Linux/Centos how to block SSH bruteforce/dictionary attacks automatically with denyhosts

A lot of people become nervous (and understandably so) when checking their auth or security logs, in Centos /var/log/secure and see dozens, hundreds of even thousands of attempted logins to various services, especially SSH.

Of course you could manually block these people/IPs but no one has time to read the logs like that, what if some program or script could do it for you?

This is what denyhosts does for you, it checks the logs and based on a certain number of failed SSH attempts, automatically adds an entry with the offending IPs to /etc/hosts.deny

How to install denyhosts

yum -y install denyhosts

chkconfig denyhosts on

service denyhosts on

That's all there is to it and your system becomes more secure in just 3 commands and a few seconds of your time, in my opinion most Linux distros should have this enabled by default.  Just make sure you don't get you own IP blocked by numerous SSH auth failures.


Tags:

linux, centos, ssh, bruteforce, dictionary, attacks, automatically, denyhostsa, understandably, auth, logs, var, dozens, logins, various, manually, ips, denyhosts, attempts, adds, entry, offending, etc, hosts, install, yum, chkconfig, commands, distros, enabled, default, ip, blocked, numerous, failures,

Latest Articles

  • CentOS 6 impossible to compile a newer libguestfs
  • chroot
  • How To Get Started on Ubuntu with gpt-2 OpenAI Text Prediction
  • Remove cloud-init in your VM
  • QEMU-KVM KVM Command Line Practical Guide
  • Linux How To Change NIC Name to eth0 instead of enps33 or enp0s25
  • virt-resize: error: libguestfs error: could not create appliance through libvirt.
  • Asterisk Does Not Retry When Authentication Fails
  • Linux Debian Ubuntu How To Install PEPPER Faster and Latest Adobe Flash Player in Firefox
  • How To Speed Up Linux Ubuntu and Debian Based Computers By Improving CPU Performance and Changing the CPU Governor
  • Convert data or file to base64 on a single line
  • Linux Mint Ubuntu Debian radeon slow 2D performance issues radeon_dp_aux_transfer_native: 158 callbacks suppressed
  • mdadm: super0.90 cannot open /dev/sdb1: Device or resource busy mdadm: /dev/sdb1 is not suitable for this array.
  • How To Install NextCloud on Centos 7 and Centos 8
  • AH01630: client denied by server configuration:
  • ERROR: Could not find a version that satisfies the requirement PIL (from versions: none) ERROR: No matching distribution found for PIL
  • ZTE Camera Cannot Work unable to connect to camera. Camera has been disabled becaue of security policies or is being used by other apps
  • QEMU KVM how to boot off a physical CD/DVD/BDROM Drive
  • How To Install OpenProject on Centos 7 Step-by-Step Guide
  • Ubuntu Debian Linux Cannot Install Wine Solution - wine1.6 : Depends: wine1.6-i386 (= 1:1.6.2-0ubuntu14.2) but it is not installable wine1.4 : Depends: wine1.6 but it is not going to be installed