Mr.TechSparrow

As a business evolves from a small local operation into a large enterprise, its technological and security requirements scale rapidly. Opening international branch offices and establishing third-party vendor partnerships mean that users across the globe suddenly need constant, reliable access to centralized servers in the corporate HQ, private data centers, or cloud environments.  Historically, companies relied on dedicated leased lines (like MPLS) to achieve this. However, leased lines are notoriously expensive, slow to provision, and lock businesses into rigid carrier contracts. This is where Site-to-Site VPNs come into play. By leveraging standard, cost-effective internet connections, a Site-to-Site VPN creates a secure, encrypted tunnel over the public internet, allowing remote locations to access corporate resources as if they were physically present on the local network. In this guide we will look into how to setup a Route-Based VPN which is easier to configure and manage tha...

GNS3 is an industry-standard tool used by students and network professionals alike for emulating complex network environments. While it runs natively on Linux distributions with virtually no issues, Windows users often face frustrating limitations when trying to emulate modern appliances from various vendors. To run heavy network emulations on Windows, the official recommendation is to use the GNS3 VM running inside VMware Workstation. However, this creates a massive headache for modern Windows users. If you are running Docker, WSL2 (Windows Subsystem for Linux), or Hyper-V, Windows requires the "Virtual Machine Platform" feature to be enabled. Historically, this feature violently clashes with VMware, preventing the GNS3 VM from booting or causing massive performance drops. The ultimate workaround? Stop fighting Windows. In this guide, we will learn how to bypass these nested virtualization issues entirely by building your own dedicated GNS3 Server on a native Linux backend....

Recently, I set up a GNS3 server using an Ubuntu 24.04 VM to run and test my network emulations. While working on a project, I needed to establish an SSH connection between the host (the Ubuntu 24.04 server) and the virtual GNS3 appliances running inside it. The basic network configuration was straightforward, and I could ping the devices just fine. However, I quickly hit a wall when trying to SSH into legacy appliances (like the Cisco C7200). Because modern Ubuntu 24.04 uses updated OpenSSH protocols, it actively rejects the older cryptographic algorithms offered by these legacy devices. Getting this working required some specific SSH workarounds, so I decided to turn this into a runbook documentation for my future self—and for anyone else dealing with connection refused errors in their GNS3 labs. Prerequisites Before we jump into the SSH workarounds, make sure you have the base lab environment up and running: A Working GNS3 Server: For this guide, we are using an Ubuntu 24.04 host. ...