telnet 测试端口是否打开

[root@mysqld ~]# yum list |grep telnet
telnet.x86_64                               1:0.17-48.el6               @base   
telnet-server.x86_64                        1:0.17-48.el6               base    
[root@mysqld ~]# which telnet
/usr/bin/telnet
[root@mysqld ~]# yum list |grep telnet