Denyhosts Infrastructure SOP

Denyhosts provides a protection against brute force attacks.

Contents

  1. Contact Information

  2. Description

  3. Troubleshooting and Resolution

  1. Connection issues

Contact Information

Owner

Fedora Infrastructure Team

Contact

#fedora-admin, sysadmin-main group

Location

Anywhere

Servers

All

Purpose

Denyhosts provides a protection against brute force attacks.

Description

All of our servers now implement denyhosts to protect against brute force attacks. Very few boxes should be in the 'allowed' list. Especially internally.

Troubleshooting and Resolution

Connection issues

The most common issue will be legitimate logins failing. First, try to figure out why a host ended up on the deny list (tcptraceroute, failed login attempts, etc are all good candidates). Next do the following directions. The below example is for a host (10.0.0.1) being banned. Login to the box from a different host and as root do the following.:

cd /var/lib/denyhosts
sed -si '/10.0.0.1/d' * /etc/hosts.deny
/etc/init.d/denyhosts restart

That should correct the problem.