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https://github.com/clearlinux/clear-linux-documentation.git
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Kevin Putnam
153 lines
4.9 KiB
ReStructuredText
153 lines
4.9 KiB
ReStructuredText
.. _autoproxy:
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Autoproxy
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#########
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Autoproxy is provided to enable |CL-ATTR| to work smoothly behind a
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corporate proxy.
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.. contents::
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:local:
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:depth: 1
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Description
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***********
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Autoproxy tries to detect a Proxy Auto-Config (PAC) script and use it to
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automatically resolve the proxy needed for a given connection. With
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Autoproxy, you can use |CL| inside any proxy environment without having to
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manually configure the proxies.
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Corporate and private networks can be very complex, needing to restrict and
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control network connections for security reasons. The typical side effects
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are limited or blocked connectivity, and require manual configuration of
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proxies to perform the most mundane tasks, such as cloning a repo or checking
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for updates. With |CL|, all of the work is done behind the scenes to
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effortlessly use your network and have connections “just work”.
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This feature removes severe complications with network connectivity due to
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proxy issues. You can automate tasks, such as unit testing, without worrying
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about the proxy not being set, and you can remove unset proxies from the
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equation when dealing with network unavailability across systems.
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How it works
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************
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We designed Autoproxy around tools provided by most Linux\*
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distributions with a few minor additions and modifications. We leveraged the
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DHCP and network information obtained from systemd and created a
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PAC-discovery daemon. The daemon uses the information to resolve a URL for a
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PAC file. The daemon then passes the URL into PACrunner\*. PACrunner
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downloads the PAC file and uses the newly implemented Duktape\* engine to
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parse it.
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.. figure:: figures/autoproxy_0.png
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:width: 400px
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Figure 1: Autoproxy Flow
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From that point on, any cURL\* or network requests query PACrunner for the
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correct proxy to use. We modified the cURL library to communicate with
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PACrunner over DBus. However, cURL will ignore PACrunner and run normally if
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no PAC file is loaded or if you manually set any proxies. Thus, your
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environment settings are respected and no time is wasted trying to resolve a
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proxy. All these steps happen in the background with no user interaction.
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Troubleshooting
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===============
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Autoproxy allows |CL| to operate seamlessly behind a proxy
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because :ref:`swupd <swupd-guide>` and other |CL| tools are implemented on
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top of libcurl. Tools that do not use libcurl, like git, must
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be configured independently.
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If you are familiar with PAC files and WPAD, you can use
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:command:`pacdiscovery` and :command:`FindProxyForURL` to
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troubleshoot problems with autproxy.
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.. note::
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Learn more about WPAD, PAC files, and PAC functions at `findproxyforurl`_.
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.. _findproxyforurl: http://findproxyforurl.com/
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Run :command:`pacdiscovery` with no arguments to indicate
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1. if there is a problem resolving the :command:`WPAD` host name resolution:
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.. code-block:: bash
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pacdiscovery
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.. code-block:: console
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failed getaddrinfo: No address associated with hostname
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Unable to find wpad host
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2. or if the :command:`pacrunner` service is disabled (masked).
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.. code-block:: bash
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pacdiscovery
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.. code-block:: console
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PAC url: http://autoproxy.your.domain.com/wpad.dat
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Failed to create proxy config: Unit pacrunner.service is masked.
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Unmask the :command:`pacrunner` service by running:
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.. code-block:: bash
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systemctl unmask pacrunner.service
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:command:`FindProxyForURL` with :command:`busctl` can also indicate if the
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:command:`pacrunner.service` is masked.
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.. code-block:: bash
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busctl call org.pacrunner /org/pacrunner/client org.pacrunner.Client
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.. code-block:: console
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FindProxyForURL ss "http://www.google.com" "google.com"
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Unit pacrunner.service is masked.
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dig wpad, dig wpad.<domain>
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:command:`FindProxyForURL` returns the URL and port of the proxy server when
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an external URL and host are provided as arguments.
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.. code-block:: bash
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busctl call org.pacrunner /org/pacrunner/client org.pacrunner.Client
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.. code-block:: console
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FindProxyForURL ss "http://www.google.com" "google.com"
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s "PROXY proxy.your.domain.com:<port>"
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If a proxy server is not avialable, or if :command:`pacrunner` is running
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without a PAC file, :command:`FindProxyForURL` will return "DIRECT".
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.. code-block:: bash
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busctl call org.pacrunner /org/pacrunner/client org.pacrunner.Client
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.. code-block:: console
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FindProxyForURL ss "http://www.google.com" "google.com"
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s "DIRECT"
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Once :command:`pacdiscovery` is able to look up :command:`WPAD`, restart the
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:command:`pacrunner` service:
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.. code-block:: bash
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systemctl stop pacrunner
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systemctl restart pacdiscovery
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.. note::
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A "domain" or "search" entry in :file:`/etc/resolv.conf` is required
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for short name lookups to resolve. The :file:`resolv.conf` man page has
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additional details. |