Sorry in advance for the huge amount of command output text, I thought it would be more clear than paraphrasing myself.
I am using CentOS 7 and tigervnc:
(base) [carlos@pulsar .vnc]$ cat /etc/centos-release
CentOS Linux release 7.7.1908 (Core)
(base) [carlos@pulsar .vnc]$ yum list installed | grep tigervnc
Skipping unreadable repository '/etc/yum.repos.d/github_git-lfs.repo'
Skipping unreadable repository '/etc/yum.repos.d/perforce.repo'
Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast
tigervnc.x86_64 1.8.0-17.el7 @base
tigervnc-icons.noarch 1.8.0-17.el7 @base
tigervnc-license.noarch 1.8.0-17.el7 @base
tigervnc-server.x86_64 1.8.0-17.el7 @base
tigervnc-server-minimal.x86_64 1.8.0-17.el7 @base
When trying to start a vnc session on display :16 (corresponding to port 5916), I get this error,
(base) [carlos@pulsar ~]$ vncserver :16
A VNC server is already running as :16
New 'pulsar:20 (carlos)' desktop is pulsar:20
Starting applications specified in /home/carlos/.vnc/xstartup
Log file is /home/carlos/.vnc/pulsar:20.log
(base) [carlos@pulsar ~]$ vncserver -list
TigerVNC server sessions:
X DISPLAY # PROCESS ID
:17 22581
:20 222978
which I'm used to seeing, so I start looking for the culprit.
Check if there are any locks: No
(base) [carlos@pulsar ~]$ ls -l /tmp/.X*
-r--r--r--. 1 carlos phoelex 11 Mar 16 19:17 /tmp/.X20-lock
-r--r--r--. 1 bindu phoelex 11 Mar 16 14:05 /tmp/.X28-lock
/tmp/.X11-unix:
total 0
srwxrwxrwx. 1 amir phoelex 0 Nov 18 13:35 X1
srwxrwxrwx. 1 stuart phoelex 0 Nov 18 13:35 X10
srwxrwxrwx. 1 ranga phoelex 0 Nov 18 13:35 X11
srwxrwxrwx. 1 scott phoelex 0 Dec 18 13:49 X13
srwxrwxrwx. 1 pablo phoelex 0 Nov 18 15:05 X14
srwxrwxrwx. 1 zak phoelex 0 Nov 18 13:35 X15
srwxrwxrwx. 1 carlos phoelex 0 Nov 18 13:35 X17
srwxrwxrwx. 1 marco phoelex 0 Nov 18 13:35 X18
srwxrwxrwx. 1 michal phoelex 0 Nov 18 13:35 X19
srwxrwxrwx. 1 greg greg 0 Nov 18 13:35 X2
srwxrwxrwx. 1 carlos phoelex 0 Mar 16 19:17 X20
srwxrwxrwx. 1 candido phoelex 0 Nov 18 14:11 X23
srwxrwxrwx. 1 mihai phoelex 0 Nov 18 14:00 X25
srwxrwxrwx. 1 hakim phoelex 0 Jan 20 18:41 X26
srwxrwxrwx. 1 bindu phoelex 0 Mar 16 14:05 X28
srwxrwxrwx. 1 michal phoelex 0 Nov 18 13:51 X3
srwxrwxrwx. 1 candido phoelex 0 Feb 2 22:47 X33
srwxrwxrwx. 1 andrew phoelex 0 Nov 20 13:03 X4
srwxrwxrwx. 1 candido phoelex 0 Nov 18 14:11 X44
srwxrwxrwx. 1 ed phoelex 0 Nov 18 13:35 X5
srwxrwxrwx. 1 leighton phoelex 0 Nov 18 13:35 X50
srwxrwxrwx. 1 kathryn phoelex 0 Nov 18 13:35 X6
srwxrwxrwx. 1 candido phoelex 0 Nov 18 14:11 X66
srwxrwxrwx. 1 candido phoelex 0 Nov 18 14:11 X77
srwxrwxrwx. 1 simon phoelex 0 Dec 2 16:10 X8
srwxrwxrwx. 1 valerio phoelex 0 Nov 18 13:35 X9
srwxrwxrwx. 1 candido phoelex 0 Nov 18 14:11 X99
/tmp/.XIM-unix:
total 0
Check if there are any Xvnc processes using that display: No
(base) [carlos@pulsar ~]$ ps -ef | grep Xvnc
bindu 5815 1 0 14:05 ? 00:00:00 /usr/bin/Xvnc :28 -auth /home/bindu/.Xauthority -desktop pulsar:28 (bindu) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/bindu/.vnc/passwd -rfbport 5928 -rfbwait 30000
scott 6368 1 0 2020 ? 00:05:09 /usr/bin/Xvnc :13 -auth /home/scott/.Xauthority -desktop pulsar:13 (scott) -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/scott/.vnc/passwd -rfbport 5913 -rfbwait 30000
stuart 21911 1 0 2020 ? 1-04:07:56 /usr/bin/Xvnc :10 -auth /home/stuart/.Xauthority -desktop pulsar:10 (stuart) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/stuart/.vnc/passwd -rfbport 5910 -rfbwait 30000
kathryn 22580 1 0 2020 ? 01:28:35 /usr/bin/Xvnc :6 -auth /home/kathryn/.Xauthority -desktop pulsar:6 (kathryn) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/kathryn/.vnc/passwd -rfbport 5906 -rfbwait 30000
carlos 22581 1 0 2020 ? 11:55:01 /usr/bin/Xvnc :17 -auth /home/carlos/.Xauthority -desktop pulsar:17 (carlos) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/carlos/.vnc/passwd -rfbport 5917 -rfbwait 30000
