A port scan is a series of messages sent by someone attempting to break into a computer to learn which computer network services, each associated with a "well-known" port number, the computer provides. Port scanning, a favorite approach of computer cracker, gives the assailant an idea where to probe for weaknesses. Essentially, a port scan consists of sending a message to each port, one at a time. The kind of response received indicates whether the port is used and can therefore be probed for weakness.
By submitting your email address, you agree to receive emails regarding relevant topic offers from TechTarget and its partners. You can withdraw your consent at any time. Contact TechTarget at 275 Grove Street, Newton, MA.
Types of port scans include:
- Vanilla - An attempt to connect to all ports (there are 65,536)
- Strobe - An attempt to connect to only selected ports (typically, under 20)
- Stealth scan - Several techniques for scanning that attempt to prevent the request for connection being logged
- FTP Bounce Scan - Attempts that are directed through an File Transfer Protocol server to disguise the cracker's location
- Fragmented Packets - Scans by sending packet fragments that can get through simple packet filters in a firewall
- UDP - Scans for open User Datagram Protocol ports
- Sweep - Scans the same port on a number of computers