Security plays a key role in keeping unwanted third parties from accessing servers. Criminals have many motives for their attacks, and every successful breach presents a risk to the server operator. Written in the programming language Python, the security framework Fail2ban is a server module that can be used on all Linux and POSIX systems with firewalls or packet filters. Once a certain number of failed attempts is reached, the suspicious address is automatically blocked for a predetermined period of time. Fail2Ban administrators can also receive notices of the IP addresses via e-mail. By default, Fail2Ban comes with a range of filters for Apache, Postfix, or Courier; these recognize certain strings in log files. These filters trigger actions , which are commands that are executed at a predetermined point in time.
The jail mechanism is an implementation of FreeBSD 's OS-level virtualisation that allows system administrators to partition a FreeBSD -derived computer system into several independent mini-systems called jails , all sharing the same kernel, with very little overhead . It is implemented through a system call, jail 2 ,  as well as a userland utility, jail 8 ,  plus, depending on the system, a number of other utilities. Woolworth desire to establish a clean, clear-cut separation between their own services and those of their customers, mainly for security and ease of administration jail 8. Instead of adding a new layer of fine-grained configuration options, the solution adopted by Poul-Henning Kamp was to compartmentalize the system — both its files and its resources — in such a way that only the right people are given access to the right compartments. Jails were first introduced in FreeBSD version 4. Unlike chroot jail , which restricts processes to a particular view of the filesystem , the FreeBSD jail mechanism restricts the activities of a process in a jail with respect to the rest of the system. In effect, jailed processes are sandboxed. They are bound to specific IP addresses , and a jailed process cannot access divert or routing sockets.
Fail2ban: installation and configuration
It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search. The part that I'm missing is the way privileges are set for the webmasters so that they don't see each others directories. I'm trying to set up a multi-users web server and for that I'd like that each user can use both connect with SSH and SFTP but, most important, only sees their own directory.
Have you ever logged into your server and seen a message like this? This message is informing me that while I was logged out, there were failed attempts to access my server via SSH! In this type of scenario, an attacker will attempt to randomly guess passwords repeatedly until they get lucky with the correct password. This is one reason why using a secure password is so important!