ed 22583 1 0 2020 ? 00:05:02 /usr/bin/Xvnc :5 -auth /home/ed/.Xauthority -desktop pulsar:5 (ed) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/ed/.vnc/passwd -rfbport 5905 -rfbwait 30000
amir 22586 1 0 2020 ? 00:31:29 /usr/bin/Xvnc :1 -auth /home/amir/.Xauthority -desktop pulsar:1 (amir) -fp catalogue:/etc/X11/fontpath.d -geometry 3840x2160 -pn -rfbauth /home/amir/.vnc/passwd -rfbport 5901 -rfbwait 30000
ranga 22587 1 6 2020 ? 7-11:43:15 /usr/bin/Xvnc :11 -auth /home/ranga/.Xauthority -desktop pulsar:11 (ranga) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/ranga/.vnc/passwd -rfbport 5911 -rfbwait 30000
zak 22588 1 0 2020 ? 00:05:09 /usr/bin/Xvnc :15 -auth /home/zak/.Xauthority -desktop pulsar:15 (zak) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/zak/.vnc/passwd -rfbport 5915 -rfbwait 30000
marco 22589 1 0 2020 ? 00:00:00 /usr/bin/Xvnc :18 -auth /home/marco/.Xauthority -desktop pulsar:18 (marco) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/marco/.vnc/passwd -rfbport 5918 -rfbwait 30000
valerio 22590 1 0 2020 ? 00:21:37 /usr/bin/Xvnc :9 -auth /home/valerio/.Xauthority -desktop pulsar:9 (valerio) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/valerio/.vnc/passwd -rfbport 5909 -rfbwait 30000
greg 22591 1 0 2020 ? 01:05:06 /usr/bin/Xvnc :2 -auth /home/greg/.Xauthority -desktop pulsar:2 (greg) -fp catalogue:/etc/X11/fontpath.d -geometry 3840x2107 -pn -rfbauth /home/greg/.vnc/passwd -rfbport 5902 -rfbwait 30000
leighton 22592 1 0 2020 ? 00:00:00 /usr/bin/Xvnc :50 -auth /home/leighton/.Xauthority -desktop pulsar:50 (leighton) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/leighton/.vnc/passwd -rfbport 5950 -rfbwait 30000
michal 22593 1 0 2020 ? 05:05:55 /usr/bin/Xvnc :19 -auth /home/michal/.Xauthority -desktop pulsar:19 (michal) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/michal/.vnc/passwd -rfbport 5919 -rfbwait 30000
ext-gue+ 26418 26214 0 2020 pts/0 00:02:22 /usr/bin/Xvnc :7 -auth /home/ext-guest/.Xauthority -desktop pulsar:7 () -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/ext-guest/.vnc/passwd -rfbport 5907 -rfbwait 30000
ext-jiri 26446 26212 0 2020 pts/0 00:04:36 /usr/bin/Xvnc :12 -auth /home/ext-jiri/.Xauthority -desktop pulsar:12 () -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/ext-jiri/.vnc/passwd -rfbport 5912 -rfbwait 30000
michal 34129 1 0 2020 ? 00:04:41 /usr/bin/Xvnc :3 -auth /home/michal/.Xauthority -desktop pulsar:3 (michal) -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/michal/.vnc/passwd -rfbport 5903 -rfbwait 30000
mihai 35252 1 2 2020 ? 3-10:20:08 /usr/bin/Xvnc :25 -auth /home/mihai/.Xauthority -desktop pulsar:25 (mihai) -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/mihai/.vnc/passwd -rfbport 5925 -rfbwait 30000
candido 38366 1 0 2020 ? 17:13:51 /usr/bin/Xvnc :23 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:23 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5923 -rfbwait 30000
candido 38417 1 0 2020 ? 06:14:52 /usr/bin/Xvnc :44 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:44 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5944 -rfbwait 30000
candido 39445 1 0 2020 ? 00:08:03 /usr/bin/Xvnc :66 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:66 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5966 -rfbwait 30000
candido 40622 1 0 2020 ? 00:05:32 /usr/bin/Xvnc :77 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:77 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5977 -rfbwait 30000
candido 41288 1 0 2020 ? 04:14:29 /usr/bin/Xvnc :99 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:99 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5999 -rfbwait 30000
