fail2ban
Fail2Ban is an intrusion prevention software framework that protects devices from brute-force attacks. Fail2Ban is typically set up to unban a blocked host within a certain period, so as to not "lock out" any genuine connections that may have been temporarily misconfigured. However, an unban time of several minutes is usually enough to stop a network connection being flooded by malicious connections, as well as reducing the likelihood of a successful dictionary attack.[1]
The primary purpose of fail2ban is to jail services. When a service, such as SSHd, is jailed, then fail2ban will continuously look in the log(s) of that service for possible repeated attempts. The moment that a given number (maxretry) of attempts is detected within a particular time window (findtime) then a blocking rule (such as through iptables) is automatically set for a given time period (bantime).[2]
Verifying Configuration
If you want to verify the current configuration, enter the show system fail2ban. The result shows
LYSH@MyHostName# show system fail2ban fail2ban(ssh) : inactive, bantime:1m, findtime:1d, maxretry:5
Configuring the fail2ban
You can configure the fail2ban in the configuration mode.
LYSH@MyHostName# configure configure# fail2ban add -h usage: fail2ban add [-h] [<1->] [<1->] [<1->] positional arguments: <1-> Enter the number of seconds that a host is banned <1-> Enter the length of time between login attempts before a ban is set <1-> how many attempts can be made to access the server before a ban is imposed
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