Cisco Certification Central

More Information on Firewalls

It seems nowadays if you are not online, you don?t exist. It really does not matter what type of company you run, you should have an online presence to let your prospects and clients know about your company and services. When you decide to take the leap onto the Internet there are some precautions you should take. I have friends who say all the time, I really have nothing to hide or worry about. This may be true, but malicious users like to deface websites.Which can ruin you and your businesses reputation.

This is a paper about firewalls protecting your company from outside threats and unauthorized access.

A firewall is a great start. Firewalls can be both hardware and software based. There are many different firewall vendors some of the bigger names are Cisco, Symantec, and Checkpoint. The difficult part is configuring the firewall. This is where many intruders bypass security, because the firewall is poorly configured.

I would like to mention that there are many Open Source programs and operating systems that offer great firewall software. I personally believe that OpenBSD has one of the most secure operating systems and firewall configurations if done right. FreeBSD also has firewall software, it is called IPTABLES.IPTABLES offers packet filtering, NAT and you can even change packets in Linux. I have to say you can do anything you want in Linux, because the source code is right there. It?s a beautiful thing. Linux also uses this; you can build a firewall with the old system sitting in your garage and two Linux compatible network cards.Linux can be hardened, this means to make the operating system more secure. I like the tool Bastille Linux its is developed by Jeff Beale. To really get a grasp on firewalls you need to understand TCP/IP and allot of different protocols to know if you should allow or deny them into your network. IP addresses identify hosts on the Internet they look like this 127.214.234.54. Firewalls can block IP addresses, ports, protocols and even keywords that come into packets. Hackers that want into you network have many different tools at their disposal to try to bypass firewalls. One common attack is known as Denial Of Service or DOS attacks. The attacker simply floods your network, firewalls with so many packets that it cannot handle them and sometimes crashes. Firewalls are available with DOS filtering to keep these attacks low, and start dropping packets.

Firewalls do not protect you from internal threats such as employees bringing in viruses from home. Or remote users using VPN's (virtual Private Networks) bypassing your firewall. Think about if you bring your son to work and he downloads music on your fast company internet connection only to introduce your corporate network with a worm or even worst a Trojan horse. Service ports that are open to the public such as Port 80 HTTP, have know vulnerabilities on the Internet. FTP has many vulnerabilities as well.

Are there different types of firewalls?

Full List of Articles