Network Ports and Services
CPS 411, Essentials: IT Network Practitioners, Boise State University Boise, Idaho
Darren Dayton
darrendayton@u.boisestate.edu
Abstract—Network ports and services are utilized extensively throughout the world to
facilitate and expedite the internet as a whole, and the commerce, record storage,
entertainment, and utility contained therein.
Index Terms—Ports, Network, Services, Internet, Intranet
Table of Contents
Item Page(s)
Abstract
Index Terms Page 1
Introduction
Section 1: Ports Pages 2 and 3
Section 2: Charts and Graphs Page 3
Conclusion Page 4
References
I. INTRODUCTION should not be in use for a given
The internet is a great tool to use for organization.
businesses, but if not used and understood Listed in the following sections are, in
properly it can also be a great tool for my opinion, the five most important ports,
criminals to use against businesses. followed by a brief description of them, and
One of the most important things when their uses.
setting up and securing a network, in order After that I will list some services that
for a business to successfully and securely aren’t necessarily bound to ports that are
access the internet, is to understand what also important to both understand, and to
ports are used for, and what ones should and have locked down for security.
II. ANY PORT IN A STORM[1] their own, they get grouped together. These
There are quite literally over sixty- are the ports that make the internet run, in a
five thousand ports available, and they are very real and literal way. If we couldn’t
divided into three groups: well-known, transfer files, and more importantly control
registered, and dynamic. the transfer of files, then a large portion of
the internet would be at best useless.
Ports 0-1023 are the well-known
ports, while the registered ports are from To be completely fair, though, ports
1024-49151, and dynamic from 49152- 20 and 21 are considered outdated and
65535. Now obviously there’s no need or insecure, and port 22 has taken over the job
really any use in memorizing these port to a certain extent. Port 22 does quite a few
numbers, but there is a use in being familiar important things, including SSH, or Secure
with how they function and recognizing at Shell, which allows remote logins among
least a few of the most commonly used ones. other things, but also secure logins, secure
file transfers through SCP or SFTP, and
The ones we will talk about here are,
even port forwarding. [2],[3]
of course, the well-known ones. To some
extent, any of these ports could be in this As for some other ports that are
listing, but these are the ones I think are important, near to our last few is another
most critical to understanding what is critical port, port 25, or SMTP. SMTP
happening to our business electronically. (Simple Mail Transfer Protocol) is basically
another name for email, and that has had one
Starting with ports 20 and 21, we
of the most profound effects on business and
have FTP, or File Transfer Protocol. To be
communications in general.
specific, port 20 is FTP data, and port 21 is
FTP control, but since they’re rarely used on
The next port to talk about is port 53, III. CHARTS AND GRAPHS
or DNS. Domain Name Server is another Here are a couple of helpful charts and
name for the service that allows us to use listings of commonly used ports, and what
names like Google.com instead of having to they are used for, courtesy of StationX, a
memorize or otherwise document and store cybersecurity company. [4]
their IP addresses. If DNS didn’t exist, and
we hadn’t already created a similar
workaround, then the internet as it stands
would be a far less useful and user-friendly
place.
Speaking of the internet, let’s talk
about the port(s) that make it functional for
us humans: ports 80 and 443. HTTP and
HTTPS. These are the ports and services
that make web browsers useable, and
therefore control and delineate our ability to
use the internet as we do. HTTPS, or port
443, is the more secure, and therefore the
recommended option, but much of the
internet is still using HTTP, in the same vein
that many file servers are still using ports 20
and 21, rather than 22.
IV. CONCLUSION
In conclusion, there are a number of ports and services that are important to know about,
whether you work in networking or not, and while refreshers or quick overviews like this are
excellent for gaining a bare minimum understanding of how they work, it is both critical and
fairly easy to get a far more in-depth education on this subject.
REFERENCES
[1]
CISA.gov, “Cyber Storm | CISA,” Cybersecurity and Infrastructure Security Agency CISA,
2024. https://www.cisa.gov/resources-tools/services/cyber-storm (accessed Sep. 09, 2024).
[2]
W. Goralski, “Registered Port - an Overview | ScienceDirect Topics,” www.sciencedirect.com,
2017. https://www.sciencedirect.com/topics/computer-science/registered-port (accessed Sep. 08,
2024).
[3]
“50 Common Ports You Should Know,” GeeksforGeeks, Feb. 25, 2022.
https://www.geeksforgeeks.org/50-common-ports-you-should-know/ (accessed Sep. 08, 2024).
[4]
N. House, “List of Common Ports Cheat Sheet,” Station X, Jul. 07, 2020.
https://www.stationx.net/common-ports-cheat-sheet/ (accessed Sep. 08, 2024).
