How does a firewall work?
A firewall is a system designed to prevent unauthorized access to or from a private network. Firewalls can be hardware- or software-based. Hardware-based firewalls are usually installed as part of a router, while software-based firewalls can be installed on any computer.
Firewalls work by inspecting incoming and outgoing packets and comparing them to a set of rules. If a packet is allowed by the rules, it is forwarded to its destination. If a packet is not allowed by the rules, it is dropped.
Most firewall rules are designed to block all incoming traffic unless it is specifically allowed. This is because it is generally easier to know which traffic should be allowed than it is to know which traffic should be blocked. For example, a firewall might allow all traffic from the IP address of a trusted website, but block all traffic from IP addresses that are known to be used by hackers.
Some firewalls can also inspect the contents of packets and block them based on keywords or other patterns. This kind of inspection is more processor-intensive than simply looking at the headers of packets, so it is not always used.
Firewalls can also be used to NAT (Network Address Translation) traffic. NAT allows a single public IP address to be used for multiple private IP addresses. This can be useful for conserving IP addresses, or for hiding the IP addresses of computers on a private network.
Firewalls are an important part of network security, but they are not a panacea. They can usually be bypassed by knowledgeable attackers, and they do not protect against threats that do not involve network traffic, such as malicious software that is transferred via USB drive.
How do firewall policies work?
A firewall policy is a set of rules that determine how the firewall will handle different types of traffic. For each type of traffic, the administrator can specify what action to take – allow, deny, or reject. Firewall policies can be very simple, or very complex, depending on the needs of the network.
In most cases, firewall policies are implemented as a set of rules that are applied to all traffic. The administrator can allow or deny traffic based on different criteria, such as the source and destination IP address, the port number, or the protocol. In some cases, the administrator may also specify how the traffic should be handled – for example, whether it should be allowed or denied.
In some cases, the administrator may want to allow certain types of traffic while denying others. For example, the administrator may want to allow all traffic from the internal network to the Internet, but only allow certain types of traffic from the Internet to the internal network. In this case, the administrator would need to create two sets of rules – one for each direction.
Firewall policies can be implemented in hardware or software, or a combination of both. Hardware-based firewalls are usually more expensive, but they offer better performance and security. Software-based firewalls are less expensive, but they may not be able to handle as much traffic.
Visit malwarezero.org to learn more about firewall. Disclaimer: We used this website as a reference for this blog post.