How to install squid proxy on centos 6

August 1, 2012 krizna Centos 146

Squid proxy :

Squid is a proxy server for caching and filtering web content . Squid proxy is used by various organisation and internet providers to reduce bandwidth and to increase response time .

Squid proxy service will cache the requested web-content and re-using it for the further request of the same content .

In the above diagram, squid proxy will cache the webcontent of krizna.com from the ISP during the first request and it will deliver the cached content for the further requests of krizna.com without requesting from ISP. This will reduce bandwidth and will increase response time as the content is delivered from the local network.
» Install squid proxy
» Restricting Access to specific web sites
» Restricting Access to specific keywords
» Restricting Access to specific ipaddress
» Allow Full access to specific ipaddress
» Changing squid proxy port number
» Restricting download size
» Configure squid as transparent proxy

» Install squid proxy on centos 6 :

In this article we can see how to install and configure squid proxy on centos 6 . After installing Centos 6 (Centos 6 installation step by step screenshots ) and configuring network (How to setup network in centos 6)
Update yum repositories and packages by typing the below command

[root@leela ~]# yum update

Step 1 » Install squid package and dependencies using the below command

[root@leela ~]# yum install squid

» By default squid configuration file “/etc/squid/squid.conf” will contains recommended minimum configuration and squid caching feature will work without making any changes . Recommended minimum configuration will looks like the below

#
# Recommended minimum configuration:
#
acl manager proto cache_object
acl localhost src 127.0.0.1/32 ::1
acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1

# Example rule allowing access from your local networks.
# Adapt to list your (internal) IP networks from where browsing
# should be allowed
acl localnet src 10.0.0.0/8     # RFC1918 possible internal network
acl localnet src 172.16.0.0/12  # RFC1918 possible internal network
acl localnet src 192.168.0.0/16 # RFC1918 possible internal network
acl localnet src fc00::/7       # RFC 4193 local private network range
acl localnet src fe80::/10      # RFC 4291 link-local (directly plugged) machines

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

#
# Recommended minimum Access Permission configuration:
#
# Only allow cachemgr access from localhost
http_access allow manager localhost
http_access deny manager

# Deny requests to certain unsafe ports
http_access deny !Safe_ports

# Deny CONNECT to other than secure SSL ports
http_access deny CONNECT !SSL_ports

# We strongly recommend the following be uncommented to protect innocent
# web applications running on the proxy server who think the only
# one who can access services on "localhost" is a local user
#http_access deny to_localhost

#
# INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
#
# Example rule allowing access from your local networks.
# Adapt localnet in the ACL section to list your (internal) IP networks
# from where browsing should be allowed
http_access allow localnet
http_access allow localhost

# And finally deny all other access to this proxy
http_access deny all

# Squid normally listens to port 3128
http_port 3128

# We recommend you to use at least the following line.
hierarchy_stoplist cgi-bin ?

# Uncomment and adjust the following to add a disk cache directory.
#cache_dir ufs /var/spool/squid 100 16 256

# Leave coredumps in the first cache dir
coredump_dir /var/spool/squid

# 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 .               0       20%     4320

Step 2» Now start squid service

[root@leela ~]# service squid start

and type this below command to start squid service automatically while booting.

[root@leela ~]# chkconfig --levels 235 squid on

Step 3 » Setup your web browser to access Internet through proxy server on port 3128 .

IE : Tools » Internet options »Connections » LAN settings » Choose “Use a proxy server for your LAN” » Type your Proxy server ip (192.168.1.11 ) and port no 3128

Firefox : Options / Preferences » Advanced » Network » Settings » Choose “Manual proxy configuration ” » Type your Proxy server ip (192.168.1.11 ) and port no 3128

