A stateless firewall is a network security solution that filters data packets without regard to the context or history of a specific network connection. They’re more performant than stateful firewalls but may be less secure if they lack context monitoring.
They’re best suited for networks that experience heavy traffic flow. But they’re also known to bog down smaller networks and are less efficient than stateful firewalls.
Performance
Using stateful firewall filters on an ingress or egress interface provides network security by filtering packets based on header information, such as source and destination IP addresses, port numbers, sequence numbers, etc. This type of filter can also monitor application layer traffic to a certain degree.
To assess the context of a packet, stateful firewalls maintain a state table. This table tracks the logical connection history of all active communication streams. The firewall then compares new packages to the state table, allowing it to filter and approve communication with appropriate rules.
Once a connection is approved, the firewall will promote the internal state of the session to ESTABLISHED. If the firewall sees an RST or FIN+ACK packet, it will mark the connection state for deletion and reject all future packets from the same source.
Stateful inspection firewalls are a great choice for networks with extensive data and complex infrastructure. They provide the protection enterprises need to avoid costly downtime and loss of sensitive information.
However, because they only examine packet headers, stateless inspection firewalls are blind to attacks that rely on application layers. Distributed denial-of-service attacks, for instance, often exploit web application vulnerabilities to infiltrate a network. These attacks can be difficult for stateless inspection firewalls to detect. To mitigate these threats, consider a next-generation firewall (NGFW) that offers stateful inspection and other frontline defenses.
Configuration
It is essential to understand what is a stateless firewall before using it with stateless inspection. The firewall only inspects packets based on predefined rules and does not look past the protocol header. This is a vulnerability, as attackers can exploit it to bypass security checks. Stateful firewalls can prevent such attacks by analyzing the data within each packet and looking for signs of malware or malicious activity.
With a stateful firewall, each type of traffic is stored in a table to be analyzed quickly and accurately. When a new packet arrives, it looks for any existing session information in the table and then passes or blocks it accordingly. This allows the firewall to save time and resources for other tasks.
As a result, stateful firewalls are more efficient than other types of firewalls. This is particularly true in environments where network connections change frequently or when a dynamic IP address is used.
Additionally, stateful firewalls can detect out-of-sequence packets, a common attack vector. This is because stateful firewalls can keep track of the full connection history for TCP streams and UDP datagrams. This is important for detecting certain kinds of network scans and other potentially malicious activities that stateless firewalls might not catch.
Security
A stateful firewall filters network traffic based on context and state. It keeps track of the state of TCP streams, UDP datagrams, and ICMP messages. This allows it to identify future threats by analyzing network connections’ past and present behavior. This type of firewall also requires a high amount of memory and processing power.
Stateful firewalls monitor packets based on rules and approve them to move freely in the network if they meet specified criteria. This approach provides superior security compared to stateless firewalls. In addition to inspecting packets, stateful firewalls can detect attacks at the application layer. However, they can be blind to attacks that use legitimate packets, such as Distributed Denial of Service (DDoS) attacks.
Firewalls can use the state information in their internal connection table to impose security policies on network traffic. For example, TCP connections must go through a three-way handshake identified by the SYN flag. Once a connection is established, it will be promoted to the ESTABLISHED state. After that, the firewall will remove the entry from its state table when it receives a FIN message from the connection.
Stateful firewalls can also filter ICMP packets that are sent out of sequence. They can also recognize TCP scans, such as ACK or FIN scans, by examining the state of their internal connections. This method of detecting out-of-sequence packets can prevent attackers from exploiting vulnerabilities in your network.
Cost
A stateless firewall is a good option for small businesses, as it can perform well with lower traffic volumes and fewer threats. These firewalls are also less expensive than stateful firewalls. They don’t track the details of network connections, but they examine incoming data packets and look for clues indicating potential malicious activity.
They also monitor basic information such as source and destination addresses, port numbers, and network protocols. Based on these factors, They then decide whether to allow or restrict a data packet. However, forged packets and other attacks can easily fool these firewalls.
For instance, they may overlook SYN/ACK packets that are part of a standard TCP handshake. These packets are sent in response to a SYN request, which is sent from the client to the server to initiate a connection. As a result, stateless firewalls are vulnerable to online attacks that can spread across different packets and attack the system from multiple angles.
To ensure that your clients have the best firewall performance, evaluate their network environment and identify their security requirements. This can include the number of concurrent connections, bandwidth requirements, and integration with other technologies. Also, consider the growth of their network and how much more security they might need in the future. Investing in a robust stateful firewall can help prevent future attacks and avoid expensive remediation costs.