Deﬁnition: A proxy server isolates clients in a private network from the Internet or external servers by downloading and storing ﬁles on behalf of the clients. It intercepts requests for web-based or other resources that come from the clients, and, if it does not have the data in its cache, can generate a completely new request packet using itself as the source. In addition to providing security, the data cache can also improve client response time and reduce network traffic by providing frequently used resources to clients from a local source.
Proxy Servers for Different Services
Depending on the traffic level and network needs, different proxy servers can be conﬁgured for different external services. For example, one proxy server can handle HTTP requests, while another server can handle FTP content.
Client-side Proxy Setting Issues
You might be called upon to troubleshoot client-side proxy setting issues. Most of these issues can be addressed and ﬁxed within the web browser’s conﬁguration settings. Possible issues include:
- Proxy server settings are set to look at the wrong IP address.
- Exceptions can be set to include ranges (for example, you can bypass a proxy server if you access anything in the 192.168.x.y scope). The range could be mistyped.
- Often, proxy settings are handled within a browser. If the user has downloaded a new browser, or if there was a problem upgrading an older browser, these proxy settings might not be stored in the new browser.
- Proxy settings can be set so that all HTTP or FTP connections use a proxy server, but no other connections. It is possible that the FTP server information was entered into the HTTP server ﬁeld, or vice versa.