What is Firewall? And Firewall Architecture

What Is Firewall? & Firewall Architecture

What is Firewall? And Firewall Architecture – Firewalls are hardware and/or software designed to prevent unauthorized access to or from a private network.

They Are Placed at the junction or gateway between the two networks, which is usually a private network and a public network such as the Internet.

Firewalls examine all message entering or leaving the Intranet and block those that do not meet the specified security criteria.

What is Firewall? And Firewall Architecture

Firewall is a software or hardware-based system located at the network gateway that protects the resources of a private network from unauthorized access of users on other networks. They are placed at the juction or gateway between the two networks, which is usually a private network and a public network such as the Intranet.

Firewalls examine all messages entering or leaving the Intranet and blocks those that do not meet the specified security criteria. Firewalls may be concerned with the type of traffic or with the source or destination addresses and ports.

They include a set of tools that monitor the flow of traffic between networks. A firewall placed at the network level and working closely with a router filters all network packets to determine whether to forward them toward their destinations or not. Always install firewalls away from the rest of the network, so that none of the incoming request can get direct access to a private network resource.

If appropriately configured, the firewall protects systems on one side of it from systems on th other side of the firewall.

  • A firewall is an intrusion detection mechanism that is designed by each organization’s security policy. Its settings can change to make appropriate changes to its functionality.
  • Firewalls can configure to restrict incoming traffic to POP and SMTP and to enable email access. Certain firewalls block specific email services to secure against spam.
  • A firewall can configure to check inbound traffic at a “checkpoint” where a security audit is performed. It can also act as an active “phone tap” tools for identifying an intruder’s attempt to dial into modems in a secured network. Firewall logs consist of logging information that reports to the administrator all attempts to access various services.
  • The Firewall verifies the incoming and outgoing traffic against firewall rules and acts as a router to move data between networks. Firewalls allow or deny access request made from one side of the firewall to services on the other side of the firewall.
  • Identify all the attempts to log into the network for auditing. Unauthorized attempts can be identified by embedding an alarm that is triggered when an unauthorized user attempts to log in. Firewalls can filter packets based on address and types of traffic. they recognize the source, destination addresses, and port numbers when address filtering, and they identify types of network traffic when protocol filtering. Firewalls can identify the state and attributes of data packets.

What is Firewall? And Firewall Architecture

Firewall Architecture

Bastion Host

The Bastion host designed for defending the network against attacks. it acts as a mediator between inside and outside networks. A bastion host is a computer system designed and configured to protect network resources from attack. Traffic entering or leaving the network passes through the firewall, it has two interfaces:

  • Public interface directly connected to the Internet.
  • Private interface connected to the Intranet.

Screened Subnet

A Screened subnet (DMZ) is a protected network created with a two or three-homed firewall behind a screening firewall and is a name commonly used to refer to the DMZ When using a three-homed firewall, connect the first interface to the internet, the second interface to the DMZ, no hosts accessed by the private network. Internet users can not access the private zone.

The advantage of screening a subnet away from the intranet is that public requests can be responded to without allowing traffic into the intranet. A disadvantage with the three-homed firewall is that if it compromised, both the DMZ an intranet could also be compromised. A safer technique is to use multiple firewalls to separate the Internet form the DMZ, and then to separate the DMZ from the Intranet.

What is Firewall? And Firewall Architecture

Multi-Homed Firewall

A Multi-Homed firewall is a node with multiple NICs that connects to two or more networks. It connects each interface to the separate network segments logically and physically. A multi-Homed firewall helps in increasing efficiency and realibility of an IP network. In the Multi-Homed firewall helps, more thatn three interfaces are present that allow for further subdividing the systems based on the specific security objectives of the organiztions. However, the model that adds depth of protection is the back-to-back firewall.

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