Outside of using a Firewall, it is important to understsand that there are other methods of configuring a service with host based security restrictions. Using the hosts.allow and deny files, we will explore how TCP Wrappers works to secure our systems.
Learning Objectives
Successfully complete this lab by achieving the following learning objectives:
- Keep Client System from Connecting Over SSH
This is accomplished using the /etc/hosts.deny file (remember, if we try to allow specific locations, whatever is in /etc/hosts.allow will be applied first). You can accomplish this by making the following addition to the /etc/hosts.deny file:
sshd: 10.0.1.101- Log All Connection Denials
Within the /etc/hosts.deny file, you will need to add the following in order to log connections:
sshd: 10.0.1.101 : spawn /bin/echo $(/bin/date) %a access denied >> /var/log/sshd :deny- Reload the SSH Service and Verify
You can reload (without disconnecting yourself) the SSH configuration via:
systemctl reload sshdThen verify by trying to connect to the SERVER from the CLIENT system over SSH and viewing the denial message in /var/log/sshd.log
