since last checked, and numerous other means to detect unusual events. Once a system administrator has constructed a suitable object-database – ideally with help and advice from the HIDS installation tools – and initialized the checksum-database, the HIDS has all it requires to scan the monitored objects regularly and to report on anything that may appear to have gone wrong. Reports can take the form of logs, e-mails or similar. Protecting the HIDS A HIDS will usually go to great lengths to prevent the object-database, checksum-database and its reports from any form of tampering. After all, if intruders succeed in modifying any of the objects the HIDS monitors, nothing can stop such intruders from modifying the HIDS itself – unless security administrators take appropriate precautions. Many worms and viruses will try to disable anti-virus tools, for example. Apart from crypto-techniques, HIDS might allow administrators to store the databases on a CD-ROM or on other read-only memory devices (another factor in favor of infrequent updates...) or storing them in some off-system memory. Similarly, a HIDS will often send its logs off-system immediately – typically using VPN channels to some central management system. One could argue that the trusted platform module comprises a type of HIDS. Although its scope differs in many ways from that of a HIDS, fundamentally it provides a means to identify whether anything/anyone has tampered with a portion of a computer. Architecturally this provides the ultimate (at least ) host-based intrusion detection, as depends on hardware external to the CPU itself, thus making it that much harder for an intruder to corrupt its object and checksum databases. Reception InfoWorld states that host-based intrusion-detection system software is a useful way for network managers to find malware, and suggest they run it on every server, not just critical servers. See also Host-based intrusion detection system comparison IBM Internet Security Systems – commercial HIDS / NIDS Open Source Tripwire – open source HIDS OSSEC – a multi-platform open source HIDS Trusted Computing Group References External links Deep Security – a commercial multi-platform HIDS Lacework HIDS – a commercial HIDS for cloud deployments Intrusion detection systems