[squid-users] Squid 3.3.11 in Transparent mode Access Denied

I have configured Squid 3.3.11 in Transparent mode on ubuntu 12.04 by
below squid.conf:

acl localhost src 127.0.0.1/32 ::1
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

http_access allow all
http_access allow localhost

http_port 3128 transparent

cache_dir ufs /usr/local/squid/var/cache/squid 100 16 256

debug_options rotate=1 ALL,5

coredump_dir /var/spool/squid3

# Add any of your own refresh_pattern entries above these.
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern -i (/cgi-bin/|?) 0 0% 0
refresh_pattern (Release|Packages(.gz)*)$ 0 20% 2880
# example lin deb packages
#refresh_pattern (.deb|.udeb)$ 129600 100% 129600
refresh_pattern . 0 20% 4320

I have one network interface eth0 so I have added below rule to
iptables:

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT
--to-port 3128

and I configured firefox's proxy as IP:127.0.0.1 and port:3128
Now when I send request to squid I'm getting access denied error as
below:

The following error was encountered while trying to retrieve the URL:
http://stackoverflow.com/

  ACCESS DENIED.

Access control configuration prevents your request from being allowed at
this time. Please contact your service provider if you feel this is
incorrect.

Your cache administrator is webmaster.
Received on Tue Jun 24 2014 - 07:08:09 MDT