Connectivity Testing Beyond the Network Layer 🌐

Netcat: A Swiss Army Knife for Connectivity Testing 🛠️

Netcat on Linux and MacOS is a powerful tool that can be used to test connectivity at the transport layer. The nc command has two mandatory arguments: a host and a port. Running nc google.com 80 would try to establish a connection on port 80 to google.com. If the connection succeeds, you'll see a blinking cursor waiting for more input, allowing you to send application-layer data to the listening service.

Checking Port Status 🔍

To simply check the status of a port, you can use the -z (zero input output mode) and -v (verbose) flags with the nc command. The output will tell you whether a connection to the specified port is possible or not.

Test-NetConnection on Windows 💻

On Windows, the Test-NetConnection command provides similar functionality. If you run Test-NetConnection with only a host specified, it will default to using an ICMP echo request, much like the ping program, but it will display more data, including the data link layer protocol being used. When you add the -port flag, you can test connectivity to a specific port.

Beyond the Basics 🚀

It's important to note that both Netcat and Test-NetConnection are way more powerful than the brief port connectivity examples covered here. These are complex tools with a wide range of functionality, and covering all their capabilities would be too much for a single article. We encourage you to explore the full capabilities of these super powerful tools through further research and experimentation.