Authfail

Authfail is a software that allows for real-time updating on a first-in, first-out (FIFO) file whilst adding IP addresses into netfilter with either a DROP or REJECT policy in real-time. The FIFO file that is used in Authfail is located at /dev/authfail, whilst the rejected hosts database can be found in /var/log/authfail. The software will count each time a specific host tries and fails authentication via syslog, and if it happens more than the parameters given to the program, that given host will be dropped or rejected via Netfilter. It is also possible to receive a Whois notification.

Authfail is configurable, and this can be done easily through the /etc/authfail.conf file. Additionally, the program is released under the GNU GPL Public License, and there have been recent modifications made to its Setup.pl file. These changes ensure that private RFC 1918 networks are not notified during the setup process.

In conclusion, Authfail is an excellent software that ensures only authorized users have access to a system by blocking any unauthorized users. With real-time updates, easy configuration, and Whois notification possibilities, Authfail is the go-to software for network security.