- –Either a hardware or software entity (or a combination of both) that protects a network by stopping network traffic from passing through it.
- –In most cases, a firewall is placed on the network to allow all internal traffic to leave the network (email to the outside world, web access, etc.), but stop unwanted traffic from the outside world from entering the internal network.
–This is achieved by granting and denying access to resources based on a set of configurable rules
–Firewalls are used to protect private networks from external intrusion.
–Firewalls can control what data is allowed in or out of a network.
–Firewalls can be created with hardware or software.
- •Proxy Servers
- –A proxy server acts as a middle-man between clients and the Internet providing security, administrative control, and caching services.
–When a user makes a request for an internet service and it passes filtering requirements, the proxy server looks in its local cache of previously downloaded web pages.
–If the item is found in cache, the proxy server forwards it to the client. This reduces bandwidth through the gateway.
–If the page is not in the cache, the proxy server will request the page from the appropriate server.
- –Nowadays, the functions of proxy servers are often built into firewalls.
- –Serve 3 main purposes.
– Disguise an end users actual identity using NAT.
– Cache requests to save bandwidth.
– Control content permitted to be requested from the Internet.