My squid conf this way:
http_port 3128 transparent tproxy
cache_mem 256 MB
cache_swap_low 90
cache_swap_high 95
maximum_object_size 400096 KB
cache_replacement_policy lru
memory_replacement_policy lru
cache_dir ufs /var/spool/squid/squid 30000 16 256
cache_dir ufs /var/spool/squid/squid1 30000 16 256
cache_dir ufs /var/spool/squid/squid2 30000 16 256
access_log /var/log/squid/access.log squid
cache_log /var/log/squid/cache.log
cache_store_log /var/log/squid/store.log
pid_filename /var/run/squid.pid
client_netmask 255.255.255.255
request_header_max_size 20 KB
acl all src 0.0.0.0/0.0.0.0
dns_nameservers 127.0.0.1 201.30.200.3
acl manager proto cache_object
acl minha_rede src 201.30.200.0/25 189.3.1.0/24 189.3.0.0/25
acl localhost src 127.0.0.1/255.255.255.255
acl to_localhost dst 127.0.0.0/8
acl purge method PURGE
http_access allow minha_rede
http_access allow manager localhost
http_access deny manager
http_access allow purge localhost
http_access deny purge
http_access allow localhost
http_access deny all
http_reply_access allow all
icp_access allow all
cache_mgr rodrigofsantos@gmail.com
cache_effective_user proxy
cache_effective_group proxy
logfile_rotate 0
forwarded_for on
error_directory /usr/share/squid/errors/Portuguese
tcp_outgoing_address 0
always_direct allow all
wccp_router 201.30.200.1
wccp_version 42
coredump_dir /var/spool/squid