Step 4 » Browse some sites and check the access log file on proxy server

[root@leela ~]# cat /var/log/squid/access.log
1343759484.331   1828 192.168.1.15 TCP_MISS/200 7005 GET https://www.krizna.com/ - DIRECT/216.172.163.231 text/html
1343759484.645    265 192.168.1.15 TCP_MISS/304 477 GET http://platform.twitter.com/widgets.js - DIRECT/23.64.79.144 application/javascript
1343759484.681    309 192.168.1.15 TCP_MISS/304 839 GET http://apis.google.com/js/plusone.js - DIRECT/173.194.36.36 -
1343759485.005    178 192.168.1.15 TCP_MISS/200 495 GET http://www.google-analytics.com/__utm.gif? - DIRECT/74.125.236.142 image/gif
1343759502.763  20292 192.168.1.15 TCP_MISS/200 1898 CONNECT s-static.ak.facebook.com:443 - DIRECT/23.64.66.110 -
1343759502.765  20292 192.168.1.15 TCP_MISS/200 1898 CONNECT s-static.ak.facebook.com:443 - DIRECT/23.64.66.110 -
1343759723.040 240567 192.168.1.15 TCP_MISS/200 2904 CONNECT plusone.google.com:443 - DIRECT/173.194.36.41 -
1343759933.642    958 192.168.1.15 TCP_MISS/304 394 GET https://www.krizna.com/ - DIRECT/216.172.163.231 -
1343759934.518    459 192.168.1.15 TCP_MISS/200 495 GET http://www.google-analytics.com/__utm.gif? - DIRECT/173.194.36.8 image/gif
1343759943.131   2186 192.168.1.15 TCP_MISS/200 8343 CONNECT www.facebook.com:443 - DIRECT/66.220.146.94 -
1343759943.266  10616 192.168.1.15 TCP_MISS/200 2790 CONNECT apis.google.com:443 - DIRECT/74.125.236.128 -
1343759943.267  10615 192.168.1.15 TCP_MISS/200 2228 CONNECT ssl.gstatic.com:443 - DIRECT/74.125.236.143 -
1343759950.875   2596 192.168.1.15 TCP_MISS/200 32219 CONNECT www.facebook.com:443 - DIRECT/66.220.146.94 -
1343759961.388  20443 192.168.1.15 TCP_MISS/200 1911 CONNECT s-static.ak.fbcdn.net:443 - DIRECT/23.64.77.177 -

Troubleshooting :

If you not able to browse using proxy settings , Disable the firewall ( iptables ) and selinux service on your squid proxy server .
Disable firewall ( Iptables ) »
[root@leela ~]# service iptables stop [root@leela ~]# chkconfig iptables off

Disable Selinux » open the file /etc/selinux/config and find the line
SELINUX=enforcing

and replace with
SELINUX=disabled

now reboot the server and try step 4.

Configure squid proxy as web filter:

You can restrict user access to particular websites or keywords using access control lists (ACLs) .

» Restricting Access to specific web sites :

For example , we can see how to block facebook.com and gmail.com .
Step 1 » create a file ( /etc/squid/blockedsites.squid ) and add the site names one per line.
[root@leela ~]# cat /etc/squid/blockedsites.squid #blocked sites www.facebook.com www.gmail.com

Step 2 » Open the /etc/squid/squid.conf and create a new acl ” blocksites” and acl type “dstdomain” in the acl section like the below .

acl Safe_ports port 488         # gss-http
acl Safe_ports port 591         # filemaker
acl Safe_ports port 777         # multiling http
acl CONNECT method CONNECT
# ACL blocksites 
acl blocksites dstdomain "/etc/squid/blockedsites.squid"

and add the following line “http_access deny blocksites” to http_section to deny the access to the acl “blocksites” .

# Recommended minimum Access Permission configuration:
#
# Only allow cachemgr access from localhost
http_access allow manager localhost
# Deny access to blocksites ACL
http_access deny blocksites

Step 3 » Now restart squid service

[root@leela ~]# service squid restart

Step 4 » Try to access facebook.com in your browser . you could see the blocked page as below .

and check the log file you can see the facebook request is denied .

 [root@leela ~]# tail -f /var/log/squid/access.log
.................................................................................
1343820985.542      1 192.168.1.15 TCP_DENIED/403 4255 GET http://www.facebook.com/ - NONE/- text/html
1343820986.998   1411 192.168.1.15 TCP_MISS/200 13152 GET http://www.squid-cache.org/Artwork/SN.png - DIRECT/198.186.193.234 image/png
1343820987.004      0 192.168.1.15 TCP_DENIED/403 4178 GET http://www.facebook.com/favicon.ico - NONE/- text/html

» Restricting Access to specific keywords :

Step 1 » create a file ( /etc/squid/blockkeywords.squid ) and add the keywords one per line.
[root@leela ~]# cat /etc/squid/blockkeywords.squid #blocked keywords sex porn xxx

Step 2 » Open the /etc/squid/squid.conf and create a new acl “blockkeywords” and acl type “url_regex” in the acl section

acl Safe_ports port 488         # gss-http
acl Safe_ports port 591         # filemaker
acl Safe_ports port 777         # multiling http
acl CONNECT method CONNECT
# ACL blocksites 
acl blocksites dstdomain "/etc/squid/blockedsites.squid"
# ACL blockkeywords
acl blockkeywords url_regex -i "/etc/squid/blockkeywords.squid"

and add the following line “http_access deny blockkeywords” to http_section to deny the access to the acl “blockkeywords” .

