步骤：

• sudo apt-get install xinetd telnetd     安装成功后，系统会显示有相应得提示
• sudo vim /etc/inetd.conf  并加入内容:  telnet stream tcp nowait telnetd /usr/sbin/tcpd /usr/sbin/in.telnetd
• 输入sudo vim /etc/xinetd.conf并加入内容：

# Simple configuration file for xinetd
# Some defaults, and include /etc/xinetd.d/
defaults
  {
    # Please note that you need a log_type line to be able to use log_on_success
    # and log_on_failure. The default is the following :
    # log_type = SYSLOG daemon info
    instances = 60
    log_type = SYSLOG authpriv
    log_on_success = HOST PID
    log_on_failure = HOST
    cps = 25 30
  }
  includedir /etc/xinetd.d

• sudo vim /etc/xinetd.d/telnet并加入以下内容：

# default: on
# description: The telnet server serves telnet sessions; it uses # unencrypted username/password pairs for authentication.
service telnet
  {    
    disable = no
    flags = REUSE
    socket_type = stream
    wait = no
    user = root
    server = /usr/sbin/in.telnetd
    log_on_failure += USERID
  }

• 重启机器或重启网络服务sudo /etc/init.d/xinetd restart
• telnet localhost 23 测试

linux开启telnet服务