Description:

PHREL is a Per Host RatE Limiter written in C to efficiently track the rate of
incoming traffic on a per host basis and insert a chain into iptables when a
configured threshold is crossed. The inserted chain may either rate limit or
completely block the offending host for a period of time and will be
automatically removed when the offending host's traffic levels return to
normal. PHREL can be used with any type of traffic, but it is particularly
well suited to protecting name servers from random hosts that flood DNS
requests and preventing SSH brute force login attempts.