ngrep:tldr:19dd3

The command ngrep -d ${eth0} port ${22} is used to perform a network packet capture on the specified interface (eth0 in this case) and filter the captured packets based on the port number (22 in this case).

Here's a breakdown of the command:

• ngrep: This is the name of the command-line network packet analyzer tool that will be used for capturing and analyzing network traffic.
• -d ${eth0}: This option specifies the network interface to capture packets from. In this case, it is set to ${eth0}, which is typically an environment variable that holds the name of the network interface. Replace ${eth0} with the actual interface name (e.g., eth0) when running the command.
• port ${22}: This is a filter expression used to capture packets that are specific to the port number 22. Port 22 is commonly used for SSH (Secure Shell) traffic. Replace ${22} with the actual port number if needed.

In summary, this command captures all network traffic on the specified network interface (eth0) that is related to the SSH protocol (port 22). It can be useful for monitoring SSH connections and analyzing network activity related to SSH.