vncserver@:2.service

And checked with

systemctl status vncserver@:2.service

, got:

● vncserver@:2.service - Remote desktop service (VNC)
Loaded: loaded (/usr/lib/systemd/system/vncserver@.service; enabled; vendor preset: disabled)
Active: active (running) since Mon 2021-12-13 19:08:14 UTC; 5min ago
Process: 992 ExecStart=/usr/bin/vncsession-start :2 (code=exited, status=0/SUCCESS)
Main PID: 1000 (vncsession)
Tasks: 0 (limit: 9364)
Memory: 944.0K
CPU: 15ms
CGroup: /system.slice/system-vncserver.slice/vncserver@:2.service
‣ 1000 /usr/bin/vncsession lhqwd :2

Plz, help

Last edited by arch_user_xric (2021-12-13 17:09:34)

graysky · 2021-12-13 11:33:52

Are you trying to connect from the local machine or tunneling over ssh? The localhost directive will enforce localhost only.

arch_user_xric · 2021-12-13 12:50:27

graysky wrote:

Are you trying to connect from the local machine or tunneling over ssh? The localhost directive will enforce localhost only.

Thanks for your reply.
I did try to connect VNC-server while a ssh is still linked to Arch, so I:
1) turned off ssh service by:

systemctl stop sshd

2) disabled sshd (to stop it from auto start ?):

systemctl disable sshd

3)Reboot my Arch.

However, the error still exists.

The machine I use as a client(192.168.1.102) is in the same WLAN as my Arch(192.168.1.103::5902).

Last edited by arch_user_xric (2021-12-13 12:51:17)

seth · 2021-12-13 13:27:32

On the VNC host (server):

ss -tulpen

On the client:

nmap 192.168.1.103
nmap -Pn -p 5902 192.168.1.103

arch_user_xric · 2021-12-13 14:21:32

seth wrote:

On the VNC host (server):
ss -tulpen
On the client:
nmap 192.168.1.103
nmap -Pn -p 5902 192.168.1.103

On server, by ss -tulpen:

Netid      State       Recv-Q      Send-Q             Local Address:Port             Peer Address:Port      Process
udp        UNCONN      0           0                              *:1716                        *:*          uid:1001 ino:44633 sk:2002 cgroup:/user.slice/user-1001.slice/session-6.scope v6only:0 <->
udp        UNCONN      0           0                              *:1716                        *:*          users:(("kdeconnectd",pid=914,fd=14)) uid:1000 ino:25697 sk:1 cgroup:/user.slice/user-1000.slice/session-4.scope v6only:0 <->
tcp        LISTEN      0           5                      127.0.0.1:5902                  0.0.0.0:*          uid:1001 ino:43753 sk:2003 cgroup:/user.slice/user-1001.slice/session-6.scope <->
tcp        LISTEN      0           5                          [::1]:5902                     [::]:*          uid:1001 ino:43754 sk:2004 cgroup:/user.slice/user-1001.slice/session-6.scope v6only:1 <->
tcp        LISTEN      0           50                             *:1716                        *:*          uid:1001 ino:44634 sk:2005 cgroup:/user.slice/user-1001.slice/session-6.scope v6only:0 <->
tcp        LISTEN      0           50                             *:1717                        *:*          users:(("kdeconnectd",pid=914,fd=15)) uid:1000 ino:25699 sk:1004 cgroup:/user.slice/user-1000.slice/session-4.scope v6only:0 <->

On client, by nmap -Pn -p 5902 192.168.1.103:

Nmap scan report for 192.168.1.103
Host is up (0.063s latency).

