proxy server

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proxy server

Computing a computer that acts as an intermediary between a client machine and a server, caching information to save access time

proxy server

[′präk·sē ‚sər·vər]
(computer science)
Software for caching and filtering Web content to reduce network traffic on intranets, and for increasing security by filtering content and restricting access.

Proxy Server

(software, security)
Microsoft's proxy server and proxy gateway, designed to provide extensible firewall and network security. Proxy Server is part of BackOffice.

proxy server

(programming, World-Wide Web)
A process providing a cache of items available on other servers which are presumably slower or more expensive to access.

This term is used particularly for a World-Wide Web server which accepts URLs with a special prefix. When it receives a request for such a URL, it strips off the prefix and looks for the resulting URL in its local cache. If found, it returns the document immediately, otherwise it fetches it from the remote server, saves a copy in the cache and returns it to the requester. The cache will usually have an expiry algorithm which flushes documents according to their age, size and access history.

Compare proxy gateway.

proxy server

A proxy server is a computer system or router that functions as a relay between client and server. It helps prevent an attacker from invading a private network and is one of several tools used to build a firewall.

The word proxy means "to act on behalf of another," and a proxy server acts on behalf of the user. All requests to the Internet go to the proxy server first, which evaluates the request and forwards it to the Internet. Likewise, responses come back to the proxy server and then to the user.


Proxy Servers Provide Anonymity
Like a virtual private network (VPN), a proxy server hides the user's IP address when accessing the Internet. See VPN and TLS.







Address Translation and Caching
The proxy server is a dual-homed host with two network IP addresses. The address on the outbound side is the one the Internet sees. Proxies are often used in conjunction with network address translation (NAT), which hides the users' IP addresses on the internal network. Proxy servers may also cache Web pages so that the next request for that page can be retrieved much faster. See NAT and proxy cache.

Other Proxies
Anonymous proxy servers let users surf the Web and keep their IP address private (see anonymous proxy). Although not specifically called proxies, Internet email (SMTP) and the Usenet new system (NNTP) are somewhat similar because messages are relayed from sender to recipient. See firewall.

Application Level and Circuit Level
"Application-level" proxies or "application-level gateways" are dedicated to specific content such as HTTP (Web) and FTP (file transfer). In contrast, a "circuit-level" proxy supports every application (see SOCKS).

Forward and Reverse Proxies
In this definition, the proxy servers are "forward proxies" that hide the details of the clients from the servers. However, proxies can also reside at the website to hide details from the clients (see reverse proxy).


A Proxy Server in a LAN
In this example, the proxy server functions as a firewall in the public side of a company network, which is called the "demilitarized zone" (see DMZ).
References in periodicals archive ?
13, 2009), available at http://epub.uniregensburg.de/11919/l/authorsversion-ccsw09.pdf; see also John Borland, Flaws Spotlighted in Tor Anonymity Network, WIRED (Dec.
(65.) David Talbot, China Cracks Down on Tor Anonymity Network TECH.
(29) However, many have also complained that anonymity networks provide a safe haven for criminal activity.
(49) The question is whether Tor violates "[section] 512(i)'s mandate that all such networks not interfere with 'standard technical measures,' which [section] 512(i)(2) describes as 'technical measures that are used by copyright owners to identify or protect copyrighted works.'" (50) Because the DMCA was not intended to cover and did not anticipate anonymity networks like Tor, it seems unlikely that a court would apply its provisions to Tor.
Significantly, President Obama has proposed measures that would inhibit Internet privacy, including anonymity networks like Tor.
(76) While Saudi Arabia's ban on anonymity networks is partially intended to give teeth to its censorship efforts, the government has also made clear that it is interested in surveillance.
The United Arab Emirates' objective in banning anonymity networks is twofold.
If the new provisions have the effect of banning anonymity networks that completely hide the user's identity, then this could effectively outlaw Tor.
The anonymity network hides your computer's IP address, thereby making it really difficult to find the true identity of users.
Individual IP addresses can be hid by anonymity networks like Tor.
Such a weakness could be used to launch targeted attacks that track users' online activity, forcibly terminate a communication, hijack a conversation between hosts or degrade the privacy guarantee by anonymity networks such as Tor.
The weakness would allow attackers to degrade the privacy of anonymity networks, such as Tor, by forcing the connections to route through certain relays.