You have paid much attention to your Application level and Operating System security but you don’t feel it`s good enough. You need a Linux border firewall for perimeter security and to share your internet connection for your whole LAN.

The issue is you don’t know much about Firewalls and you have these concerns to look Into-

• What is a firewall?
• Do I need one? If yes , Why?
• Is a firewall a cure-all? What can they possibly do and what can they not do?
• I have a public routable address (statically assign) that hooks me up to the internet. How can I share my internet connection with host on my LAN, using private non-routable addresses?
• My public IP is dynamically assign by my ISPs DHCP Server. How do I get my LAN using private non-routable addresses connected to the internet?
• Can I effectively control network traffic to/from my LAN using very few rules?
• Sure, discover the magic behind statefull inspection with IP Tables.
• Firewalling is managed differently on all Linux Distributions. I need a method, a
script or something that works for all - something very portable.
• You want to test your firewall from inside and outside your LAN; especially the way the big bad internet sees it. How can I go about that?
• You want to SSH into your border firewall and administer Servers remotely. You might want to login from over the internet, or you might want to restrict SSH to LAN access only. You also want the options of restricting access to certain specific source IP addresses.
• What does it take to run public services on private IP addresses?
• Besides my border firewall, I strongly desire a host based firewall on all host running public services.
• Can I possibly configure IP Tables logging, at least for monitoring and debugging?

Practice Labs:

• Basic network configuration;
  - IP addressing, name service configuration (/etc/hosts), using route and
  Net stat and network troubleshooting
  - Setting up a DHCP Client and DHCP Server
• Working with Open SSH
• Building an Internet connection sharing firewall on a dynamic WAN IP address
• Building an Internet connection sharing firewall on a static WAN IP address
• Creating a scripts that handle starting IP Tables at boot, and manually bring the firewall up and down
• Testing your Firewall from within and outside your LAN
• Configuring the Firewall for remote SSH administration
• Allowing remote SSH through a NAT Firewall
• Running Public services on private IP addresses
• Setting up a single host and Server Firewall
• Configuring ip tables logging
• Writing Egress rules