For those of you who didn’t know, DenyHosts is a log-based intrusion prevention security tool for SSH servers written in Python. It is intended to prevent brute-force attacks on SSH servers by monitoring invalid login attempts in the authentication log and blocking the originating IP addresses. Due to the simplicity of DenyHost and the ability to manually configure your rules it is widely used as an alternative to Fail2ban which is a bit more complicated to use and configure. DenyHosts unfortunately does not support IPv6.
This article assumes you have at least basic knowledge of linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple. I will show you through the step by step installation DenyHost on Ubuntu 14.04 server.
Install DenyHost on Ubuntu 14.04
Step 1. First of all make sure that all packages are up to date.
Step 2. Install DenyHost.
DenyHosts is very easy to install on Ubuntu:
sudo apt-get install denyhosts
Step 3. Configure DenyHosts.
Once the Denyhosts installed, make sure to whitelist your own IP address, so you will never get locked out. To do this, open a file /etc/hosts.allow:
sudo nano /etc/hosts.allow
Below the description, add the each IP address one-by-one on a separate line, that you never want to block. The format should be as follows:
# hosts.allow This file contains access rules which are used to
# allow or deny connections to network services that
# either use the tcp_wrappers library or that have been
# started through a tcp_wrappers-enabled xinetd.
# See 'man 5 hosts_options' and 'man 5 hosts_access'
# for information on rule syntax.
# See 'man tcpd' for information on tcp_wrappers
You can further configure any settings in the DenyHosts.conf file by going to the following and updating according to your preference:
sudo nano /etc/denyhosts.conf
Save your work and restart DenyHosts with the following command:
sudo /etc/init.d/denyhosts restart
View DenyHosts logs:
tail -f /var/log/denyhosts
tail -f /var/log/secure
Congratulation’s! You have successfully installed DenyHost. Thanks for using this tutorial for installing DenyHost on Ubuntu 14.04 system. For additional help or useful information, we recommend you to check the official DenyHost web site.