Mastering Linux Security and Hardening - Second Edition

Hands-on lab for blocking invalid IPv4 packets

For this lab, you'll use the same virtual machine that you used for the previous lab. You won't replace any of the rules that you already have. Rather, you'll just add a couple. Let's get started:

1. Look at the rules for the filter and the mangle tables. (Note that the -v option shows you statistics about packets that were blocked by DROP and REJECT rules.) Then, zero out the blocked packets counter:

sudo iptables -L -vsudo iptables -t mangle -L -vsudo iptables -Zsudo iptables -t mangle -Z

2. From either your host machine or another virtual machine, perform the NULL and Windows Nmap scans against the virtual machine:

sudo nmap -sN ip_address_of_your_VMsudo nmap -sW ip_address_of_your_VM

3. Repeat ...