pablo 52358 1 0 2020 ? 04:15:07 /usr/bin/Xvnc :14 -auth /home/pablo/.Xauthority -desktop pulsar:14 (pablo) -fp catalogue:/etc/X11/fontpath.d -geometry 3840x2160 -pn -rfbauth /home/pablo/.vnc/passwd -rfbport 5914 -rfbwait 30000
andrew 95615 1 0 2020 ? 01:11:49 /usr/bin/Xvnc :4 -auth /home/andrew/.Xauthority -desktop pulsar:4 (andrew) -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/andrew/.vnc/passwd -rfbport 5904 -rfbwait 30000
candido 177587 1 0 Feb02 ? 00:10:23 /usr/bin/Xvnc :33 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:33 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5933 -rfbwait 30000
hakim 218843 1 0 Jan20 ? 02:20:58 /usr/bin/Xvnc :26 -auth /home/hakim/.Xauthority -desktop pulsar:26 (hakim) -fp catalogue:/etc/X11/fontpath.d -geometry 3840x2160 -pn -rfbauth /home/hakim/.vnc/passwd -rfbport 5926 -rfbwait 30000
carlos 222978 1 0 19:17 pts/182 00:00:00 /usr/bin/Xvnc :20 -auth /home/carlos/.Xauthority -desktop pulsar:20 (carlos) -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/carlos/.vnc/passwd -rfbport 5920 -rfbwait 30000
simon 229121 1 2 2020 ? 2-19:19:09 /usr/bin/Xvnc :8 -auth /home/simon/.Xauthority -desktop pulsar:8 (simon) -fp catalogue:/etc/X11/fontpath.d -geometry 3840x2080 -pn -rfbauth /home/simon/.vnc/passwd -rfbport 5908 -rfbwait 30000
carlos 237583 126579 0 19:22 pts/182 00:00:00 grep --color=auto Xvnc
(base) [carlos@pulsar .vnc]$ pgrep Xvnc --list-full
5815 /usr/bin/Xvnc :28 -auth /home/bindu/.Xauthority -desktop pulsar:28 (bindu) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/bindu/.vnc/passwd -rfbport 5928 -rfbwait 30000
6368 /usr/bin/Xvnc :13 -auth /home/scott/.Xauthority -desktop pulsar:13 (scott) -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/scott/.vnc/passwd -rfbport 5913 -rfbwait 30000
21911 /usr/bin/Xvnc :10 -auth /home/stuart/.Xauthority -desktop pulsar:10 (stuart) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/stuart/.vnc/passwd -rfbport 5910 -rfbwait 30000
22580 /usr/bin/Xvnc :6 -auth /home/kathryn/.Xauthority -desktop pulsar:6 (kathryn) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/kathryn/.vnc/passwd -rfbport 5906 -rfbwait 30000
22581 /usr/bin/Xvnc :17 -auth /home/carlos/.Xauthority -desktop pulsar:17 (carlos) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/carlos/.vnc/passwd -rfbport 5917 -rfbwait 30000
22583 /usr/bin/Xvnc :5 -auth /home/ed/.Xauthority -desktop pulsar:5 (ed) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/ed/.vnc/passwd -rfbport 5905 -rfbwait 30000
22586 /usr/bin/Xvnc :1 -auth /home/amir/.Xauthority -desktop pulsar:1 (amir) -fp catalogue:/etc/X11/fontpath.d -geometry 3840x2160 -pn -rfbauth /home/amir/.vnc/passwd -rfbport 5901 -rfbwait 30000
22587 /usr/bin/Xvnc :11 -auth /home/ranga/.Xauthority -desktop pulsar:11 (ranga) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/ranga/.vnc/passwd -rfbport 5911 -rfbwait 30000
22588 /usr/bin/Xvnc :15 -auth /home/zak/.Xauthority -desktop pulsar:15 (zak) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/zak/.vnc/passwd -rfbport 5915 -rfbwait 30000
22589 /usr/bin/Xvnc :18 -auth /home/marco/.Xauthority -desktop pulsar:18 (marco) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/marco/.vnc/passwd -rfbport 5918 -rfbwait 30000
22590 /usr/bin/Xvnc :9 -auth /home/valerio/.Xauthority -desktop pulsar:9 (valerio) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/valerio/.vnc/passwd -rfbport 5909 -rfbwait 30000
22591 /usr/bin/Xvnc :2 -auth /home/greg/.Xauthority -desktop pulsar:2 (greg) -fp catalogue:/etc/X11/fontpath.d -geometry 3840x2107 -pn -rfbauth /home/greg/.vnc/passwd -rfbport 5902 -rfbwait 30000
22592 /usr/bin/Xvnc :50 -auth /home/leighton/.Xauthority -desktop pulsar:50 (leighton) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/leighton/.vnc/passwd -rfbport 5950 -rfbwait 30000
