【Application layer】
Function: Work with applications to exchange application-specific data using the underlying network.
——Application layer protocol application——
21 FTP file transfer protocol, used for uploading and downloading.
69 TFTP Trivial File Transfer Protocol.
25 SMTP Simple Mail Transfer Protocol, send and receive mail.
110 POP3 Post Office Protocol version 3, the client receives mail.
53 DNS Domain Name Resolution Protocol.
80 HTTP Hypertext Transfer Protocol.
443 HTTPS Secure Hypertext Transfer Protocol.
23 Telnet remote management login target host.
——Telnet remote management——
Premise setting: Set management IP, console password.
Switch: (any VLAN interface)
Switch(config)# int v 1
Switch(config-if)# ip address 192.168.1.1 255.255.255.0
Configure remote management IP address
Router: (any network interface)
Route(config)# int f 0/1
Route(config-if)# ip address 192.168.1.1 255.255.255.0
Switch(config-line)# line vty 0 4 represents 01234, while allowing 5 remote management terminals
Route(config-line)# line vty 0 4 stands for 01234, allowing 5 remote management terminals at the same time
Configure the remote management IP address
Computer
Start-->Run-->cmd
to execute: telnet <target host IP address> [port number 23] Remote management host
ip routing The Layer 3 switch enables the routing function.
----telnet 192.168.1.1 192.168.1.254 routing