The Proxy Problem

Posted by Scott on Sep 29th, 2011

The following originally appeared on the Yocto Project’s blog:

The Yocto Project’s developers have been working hard to improve the usability of our software, especially its “out of the box” user experience. One area that has admittedly been a thorn in our side is when users need to access the internet via a network proxy server*. I thought I’d take a few moments to explain the situation, why we don’t have a “silver bullet” solution yet, and how to work around it.

If your personal or corporate network doesn’t require you to use a network proxy to access the Internet, consider yourself lucky. Proxies complicate network communications, requiring special protocols (such as SOCKS) to pass your development computer’s packets out to the Internet and back. And while the “do one thing and do it well” design philosophy of Linux/Unix programs has allowed these utilities to weather the test of time extremely well, there is no universally adopted method of modifying the networking behavior of these programs when it comes to using proxies. Here are but a few methods Linux programs can be made to use a proxy server:

  • Some utilities check for a special environment variable (HTTP_PROXY, HTTPS_PROXY, FTP_PROXY, etc)
  • Many desktop applications (e.g, GNOME apps) look for a proxy settings key in their global desktop registry
  • Others (like Subversion, or Mozilla Firefox) have their own config files or internal configuration dialogs where you have to specify proxy settings
  • Finally, some programs don’t contain any code for working with network proxies at all! In this case, you can sometimes get away with running the program under a separate, wrapper program which intercepts its network communications and automatically routes them through your proxy (tsocks is one of these wrapper programs)

I’m reminded of the saying: “Standards are like toothbrushes – everyone has one, but no one wants to use anyone else’s.” Truth be told, there is really no single solution to the proxy problem.

Another issue that poses problems for Yocto Project developers is that many of the proxy configurations for various tools (such as Subversion) are stored in the user’s own home directory. And modifying configuration files in your home directory is not something that will endear us to many users.

So what do you need to do to work with the Yocto Project behind a network proxy? Rather than filling this blog post with configuration tips, I’ll refer you to our wiki page, Working Behind a Network Proxy, where we make every effort to keep up to date with configuration tweaks needed for network proxy users.

If anyone can devise a way of reliably automating this process into a support script we could ship with the Yocto Project, we would be very open to including it. Just keep in mind that the script’s actions cannot clobber other config customizations a user may have, and would need to be fully reversible, to work for users who need to move in and out of proxied network environments.

* Note: a network proxy is different from a “firewall” – Yocto builds should work fine when run from behind a typical firewall router. Sometimes the terms “proxy” and “firewall” are used interchangeably, but they are quite different concepts.

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