Binary is just another way of counting. Instead of using base-10 (decimal), we use base-2 where each place value is a bit.
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Basic Regex Character Matching
Learn how to match standard character classes with regular expressions.
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Access Control Lists for Beginners
Access control lists (ACLs) provide a simple but effective layer of security in modern networks.
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ARP: The Address Resolution Protocol
ARP helps us match IP addresses to hardware (MAC) addresses.
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Block Ciphers
Block ciphers operate on blocks of data of a particular size.
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CDP and LLDP
CDP and LLDP are similar layer two protocols for discovering information about neighboring devices.
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Custom Sets in Regular Expressions
Learn to define your own sets of characters to be matched with a regular expression.
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DNS: The Domain Name System
DNS is used to resolve friendly names (e.g. www.example.com) to IP addresses (e.g. 1.2.3.4), making it vital to our use of the internet.
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Collision and Broadcast Domains
Collision and broadcast domains are important properties of an Ethernet network.
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Ethernet at the Data-Link Layer
At the data-link layer, Ethernet provides an interface between the physical layer and the higher network layers. It also specifies MAC address formats.
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Ethernet at the Physical Layer
Ethernet sits at the link layer in TCP/IP but what does it define about the OSI physical layer?
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Firewalls in Computer Networking
Firewalls play an important part in protecting modern computer networks.
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Hashes and Computer Security
A cryptographic hash is a one way function for which it is very difficult to get back the input when given just the output.
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How does HTTP work?
HTTP is used by web browsers and many other applications to retrieve websites and much more.
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How does IPv4 work?
IPv4 has been at the heart of the TCP/IP stack since it's inception. It is slowly being replaced by IPv6.
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How to use the man pages on Linux
Getting help on Linux with the 'man pages' and where else to look.
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How does traceroute work?
The traceroute command is useful tool installed on hosts and network devices for troubleshooting networking issues by tracing the route of a packet across a network.
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Introduction to IPv4 Routing
IP routing is at the heart of the internet. It enables us to get packets from A to B across the globe.
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Linux directory commands for beginners
All the basics you need to learn for moving around the filesystem on the command line.
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NAT: Network Address Translation
NAT is the mapping of one address to another. It is a useful tool for conserving IP address space.
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Netcat Field Guide
Netcat (nc) is a simple but versatile utility for TCP and UDP communication.
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Regex Anchors
We can specify where we want to match with a regular expression using word and string boundaries.
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Ping and ICMP
Ping is a useful tool for checking network connectivity using the Internet Control Message Protocol (ICMP).
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Regex Subexpressions
Subexpressions let us split a regular expression up into smaller groups which we can use for many things!
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Matching a Certain Number of Repetitions with Regex
Use regular expressions to match on a certain number (or range) of repetions of a certain character or class of characters.
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RIP and RIPv2, The Routing Information Protocol
RIP was one of the first routing protocols to be implemented. RIPv2 later added a number of improvements.
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Routing Between VLANs
To let devices on one VLAN talk to the devices on another, we need to be able to route between them.
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Same layer and adjacent layer interactions
Learn about interactions at the same layer and between adjacent layers, including encapsulation and protocol data units (PDUs).
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Stream Ciphers
Stream ciphers are encryption algorithms which encrypt data one bit at a time.
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Summary of the TCP/IP Model
An overview of TCP/IP, or the Internet Protocol Suite, which underpins all modern computer networks.
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TCP: The Transmission Control Protocol
TCP is a connection-oriented protocol used at the transport layer to support protocols such as HTTP.
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Telnet vs SSH
Telnet and SSH are both protocols used for interacting with remote devices. Learn about the differences and the details.
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The Complete Guide to IPv4 Subnetting
Learn how to design subnets and calculate the number of hosts on each.
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The Linux Terminal and Shell
Learn about the Linux terminal and why it's so useful.
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The OSI 7 Layer Reference Model
A conceptual network model which is often used as a reference but not implemented practically.
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Types of Memory in Computer Architecture
There are different types of memory available for storing data in a computer. Learn about what they are and what they are used for.
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UDP: User Datagram Protocol
UDP is a simple transport layer protocol.
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Virtual LANs (VLANs)
VLANs are used in modern computer networks to support logically separate LANs on a single device.
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VLSM Subnetting in Networks
VLSM helps make more efficient use of available IP address space.
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What are Regular Expressions?
Regular expressions are patterns specified with a defined syntax which are used to search text for specific sequences of characters with many practical applications.
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WAN Technologies - HDLC, PPP, Frame Relay and Ethernet
Wide Area Networks may use one of several layer 2 technologies to encapsulate data as it cross a service providers network between a customer’s sites.
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What do network switches do?
Learn what network switches do in a TCP/IP network and how they work.
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What is a computer network?
An overview of what might constitute a computer network.
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What is a LAN?
Learn about devices found on local-area networks and how they are connected.
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What is a WAN?
Wide area networks enable data to be transferred across large geographic distances.