Squid, the Caching Proxy - Squid's Major Functions
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On the previous page we tried to explain that web caching means saving bandwidth and decreasing latencies. Squid's major features and related to its two-pronged web cache and proxy server existence. These advantages are extended by fantastic logging features (thus, network monitoring benefits), access control, traffic management, authorization, limitation, and plenty of TCP/IP optimizations.
Squid is used all over the world by ISPs and numerous websites, as well as content delivery providers. A lot of server administrators have found that implementing Squid into their network decreased or even eliminated their need for a hardware upgrade. This means that a struggling and overloaded setup, with the help of Squid, turned into a high-performing and optimized combination that allows a better user experience.
Summing up, Squid is a tried and proven server accelerator. However, once Squid is up and running, you should also take advantage of its other features. By this I mean the ACL (Access Control List). These ACLs are built from rules, and those are composed of access control elements.
Well-configured ACLs improve the security of your server. This means that you can take control and independently configure the type of content you allow, through which ports, to which users, and so forth. You can also fiddle with content request rewrites. Educational organizations have found that configuring ACLs can offer great help in imposing limits on specific content which the students must not access.
Once Squid is running, you should pay attention to the way it works, meaning you ought to always monitor its logs, especially "cache.log." This log file fills with informational messages, warnings, and error messages, if need be. So if you are experiencing problems or it just seems to be acting funky, then you should look inside the logs to find the root cause of the problem(s).
This is all well and good, but cache.log isn't the only logging that Squid does. Aside from that, we have a wide range of other log files for different purposes. First you have the "store.log" that enlists Squid's decisions regarding the content stored in the cache, and "access.log" records HTTP transactions (along with their origin, content type, etc.). For a detailed overview of these, check the official docs. And yes, there are even more log files.
As you can see, Squid can be an amazing addition to your network even without taking advantage of its web caching functions, though that would be quite dumb -- but there are reasons why one would opt for that, too. Squid can work as a feature-laden transparent proxy. And once it is optimized and its accelerator mode kicks in, you are going to notice better performance from your server.
System administrators should invest time in learning Squid's configuration.
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