The following lines were added (+) and removed (-):
Blocking SMTP authentication brute force attacks using Fail2Ban - Fail2Ban can be used to block brute force attacks against your mail server. The attackers are blocked by their source IP using iptables. Although it doesn't block SMTP attacks by default, Fail2Ban can be configured to do so.Blocking SMTP authentication brute force attacks using [[Fail2Ban]] - Fail2Ban can be used to block brute force attacks against your mail server. The attackers are blocked by their source IP using iptables. Although it doesn't block SMTP attacks by default, Fail2Ban can be configured to do so.First, you need to install Fail2Ban. For Redhat/Fedora use yum.{{:Linux fail2ban Installation}} yum install fail2banCentOS: fail2ban is not available from CentOS. It will have to be manually downloaded. You can get it from EPEL, the Fedora repository. ==== configure ==== wget http://mirror.pnl.gov/epel//6/i386/fail2ban-0.8.11-2.el6.noarch.rpm rpm -qR fail2ban-0.8.11-2.el6.noarch.rpm ALL LINUX DISTRIBUTIONS - Fail2ban is written in Python, thus no compilation is required. You can even run Fail2ban without installing it. It can always be obtained directly from http://www.fail2ban.orgConfiguration for Fail2ban on a Redhat/Fedora/CentOS style distribution. This is using fail2ban with dovecot 2.x (versions 2 and above) - filtering and pattern matching.==== configure ====#configuration files: ./fail2ban#regex filters: ./fail2ban/filter.d#action file (do/block): ./fail2ban/action.dNow modify the configuration fileFirst edit the dovecot.conf filter file. vi /etc/fail2ban/fail2ban.conf vi ./fail2ban/[[sample-filter.d|filter.d]]Set the path to the log file.Next edit the postfix-sasl.conf and iptables-multiport-tcp.conf action files. vi ./fail2ban/filter.d/[[sample-postfix-sasl.conf|postfix-sasl.conf]] vi ./fail2ban/action.d/[[sample-iptables-multiport-tcp.conf|iptables-multiport-tcp.conf]]Configuration Parameters:Do not directly edit jail.conf. Comments in jail.conf clearly warn against modifications in jail.conf. Put your customizations in a jail.local file or a jail.d/customisation.local cp ./fail2ban/jail.conf ./fail2ban/jail.local vi ./fail2ban/[[sample-jail.local|jail.local]] Important Configuration Parameters:*filter: Refers to the appropriate filter file in "/etc/fail2ban/filter.d".*filter: Refers to the appropriate filter file in "./fail2ban/filter.d". ignoreip = 127.0.0.1 192.168.254.0/24Set the IP addresses of trusted hosts for fail2ban to ignore. Replace the 192x non-routable with the address of your machine or network. You can also add other trusted networks. Put your mom's IP address in there because sometimes she gets her password wrong more than 3 times in a row!