• 安装 telnet 服务

yum install xinetd telnet telnet-server -y

telnet安装

• 启动 telnet 服务

# 这两条命令设置开机时自动启动telnet服务
systemctl enable telnet.socket
systemctl enable xinetd

# 启动telnet服务
systemctl start telnet.socket
systemctl start xinetd

# 查看telnet服务的状态
systemctl status telnet.socket
systemctl status xinetd

查看telnet服务的状态

• 防火墙开放 telnet 服务端口

cd /usr/lib/firewalld/services
vim telnet.xml

写入以下内容:

<?xml version="1.0" encoding="utf-8"?>
<service>
  <short>Telnet</short>
  <description>Telnet is a protocol for logging into remote machines. It is unencrypted, and provides little security from network snooping attacks. Enabling telnet is not recommended. You need the telnet-server package installed for this option to be useful.</description>
  <port port="23" protocol="tcp"/>
</service>

然后在终端键入命令:

firewall-cmd --add-service=telnet --zone=public --permanent

查看防火墙是否开放 telnet 服务端口的命令:

查看防火墙是否开放telnet服务端口

• 关闭 telnet 服务

  由于 telnet 服务安全性低, 现在普遍都是用 ssh 远程连接, 故在必要地时候可以关闭 telnet服务:

systemctl stop telnet.socket
systemctl stop xinetd
firewall-cmd --remove-service=telnet --permanent # 防火墙不开放telnet服务端口
firewall-cmd --reload