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Back in Windows land, it was only Chrome and IE and few other softwares that used IE's internal proxy settings. I'm interested to know how does it work in Ubuntu/Linux in general?

Often just setting the HTTP_PROXY environment variable would be caught by the program, it seems to me, but it is all that open network-proxy does ? Can softwares neglect this setting, by making direct connections? Is it actually up to them to decide ? Or if once I set a system wide proxy setting, it re-routes everything ?

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up vote 3 down vote accepted

System wide proxy settings are just another consolidated place for proxy settings. It actually modifies the places where different apps' config files. Have you noticed, system wide proxy setting asks for password 2 times? This is mainly because of the modification of two admin files which corresponds to config file.

And yes, from 10.10 and 11.10, some apps have been left out of system wide proxy setting most notable among them is the synaptic.

and moreover, apps can bypass the system wide setting and make use of their own setting again most notable synaptics and Mozilla Firefox(which contains system settings option as well).

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Could you state which files ? – Abhay Rana Sep 30 '11 at 11:15
read about it… – Vineet Menon Sep 30 '11 at 11:51

It is up to the programmer if his software uses proxy settings. Though a lot of software does, there are some programs which are not working with proxies at all (e.g. ubuntuone-filesync).

System wide proxy settings modifies

  • /etc/environment
  • /etc/apt/apt.conf
  • /etc/gconf/gconf.xml.defaults/%gconf-tree.xml

(This is for Ubuntu 11.04)

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