Have you ever been curious about the different types of network protocols? Computer networking is a very diverse subject, with protocols for a variety of scenarios. These protocols all interact on some level to accomplish an overall goal, but their stated purposes are fairly focused in scope.
So, without bogging you down with jargon, terminology, and technical details, this will instead be a high-level guide to the world of computer networking. You don’t need to be a whiz with wire crimpers and a line tester, though that might come later if this is an interesting subject.
Mail and Communication Protocols
Mail and communication protocols have a long history in computer networking. Some of the most basic messaging protocols used date back well into the late 70s and early 80s. However, you’ll typically only see a handful of these with modern use.
Mail protocols are still in heavy use today, typically with email clients on the web and as standalone applications. You’re likely interacting with at least one of these regularly without even thinking about it. Out of the many different types of network protocols, mail and communication have the slimmest focus.
SMTP, or Simple Mail Transfer Protocol, is one of two primary ways computers can receive and send emails. This protocol uses header information to determine where an email is intended to go. Outgoing emails are the primary concern of SMTP.
This is a much older protocol, dating back to 1978 when it was first implemented. As such, it doesn’t incorporate some of the newer features you’ll see. End-to-end encryption and obfuscation aren’t built into the protocol, so might have to be implemented elsewhere.
SMTP is still in wide use, with popular hosts like Hotmail, Gmail, and others using it as the primary means of sending and routing emails.
POP3, or Post Office Protocol version 3, is yet another mail protocol. Where it differs from SMTP is that it’s solely concerned with the retrieval of emails. SMTP is concerned with outbound messages, and POP3 handles inbound messages.
It’s a little more complicated than SMTP. POP3 uses a pair of internal agents, or MAAs. These messaging agents reside on the server and whichever computer is accessing the email. The pair of agents allows for the retrieval and management of emails.
POP3 is the most recent revision of the protocol, but this is still a very dated protocol. More modern email clients have been slowly phasing out the reliance on POP3, with newer protocols being more flexible.
The third and final mail-specific protocol is IMAP. It stands for Internet Message Access Protocol, and it is often used as an alternative to POP3. The greatest strength of IMAP is that it allows for multiple computers to access the same email account.
Everything on IMAP is stored on the server. Messages, emails, and other forms of communication are stored off-site. This allows for greater access to email if you’ve got multiple devices, like say a laptop, smartphone, and desktop.
IMAP isn’t an ideal solution, similar to POP3. Its usage is very situational. Further, it requires greater bandwidth needs, making it a poor choice for low-bandwidth network connections.
You’d be forgiven for thinking this is another client-specified protocol. ICMP, or Internet Control Message Protocol, is a little more specialized, though. This protocol is used for the delivery of error reports and diagnostic data.
As such, this is something more familiar to IT personnel than home networks. ICMP is a great solution for error reporting because of the size of the messages. Normally, an error message might be too large for a malfunctioning router to handle.
Routers deal with a slew of different data formats like packets, frames, and so forth. In the event that a packet is too large for a router to deal with, an ICMP message is used. This is typically used to trace routes in a network or to ping web servers.
ICMP does have its drawbacks and is a very common method of attack for bad actors. Since messaging isn’t authenticated, any user can send a deluge of ICMP requests. This can lead to a loss of service for servers.
File Transfer Protocols
When it comes to file transfer protocols, they have a very niche focus and purpose. The average user isn’t likely to interact with most of these directly. However, direct access is still in common use for IT personnel. These protocols are built for the express purpose of sending or receiving files.
Now, most file transfers are handled with these protocols but usually work in conjunction with other connection or web protocols. As such, the access from the end-user is a little more streamlined.
FTP, or File Transfer Protocol, is straight to the point in its overall goal. It can be thought of as the backbone for most network access. If you’ve accessed a web page at any point in your life, you’ve used FTP. Directly accessing FTP is a little more involved than clicking a link on a web page.
You’ll often need a client, login information, and a server. What makes FTP great is that it scales well, depending on the needs of whoever is using it. FTP is also the backbone of modern cloud computing. It does lack security, with login information being transmitted in cleartext. FTP is suited more for internal communications these days, with its more recent variant being suitable for external use.
SFTP is a more modern take on FTP and stands for Secure File Transfer Protocol. Unlike the older FTP, SFTP utilizes encryption and other security measures. This is the typical method you’ll see for most web transfers online, even if you don’t see the nuts and bolts of the interaction.
SFTP is a better choice for enterprise use, as well, since data is encrypted along with login details. SFTP also readily integrates with SSH, which is a secure connectivity protocol that will be looked at later on. Simply put, if you’re doing any sort of file sharing or uploading online, SFTP is the preferred method of doing it these days.
Gopher is a file transfer protocol that has fallen by the wayside in recent years. It was originally introduced in the early 90s to serve as a means of obtaining and sending files to web documents. Its heyday was in the early days of the web.
Gopher was an interesting solution for an emerging problem, combining search engines, Usenet, and FTP functionality to deliver files to users. However, by the late 1990s, it had fallen out of use entirely for most consumers. These days, it is relegated to a small band of die-hard users and doesn’t see much serious use.
Of the different types of network protocols, the web is probably the most commonly seen and used. This is the domain of things like websites, online apps, and anything else accessing the greater web. There are only two main variants, which you’ll see below.
HTTP, or Hypertext Transfer Protocol, is the way the world interacts with the internet at large. When you open a web browser, even when it loads a start page, you’re using HTTP. HTTP itself is a bit outdated these days, and rather insecure since information can be seen clearly.
