Squid

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From the squid website:

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. Squid has extensive access controls and makes a great server accelerator. It runs on Unix and Windows and is licensed under the GNU GPL.

While squid works wonderfully in large corporations and schools, it can also benefit the home user too. However, if you're looking for a more lightweight single-user proxy, you should try Polipo (website).

Contents

Installation

To install the latest version of Squid, run

pacman -Sy squid

Configuration

By default, the cache directories will be created in /var/cache/squid, and the appropriate permissions set up for those directories. However, for greater control, we need to delve into /etc/squid/squid.conf.

Everything is well commented, but if you want to strip the comments out you should run:

sed -i "/^#/d;/^ *$/d" /etc/squid/squid.conf

The following options might be of some use to you. If you do not have the option present in your configuration file, add it!

  • http_port - Sets the port that Squid binds to on your local machine. You can have Squid bind to multiple ports by specifying multiple http_proxy lines. By default, Squid binds to port 3128.
http_port 3128
http_port 3129
  • http_access - This is an access control list for who is allowed to use the proxy. By default only localhost is allowed to access the proxy. For testing purposes, you may want to change the option http_access deny all to http_access allow all, which will allow anyone to connect to your proxy. If you wanted to just allow access to your subnet, you can do:
acl ip_acl src 192.168.1.0/24
http_access allow ip_acl
http_acesss deny all
  • cache_mgr - This is the email address of the cache manager.
cache_mgr squid.admin@example.com
  • shutdown_lifetime - Specifies how long Squid should wait when its rc.d script is asked to stop. If you're running squid on your desktop PC, you may want to set this to something short.
shutdown_lifetime 10 seconds
  • cache_mem - This is how much memory you want Squid to use to keep objects in memory rather than writing them to disk. Squid's total memory usage will exceed this! By default this is 8MB, so you might want to increase it if you have lots of RAM available.
cache_mem 64 MB
  • visible_hostname - Pretty much self explanatory!
visible_hostname cerberus
  • cache_peer - If you want your Squid to go through another proxy server, rather than directly out to the Internet, you need to specify it here.
  • never_direct - Tells the cache to never go direct to the internet to retrieve a page. You will want this if you have set the option above.
cache_peer 10.1.1.100 parent 8080 0 no-query default
never_direct allow all
  • maximum_object_size - The largest size of a cached object. By default this is small (256KB I think), so if you have a lot of disk space you will want to increase the size of it to something reasonable.
maximum_object_size 10 MB
  • cache_dir - This is your cache directory, where all the cached files are stored. There are many options here, but the format should generally go like:
cache_dir diskd <directory> <size in MB> 16 256

So, in the case of a school's internet proxy:

cache_dir diskd /cache0 200000 16 256

If you change the cache directory from defaults, you must set the correct permissions on the cache directory before starting Squid, else it won't be able to create its cache directories and will fail to start.

Starting

Once you have finished your configuration, you should check that your configuration file is correct:

squid -k check

Then create your cache directories:

squid -z

Then you can start Squid!

/etc/rc.d/squid start

Don't forget to add squid to the DAEMONS=() section of rc.conf if you want it to start on boot.

Other Software

If you're looking for a content filtering solution to work with Squid, you should check out the very powerful DansGuardian (website). If you'd like a web-based frontend for managing Squid, Webmin is your best bet.

NTLM

This section is really unclear...

To get Windows authentication, we should change /etc/squid/squid.conf:

http_port 3128
hierarchy_stoplist cgi-bin ?
acl apache rep_header Server ^Apache
broken_vary_encoding allow apache
acl apache rep_header Server ^Apache
broken_vary_encoding allow apache
cache_mem 50 MB
access_log /var/log/squid/access.log squid
auth_param ntlm children 20
auth_param ntlm program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp
authenticate_ip_ttl 9 hour
refresh_pattern ^ftp:           1440    20%     10080
refresh_pattern ^gopher:        1440    0%      1440
refresh_pattern .               0       20%     4320
acl all src 0.0.0.0/0.0.0.0
acl manager proto cache_object
acl localhost src 127.0.0.1/255.255.255.255
acl to_localhost dst 127.0.0.0/8
acl SSL_ports port 443
acl Safe_ports port 80          # http
acl Safe_ports port 21          # ftp
acl Safe_ports port 443         # https
acl Safe_ports port 70          # gopher
acl Safe_ports port 210         # wais
acl Safe_ports port 1025-65535  # unregistered ports
acl Safe_ports port 280         # http-mgmt
acl Safe_ports port 488         # gss-http
acl Safe_ports port 591         # filemaker
acl Safe_ports port 777         # multiling http
acl CONNECT method CONNECT
acl auth  proxy_auth REQUIRED

http_access allow manager localhost
http_access deny manager
http_access deny !Safe_ports
http_access deny CONNECT !SSL_ports
http_access allow all auth
http_access deny all

http_access allow all

http_reply_access allow all
icp_access allow all

cache_effective_user proxy
cache_effective_group proxy

coredump_dir /var/cache/squid

visible_hostname yourhostname
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