Hughes Network DirecWay DW4020, User Manual, Page: 79 / 102

Configuring the Firewall
49
Port Numbers and
Protocol IDs
The Internet Assigned Numbers Authority (IANA) maintains the official list of
Port Numbers and Protocol IDs used on the Internet. You can see this list at:
http://www.iana.org/numbers.html.
Some common port numbers that you might want to use in firewall rules are
shown in Table 1. Some common protocol IDs are shown in Table 2.
Port
Number
Internet Application or Protocol
80 Hypertext Transfer Protocol (HTTP). Used to access Web servers.
21 FTP control port. Used to access File Transfer Protocol (FTP) servers.
23 Telnet. Used to login to other computers.
53 Domain Name Server (DNS). Used to obtain an IP address corresponding to a computer’s name.
25 Simple Mail Transfer Protocol (SMTP). Used to send E-mail to an E-mail server.
79 Finger. Used to check if a computer is up.
107 Remote Telnet Service (RTELNET). Used to login to computers.
110 Post Office Protocol – Version 3 (POP3). Used for retrieving E-mail from and E-mail server.
119 Network News Transfer Protocol (NNTP). Used for accessing Usenet News.
Table 6: Common port numbers
Protocol
ID
Internet Protocol
1 Internet Control Message Protocol (ICMP). Includes control messages such as “ping”.
6 Transmission Control Protocol (TCP).
17 User Datagram Protocol (UDP). Used for streaming audio and video, DNS service, and many other
applications.
Table 7: Common protocol IDs