How do I allow access to all requests through squid proxy server?

You need to edit the squid config file to enable access. The default location for the squid file on ubuntu is : /etc/squid3/squid.conf

The following lines enable access to all requests:

# allow all requests    
acl all src 0.0.0.0/0
http_access allow all

# Make sure your custom config is before the "deny all" line
http_access deny all

Note: Make sure you insert this before the final deny block in the squid config file:

If you’d like to debug your requests , use the following line in your config file:

debug_options ALL,1 33,2 28,9

This enables extensive logging for every request. The logs can be found in /var/log/squid3/cache.log