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Firewall Testing About VESARiA |
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3.3 What are proxy servers and how do they work?
A proxy server (sometimes referred to as an application gateway or
forwarder) is an application that mediates traffic between a protected
network and the Internet. Proxies are often used instead of
router-based traffic controls, to prevent traffic from passing
directly between networks. Many proxies contain extra logging or
support for user authentication. Since proxies must ``understand'' the
application protocol being used, they can also implement protocol
specific security (e.g., an FTP proxy might be configurable to permit
incoming FTP and block outgoing FTP).
Proxy servers are application specific. In order to support a new
protocol via a proxy, a proxy must be developed for it. One popular
set of proxy servers is the TIS Internet Firewall Toolkit (``FWTK'')
which includes proxies for Telnet, rlogin, FTP, X-Window, HTTP/Web,
and NNTP/Usenet news. SOCKS is a generic proxy system that can be
compiled into a client-side application to make it work through a
firewall. Its advantage is that it's easy to use, but it doesn't
support the addition of authentication hooks or protocol specific
logging. For more information on SOCKS, see
http://www.socks.nec.com/
.
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Vesaria
3640 Fords Lane, Suite D
Baltimore, MD 21215
443 - 501 - 4044
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