Linux – Web Site Block with squid server

Thanks all of you for your ans. I understand the problem now and i move into squid server. First of all i install a squid server on my server PC[I am using CentOS 5.5].
First i download a yum package:

yum install squid

Then i configure the squid server in this way:

vi /etc/squid/squid.conf

Add Those line into squid.conf file:

httpd_accel_host virtual
httpd_accel_port 80
httpd_accel_with_proxy on
httpd_accel_uses_host_header on
acl localhost src 127.0.0.1/8
acl lan src 202.51.176.42 192.168.10.1/24
http_access allow localhost
http_access allow lan

And then save and exit [As i use 202.51.176.42 as a real IP in eth2 and the sub network in eth0 as 192.168.10.1]. Then Add a file:

cat > /etc/fw.proxy

Then add Those line into the fw.proxy file:

#!/bin/sh
# ------------------------------------------------------------------------------------
# See URL: http://www.cyberciti.biz/tips/linux-setup-transparent-proxy-squid-howto.html
# (c) 2006, nixCraft under GNU/GPL v2.0+
# -------------------------------------------------------------------------------------
# squid server IP
SQUID_SERVER="202.51.176.42"
# Interface connected to Internet
INTERNET="eth2"
# Interface connected to LAN
LAN_IN="eth0"
# Squid port
SQUID_PORT="3128"
# Clean old firewall
iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
# Load IPTABLES modules for NAT and IP conntrack support
modprobe ip_conntrack
modprobe ip_conntrack_ftp
# For win xp ftp client
#modprobe ip_nat_ftp
echo 1 > /proc/sys/net/ipv4/ip_forward
# Setting default filter policy
iptables -P INPUT DROP
iptables -P OUTPUT ACCEPT
# Unlimited access to loop back
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT
# Allow UDP, DNS and Passive FTP
iptables -A INPUT -i $INTERNET -m state --state ESTABLISHED,RELATED -j ACCEPT
# set this system as a router for Rest of LAN
iptables --table nat --append POSTROUTING --out-interface $INTERNET -j MASQUERADE
iptables --append FORWARD --in-interface $LAN_IN -j ACCEPT
# unlimited access to LAN
iptables -A INPUT -i $LAN_IN -j ACCEPT
iptables -A OUTPUT -o $LAN_IN -j ACCEPT
# DNAT port 80 request comming from LAN systems to squid 3128 ($SQUID_PORT) aka transparent proxy
iptables -t nat -A PREROUTING -i $LAN_IN -p tcp --dport 80 -j DNAT --to  $SQUID_SERVER:$SQUID_PORT
# if it is same system
iptables -t nat -A PREROUTING -i $INTERNET -p tcp --dport 80 -j REDIRECT --to-port $SQUID_PORT
# DROP everything and Log it
iptables -A INPUT -j LOG
iptables -A INPUT -j DROP

Then save the script. And Execute the script:

chmod +x /etc/fw.proxy
/etc/fw.proxy
service iptables save
chkconfig iptables on

Then restart the proxy server:
/etc/init.d/squid restart
But this cause a output like this:

Stopping squid:                                            [FAILED]
init_cache_dir /var/spool/squid... /etc/init.d/squid: line 62:  8990 Aborted                 $SQUID -z -F -D >> /var/log/squid/squid.out 2>&1
Starting squid: /etc/init.d/squid: line 42:  8991 Aborted                 $SQUID $SQUID_OPTS >> /var/log/squid/squid.out 2>&1
                                                       [FAILED]

In my "/var/log/messages" i find this two line:

Dec 27 06:48:42 ns1 squid[8990]: Could not determine fully qualified hostname.  Please set 'visible_hostname' 
Dec 27 06:48:45 ns1 squid[8991]: Could not determine fully qualified hostname.  Please set 'visible_hostname'

Please someone help me to solve this problem.