However, HTTP has served as the primary means of interaction for decades. The protocol itself has some strict definitions for formatting and sending data. As such, it remains the dominant way of seeing text, video, images, and audio on the internet. HTTP also directly interacts with other network protocols, but its primary use is the delivery of information from the web.
HTTPS, or Hypertext Transfer Protocol Secure, is functionally identical to HTTP in terms of scope. However, where it diverges from the older standard is the incorporation of security features. Web pages using HTTPS are required to use SSL/TLS connections and are generally certified. Why this is good for users comes down to why masking any data in motion is a great idea. It protects the user while keeping the base functionality of the service
Of the different types of network protocols, connectivity is arguably the most vital. These are the network protocols that actually allow computers to see and communicate with each other directly. Most of these protocols are in use by the lion’s share of devices on the web.
IPv4, or Internet Protocol Version 4, is the most popular internet protocol in existence. You interact with it daily, and every device in your home likely uses it. At its core, IPv4 is an addressing system. It logically assigns a hexadecimal address to each device on a network.
Despite being a connectivity protocol, both IPv4 and IPv6 don’t have an explicit need for an established connection. It works in tandem with TCP and UDP, which will be covered a little further down. IPv4 is outmoded, despite being the most popular internet protocol.
IPv4 has a limited number of potential addresses, with the grand total allowed being a little over four billion. There are far more networked devices on the planet, however, so there are alternative solutions. That said, most internet connections are going to assign your device an address based on IPv4.
IPv6, or Internet Protocol Version 6, directly addresses the shortcomings of IPv4. At its core, it is functionally similar. It is a logical addressing system that doesn’t require a connection to function. IPv6 has a number of noteworthy benefits in addition to its larger potential addresses.
IPv6 provides authentication and encryption, which are going to be more and more vital as the internet grows with humanity. The adoption of IPv6 is slow going, but more and more internet service providers are using it. With time, it’ll likely be the dominant means of logically assigning an ID to devices going forward.
TCP is the backbone of data exchange between computers. Transmission Control Protocol, or TCP, is what works alongside IPv4, IPv6, and a host of other interfaces to actually connect to the internet. At its most basic level, TCP allows for data to be broken down into more acceptable formats for computers to interpret.
You don’t see this while actually browsing the web or listening to Spotify. Instead, it happens seamlessly in the background. TCP is the replacement for the older UDP, with both working to complete network handshakes between two or more computers. TCP is a more secure and overall complete solution compared to UDP, however.
UDP, or User Datagram Protocol, is another connectivity protocol that doesn’t bear the same benefits as TCP. Both UDP and TCP operate as a connection suite. UDP/IP has largely fallen out of favor, and for good reason. Whereas TCP waits to establish a connection, UDP can send data without a connection.
This can lead to lost data or less reliable connections. In the event that a connection isn’t stable, UDP will actually lose data, compared to TCP delaying sending it. As such, UDP is better suited for local area connections. If you’re looking for a more viable means of handling internal and external connections, TCP is the way to go.
PPP is the most basic means of connecting two computers. This is a largely outdated method of establishing a connection but still seems some use from time to time. You’ll more commonly see it as the primary means of connecting a modem to an internet service provider.
PPP is short for Point-to-Point Protocol and is fairly limited in scope. Since it’s a two-way communication, a PPP connection will allow for mutual authentication and handshake completion. You won’t see this in typical local area networks. That said, it’ll usually be implemented as the final link in the chain, providing connectivity to the wider web as a whole.
TELNET was one of the first ways a computer could reliably remotely access another computer. It has largely fallen out of favor. TELNET, or terminal network, has its origins in the earliest days of computer networking. It still sees use, mostly in local area connections where you’re handling connecting to a server or nearby workstations.
However, it sends data with no masking, and there is no encryption. If a network administrator or user is accessing something on the wider web with TELNET, any bad actor can see what is happening. As such, you’ll want to use TELNET’s successor for more secure remote access.
SSH, or Secure Shell, is the final protocol in this exhaustive list. Like TELNET, SSH allows for remote access to another computer. Where it differs is in authentication. SSH requires you to have valid and proven credentials, usually handled by administrators further up the chain.
Data is also encrypted, meaning commands, text, and everything else is masked from the public eye. SSH is the preferred method of remote connection for Linux and Unix-based operating systems. Any IT personnel working with these operating systems are going to rely on SSH quite heavily.
SSH is a great choice for internal or external access to resources, thanks in part to the built-in security. Functionally, it is identical to TELNET, allowing remote access of resources and commands to another computer.
Why Are There So Many Network Protocols?
Why are there so many different network protocols, anyway? To put it simply, each protocol has its own purpose and use. As such, you’re not going to rely on a basic file transfer protocol to handle your mail and vice versa. These network protocols don’t operate on their own.
Each one described over the course of this exhaustive guide will interact with others over the course of a transaction. Take getting an email as an example. You’ll be retrieving messages with POP3 and sending them out with SMTP. However, you’ll still need to be connected to a network, so you’re using IPv4 or IPv6 along with TCP.
The email still has to leave your home network and go out to the wider world, so it’ll be going out on a PPP connection. This is a massive oversimplification of the whole process, but networking is complex. This article could very easily cover just one of these protocols just as exhaustively, and these are the building blocks of the modern network.
That said, there are so many network protocols because having specialized protocols to handle a single task is a lot easier than trying to cram functionality into one single protocol. Think of it like various tools. You wouldn’t use a hammer to cut a board, nor would you use a screwdriver to level concrete.
Hopefully, you’ve come away from this massive list with a better understanding of the different network protocols and their overall use. Computer networking is a dense subject, but it can be quite a bit of fun to see how everything works together.
The image featured at the top of this post is ©Eakrin Rasadonyindee/Shutterstock.com.