A firewall is designed to block unwanted outside traffic from reaching your computer system or network while allowing authorized traffic to pass through the firewall and reach its intended destination inside your network.
There are over 65,000 ports that are available to allow connections from the Internet to your network. Each port is like a door that allows specific traffic in and out. A firewall should by default block all ports that are not necessary to reduce the chances of an intruder gaining unauthorized access. Some ports, such as 25 (email) and 80 (web access) will have to remain open on your firewall for necessary services to work. business firewalls
1. Packet filter: A packet filter doesnt analyze the content of each packet that attempts to access your network; it simply decides whether or not to pass the information through the firewall based on its port number and IP address. If a service tries to access any port aside from the one it is intended to use, the packet filter firewall will simply discard the message.firewall hardware
2. Proxy firewall: A proxy firewall often disguises the actual IP address of each individual network or computer from each other. A proxy firewall can either simply provide a circuit between the client and the server, or it can read and record each individual command for auditing and accounting purposes.
3. Stateful inspection firewall: With a stateful inspection firewall each individual connection is recorded using a state table that inspects all incoming and outgoing IP addresses and port numbers. Stateful inspection firewalls are the most advanced and offer the fullest protection for your network.
It is absolutely essential that you run a firewall on your home network and keep it updated with the latest firewall rules. Most routers can be configured as packet filtering firewalls, and if possible for maximum security a stateful inspection firewall should be set up between your modem and your router.
- 2011/12/22(木) 20:10:54|