03-20-2023, 06:05 PM
Packet Filtering (Stateless) Firewall
Packet filtering firewalls are usually part of a router firewall, which permits or denies traffic based on Layer 3 and Layer 4 information. They are stateless firewalls that use a simple policy table look-up that filters traffic based on specific criteria.
For example, SMTP servers listen to port 25 by default. An administrator can configure the packet filtering firewall to block port 25 from a specific workstation to prevent it from broadcasting an email virus.
Stateful firewall
Stateful firewalls are the most versatile and the most common firewall technologies in use. Stateful firewalls provide stateful packet filtering by using connection information maintained in a state table. Stateful filtering is a firewall architecture that is classified at the network layer. It also analyzes traffic at OSI Layer 4 and Layer 5.
Application Gateway Firewall
An application gateway firewall (proxy firewall), filters information at Layers 3, 4, 5, and 7 of the OSI reference model. Most of the firewall control and filtering is done in software. When a client needs to access a remote server, it connects to a proxy server. The proxy server connects to the remote server on behalf of the client. Therefore, the server only sees a connection from the proxy server.
Next Generation Firewall
Next-generation firewalls (NGFW) go beyond stateful firewalls by providing:
Integrated intrusion prevention
Application awareness and control to see and block risky apps
Upgrade paths to include future information feeds
Techniques to address evolving security threats
Other methods of implementing firewalls include:
Host-based (server and personal) firewall - A PC or server with firewall software running on it.
Transparent firewall - Filters IP traffic between a pair of bridged interfaces.
Hybrid firewall - A combination of the various firewall types. For example, an application inspection firewall combines a stateful firewall with an application gateway firewall.
Packet filtering firewalls are usually part of a router firewall, which permits or denies traffic based on Layer 3 and Layer 4 information. They are stateless firewalls that use a simple policy table look-up that filters traffic based on specific criteria.
For example, SMTP servers listen to port 25 by default. An administrator can configure the packet filtering firewall to block port 25 from a specific workstation to prevent it from broadcasting an email virus.
Stateful firewall
Stateful firewalls are the most versatile and the most common firewall technologies in use. Stateful firewalls provide stateful packet filtering by using connection information maintained in a state table. Stateful filtering is a firewall architecture that is classified at the network layer. It also analyzes traffic at OSI Layer 4 and Layer 5.
Application Gateway Firewall
An application gateway firewall (proxy firewall), filters information at Layers 3, 4, 5, and 7 of the OSI reference model. Most of the firewall control and filtering is done in software. When a client needs to access a remote server, it connects to a proxy server. The proxy server connects to the remote server on behalf of the client. Therefore, the server only sees a connection from the proxy server.
Next Generation Firewall
Next-generation firewalls (NGFW) go beyond stateful firewalls by providing:
Integrated intrusion prevention
Application awareness and control to see and block risky apps
Upgrade paths to include future information feeds
Techniques to address evolving security threats
Other methods of implementing firewalls include:
Host-based (server and personal) firewall - A PC or server with firewall software running on it.
Transparent firewall - Filters IP traffic between a pair of bridged interfaces.
Hybrid firewall - A combination of the various firewall types. For example, an application inspection firewall combines a stateful firewall with an application gateway firewall.