我有一個正在運行的系統xenial，我需要驗證特定連接埠是否打開，127.0.0.1因此我決定安裝telnet以嘗試連接該特定連接埠。
I've tried the following:
ron@regDesktopHome:/etc/ssl/certs$ sudo apt-get install telnetd -y
Reading package lists... Done
Building dependency tree
Reading state information... Done
telnetd is already the newest version (0.17-40).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
ron@regDesktopHome:/etc/ssl/certs$ sudo systemctl status inetd
● xinetd.service - LSB: Starts or stops the xinetd daemon.
Loaded: loaded (/etc/init.d/xinetd; bad; vendor preset: enabled)
Active: active (running) since Sun 2019-06-09 18:02:19 PDT; 10min ago
Docs: man:systemd-sysv-generator(8)
Process: 2050 ExecStop=/etc/init.d/xinetd stop (code=exited, status=0/SUCCESS)
Process: 2062 ExecStart=/etc/init.d/xinetd start (code=exited, status=0/SUCCESS)
Tasks: 1
Memory: 192.0K
CPU: 22ms
CGroup: /system.slice/xinetd.service
└─2080 /usr/sbin/xinetd -pidfile /run/xinetd.pid -stayalive -inetd_compat -inetd_ipv6
Jun 09 18:02:19 regDesktopHome xinetd[2080]: removing daytime
Jun 09 18:02:19 regDesktopHome xinetd[2080]: removing daytime
Jun 09 18:02:19 regDesktopHome xinetd[2080]: removing discard
Jun 09 18:02:19 regDesktopHome xinetd[2080]: removing discard
Jun 09 18:02:19 regDesktopHome xinetd[2080]: removing echo
Jun 09 18:02:19 regDesktopHome xinetd[2080]: removing echo
Jun 09 18:02:19 regDesktopHome xinetd[2080]: removing time
Jun 09 18:02:19 regDesktopHome xinetd[2080]: removing time
Jun 09 18:02:19 regDesktopHome xinetd[2080]: xinetd Version 2.3.15 started with libwrap loadavg options compiled in.
Jun 09 18:02:19 regDesktopHome xinetd[2080]: Started working: 1 available service
ron@regDesktopHome:/etc/ssl/certs$ telnet 127.0.0.1
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused
ron@regDesktopHome:/etc/ssl/certs$
這是怎麼回事，為什麼我無法連線localhost telnet？
答案1
nmap和lsof只是檢查連接埠的兩種更好的方法。
若要查看連接埠 1-100，
sudo nmap -p1-100 localhost
要查看哪些進程打開了端口80，
lsof -i tcp:80
當然，讀man nmap;man lsof。