1、在虚拟机安装完ubuntu（此时可能不具备安装软件的功能）
2、更新软件安装包：
sudo apt-get update
sudo apt-get upgrade
3、安装telnet服务：
sudo apt-get install openbsd-inetd
sudo apt-get install xinetd telnetd
4、修改配置文件：
1）nano /etc/inetd.conf
添加：telnet stream tcp nowait telnetd /usr/sbin/tcpd /usr/sbin/in.telnetd
2）nano /etc/xinetd.conf
# 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
3）nano /etc/xinetd.d/telnet
# 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
}
5、重启网络服务
service xinetd restart
如果未安装xinetd服务，先安装一下：sudo apt-get install xinetd