Banner Grabbing is a technique used to gain information about a computer system on a network and the services running on its open ports. Administrators can use this to take inventory of the systems and services on their network. However, an intruder can use banner grabbing in order to find network hosts that are running versions of applications and operating systems with known exploits. For example, one could establish a connection to a target web server using Netcat, then send an HTTP request. The response will typically contain information about the service running on the host: