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
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

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.
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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).
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References in periodicals archive ?
To encrypt the data object M under T, the data owner computes a session key between the data owner and the proxy server [K.sub.S] = e(p([g.sup.[gamma]]).sup.a], H([ID.sub.S])) as well as the session key between the data owner and the SDS monitor [K.sub.SDS] = e([([g.sup.[sigma]]).sup.a], H([ID.sub.SDS])).
Finally, this approach increases burdens on the proxy server. If the proxy server is overloaded it could adversely affect the web browsing performance [15].
This article will address some of the more common technological roadblocks (i.e., the IP address, hotspots, and proxy servers) that an attorney can run into when attempting to track down anonymous Internet abusers.
The SIP session creation and communication process begins with the registration of the user in the proxy server. The SIP proxy server plays the role of requesting call connection and termination for the user.
Anonymous proxy servers are easy to use, and many are free, requiring no registration or identifying information from the end user.
The Proxy servers represent a special arrangement where the firewall interposes the client transaction between the outer unprotected network and the inner protected network server.
Generally speaking, using a proxy server works, but it does give you a delay time of some five to 10 seconds per Web page accessed.
When companies build out their Internet access systems in this way--i.e., by adding general-purpose servers with proxy server software--they increase hardware, software and administrative costs proportionally and have little power to improve the productivity of even the most competent and dedicated IT staff.
The proxy server and software now enable NMCI users at China Lake and Point Mugu to access the valuable electronic periodicals and databases available via the library Web site located at
The three warnings, all issued last week, involve the Microsoft Virtual Machine for running Java applets on Windows; a cross-site scripting bug in a component of Windows 2000 and Windows NT 4.0; and a DoS (denial-of-service) bug affecting Proxy Server 2.0 and ISA Server.
If an organization has restrictions about the nature of Internet sites that an employee can visit, both the employee's browser records and the records of the company's Internet firewall and/or Internet proxy server could be called into evidence in an employee termination proceeding.
We have provided a partial solution for them that involves logging on the Security Assistance Network (SAN) and using the SAN proxy server. Some users who are having trouble with .MIL access have not yet registered to use the SAN proxy server.