Figure 1 shows the three ranges used for port numbers.  Ports 0 through 1023 are classified as well known ports.  Numbers 1024 through 49151 are registered ports.  Ports 49152 through 65535 are considered private and slash or dynamic ports. Figure 2 lists a dozen of the more common well-known port numbers including FTP (20 and 21), SSH (22), SMTP (25), DNS (53), DHCP (67 and 68), TFTP (69), HTTP (80), POP3 (110), IMAP (143), SNMP (161), and HTTPS (443).