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Fail2ban

Fail2ban scans log files (e.g. /var/log/apache/error_log) and bans IPs that show the malicious signs -- too many password failures, seeking for exploits, etc. Generally Fail2Ban then used to update firewall rules to reject the IP addresses for a specified amount of time, although any arbitrary other action (e.g. sending an email, or ejecting CD-ROM tray) could also be configured. Out of the box Fail2Ban comes with filters for various services (apache, curier, ssh, etc). For more info refer to the official web site
How to install Fail2ban. Enable Epel repository first:

wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

wget http://rpms.famillecollet.com/enterprise/remi-release-6.rpm

rpm -Uvh remi-release-6*.rpm epel-release-6*.rpm

Enable the remi repository.
Open the file /etc/yum.repos.d/remi.repo and set enable=1 in remi section of the file.

name=Les RPM de remi pour Enterprise Linux $releasever - $basearch

#baseurl=http://rpms.famillecollet.com/enterprise/$releasever/remi/$basearch/

mirrorlist=http://rpms.famillecollet.com/enterprise/$releasever/remi/mirror

enabled=1

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-remi

failovermethod=priority

Now install Fail2ban:

yum install fail2ban

Set Fail2ban to start at boot

chkconfig fail2ban on

Copy config file to keep the original backup.

cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local

Now we have a working config file /etc/fail2ban/jail.local, configure it according to your needs.
Start service

service fail2ban start

Now you have working Fail2ban server. To display banned hosts, enter:

iptables -L

To unlock IP, enter

iptables -D fail2ban-ssh 1

 

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