22593 /usr/bin/Xvnc :19 -auth /home/michal/.Xauthority -desktop pulsar:19 (michal) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/michal/.vnc/passwd -rfbport 5919 -rfbwait 30000
26418 /usr/bin/Xvnc :7 -auth /home/ext-guest/.Xauthority -desktop pulsar:7 () -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/ext-guest/.vnc/passwd -rfbport 5907 -rfbwait 30000
26446 /usr/bin/Xvnc :12 -auth /home/ext-jiri/.Xauthority -desktop pulsar:12 () -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/ext-jiri/.vnc/passwd -rfbport 5912 -rfbwait 30000
34129 /usr/bin/Xvnc :3 -auth /home/michal/.Xauthority -desktop pulsar:3 (michal) -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/michal/.vnc/passwd -rfbport 5903 -rfbwait 30000
35252 /usr/bin/Xvnc :25 -auth /home/mihai/.Xauthority -desktop pulsar:25 (mihai) -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/mihai/.vnc/passwd -rfbport 5925 -rfbwait 30000
38366 /usr/bin/Xvnc :23 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:23 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5923 -rfbwait 30000
38417 /usr/bin/Xvnc :44 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:44 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5944 -rfbwait 30000
39445 /usr/bin/Xvnc :66 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:66 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5966 -rfbwait 30000
40622 /usr/bin/Xvnc :77 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:77 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5977 -rfbwait 30000
41288 /usr/bin/Xvnc :99 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:99 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5999 -rfbwait 30000
52358 /usr/bin/Xvnc :14 -auth /home/pablo/.Xauthority -desktop pulsar:14 (pablo) -fp catalogue:/etc/X11/fontpath.d -geometry 3840x2160 -pn -rfbauth /home/pablo/.vnc/passwd -rfbport 5914 -rfbwait 30000
95615 /usr/bin/Xvnc :4 -auth /home/andrew/.Xauthority -desktop pulsar:4 (andrew) -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/andrew/.vnc/passwd -rfbport 5904 -rfbwait 30000
115649 /usr/bin/Xvnc :21 -auth /home/humberto/.Xauthority -desktop pulsar:21 (humberto) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/humberto/.vnc/passwd -rfbport 5921 -rfbwait 30000
177587 /usr/bin/Xvnc :33 -auth /home/candido/.Xauthority -depth 24 -desktop pulsar:33 (candido) -fp catalogue:/etc/X11/fontpath.d -geometry 1920x1080 -pn -rfbauth /home/candido/.vnc/passwd -rfbport 5933 -rfbwait 30000
218843 /usr/bin/Xvnc :26 -auth /home/hakim/.Xauthority -desktop pulsar:26 (hakim) -fp catalogue:/etc/X11/fontpath.d -geometry 3840x2160 -pn -rfbauth /home/hakim/.vnc/passwd -rfbport 5926 -rfbwait 30000
222978 /usr/bin/Xvnc :20 -auth /home/carlos/.Xauthority -desktop pulsar:20 (carlos) -fp catalogue:/etc/X11/fontpath.d -geometry 1024x768 -pn -rfbauth /home/carlos/.vnc/passwd -rfbport 5920 -rfbwait 30000
229121 /usr/bin/Xvnc :8 -auth /home/simon/.Xauthority -desktop pulsar:8 (simon) -fp catalogue:/etc/X11/fontpath.d -geometry 3840x2080 -pn -rfbauth /home/simon/.vnc/passwd -rfbport 5908 -rfbwait 30000
Check if there are any processes listening on the corresponding ports: No
(base) [carlos@pulsar ~]$ sudo netstat -ltnp | grep -w ':5916'
(base) [carlos@pulsar ~]$ sudo netstat -ltnp | grep -w ':6016'
For comparison, this is for a working VNC session:
(base) [carlos@pulsar ~]$ sudo netstat -ltnp | grep -w ':5917'
tcp6 0 0 :::5917 :::* LISTEN 22581/Xvnc
(base) [carlos@pulsar ~]$ sudo netstat -ltnp | grep -w ':6017'
tcp6 0 0 :::6017 :::* LISTEN 22581/Xvnc
Check that the port is open: Yes
(base) [carlos@pulsar ~]$ sudo firewall-cmd --permanent --zone=public --add-port=5916/tcp
Warning: ALREADY_ENABLED: 5916:tcp
success
(base) [carlos@pulsar ~]$ sudo firewall-cmd --reload
success
So I tried to telnet from the server itself:
(base) [carlos@pulsar .vnc]$ telnet localhost 5916
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
telnet: connect to address 127.0.0.1: Connection refused
In the case of a working session I can connect:
(base) [carlos@pulsar .vnc]$ telnet localhost 5917
Trying ::1...
Connected to localhost.
Escape character is '^]'.
RFB 003.008
^CConnection closed by foreign host.
When scanning the ports from a different machine in the same LAN:
(base) [carlos@blazar ~]$ nmap pulsar.phoelex.com -Pn -p 5916
Starting Nmap 6.40 ( http://nmap.org ) at 2021-03-16 19:32 GMT
Nmap scan report for pulsar.phoelex.com (192.168.1.33)
Host is up (0.00028s latency).
PORT STATE SERVICE
5916/tcp closed unknown
Nmap done: 1 IP address (1 host up) scanned in 0.04 seconds
(base) [carlos@blazar ~]$ nmap pulsar.phoelex.com -Pn -p 5917
Starting Nmap 6.40 ( http://nmap.org ) at 2021-03-16 19:33 GMT
Nmap scan report for pulsar.phoelex.com (192.168.1.33)
Host is up (0.00035s latency).
PORT STATE SERVICE
5917/tcp open unknown
Nmap done: 1 IP address (1 host up) scanned in 0.04 seconds
Looking at the IP tables, IN_public_allow/deny section:
(base) [carlos@pulsar .vnc]$ sudo iptables -L -n
Chain IN_public_allow (1 references)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 ctstate NEW,UNTRACKED
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:137 ctstate NEW,UNTRACKED
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:138 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:139 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:445 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5901 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5902 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5915 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5913 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5917 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5916 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5908 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5914 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5009 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5909 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5921 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5920 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5922 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5904 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5905 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5906 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5950 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5918 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5919 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5910 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5911 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:111 ctstate NEW,UNTRACKED
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:111 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:2049 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:24007 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:24008 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5907 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5923 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5924 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5925 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5903 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5926 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5928 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5912 ctstate NEW,UNTRACKED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5927 ctstate NEW,UNTRACKED
Chain IN_public_deny (1 references)
target prot opt source destination
At this point I'm out of ideas what could be causing this, and starting to worry that it might be something malicious. Any further steps to debug this issue would be highly appreciated.
