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11.6. بروكسي HTTP/FTP

يعمل بروكسي HTTP/FTP كوسيط في اتصالات HTTP و (أو) FTP. يتمثل دور البروكسي في جزأين:
اختارت شركة فلكوت Squid كمخدم بروكسي.

11.6.1. التثبيت

The squid[2] Debian package only contains the modular (caching) proxy. Turning it into a filtering server requires installing the additional squidguard package. In addition, squid-cgi provides a querying and administration interface for a Squid proxy.
قبل التثبيت، يجب الانتباه إلى التحقق من أن النظام يستطيع التعرّف على اسمه الكامل: يجب أن يعيد الأمر hostname -f اسماً كامل التوصيف fully-qualified (أي يتضمن اسم نطاق). إذا لم يُعِد ذلك، يجب تعديل الملف /etc/hosts حتى يحوي الاسم الكامل للنظام (مثلاً، arrakis.falcot.com). يجب التحقق من الاسم الرسمي للحاسوب مع مدير الشبكة لتفادي أي تضاربات.

11.6.2. إعداد خدمة التخبئة

Enabling the caching server feature is a simple matter of editing the /etc/squid/squid.conf configuration file and allowing machines from the local network to run queries through the proxy. The following example shows the modifications made by the Falcot Corp administrators:

مثال 11.22. The /etc/squid/squid.conf file (excerpts)

# INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
#
include /etc/squid/conf.d/*

# Example rule allowing access from your local networks.
# Adapt localnet in the ACL section to list your (internal) IP networks
# from where browsing should be allowed

acl our_networks src 192.168.1.0/24 192.168.2.0/24
http_access allow our_networks
http_access allow localhost
# And finally deny all other access to this proxy
http_access deny all

11.6.3. إعداد خدمة الترشيح

squid itself does not perform the filtering; this action is delegated to squidGuard. The former must then be configured to interact with the latter. This involves adding the following directive to the /etc/squid/squid.conf file:
url_rewrite_program /usr/bin/squidGuard -c /etc/squid/squidGuard.conf
The /usr/lib/cgi-bin/squidGuard.cgi CGI program also needs to be installed, using /usr/share/doc/squidguard/examples/squidGuard.cgi.gz as a starting point. Required modifications to this script are the $proxy and $proxymaster variables (the name of the proxy and the administrator's contact email, respectively). The $image and $redirect variables should point to existing images representing the rejection of a query.
The filter is enabled with the service squid reload command. However, since the squidguard package does no filtering by default, it is the administrator's task to define the policy. This can be done by creating the /etc/squid/squidGuard.conf file (using /etc/squidguard/squidGuard.conf.default as template if required).
يجب إعادة توليد قاعدة بيانات العمل باستخدام update-squidguard بعد كل تعديل على ملف ضبط squidGuard (أو تعديل إحدى قوائم النطافات أو عناوين URL التي يحويها). صيغة ملف الضبط موثّقة على الموقع التالي:


[2] The squid3 package, providing Squid until Debian Jessie, is now a transitional package and will automatically install squid.
[3] PICS has been superseded by the Protocol for Web Description Resources (POWDER system: https://www.w3.org/2009/08/pics_superseded.html.