Firewalls monitor incoming and outgoing traffic and allow or deny access with predefined rules. They protect against threats such as viruses and malware by screening network packets.
Stateful firewalls are more complex than their stateless counterparts, so they are best suited for large enterprises with high security and the resources to support them. However, they can be expensive.
They don’t maintain state
What is a stateless firewall? Stateless firewalls filter network traffic by using static data, such as a packet's header. Since this method does not require the lengthier path/control panel processing to evaluate whether the packets comply with the specified firewall rules, it may be more effective and quicker. Your network could be exposed to assaults that could be concealed within a single packet, though, if this happens.
Stateful firewalls – offering dynamic packet filtering or state-and-context-based network connection security – can be more effective against sophisticated cyber threats. These firewalls can perform well under pressure and in heavy traffic networks. They also offer extensive logging capabilities and robust attack prevention. Yet, as simple as viewing a webpage, they can be more sensitive to man-in-the-middle attacks where an attacker could be tricked into allowing harmful connections into your network.
Stateful firewalls are often used to protect proxies, File Transfer Protocol (FTP), Network Address Translation (NAT), and to implement network segmentation. They are also commonly deployed to protect against DDoS attacks. In today’s more advanced firewalls, stateless technology can be combined with other security features to provide a broader range of protection.
They don’t keep track of connections
As you can imagine, stateful firewalls require much CPU processing power to perform their duties. It can make them susceptible to DDoS attacks. It’s also why they typically cost more than stateless firewalls.
However, these firewalls provide an effective solution to protecting a network from various threats, including malware, viruses, and other malicious activities. Stateful firewalls can detect malicious traffic that cannot be seen by stateless firewalls, making them the ideal choice for larger organizations and enterprises.
To protect data communications, stateful firewalls use clues from crucial values, such as the source and destination of the packet, to determine if it’s a threat. On detecting a threat, they block it. It makes stateful firewalls more rigorous compared to stateless firewalls.
It is especially true when it comes to handling large volumes of data. They’re fast and efficient in filtering traffic without sapping network bandwidth or demanding active IT monitoring.
However, they’re less effective than stateful firewalls when providing security for a more complex network. For example, a common application such as FTP dynamically negotiates data ports during each connection. Since stateless firewalls don’t keep track of states, they cannot whitelist data connections. It makes them unsuitable for applications that require finer policy controls, such as a micro-segmentation framework.
They don’t have a policy database
When a stateless firewall sees return traffic from an incoming connection, it looks at the IP address and port of the source and destination in the packet header to determine whether or not to whitelist it. The firewall does this to protect against attacks that attempt to trick the firewall into allowing unwanted traffic back through.
Unlike stateless firewalls, stateful inspection firewalls keep track of the context and state of network connections as they occur, making them more effective at blocking malicious attacks. They also perform a more thorough analysis of data packets, inspecting everything inside them, their characteristics, and communication channels.
It allows them to recognize what kind of traffic or package is coming in and the type of threat it may be. Stateful firewalls are ideal for larger enterprises that face more dangers and have the budget to afford them.
For instance, the firewall creates a flow entry in its memory whenever a client delivers an SYN packet to a server. The next time the server receives an SYN packet from the same client, it knows the flow is still active and can send an ACK. The firewall can then whitelist the incoming TCP/UDP reply traffic because it matches the rules in its memory of the ongoing session.
They don’t have a flow table
Unlike stateful firewalls that use a flow table to track network connections, stateless firewalls don’t have one. They look at the packets as standalone units and apply security rules based on the information in each of them.
As a result, stateless firewalls can’t identify different traffic types. For example, a data packet sent by a server may include the IP address of its destination. Still, it can also contain a hostname and port number, which are not unique to that particular server or service.
When a data packet arrives at the firewall, it will inspect it from OSI layers 2 to 4. It then compares the packet’s metadata (source IP, source port, destination port) and its contents against the policies in the policy table. If there is a match, the firewall will allow the packet through.
However, because a stateless firewall doesn’t keep track of the context of each data communication, it’s vulnerable to attacks that spread across multiple packets, such as man-in-the-middle. It is why stateful firewalls offer more advanced security features and require a more excellent hardware investment than stateless ones. As a result, they’re also slower regarding data transmission. Nonetheless, they’re ideal for larger businesses that experience heavy incoming and outgoing traffic. As such, they can perform well under pressure and prevent threats that a stateless firewall might not detect.