# Recommended minimum Access Permission configuration:
#
# Only allow cachemgr access from localhost
http_access allow manager localhost
# Deny access to blocksites ACL
http_access deny blocksites
# Deny access to blockkeywords ACL
http_access deny blockkeywords

» Restricting Access to specific Ipaddress :

Step 1 » create a file ( /etc/squid/blockip.squid ) and add the ip adresses one per line.
[root@leela ~]# cat /etc/squid/blockip.squid #blocked ips 192.168.1.20 192.168.1.21

Step 2 » Open the /etc/squid/squid.conf and create a new acl “blockip” and acl type “src” in the acl section

acl Safe_ports port 488         # gss-http
acl Safe_ports port 591         # filemaker
acl Safe_ports port 777         # multiling http
acl CONNECT method CONNECT
# ACL blocksites 
acl blocksites dstdomain "/etc/squid/blockedsites.squid"
# ACL blockkeywords
acl blockkeywords url_regex -i "/etc/squid/blockkeywords.squid"
# ACL blockip
acl blockip src "/etc/squid/blockip.squid"

and add the following line “http_access deny blockip” to http_section to deny the access to the acl “blockip” .

# Recommended minimum Access Permission configuration:
#
# Only allow cachemgr access from localhost
http_access allow manager localhost
# Deny access to blockip ACL
http_access deny blockip
# Deny access to blocksites ACL
http_access deny blocksites
# Deny access to blockkeywords ACL
http_access deny blockkeywords

» Allow Full access to specific Ipaddress :

You can allow specific ip address to gain full access without blocking sites and keywords . just create a file “/etc/squid/allowip.squid ” and add the ip address one per line and create an acl “allowip” and acl type “src” in the acl section

# ACL allowip
acl allowip src "/etc/squid/allowip.squid"

and add the “allowip” in the http_access as below

# Recommended minimum Access Permission configuration:
#
# Only allow cachemgr access from localhost
http_access allow manager localhost
# Deny access to blockip ACL
http_access deny blockip
# Deny access to blocksites ACL
http_access deny blocksites !allowip
# Deny access to blockkeywords ACL
http_access deny blockkeywords !allowip

» Changing squid proxy port number:

You can change squid proxy port number , by default it uses 3128 port .

Just find the below line in “/etc/squid/squid.conf”

http_port 3128

and replace with

http_port 8000 # whatever port number you want

» Restricting Download size :

You can restrict download file size using reply_body_max_size .

Add the below line at the bottom of the http_access section

#Restrict download size reply_body_max_size 10 MB all

#Restrict download size reply_body_max_size 10 MB !allowip

» Configuring Squid as Transparent Proxy :

You can configure squid as transparent proxy .

Step 1 » just find the below line

# Squid normally listens to port 3128 http_port 3128

and replace with

# Squid normally listens to port 3128 http_port 3128 intercept

Step 2 » Create a file “/root/squidfw.sh” and add the following firewall script ( modify as per your interface configuration ).

#!/bin/sh
# squid server IP
SQUID_SERVER="192.168.1.11"
# Interface connected to Internet
INTERNET="eth0"
# Interface connected to LAN
LAN_IN="eth1"
# Squid port
SQUID_PORT="3128"
# DO NOT MODIFY BELOW
# 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

Step 3 » just run the script
[root@leela ~]# sh /root/squidfw.sh
and add the below line to “/etc/rc.local” to run the script during startup
sh /root/squidfw.sh
Step 4 (Updated) » Change default gateway ip to squid server ip on the user machines .
Now users can access Internet without setting proxy in the browser settings.

That’s it , hope this article will help you to learn little things about configuring squid proxy on centos 6.

