 |
|
The Proxy Server
System administration can set up proxy servers to be used for many services, such as FTP, the Web, and Telnet. Systems admi
nistrators decide which Internet services must go through a proxy server. Specific proxy server software is required for ea
ch different kind of Internet.
When a computer from the corporate network makes a request to the Internet -- such as to get a Web page from a Web server -
- it looks to that computer as if it connects directly to the Web server on the Internet. In fact, however, the internal co
mputer contacts the proxy server with its request, which in turn contacts the Internet server. The Internet server sends th
e Web page to the proxy server, which then forwards the page to the proxy server, which then forwards the p[age to the corp
orate computer.
Proxy servers can be used as a way to log the Internet traffic between an Internet corporate network and the Internet. For
example, a Telnet proxy server could track every single keystroke hot in every Telnet session -- and could also track how
the external server on the internal reacts to the keystrokes. Proxy servers can log every IP address, date and time of acce
ss, URL, number of bytes downloaded, and so on. This information can be used to analyze any attacks launched against the ne
twork.
Proxy servers can do more than simply relay requests back and forth between a computer on a network and a server on the Int
ernet implement security schemes as well. For example, an FTP proxy server could be set up to allow files to be sent from
the Internet to a computer on a network, but not to allow files to be sent from the corporate network out to the Internet -
- or vice versa.
Proxy servers can also be used to speed up performance of some Internet services by caching data -- keeping copies of the r
equested data. For example, a Web proxy server could cache many Web pages. Then, whenever someone from the internal corpor
ate network wanted to get one of those Web pages, that person could get it directly from the server at a high speed, instea
d of having to go out across the Internet and get the page at a lower speed.
|