PORT     STATE  SERVICE
5902/tcp closed vnc-2

Nmap done: 1 IP address (1 host up) scanned in 0.13 seconds

Last edited by arch_user_xric (2021-12-13 14:23:06)

seth · 2021-12-13 14:56:30

Something is listening on that port, but it's closed for nmap -Pn, what about the general nmap scan?
Are you absolutely sure about the server IP?
If so, is there a local firewall?

iptables -nvL
nft list tables

If not, does the router/switch filter traffic?

arch_user_xric · 2021-12-13 16:14:54

seth wrote:

Something is listening on that port, but it's closed for nmap -Pn, what about the general nmap scan?
Are you absolutely sure about the server IP?
If so, is there a local firewall?
iptables -nvL
nft list tables
If not, does the router/switch filter traffic?

nmap -Pn is working for me (tested for SSH port) while general nmap get:

Nmap scan report for 192.168.11.134
Host is up (0.0056s latency).
All 1000 scanned ports on 192.168.11.134 are in ignored states.
Not shown: 1000 closed tcp ports (conn-refused)

Nmap done: 1 IP address (1 host up) scanned in 1.55 seconds

No record for iptables -nvL, or nft list tables.

I reinstalled tigervnc, yet still same output for ss -tulpen

seth · 2021-12-13 16:22:11

Not shown: 1000 closed tcp ports (conn-refused)

seth wrote:

Are you absolutely sure about the server IP?

Eg. why are you scanning 192.168.11.134 when you previously stated that the server is 192.168.1.103 ??
Where does that other IP come from? It's not even in the same /24 segment.

graysky · 2021-12-13 16:32:30

arch_user_xric wrote:

And ~/.vnc/config file:

session=plasma
geometry=1920x1080
localhost
alwaysshared

graysky wrote:

Are you trying to connect from the local machine or tunneling over ssh? The localhost directive will enforce localhost only.

Remove the locahost directive from your config. Does your connection work?

arch_user_xric · 2021-12-13 17:24:59

graysky wrote:

Are you trying to connect from the local machine or tunneling over ssh? The localhost directive will enforce localhost only.

graysky is correct, Thanks a lots!

It took me a long time to realize the obvious solution here.

So short version SOLUTION:

edit ~/.vnc/config as follow:

session=plasma
geometry=1920x1080
#localhost
alwaysshared

END of SOLUTION

Thank seth for providing multiple ways to check the ports status from server or client machine. After I commenting the "localhost" , nmap -nP shows that 5901 port which I set for vnc is in open status.

PORT     STATE SERVICE
5901/tcp open  vnc-1

(P.S.: Before log in via VNC, log out the same user from the physical monitor. Otherwise, VNC only receives a black screen)

Last edited by arch_user_xric (2021-12-13 17:28:04)

graysky · 2021-12-13 17:30:48

Again, you can tunnel in and keep it for added security.

arch_user_xric · 2021-12-13 17:44:01

graysky wrote:

Again, you can tunnel in and keep it for added security.

Thanks, in the same article https://wiki.archlinux.org/title/TigerVNC, under the subtitle "Accessing vncserver via SSH tunnels", there is a clear instruction for it. (Maybe I should spend more time to read the Wiki next time )

Last edited by arch_user_xric (2021-12-13 17:44:52)

Arch Linux

#1 2021-12-13 11:16:16

[SOLVED]Error with TigerVNC

#2 2021-12-13 11:33:52

Re: [SOLVED]Error with TigerVNC

#3 2021-12-13 12:50:27

Re: [SOLVED]Error with TigerVNC

#4 2021-12-13 13:27:32

Re: [SOLVED]Error with TigerVNC

#5 2021-12-13 14:21:32

Re: [SOLVED]Error with TigerVNC

#6 2021-12-13 14:56:30

Re: [SOLVED]Error with TigerVNC

#7 2021-12-13 16:14:54

Re: [SOLVED]Error with TigerVNC

#8 2021-12-13 16:22:11

Re: [SOLVED]Error with TigerVNC

#9 2021-12-13 16:32:30

Re: [SOLVED]Error with TigerVNC

#10 2021-12-13 17:24:59

Re: [SOLVED]Error with TigerVNC

#11 2021-12-13 17:30:48

Re: [SOLVED]Error with TigerVNC

#12 2021-12-13 17:44:01

Re: [SOLVED]Error with TigerVNC

Board footer