FTP: file transfer protocol, TCP, 2 1 control port, 20 data transfer port, file transfer protocol.
SNMP: Simple Network Management Protocol, UDP, 16 1 and 162, Simple Network Management Protocol.
SMTP: Simple mail transfer protocol, TCP 25 corresponds to POP3, port 1 10, and mail transfer protocol.
ICMP: Internet control message protocol, which belongs to neither TCP nor UDP, is a transmission control protocol, mainly used for network testing and error notification.
HDLC: It is not a part of TCP/IP protocol, but an underlying control, which is mainly used for wide-area line, point-to-point and synchronous link control.
TELNET:TCP 23
Arp/rarp: Address resolution protocol/reverse address resolution protocol Address resolution and reverse address resolution do not belong to TCP and UDP, but the bottom layer of IP protocol, IP and MAC address resolution.