对于大量的命令输出文本，我提前表示抱歉，我认为这比我自己解释更清楚。
我正在使用 CentOS 7 和 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
当我尝试在显示器 :16（对应端口 5916）上启动 vnc 会话时，出现此错误，
(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
我已经习惯了这种情况，所以我开始寻找罪魁祸首。
检查是否有锁：没有
(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
检查是否有任何 Xvnc 进程使用该显示：否
(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
检查是否有任何进程在监听相应端口：否
(base) [carlos@pulsar ~]$ sudo netstat -ltnp | grep -w ':5916'
(base) [carlos@pulsar ~]$ sudo netstat -ltnp | grep -w ':6016'
为了进行比较，这是一个正在运行的 VNC 会话：
(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
检查端口是否开放：是
(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
因此我尝试从服务器本身进行 telnet：
(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
在工作会话中我可以连接：
(base) [carlos@pulsar .vnc]$ telnet localhost 5917
Trying ::1...
Connected to localhost.
Escape character is '^]'.
RFB 003.008
^CConnection closed by foreign host.
当从同一局域网内的不同机器扫描端口时：
(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
查看 IP 表，IN_public_allow/deny 部分：
(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
此时，我不知道是什么原因导致了这种情况，并开始担心这可能是恶意的。任何进一步的调试此问题的步骤都将不胜感激。
答案1
这并不是真正的解决方案，但由于不相关的原因，我们不得不重新启动服务器，然后问题就消失了。