FTP: Defines the file transfer protocol, port 2 1.

Elnet: it is a port for remote login. Users can connect to the computer remotely as themselves. Through this port, communication service based on DOS mode can be provided. Port 23

SMTP: A simple mail transmission protocol is defined, and now many mail servers use it to send mail. Simple mail transfer protocol

POP3: corresponding to SMTP, POP3 is used to receive mail. 1 10 port

Commonly used UDP protocol ports are:

HTTP: This is the most commonly used protocol, which is usually called Hypertext Transfer Protocol. Hypertext transfer protocol

DNS: used for domain name resolution service, which is most used in Windows NT system. Port 53

SNMP: Simple network management protocol, used to manage network devices.

16 1 port

Service type default port

Echo 7 daytime 13

FTP 2 1

Telnet 23

SMTP 25

Time 37

Whois 43

DNS 53

Gopher 70

Finger 79

WWW 80

POP3 1 10

NNTP 1 19

IRC 194