The web proxy in ClearOS is a high-performance proxy caching server for web clients, supporting HTTP, FTP and some lesser known protocols. The software not only saves bandwidth and speeds up access time, but also gives administrators the ability to track web usage via web-based reports.
Maximum Cache Size
The maximum size on your hard disk to use for the proxy server cache.
Maximum Object Size
Any file (image, web page, PDF, etc) above the maximum object size will still go through the proxy but will not be cached. Large files (for instance, a movie file) can take up a lot of space in your proxy cache. If you have a cache size of 2 Gb and two people happen to download 1 Gb files at the same time, then these two files would replace everything else in your cache. You can limit the maximum object size to prevent this kind of scenario.
Maximum Download File Size
If you want to limit downloads of large files (for instance, movies) you can set a maximum size. Any file above this size limit will get blocked.
Web Proxy Mode
The web proxy provides several different modes to meet the needs of your network.
In transparent mode, all web requests from the local network automatically pass through the proxy. The advantage: no configuration changes are required on the workstations. The disadvantage: secure web sites (HTTPS) can not flow through the proxy.
If you would like to add the content filter feature, you must also enable it in the proxy.
Banner and Pop-up Filter
You can enable a basic banner ad and pop-up filter for you proxy server.
If you would like to require a username/password for web access, you can enable user authentication.
User authentication cannot be used in conjunction with transparent mode. If you require user authentication, then non-transparent mode is required. This is not a limitation of the software, but a limitation of the way the web protocol was designed!
Use the button to delete all the files currently stored by the web proxy server.
Web Site Bypass
In some circumstances, you may need to by-pass the proxy server. Typically, this is required for web sites that are not proxy-friendly. Some notable examples:
Older Microsoft IIS web servers send invalid web server responses
Microsoft IIS web servers can be configured with non-standard authentication
If you are running the proxy in non-transparent mode, then you also have to adjust your web browser's proxy server settings. The web site or IP address that you add to the ClearOS web proxy bypass list should also be added to your browser's proxy exception list.
Web Browser Configuration
In non-transparent mode, you must change the settings on all the web browsers running on your local network. The following describes the steps for configuring Internet Explorer, but other browsers have similar procedures. In Internet Explorer
Click on in the menu bar
Select Internet Options
Click on the tab
Click on the button
In the Proxy Server settings box, specify your ClearOS IP address and the proxy port (see next section). You may not be able to access websites on your system or local network unless you select bypass proxy server for local addresses.
Which Port Should I Use?
So which port should be configured in your web browser's proxy settings?
Are you using transparent mode? If yes, then no web browser changes are required! If not, continue.
Are you using the content filter? If yes, use port 8080. If no, use port 3128.
From the Squid Web Proxy FAQ:
Question: Can I make my regular FTP clients use a Squid cache?
Answer: It's not possible. Squid only accepts HTTP requests.