====== Squid Proxy ======

**General Information**

Squid is "a caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. It reduces bandwidth and improves response times by caching and reusing frequently-requested web pages."

Links:
  * Official Site: http://www.squid-cache.org/
  * Squid Logs: http://wiki.squid-cache.org/SquidFaq/SquidLogs

**Checklist**
  * Distro(s): Enterprise Linux 6

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====== Install Squid ======

Squid is available in CentOS base repos.
<code bash>
yum install squid
</code>

  * Main Config: /etc/squid/squid.conf
  * Log file: /var/log/squid/access.log

----

====== Configure ======

Config: /etc/squid/squid.conf

Modify "localnet" acl lines to only the networks you want talking to Squid
<code bash>
acl localnet src 10.1.2.0/24 # my network
</code>

Delete/Add to the "Safe_Ports" acl to only accept certain types of traffic
<code bash>
acl SSL_ports port 443
acl Safe_ports port 80
acl Safe_ports port 443
</code>

Change Squid listening port (if needed)
<code bash>
# Default Squid listen port 3128
http_port 3128
</code>

Uncomment the "cache_dir" line to create a space on disk to cache files
<code bash>
cache_dir ufs /var/spool/squid 512 16 256
</code>
  * The "512" means use 512 MB of space for cached content. This can be increased for busier proxies. (default is 100MB)

----

====== Run Squid ======

Start squid
<code bash>
service squid start
</code>

Enable on boot
<code bash>
chkconfig squid on
</code>

View Access Log for proxy TCP Hits and Misses
<code bash>
tail -f /var/log/squid/access.log
</code>

----

====== Point Clients to Squid ======

You can configure web browsers to go through Squid to take advantage of cached content.

  * Firefox
    * Options > Preferences > Advanced > Network tab > Connection Settings
    * Select "Manual proxy configuration"
    * HTTP Proxy: <server-ip>
    * Port: <squid-listening-port>
    * Click Ok

----

====== Web Filter ======

Squid can also be used as a web filter.

===== Block Domains =====
  - Create a file of sites to reference
    - <code bash>vim /etc/squid/blocked-sites.conf

# Blocked Websites
www.google.com</code>
  - Create a new acl in the main squid config
    - <code bash>vim /etc/squid/squid.conf

## Blocked Sites ##
acl blockedsites dstdomain "/etc/squid/blocked-sites.conf"
http_access deny blockedsites</code>
  - Reload Squid for changes to take affect
    - <code bash>service squid reload</code>

===== Block Key Words =====
  * Create file of key words
    * <code bash>vim /etc/squid/blocked-keywords.conf

# Blocked key words
gaming</code>
  * Create a new ACL in the main squid config
    * <code bash>vim /etc/squid/squid.conf
## Block keywords ##
acl blockedkeywords url_regex -i "/etc/squid/blocked-keywords.conf"
http_access deny blockedkeywords</code>

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