Anthony Griffiths
September 24, 2013 at 6:41 pm
hi, of all the tutorials I’ve ploughed through this is the only one that’s worked for me so big thankyou. I would like to run openvpn on the squid machine as a client, so that all traffic through the server gets encrypted but I’m not having any joy. I’ve installed openvpn but when I start it the internet goes down. I expect I need to edit the squidfw.sh script to cater for openvpn but I don’t know how to do this. Can you help?
Reply
Anthony Griffiths
September 24, 2013 at 6:41 pm
hi, of all the tutorials I’ve ploughed through this is the only one that’s worked for me so big thankyou. I would like to run openvpn on the squid machine as a client, so that all traffic through the server gets encrypted but I’m not having any joy. I’ve installed openvpn but when I start it the internet goes down. I expect I need to edit the squidfw.sh script to cater for openvpn but I don’t know how to do this. Can you help?
Reply
Anthony Griffiths
September 30, 2013 at 9:42 pm
neither sendmail nor postfix will work on the machine running the transparent proxy. I get constant ‘hostname lookup failure’. I’ve made sure port 25 is listed as safe in squid.conf, to correct this does the squidfw.sh file need to be modified?
Reply
- krizna
  October 1, 2013 at 5:18 am
  For “hostname lookup failure” .. you need to add hostname in /etc/hosts like below ..
  127.0.0.1 localhost localhost.localdomain yourhostname ::1 localhost localhost.localdomain yourhostname
  For mail server.. add these lines in squidfw .sh file
  #sending mails iptables -A OUTPUT -o eth0 -p tcp -m multiport --dport 25,587,465 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth0 -p tcp -m multiport --sport 25,587,465 -m state --state ESTABLISHED -j ACCEPT #Receiving mails iptables -A INPUT -i eth0 -p tcp -m multiport --dport 110,995 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp -m multiport --sport 110,995 -m state --state ESTABLISHED -j ACCEPT
  # DROP everything and Log it # Before this line iptables -A INPUT -j LOG iptables -A INPUT -j DROP
  i’m not expert in iptables .. just try it 🙂
  Reply
Anthony Griffiths
September 30, 2013 at 9:42 pm
neither sendmail nor postfix will work on the machine running the transparent proxy. I get constant ‘hostname lookup failure’. I’ve made sure port 25 is listed as safe in squid.conf, to correct this does the squidfw.sh file need to be modified?
Reply
- krizna
  October 1, 2013 at 5:18 am
  For “hostname lookup failure” .. you need to add hostname in /etc/hosts like below ..
  127.0.0.1 localhost localhost.localdomain yourhostname ::1 localhost localhost.localdomain yourhostname
  For mail server.. add these lines in squidfw .sh file
  #sending mails iptables -A OUTPUT -o eth0 -p tcp -m multiport --dport 25,587,465 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth0 -p tcp -m multiport --sport 25,587,465 -m state --state ESTABLISHED -j ACCEPT #Receiving mails iptables -A INPUT -i eth0 -p tcp -m multiport --dport 110,995 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp -m multiport --sport 110,995 -m state --state ESTABLISHED -j ACCEPT
  # DROP everything and Log it # Before this line iptables -A INPUT -j LOG iptables -A INPUT -j DROP
  i’m not expert in iptables .. just try it 🙂
  Reply
Jose Daniel Sanchez R
October 3, 2013 at 7:01 pm
pregunto para agregar mas redes LAN_IN seria asi
LAN_IN1=”192.168.1.0″
LAN_IN2=”192.168.2.0″ ???
o como se haria??
##############################
asked to add more networks so serious LAN_IN
LAN_IN1 = “192.168.1.0”
LAN_IN2 = “192.168.2.0”???

or as they would do??
Reply
Jose Daniel Sanchez R
October 3, 2013 at 7:01 pm
pregunto para agregar mas redes LAN_IN seria asi
LAN_IN1=”192.168.1.0″
LAN_IN2=”192.168.2.0″ ???
o como se haria??
##############################
asked to add more networks so serious LAN_IN
LAN_IN1 = “192.168.1.0”
LAN_IN2 = “192.168.2.0”???

