Frox is a feature we’ve built in to our Squid cache front end, and we utilize it to transparently cache FTP file transfers. Depending on the type of network you use, and your usage of the FTP protocol (often large) you can utilize a Squid and Frox combination (with some clever firewall rules) to store that content locally and accelerate the file transfers.

Squid has the ability to proxy and cache FTP transactions, but only if you are pointing to the cache. You cannot simply intercept FTP connections with a firewall and a Squid server – this is where Frox steps in. Frox is a transparent FTP proxy with a key feature – the ability to send requests through Squid.

In the diagram above, “Users” are downloading content from internet (or any over-WAN) FTP servers, and would typically go through “Firewall” and straight out. This is where the “Firewall” redirects to “Frox”. Frox then accepts the client, gets any login details and passes them along and proxies the connection through “Squid”, which fetches the objects and caches them.

This can drastically improve the speed of FTP transactions that are repeated often – for example, documents stored on FTP at head office that users require on a daily basis, but infrequently change.

Frox is freely available under the GPL license, from here, and a front end for this configuration comes standard with Snapt Squid.