Ubuntu – Start Squid Cache Proxy

The fact that there is nothing in the access.log suggests that the requests from clients aren't being routed through Squid at all but something else on the same server.

Could you post more information about your setup, Squid config and what you actually have on the same box (censoring it first of course).

I am not sure, but please take a look with this checklist:

Edit the the squid.conf file and change the following line to enable transparent proxy mode:

http_port 3128

to

http_port 3128 intercept

Then

service squid restart 
service squid reload

Add an entry to iptables NAT table to port-forward inbound traffic on the inside interface (LAN side) to the Squid server on port 3128 (assuming eth0 is the inside interface with the IP address 192.168.1.3

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT --to 192.168.1.3:3128

Now you can look at your iptables, default filter table, and NAT table, using the following commands:

iptables -L -t filter

iptables -L -t nat

Now you can add (append) to the iptable filter table with the following commands, to accept input on port 3128 for Squid

iptables -t filter -A INPUT -p tcp --dport 3128 -j ACCEPT

Also Try this:

You need both one 'intercept' and one 'forward proxy' port in config even if you don't use forward proxy:

http_port 3129 

http_port 3128 intercept

Note: The transparent option has been deprecated by intercept option since 2010.