In an attempt to further my understanding of web security, I have found myself diving deeper into networking and how devices interact on a network. Like all disciplines, the first step towards grasping more complex ideas is to learn the vernacular. Networking is complex and the design of a network plays an integral role in the security of any system. In this post, I aim to break down the fundamentals of networking lingo.
Network: Any two devices (known as nodes) connected in any way constitute the basics of a network. This can be through a wired connection, Bluetooth, Wi-Fi, or any other medium. The idea of a network is simply a connection of devices. The internet is the world’s largest network.
Server: Any device that provides a service. For example, an API (application programming interface) may serve data for use by a web application. Here is an example of a simple API that serves statistics about the United States. There is a device somewhere that is serving this information.
Client: A device that is accessing a service. Whichever device you are using to access this blog is acting as a client in two ways. Considering the last example, your device is the client accessing the data about the USA. Additionally, your device is acting as the client to access this blog, which is also being served by some device (likely a server in a large server warehouse somewhere in the USA).
Port: A communication endpoint with specific configurations depending on data-type. A port is much like a radio frequency. Certain types of music are broadcast on different frequencies. In a computer network, certain ports are used for specific purposes. There are a lot of ports and this chart illustrates the complexity quite well:
Protocol: A set of rules about data. Protocol is much like grammar in a language. There are certain rules about how words can be used, and because those rules are adhered to, communication can be achieved. Here’s a link to some more common networking protocols with detailed explanations.
Packet: A small piece of a larger message. When data is sent over a network, it is divided into smaller chunks as a way of maximizing the efficiency of the network. If information was not broken into smaller chunks, then a single transmission of data would hog the infrastructure until the transmission was complete. By dividing communication into packets, multiple transmissions can occur simultaneously. Packets can also travel in distinct routes to the same destination. Once packets arrive at a destination, they are reassembled back to their original state.
Packet Tracer: A visualization tool developed by Cisco Systems to help networking professionals understand how packets move inside of a network. Packets contain tons of information and that information can inform network engineers as networks become more and more complex.
Repeater: An antiquated device used to combat signal decay in cables over long distances.
Hub: A hub is a physical device that receives packets in a single port and repeats that signal to at least two other ports.
Switch: A switch receives packets and routes them to nodes on the network based on an address such as an IP Address or MAC address. Switches only repeat packets to their desired destination and thus improve security as well as efficiency.
Firewall: A firewall can be hardware or software, but the premise is that a firewall uses a set of rules to block certain types of traffic for a given port or ports. Firewalls use automated rules to permit or disallow a packet from passing which means that they are a great tool for filtering traffic, but not an end-all solution for cyber security.
IDS: Intrusion Detection Systems, unlike a firewall do not filter traffic, instead these systems act more like an alarm that will alert an administrator if a networking vulnerability is being exploited. IDS systems can slow down network traffic, and as a result often analyze replicas of packets travelling through a network. This eliminates latency issues on a network and allow an IDS to perform more complex analysis than a simple firewall.
IPS: Intrusion Prevention Systems work in real-time and randomly analyze network traffic for anomalies and for specific patterns. This functions a lot like a quality control engineer working on an assembly line. Every single item cannot be inspected without the assembly line slowing down significantly. Instead, an inspector can select every nth widget. If the nth widget (packet in the case of a network) is statistically different from other packets or matches the profile of other nefarious packets, then it can be discarded before it is delivered to the client.
WLC: A Wireless LAN (local area network) Controller is not only an acronym within an acronym, it is also a hardware device that can manage a large number of wireless access points. In an large building, each room may have a wireless access point that broadcasts a Wi-Fi signal to the room. All of the access points on a single floor may connect to a single WLC. WLCs often add a layer of security by controlling what kind of traffic is permitted.