TDSSKiller might be a bit more popular than Ossec. We know about 1 link to it since March 2021 and only 1 link to Ossec. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
I'd take it one step further and install OSSEC as well. It can be configured to run as a local daemon and report suspicious activity, and also intervene. So if somebody is brute-forcing the login on your web page, it'll create a burst of 401s which OSSEC will detect in the logs and block the offender for X minutes/hours. Source: over 2 years ago
I would also recommend running TDSSKiller to look for rootkits, you can download here. Source: over 1 year ago
snort - Snort is a free and open source network intrusion prevention system.
GMER - GMER is an application that detects and removes rootkits .
McAfee Network Security Platform - McAfee Network Security Platform guards all your network-connected devices from zero-day and other attacks, with a cost-effective network intrusion prevention system.
Malwarebytes Anti-Rootkit - Malwarebytes Anti-Rootkit is a rootkit removal program by the Malwarebytes best known for providing the antimalware program.
Wazuh - Open Source Host and Endpoint Security
McAfee Stinger - McAfee Stinger is a single purpose program designed to detect and remove the specific virus from the system.