A traditional firewall controls the flow of traffic based on state and port. It is typically used to protect private networks.
Next-generation firewalls offer a variety of capabilities to enhance security. These include packet filtering, network address translation (NAT), and stateful inspection.
Packet Filtering
Firewalls control the flow of incoming and outgoing data, depending on their sets of rules, protocols, ports, and IP addresses. In addition, each packet includes user and control information, which the firewall tests to determine whether it is legitimate.
Packet filtering firewalls are a network security technique that allows packets to pass through the network until one or more pre-established rules deny them. The rules can be set based on a single destination address or cover several destinations.
The advantage of packet filters is that they are efficient and fast, allowing many packets to pass through quickly without holding them for long periods. These types of firewalls also operate autonomously without user cooperation or awareness.
Another advantage of packet filters is that they are transparent to users, which makes them more user-friendly and easy to incorporate into any environment. Other firewall techniques require custom software, client machine setup, and user training or procedures, making them less transparent to users.
Some firewalls are stateless, meaning that they test each packet as it enters the network. As a result, they’re a good choice for home internet users or low-power customer-premises equipment (CPE). However, these systems lack protection from packet spoofing and may not be compatible with some protocols.
Network Address Translation (NAT)
Network Address Translation (NAT) is a function of a traditional firewall that translates an inside IP address to an outside IP address and vice versa. The NAT process occurs within a network router and works when the inside IP address is connected to a public interface on a network router or firewall.
To use NAT, a host must first have an externally-recognized IP address. It can be a registered IP address or an unregistered IP address.
The NAT device substitutes the internal source IP address in the packet header with an external IP address. It adds a port number to the source port field when a host on the internal network transmits an IP packet to the external network. The NAT then saves the internal source IP address and port number to its translation table.
Depending on the type of NAT, the translation process can be static or dynamic. Static NAT translates private networks to global addresses using one-to-one mapping. Dynamic NAT translates personal addresses to public IP addresses by selecting a target from a pool of available addresses.
Pure NAT, which uses IP, may or may not effectively interpret protocols with IP information in their payloads. It depends on whether a host interprets the protocol inside or outside the NAT. It also needs to reassemble datagrams and track their connection status.
Stateful Inspection
Stateful inspection firewalls are network firewalls that monitor the state and context of each data packet. It helps distinguish between legitimate and malicious data and prevent unauthorized connections from entering or leaving the network.
These devices also have more robust logging capabilities, which can help debug security issues or monitor network connections. They can also prevent DDoS attacks compared to basic packet filtering and help companies avoid extended downtime.
Firewalls can also use this technology to analyze incoming and outgoing packets for potential threats using a three-way handshake. It involves synchronizing both sides of a communication process to initiate and acknowledge a connection, then transferring data packets back and forth.
The firewall compares this data to store information to identify potential threats. It then uses this information to determine whether a connection should be allowed or denied.
A firewall that employs stateful inspection works with TCP protocols but can also handle other protocols, including user datagram protocol (UDP). The main difference is that UDP is a connectionless protocol, meaning the firewall must rely on different information types to determine the state.
Firewalls that use stateful inspection are more resource-intensive than packet filters. They require a lot of memory and central processing unit (CPU) time. They can also suffer from denial-of-service (DOS) attacks designed to overwhelm the firewall with traffic.
Virtual Private Network (VPN)
A virtual private network (VPN) creates a secure tunnel between your computer or mobile device and the internet. It encrypts your data and routes it through a server in a remote location, hiding your IP address and online activity from government authorities, hackers, and ISPs.
VPNs also help users stay anonymous and avoid censorship. In addition, it can protect them from being targeted and discriminated against by websites, advertisers, or governments.
The best VPNs also thwart bandwidth and data throttling from your internet service provider. It can boost your connection speeds and make streaming videos and games or downloading files from the internet easier.
Lastly, VPNs can help you avoid targeted pricing, fake websites, and bait-and-switch attacks. These are all ways internet service providers and advertising networks can discriminate against you based on your preferences or purchases.
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