About Types of Firewalls
If you have been using computers for a while, then you have no doubt heard the term firewall provided. Unfortunately, many people really do not understand what one is. After questioning, you'll hear words like security mentioned, along with protection from hackers, denial of service attacks (DoS) attacks and viruses. But you can not be given any idea of how a firewall provides any protection or what it actually does.So here's an analogy to give an explanation about what a firewall actually does for you. Imagine that your server as an office, has a fixed address, but many ports, and each port is used for a different service.
These ports are equivalent to ports on your server, traffic to your server is marked with the destination port that you want for, and by convention the services run on your specific ports, such as port 80 for web traffic, 443 for secure web traffic, 25 for SMTP mail, 143 for IMAP email, and the list goes on for a time fair. The firewall is effectively like having a security at each of the office doors decide whether each person is allowed to enter or leave or not.
There are three main types of firewall
For most people running a server, the software firewall will be the first type you will encounter. Usually this is iptables in Linux and Windows Firewall.Next, you have firewalls, the kind of thing that comes in a router or other integrated multifunction network device. Most people will get one of these on their home broadband router.
Finally, you have dedicated hardware firewalls; devices for which firewall is your primary goal.
Differences
The main differences between hardware and software firewalls are that independent hardware firewalls may tend to be more difficult to configure, but offer greater flexibility in configuration. Integrated firewalls can go in two ways, some can be a bit inflexible with simple configuration, others can provide feature sets similar to a full hardware firewall. Software firewalls, once again, can offer ranges of flexibility and are variously difficult to configure. However its main disadvantage is that as the work of the firewall is performed by the CPU then with a high traffic server.You may find a lot of CPU become too high for the server to track. In this case, a hardware firewall may be preferable, since it takes the load handling incoming network connections away from your server.
Virtually all firewalls allow you to block or allow traffic from inside or outside your server. Most allow you to create rules that define whether traffic should be allowed or not based on certain parameters. The default parameters are the destination IP address, source IP address, destination port, source port, and transmission protocol. More flexible firewalls let you choose from other parameters to set the required rules. This means that in most cases you can adapt your firewall to meet your exact needs.
How does a firewall help protect you from bad things on the internet?
A properly configured firewall should minimize the number of services available to a hacker to attempt to exploit by reducing attacks that the server could be vulnerable to. It can block unwanted traffic intended to overload services on the server in a denial of service attack. Finally, an external firewall to the server can be used to block outbound traffic that can allow viruses and trojans to call home or spread, although in addition to defense against hackers putting viruses on the server will not help much against an initial infection .Unfortunately, many modern denial of service leverage attacks a lot of servers driving large amounts of traffic to the destination server, so that instead of overloading the specific services of a server in an attempt to beat them, they saturate the network links to the server. This means that regardless of the firewall, legitimate traffic would be unable to reach the server so it adds no protection in these scenarios.
Although it is not a magic solution in terms of security for your server, a firewall is a very important tool to stay safe.
