Introducing firewalls
Using the Iptables firewall system
Designing and viewing your filtering rules
Automatically starting your firewall
After connecting to the Internet, you run the very real risk that bad guys will try to break into or otherwise harm your computer. The bad guys wear black hats, just like in the movies (as opposed to red hats, which are a bit odd but still good). You may also have heard them called hackers, crackers, the Joker, and whatever. Whatever their names and whatever their intentions, the Internet is getting more dangerous every day, so ya gotta protect yourself.
A firewall is a device that enables you to use the Internet while minimizing the possibility that the Internet will use you. Firewalls basically allow your network communications to go out but minimize the possibility of anyone making unwanted connections to your computer or private network.
This chapter describes, not surprisingly, how to build a firewall to help protect your Red Hat Linux computer from the bad guys. First, in case you doubt that you truly need a firewall, we explain why firewalls are important. Then we introduce you to Iptables, the Linux firewall system, and describe how to set up your firewall-filtering rules. After you set up your firewall filters, you need to know how to run the firewall automatically. You do that by setting up a script — something else we explain in this chapter. And, of course, what good would your firewall be if it didn’t work? So, we show you how to do a simple test to make sure that your firewall is burning brightly.
WarningThe firewall described in this chapter is designed to protect a single Red Hat Linux computer that’s connected to the Internet. The firewall isn’t designed to protect an entire network. Chapter 15 describes how to modify this firewall to protect your private network.
Introducing firewalls
Using the Iptables firewall system
Designing and viewing your filtering rules
Automatically starting your firewall
After connecting to the Internet, you run the very real risk that bad guys will try to break into or otherwise harm your computer. The bad guys wear black hats, just like in the movies (as opposed to red hats, which are a bit odd but still good). You may also have heard them called hackers, crackers, the Joker, and whatever. Whatever their names and whatever their intentions, the Internet is getting more dangerous every day, so ya gotta protect yourself.
A firewall is a device that enables you to use the Internet while minimizing the possibility that the Internet will use you. Firewalls basically allow your network communications to go out but minimize the possibility of anyone making unwanted connections to your computer or private network.
This chapter describes, not surprisingly, how to build a firewall to help protect your Red Hat Linux computer from the bad guys. First, in case you doubt that you truly need a firewall, we explain why firewalls are important. Then we introduce you to Iptables, the Linux firewall system, and describe how to set up your firewall-filtering rules. After you set up your firewall filters, you need to know how to run the firewall automatically. You do that by setting up a script — something else we explain in this chapter. And, of course, what good would your firewall be if it didn’t work? So, we show you how to do a simple test to make sure that your firewall is burning brightly.
WarningThe firewall described in this chapter is designed to protect a single Red Hat Linux computer that’s connected to the Internet. The firewall isn’t designed to protect an entire network. Chapter 15 describes how to modify this firewall to protect your private network.