为什么需要telnet？
telnet就是查看某个端口是否可访问。我们在搞开发的时候，经常要用的端口就是 8080。那么你可以启动服务器，用telnet 去查看这个端口是否可用。
Linux centos 运行telnet命令，出现下面的错误提示：
[root@localhost ~]# telnet 127.0.0.1 8080 -bash: telnet: command not found
解决方法: 安装telnet服务
centos、ubuntu安装telnet命令的方法.
yum list telnet* 列出telnet相关的安装包
yum install telnet-server 安装telnet服务
yum install telnet.* 安装telnet客户端
[root@localhost ~]# yum list telnet* Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile * base: mirrors.cn99.com * extras: mirrors.shu.edu.cn * updates: mirrors.cn99.com Available Packages telnet.x86_64 1:0.17-48.el6 base telnet-server.x86_64 1:0.17-48.el6 base
[root@localhost ~]# yum install telnet-server Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile * base: mirrors.cn99.com * extras: mirrors.shu.edu.cn * updates: mirrors.cn99.com Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package telnet-server.x86_64 1:0.17-48.el6 will be installed --> Finished Dependency Resolution Dependencies Resolved ================================================================================ Package Arch Version Repository Size ================================================================================ Installing: telnet-server x86_64 1:0.17-48.el6 base 37 k Transaction Summary ================================================================================ Install 1 Package(s) Total download size: 37 k Installed size: 54 k Is this ok [y/N]: y Downloading Packages: telnet-server-0.17-48.el6.x86_64.rpm | 37 kB 00:00 Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Warning: RPMDB altered outside of yum. Installing : 1:telnet-server-0.17-48.el6.x86_64 1/1 Verifying : 1:telnet-server-0.17-48.el6.x86_64 1/1 Installed: telnet-server.x86_64 1:0.17-48.el6 Complete! [root@localhost ~]#
[root@localhost ~]# yum install telnet.* Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile * base: mirrors.cn99.com * extras: mirrors.shu.edu.cn * updates: mirrors.cn99.com Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package telnet.x86_64 1:0.17-48.el6 will be installed --> Finished Dependency Resolution Dependencies Resolved ==================================================================================================================================== Package Arch Version Repository Size ==================================================================================================================================== Installing: telnet x86_64 1:0.17-48.el6 base 58 k Transaction Summary ==================================================================================================================================== Install 1 Package(s) Total download size: 58 k Installed size: 109 k Is this ok [y/N]: y Downloading Packages: telnet-0.17-48.el6.x86_64.rpm | 58 kB 00:00 Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Installing : 1:telnet-0.17-48.el6.x86_64 1/1 Verifying : 1:telnet-0.17-48.el6.x86_64 1/1 Installed: telnet.x86_64 1:0.17-48.el6 Complete! [root@localhost ~]#