DenyHosts is a Python script that analyzes the sshd server log messages to determine what hosts are attempting to hack into your system. It also determines what user accounts are being targeted. It keeps track of the frequency of attempts from each host.DenyHosts is designed for the use by Linux system administrators, the script can be useful to anybody running an sshd server. Now how does Denyhosts work? How to install/Configure denyhosts on Ubuntu/Debian and Fedora/RHEL/CentOS ?