These applications are mostly used in a business environment. They can log network traffic passively, or examine the logs of proxies etc... These programs are not installed on the individual computers. They are designed to run on a central server. They can only log things that pass through the network, not local things like entered passwords, keystrokes or screenshots.
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ESA is a security management application centered around providing a clean log history of potential vulnerabilities on a network. When implemented correctly it will manage all devices on the network for security exploits in real time.
