Netcat

Testing network connections and computer communications has become increasingly complicated with the deluge of new networking products and server applications. Many network administrators rely on tools such as Ping, Telnet, and packet sniffers to diagnose and test network and server connections. Although these tools let you test network connections and probe remote machines, they don't let you open an arbitrary connection across your network (e.g., specifying both source and destination ports) or set up a temporary client-server connection to quickly copy a file or redirect output from an application on one machine to another. To solve these problems and more, consider using what many call the Swiss Army knife of the network and security administrator's toolkit—Netcat.

Netcat's elegant simplicity belies its power and utility. Let's discuss how to use this handy tool to open network connections, perform port scans, transfer files, and redirect standard input and output. Attackers have also used this tool to set up back doors and infiltrate computer networks. Regardless of whether you choose to add Netcat to your repertoire of security and network tools, you'll benefit from understanding the capabilities that this flexible tool provides. . . .