Best Free Firewall
Looking for free firewall? Did you know that you can get stateful and stateless firewalls to protect your computer for free? In computing, a firewall is a network security system that controls the incoming and outgoing network traffic based on an applied rule set. A firewall establishes a barrier between a trusted, secure internal network and another network. Stand-alone firewalls exist both as firewall software appliances to run on general purpose or standard industry hardware, and as hardware-based firewall computer appliances. Personal computer operating systems may include software-based firewalls to protect against threats from the public Internet. Routers that pass data between networks contain firewall components and, conversely, many firewalls can perform basic routing functions. Hardware-based firewall appliances may also offer other functionality to the internal network they protect, such as acting as a DHCP or VPN server for that network. Network layer firewalls, also called packet filters, operate at a relatively low level of the TCP/IP protocol stack, not allowing packets to pass through the firewall unless they match the established rule set. The firewall administrator may define the rules; or default rules may apply.
Network layer firewalls generally fall into two sub-categories, stateful and stateless. Stateful firewalls maintain context about active sessions, and use that “state information” to speed packet processing. Any existing network connection can be described by several properties, including source and destination IP address, UDP or TCP ports, and the current stage of the connection’s lifetime (including session initiation, handshaking, data transfer, or completion connection). If a packet does not match an existing connection, it will be evaluated according to the rule set for new connections. If a packet matches an existing connection based on comparison with the firewall’s state table, it will be allowed to pass without further processing.
Stateless firewalls require less memory, and can be faster for simple filters that require less time to filter than to look up a session. They may also be necessary for filtering stateless network protocols that have no concept of a session. However, they cannot make more complex decisions based on what stage communications between hosts have reached. To get free firewall, you only need to accept the company’s terms and conditions, and sign up to take part in their optional surveys and other simple services.