Binary is just another way of counting. Instead of using base-10 (decimal), we use base-2 where each place value is a bit.
Learn how to match standard character classes with regular expressions.
Access control lists (ACLs) provide a simple but effective layer of security in modern networks.
ARP helps us match IP addresses to hardware (MAC) addresses.
Block ciphers operate on blocks of data of a particular size.
CDP and LLDP are similar layer two protocols for discovering information about neighboring devices.
Learn to define your own sets of characters to be matched with a regular expression.
DNS is used to resolve friendly names (e.g. www.example.com) to IP addresses (e.g. 126.96.36.199), making it vital to our use of the internet.
Collision and broadcast domains are important properties of an Ethernet network.
At the data-link layer, Ethernet provides an interface between the physical layer and the higher network layers. It also specifies MAC address formats.
Ethernet sits at the link layer in TCP/IP but what does it define about the OSI physical layer?
Firewalls play an important part in protecting modern computer networks.
A cryptographic hash is a one way function for which it is very difficult to get back the input when given just the output.
HTTP is used by web browsers and many other applications to retrieve websites and much more.
IPv4 has been at the heart of the TCP/IP stack since it's inception. It is slowly being replaced by IPv6.
Getting help on Linux with the 'man pages' and where else to look.
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.
IP routing is at the heart of the internet. It enables us to get packets from A to B across the globe.
All the basics you need to learn for moving around the filesystem on the command line.
NAT is the mapping of one address to another. It is a useful tool for conserving IP address space.
Netcat (nc) is a simple but versatile utility for TCP and UDP communication.
We can specify where we want to match with a regular expression using word and string boundaries.
Ping is a useful tool for checking network connectivity using the Internet Control Message Protocol (ICMP).
Subexpressions let us split a regular expression up into smaller groups which we can use for many things!
Use regular expressions to match on a certain number (or range) of repetions of a certain character or class of characters.
RIP was one of the first routing protocols to be implemented. RIPv2 later added a number of improvements.
To let devices on one VLAN talk to the devices on another, we need to be able to route between them.
Learn about interactions at the same layer and between adjacent layers, including encapsulation and protocol data units (PDUs).
Stream ciphers are encryption algorithms which encrypt data one bit at a time.
An overview of TCP/IP, or the Internet Protocol Suite, which underpins all modern computer networks.
TCP is a connection-oriented protocol used at the transport layer to support protocols such as HTTP.
Telnet and SSH are both protocols used for interacting with remote devices. Learn about the differences and the details.
Learn how to design subnets and calculate the number of hosts on each.
Learn about the Linux terminal and why it's so useful.
A conceptual network model which is often used as a reference but not implemented practically.
There are different types of memory available for storing data in a computer. Learn about what they are and what they are used for.
UDP is a simple transport layer protocol.
VLANs are used in modern computer networks to support logically separate LANs on a single device.
VLSM helps make more efficient use of available IP address space.
Regular expressions are patterns specified with a defined syntax which are used to search text for specific sequences of characters with many practical applications.
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.
Learn what network switches do in a TCP/IP network and how they work.
An overview of what might constitute a computer network.
Learn about devices found on local-area networks and how they are connected.
Wide area networks enable data to be transferred across large geographic distances.