DenyHosts is a utility developed by Phil Schwartz and maintained by a number of developers which aims to thwart sshd (ssh server) brute force attacks. If you've ever looked at your ssh log (/var/log/auth.log) you may be alarmed to see how many hackers attempted to gain access to your server. Denyhosts helps you: - Parses /var/log/auth.log to find all login attempts - Can be run from the command line, cron or as a daemon (new in 0.9) - Records all failed login attempts for the user and offending host - For each host that exceeds a threshold count, records the evil host - Keeps track of each non-existent user (eg. sdada) when a login attempt failed. - Keeps track of each existing user (eg. root) when a login attempt failed. - Keeps track of each offending host (hosts can be purged) - Keeps track of suspicious logins - Keeps track of the file offset, so that you can reparse the same file - When the log file is rotated, the script will detect it - Appends /etc/hosts.allow - Optionally sends an email of newly banned hosts and suspicious logins. - Resolves IP addresses to hostnames, if you want WWW: https://github.com/denyhosts/denyhosts