Some of squid's default config params are not really satisfying. 

Usually, you want to change the size of the cache to say 20 Gig ... 
cache_dir ufs /var/spool/squid 20000 16 256 
... and allow your complete LAN to access your squid: 

# after acl localhost src 
acl lan 
# and after http_access allow localhost 
http_access allow lan 

or simply change ... 
http_access allow localhost 
... to ... 
http_access allow all 
... and leave the rest to iptables + /etc/hosts.deny + /etc/hosts.allow

From: IBCL BLog.
Originally posted: 2006-06-25