What tool can help mitigate dictionary attacks on SSH by managing host access?

DenyHosts is a tool specifically designed to protect SSH servers from unauthorized access, particularly from dictionary attacks, which involve iterative guessing of passwords. It works by monitoring SSH login attempts and automatically blocking IP addresses that exhibit suspicious behavior, such as multiple failed login attempts within a short time frame. By managing host access in this way, DenyHosts effectively reduces the likelihood of successful unauthorized access.

In contrast, while fail2ban is also a valid security tool that can address dictionary attacks by banning IP addresses that fail login attempts repeatedly, DenyHosts is focused solely on SSH and is particularly geared towards handling dictionary attack scenarios. iptables, on the other hand, is a general-purpose firewall utility that can control access to a system at a more fundamental network level, but it does not specifically manage SSH login attempts dynamically based on activity. The "man in the middle" option does not relate to mitigating dictionary attacks; it describes a type of attack rather than a defense mechanism.