138 Glossary
port number
port scan
proxy
router
server
service
socket
stealth
subnet
A logical communications channel to be used by a particular TCP/IP application. Each application has unique port numbers associated with it. By convention, some protocols use a
An attempt to gain access to a computer by searching for open ports. Usually done by an automated program that sends a request to each port at an IP address, listening for responses that could reveal a vulnerability.
A mechanism that lets one system act on behalf of another system when responding to protocol requests. Security programs in firewalls use proxy services to screen the secured network from users on the Internet.
A device on a network that links computers or interconnected networks. A router receives packets and forwards them to their destination via the best available route.
The control computer on a local area network that controls software access to workstations, printers, and other parts of the network.
Protocols that let one computer access a type of data stored on another computer. Many host computers that are connected to the Internet offer services. For example, HTTP servers use the Hypertext Transfer Protocol to provide World Wide Web service and FTP servers offer File Transfer Protocol services. See also port.
An identifier for a particular service on a particular computer. A socket consists of the IP address of the computer followed by a colon and the port number.
Giving the impression of not existing by not responding to requests for information.
A local area network that is part of a larger intranet or the Internet.
