Question : Difference Between A Proxy Server and Firewall

What is the difference between a firewall and a proxy server?  I know a firewall can be configured to block certain traffic from entering your network, and a proxy server can be configured to cache files from the internet and prevent your users from accessing certain sites that you wish to prevent.  Is this correct?

Also,  if you have a T1 installed and your router contains the CSU/DSU what side of router will the firewall and proxy server reside on?

Thanks

Answer : Difference Between A Proxy Server and Firewall

You are correct

Proxy intercepts all requests to the real server to see if it can fulfill the requests itself. If not, it forwards the request to the real server and return result to client.
Proxy servers have two main purposes:
1)Improve Performance (caching)
2)Filter Requests For example, a company might use a proxy server to prevent its employees from accessing a specific set of Web sites.



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A system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.

There are several types of firewall techniques:

1) Packet filter: Looks at each packet entering or leaving the network and accepts or rejects it based on user-defined rules. Packet filtering is fairly effective and transparent to users, but it is difficult to configure. In addition, it is susceptible to IP spoofing.

2) Application gateway: Applies security mechanisms to specific applications, such as FTP and Telnet servers. This is very effective, but can impose a performance degradation.

3) Circuit-level gateway: Applies security mechanisms when a TCP or UDP connection is established. Once the connection has been made, packets can flow between the hosts without further checking.

4) Proxy server: Intercepts all messages entering and leaving the network. The proxy server effectively hides the true network addresses.


Tipicaly firewall installed between router and LAN


--modem-router----Firewall---LAN