Mastering Linux Security and Hardening - Second Edition

Hands-on lab – configuring more verbose SSH logging

For this lab, use the same VM that you've been using for the previous labs. That way, you'll get a better picture of what a complete sshd_config file should look like when it's fully locked down. Remotely log into the target VM via SSH and follow these steps: 

1. Open the main log file and scroll down to where you see the entry that was made due to your login. Observe what it says, and then exit with less for Ubuntu:

sudo less /var/log/auth.log

For CentOS:

sudo less /var/log/secure

2. As I mentioned previously, you never want to run a production machine with the SSH log level set to any of the DEBUG levels. But, just so you can see what it does log, set your machine to DEBUG now. Open the ...