it should be C

The C is correct In reference is written: A service called Fail2ban can mitigate this problem by creating rules that automatically alter your iptables firewall configuration based on a predefined number of unsuccessful login attempts. This will allow your server to respond to illegitimate access attempts without intervention from you.

It wouldn't be healthy if fail2ban would reconfigure the sshd:D

C - ok

C - ok

I think - C

Qouting usandoati: The C is correct In reference is written: A service called Fail2ban can mitigate this problem by creating rules that automatically alter your iptables firewall configuration based on a predefined number of unsuccessful login attempts. This will allow your server to respond to illegitimate access attempts without intervention from you.

I vote for C, see my comment on Armina

The C is correct In reference is written: Fail2ban can mitigate this problem by creating rules that automatically alter your iptables firewall configuration based on a predefined number of unsuccessful login attempts.

B is correct, due to [sshd] configuration in /etc/fail2ban/jail.conf file. After installing the utility, there is a new configuration directory: /etc/fail2ban. The primary configuration file is the /etc/fail2ban/jail.conf file. In addition, there are sections for different jails. For example, you can have a section that relates to SSH connections, like the following: [sshd] enabled = true maxretry = 3 This is a simple example and there are many other possible features you can use in the section. For example, you could create a custom action rule, including sending someone an e-mail in the event the rule is used to block an IP address: [sshd] enabled = true maxretry = 3 action = iptables[name=SSH, port=ssh, protocol=tcp] sendmail-whois[name=SSH, dest=root, [email protected]] The action setting tells the fail2ban daemon what actions to take. The actions are normally defined in the /etc/fail2ban/action.d/iptables.conf file.