Mastering Linux Security and Hardening - Second Edition

Hands-on lab – configuring whitelists within sshd_config

This lab will work on any of your VMs. Follow these steps:

1. On the VM that you wish to configure, create user accounts for Frank, Charlie, and Maggie. On Ubuntu, do the following:

sudo adduser frank. . .

On CentOS, do the following:

sudo useradd franksudo passwd frank. . .

2. Create the webadmins group and add Frank to it:

sudo groupadd webadminssudo usermod -a -G webadmins frank

3. From either your host machine or from another VM, have the three users log in. Then, log them back out.

4. Open the /etc/ssh/sshd_config file in your favorite text editor. At the bottom of the file, add an AllowUsers line with your own username, like so:

AllowUsers donnie

5. Then, restart the SSH service and ...