如题也如图，本例以路由器为例（思科家交换机和路由器配置大同小异）
常规配置好路由器和pc后，保证二者ping得通
首先，打开telnet，加密码
R1#conf t Enter configuration commands, one per line. End with CNTL/Z. R1(config)#line vty 0 4 //vty虚拟端口允许0-4最多五个用户同时登陆 R1(config-line)#password abc123 R1(config-line)#login //开启验证 R1(config-line)#exit R1(config)#end R1# %SYS-5-CONFIG_I: Configured from console by console R1#show running //查看配置 Building configuration... Current configuration : 797 bytes ! version 12.2 no service timestamps log datetime msec no service timestamps debug datetime msec no service password-encryption ! hostname R1 ! ! ! enable password 123456 ! ! ! ip cef no ipv6 cef ! ! ! ! ! interface FastEthernet0/0 ip address 192.168.1.1 255.255.255.0 duplex auto speed auto ! interface FastEthernet1/0 no ip address duplex auto speed auto shutdown ! interface Serial2/0 no ip address clock rate 2000000 shutdown ! interface Serial3/0 no ip address clock rate 2000000 shutdown ! interface FastEthernet4/0 no ip address shutdown ! interface FastEthernet5/0 no ip address shutdown ! ip classless ! ip flow-export version 9 ! ! line con 0 ! line aux 0 ! line vty 0 4 //证明已开启telnet password abc123 login end
在pc 上启用cmd 进行telnet远程登陆，如图，可以登陆并进入路由器
然后在再关闭telnet
R1#conf t Enter configuration commands, one per line. End with CNTL/Z. R1(config)#line vty 0 4 R1(config-line)#transport input ? all All protocols none No protocols ssh TCP/IP SSH protocol telnet TCP/IP Telnet protocol R1(config-line)#transport input none //关闭所有输入协议，ssh和telnet R1(config-line)#exit R1(config)#end R1# %SYS-5-CONFIG_I: Configured from console by console R1#show running Building configuration... line con 0 ! line aux 0 ! line vty 0 4 password abc123 login transport input none ! ! ! end
这时就不能telnet登陆了。
小结：在使用transport命令的时候发现，旗下所指transport input all 包括ssh和telnet， 如果是none，则禁止了两个协议，如果要再次开启协议的话，我们可以用
transport input telnet 或者
transport input ssh
开启响应协议