Administrators must stay aware of updates to software as well as the latest system compromise techniques. Due to this difficult task, system security is often not maintained and is lacking in many areas. This is illustrated by the increased number of reports that entail system compromise. This dilemma changed for me when I discovered the freeware tools offered by Psionic Software, Inc. called PortSentry and Logcheck. Within minutes, these tools can be installed and configured to improve system security dramatically.
Once a host is targeted by an attacker, a port scan is almost always performed. The port scan is done to expose all services available on the target host and to provide a starting point for break-in attempts. PortSentry detects such scans by monitoring the unused ports on the host. Upon a connection attempt to one of the unused ports, PortSentry is alerted and has the ability to issue a number of commands in response to the scan. The commands issued are configured by the administrator within a configuration file. Although any command may be used, the most helpful is one in which the IP address of the attacker's host is essentially "black holed" by issuing a routing command that denies all traffic from that address.
News: Host Security
