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I am using gnome-classic on Ubuntu 14.04. I am confused about different ways that can set up proxies.

  1. In gnome-classic's Settings->Network->Network Proxy,

    (1) When the method is Manual, (See screen shot below)

    • will the settings of HTTP proxy, HTTPS Proxy, and FTP proxy affect all and only the programs that use HTTP, HTTPS, and FTP respectively?

    • will the setting of SOCKS proxy with a port affect all and only those programs attached to the port?

    (2) when the method is Automatic, it says "Web Proxy AutoDiscover is used when a configurtion URL is not provided" (see screen shot below). But I check that there is no proxy. Do I miss something?

  2. In a program, such as Firefox or ssh client, if I set up a proxy in its settings, will the proxy only affect the program, not any other programs?

  3. In the way of environment variables, what programs are affected by the values of HTTP_PROXY, FTP_PROXY, and SOCKS_SERVER?

  4. What are differences and relation between the above three way? For example, are the gnome network settings for proxy essentially the same as those settings in proxy environment variables?

    How do the proxy settings in the three ways (in a program, in Gnome network settings, and in environment variables) work together?

    • Does some setting override another setting?

    • are the proxy settings all used, in the way that the proxy servers are used in a chain (i.e. the program first uses the proxy server in gnome network setting, which in turn uses the proxy server in the environment variables, which in turn uses the proxy server in the program) ?

    • are the proxy settings all used, in the way that for a program to use a proxy server, the proxy server must be set up in gnome network settings, in the program's own settings, and/or in an environment variable? For example, do I need to set up a proxy server in my browser after set up the proxy server as HTTP proxy in gnome network settings?

Thanks.

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closed as too broad by Panther, Kevin Bowen, Cornelius, user117103, user364819 Oct 14 '15 at 16:32

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    You have a lot of questions, too many IMO for this format. Yes, a proxy is set per protocol (http, https, ftp most common) and once set affects all applications / programs using that protocol. There can be some exceptions, such as apt. See wiki.archlinux.org/index.php/Proxy_settings – Panther Oct 11 '15 at 15:50
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  1. If you set this up system-wide, the application that respect system-wide setup (do not have manual override or ignore this settings) will be affected.

    a) Yes, as proposed in the comment. But the SOCKS proxy is quite different, since it should direct all the traffic through that port.

    b) Did you fill the configuration URL?

  2. Yes. If you set up manual proxy for and in Firefox, only Firefox will be affected.

Answering only parts I know. Others are left for another answerers.

  • Thanks. About 1 (2) I didn't. But it says "Web Proxy AutoDiscover is used when a configurtion URL is not provided". I don't know what is "Web Proxy AutoDiscover", but isn't this thing supposed to do the job when I didn't provide a configuration URL? By the way what is "a configuration URL" used for? – Tim Oct 11 '15 at 21:34
  • Yes. You are right. I read wrong for the first time. I have no idea how does it work, but I guess there is some protocol that can be used in corporate networks (for example on wiki). Nothing for us mortal :) – Jakuje Oct 11 '15 at 21:47

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