Network Fundamentals: Top Picks
The Importance of a Network Analyzer – Packet Sni…
Network Analyzers, also known as Packet Sniffers, are amongst the most popular network tools found inside any Network Engineer’s toolkit. A Network A…
Firewall Topologies
In this section we are going to talk about the different ways a firewall can be set up. Depending on your needs, you can have a very simple firewall…
Network Broadcast
The term "Broadcast" is used very frequently in the networking world . You will see it in most networking books and articles, or see it happening on…
Multicast - Understand How IP Multicast Works
Multicast is a communication method used in computer networking where data is sent from a single sender to a group of destination devices. In this m…
Featured Subcategories:
Netflow Articles:
Netflow vs SNMP. Two Different Approaches to Netw…
SNMP (Simple Network Management Protocol) and Netflow are both popular protocols with admins, prized for their ability to give visibility over the ne…
Netflow: Monitor Bandwidth & Network Utilization…
Monitoring network traffic & bandwidth usage via Netflow is mandatory for any type and size network. Gaining visibility into user traffic, applic…
Complete Guide to Netflow: How Netflow & its Comp…
This article will cover the basics of Netflow, including its use cases, Netflow supported devices, Netflow history, and variants. We’ll also dive int…
NetFlow Analyzer: Free Download, Step-by-Step Ins…
In our previous article we explained how a Netflow Analyzer can help you gain visibility into your user traffic, application traffic and data flows w…
Network Protocols:
IP Protocol - Part 1: Binary & The Internet Proto…
To understand the Internet Protocol, we need to learn and understand Binary. It is very important to know and understand Binary because part of the I…
The DNS Protocol - Part 4: DNS Response Message F…
The previous article covered the DNS Query message formats. In the article we analysed them in great detail and showed how various options are select…
TCP Header Anaylsis - Section 3: TCP Header Lengt…
The third field under close examination is the TCP Header length. There really isn't that much to say about the Header length other than to explain w…
UDP Protocol - Header
This article covers the UDP protocol. We examine the structure of the UDP header, the protocols that use UDP as a transport plus a lot more.
Some co…
IP Subnetting - Part 2: Subnet Masks & Their Effe…
There are a few different ways to approach subnetting and it can get confusing because of the complexity of some subnets and the flexibility they off…
TCP Header Anaylsis - Section 1: TCP Source & Des…
This section contains one of the most well-known fields in the TCP header, the Source and Destination port numbers. These fields are used to specify…
IP Subnet Calculator
This free online Subnet Calculator provides a fast and easy way to calculate all aspects of any IP Address and Subnet Mask. Simply enter your desir…
The Supernetting / CIDR Chart
This articles build upon our previous pages covering what is Supernetting (Route Summarization) & How Supernets Work and Supernetting In-De…
STP/ICMP Protocols:
ICMP Protocol - Part 2: Echo / Echo Reply (Ping)…
As mentioned in the previous page, an Echo is simply what we networking engineers call a 'ping'. The Echo Reply is, as most would guess, the 'p…
Spanning Tree Protocol – Part 2: Rapid STP Port C…
Spanning Tree Protocol, Rapid STP port costs and port states are an essential part of the STP algorithm that affect how STP decides to forward or blo…
ICMP Protocol - Part 5: Source Quench Message Ana…
The ICMP - Source Quench message is one that can be generated by either a gateway or host. You won't see any such message pop up on your workstation…
ICMP Protocol - Part 1: Introduction
The Internet Control Message Protocol (ICMP), is a very popular protocol and actually part of an Internet Protocol (IP) implementation. Because IP wa…
All-in-one protection for Microsoft 365
FREE Hyper-V & VMware Backup
Enterprise-Class Cloud & Network Monitoring
Wi-Fi Key Generator
Network and Server Monitoring
Follow Firewall.cx
Recommended Downloads
Cisco Password Crack
Decrypt Cisco Type-7 Passwords on the fly!
Bandwidth Monitor
Free PatchManager
Security Podcast
Firewall Analyzer
The VLAN Concept - Introduction to VLANs
We hear about them everywhere, vendors around the world are constantly trying to push them into every type of network and as a result, the Local Area Netw…
Dynamic VLANs
Dynamic VLANs were introduced to grant the flexibility and complexity(!) that Static VLANs did not provide. Dynamic VLANs are quite rare because of their…
VLANs - Access & Trunk Links
If you've read our previous article The VLAN Concept - Introduction to VLANs then you should feel comfortable with terms such as 'VLAN', 'Stati…
VTP Pruning
VTP (VLAN Trunking Protocol) pruning is a feature that is used in Cisco switches to reduce unnecessary traffic in VLAN (Virtual Local Area Network) trunks…
Routed Protocols
We all understand that TCP/IP, IPX-SPX are protocols which are used in a Local Area Network (LAN) so computers can communicate between with each other and…
OSPF - Part 4: OSPF Neighbor States – OSPF Neighbor Fo…
This is the third article of our OSPF series which analyzes the different OSPF States routers go through during the OSPF discovery and neighbor forming pr…
Distance Vector Routing Protocols
Distance Vector routing protocols use frequent broadcasts (255.255.255.255 or FF:FF:FF:FF) of their entire routing table every 30 sec. on all their interf…
Link State Routing Protocols
Link State routing protocols do not view networks in terms of adjacent routers and hop counts, but they build a comprehensive view of the overall network…