In this tutorial, we will show you how to install DenyHost on CentOS 6. 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.
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 the step-by-step installation DenyHost on CentOS 6 server.
Prerequisites
- A server running one of the following operating systems: CentOS 6.
- It’s recommended that you use a fresh OS install to prevent any potential issues.
- SSH access to the server (or just open Terminal if you’re on a desktop).
- A
non-root sudo useror access to theroot user. We recommend acting as anon-root sudo user, however, as you can harm your system if you’re not careful when acting as the root.
Install DenyHost on CentOS 6
Step 1. First, you need to enable the EPEL repository on your system and make sure that all packages are up to date.
## RHEL/CentOS 6 64-Bit ## # wget http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm # rpm -ivh epel-release-6-8.noarch.rpm
## RHEL/CentOS 6 32-Bit ## # wget http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm # rpm -ivh epel-release-6-8.noarch.rpm
Step 2. Install DenyHost.
Install DenyHosts from the EPEL repository by using the following command:
yum install denyhosts
Step 3. Configure DenyHosts.
Once the Denyhosts are 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:
nano /etc/hosts.allow
Below the description, add 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 # sshd: 114.124.37.154 sshd: 172.16.25.155 sshd: 172.16.25.156
You can further configure any settings in the DenyHosts.conf file by going to the following and updating according to your preference:
nano /etc/denyhosts.conf
Save your work and restart DenyHosts with the following command:
service denyhosts start chkconfig denyhosts on
View DenyHosts logs:
tail -f /var/log/denyhosts tail -f /var/log/secure
Congratulations! You have successfully installed DenyHost. Thanks for using this tutorial for installing DenyHost on CentOS 6 system. For additional help or useful information, we recommend you check the official DenyHost website.
