Port scanning software has long been in the hacker's arsenal and is finally emerging as an important defensive tool as well. This is where port scanners come in with this tool, a system, network, or security administrator can check a group of hosts all at once. But running this command means actually walking or remotely accessing each and every server and you miss other host systems that might be listening on improper ports. The most common host-based tool for checking for open ports on Windows or Unix systems is the netstat command.

In some cases, the services might be Trojans just waiting to be exploited. System administrators are constantly being advised to check their systems for open ports and services that might be running that are either unintended or unnecessary. Port Scanning: It's Not Just an Offensive Tool AnymoreĪn edited version of this paper with the title 'Plugging Leaky Holes' originally appeared in the June 2001 issue of Information Security Magazine ( Copyright © 2001.

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