Netstat, unofficially short for network statistics, is a computer program used for network monitoring and diagnostic purposes. It can detect and display active network connections or open ports on a computer, making it a useful tool for both average users and network administrators. Some potential uses for the program include diagnosing network problems and inspecting a computer for Trojans or spyware. It is included with or available for virtually every major operating system primarily as a command-line tool, although graphical interfaces also exist.
Generally the intimate details of a computer’s network connections are hidden from view. Most users are content to see whether or not their computer is connected to a network and able to exchange data over that network. There are times, however, when it is useful or necessary to dig deeper and look at just what a computer is up to behind the scenes. Netstat is a software utility that enables users to do precisely this by displaying a myriad of networking information.
Netstat works by monitoring and detecting network connections between a user’s computer and other machines on either a local network or the Internet. It’s versatile enough to differentiate between multiple network protocols and can also display routing information that shows how a computer will connect to a particular network location. The program can also detect on which ports, if any, a computer is listening for incoming connections.
There are a number of reasons a user may wish to inspect their network activity using netstat. The program can be used to look for or diagnose network problems, since it can display both open connections and the number of errors that have occurred in trying to reach a remote server. It can also be used to search for malware or spyware; unexplained network connections on a computer with few or no open programs could be caused by malicious software acting without a user’s knowledge. Open ports can also be an indication of a Trojan waiting for instructions from remote systems.
One of the factors contributing to netstat’s popularity is its inclusion in virtually all modern operating systems, from Microsoft® Windows® to Linux and Unix-like operating systems. It was designed as a command-line tool, meaning a user must type commands into a terminal or command prompt. Users unfamiliar with a command line interface may wish to consult the manual or help file by typing “netstat /?” on Windows® or “man netstat” on other platforms. Several programs that provide a graphical interface to netstat also exist and may be more appealing to those with little or no command-line experience.