DenyHosts helps system administrators thwart SSH server attacks by blocking IP addresses using failed authentication attempts, adding them to the /etc/hosts.deny file.
DenyHosts is an open-source program created in Python that helps system administrators prevent dictionary and brute force SSH attacks by analyzing SSH server log files to identify IP addresses that are performing multiple failed login attempts. When DenyHosts detects an IP address that has surpassed the allowed threshold for failed logins, it automatically adds that IP address to the system's /etc/hosts.deny file to block any further connection attempts.
Some key features of DenyHosts include:
By leveraging DenyHosts to block access from IP addresses associated with too many failed SSH login attempts, administrators can significantly reduce malicious activity on their systems. It provides a simple yet effective extra layer of security on top of SSH for both small and large server deployments.