or as they would do??
Reply
Tamil amuthan
November 20, 2013 at 7:34 am
i block http sites but https sites are working, how to block https sites..?
Reply
Tamil amuthan
November 20, 2013 at 7:34 am
i block http sites but https sites are working, how to block https sites..?
Reply
viswanath.vikas
December 9, 2013 at 6:08 pm
Hi Krizna,
Very useful tutorials.
by this tutorials i was able to install squid server,But one problem i’m facing my outlook and Thunderbird is not working so plz can help me out to configure it..?
viswanath.vikas@gmail.com
Regards
Vikas viswanath
Reply
viswanath.vikas
December 9, 2013 at 6:08 pm
Hi Krizna,
Very useful tutorials.
by this tutorials i was able to install squid server,But one problem i’m facing my outlook and Thunderbird is not working so plz can help me out to configure it..?
viswanath.vikas@gmail.com
Regards
Vikas viswanath
Reply
Patryk Moura
December 15, 2013 at 1:24 am
I have a VPS, how to make it avaiable for access on my home pc? thanks!
Reply
Patryk Moura
December 15, 2013 at 1:24 am
I have a VPS, how to make it avaiable for access on my home pc? thanks!
Reply
Rob
January 10, 2014 at 2:15 pm
Hello,
I have recently setup a box which should connect my network to the internet. Browsing on my networks pc’s works through the squid proxy. But I also do other stuff like ssh to servers on the internet. And use filezilla, for ex. I have been looking at the squid.conf, but I can’t get that to work. I tried to open ports. 22 for ssh, and 21 for ftp was already there in the config. but I can’t do an ssh from my pc on the network through the squid-box. Is there a setting I missed? or are there other ways?
Regards,
ROb
Reply
Rob
January 10, 2014 at 2:15 pm
Hello,
I have recently setup a box which should connect my network to the internet. Browsing on my networks pc’s works through the squid proxy. But I also do other stuff like ssh to servers on the internet. And use filezilla, for ex. I have been looking at the squid.conf, but I can’t get that to work. I tried to open ports. 22 for ssh, and 21 for ftp was already there in the config. but I can’t do an ssh from my pc on the network through the squid-box. Is there a setting I missed? or are there other ways?
Regards,
ROb
Reply
Naresh Vulloju
February 19, 2014 at 7:40 am
Dear sir i have configured squid in CentOS with your instructions… but the problem is site blocking & keyword blocking for the https sites in squid is not working. squid is running in transparent mode .like wetransfer,Facebook…Do u have any suggetion?…
Reply
Naresh Vulloju
February 19, 2014 at 7:40 am
Dear sir i have configured squid in CentOS with your instructions… but the problem is site blocking & keyword blocking for the https sites in squid is not working. squid is running in transparent mode .like wetransfer,Facebook…Do u have any suggetion?…
Reply
Juvial
March 4, 2014 at 6:46 am
nice …..
Reply
Juvial
March 4, 2014 at 6:46 am
nice …..
Reply
Faisal Khan
April 25, 2014 at 12:58 pm
Hi,
Any body can help how can i create acl for skype user and how can i blocked SKYPE chating in my squid
Reply
Faisal Khan
April 25, 2014 at 12:58 pm
Hi,
Any body can help how can i create acl for skype user and how can i blocked SKYPE chating in my squid
Reply
Nosayba Suleiman
May 13, 2014 at 7:28 am
can both interfaces have the same subnet? because my LAN get its IP from the WAN router!! and the proxy is their internet gateway. so it there is a way to make them in the same subnet WAN port and LAN port? but different ethernet ports?
Reply
Nosayba Suleiman
May 13, 2014 at 7:28 am
can both interfaces have the same subnet? because my LAN get its IP from the WAN router!! and the proxy is their internet gateway. so it there is a way to make them in the same subnet WAN port and LAN port? but different ethernet ports?
Reply
Faisal Khan
May 14, 2014 at 11:40 am
Hi Krinza
can you help how can i create acl for skype user and how can i blocked SKYPE chating in my squid
Reply
Faisal Khan
May 14, 2014 at 11:40 am
Hi Krinza
can you help how can i create acl for skype user and how can i blocked SKYPE chating in my squid
Reply
sam55
May 22, 2014 at 10:03 am
hey dear all https site not working in transparent squid. please get solution for this… urgent……….
Reply
sam55
May 22, 2014 at 10:03 am
hey dear all https site not working in transparent squid. please get solution for this… urgent……….
Reply
ajay
August 5, 2014 at 1:58 pm
Dear Sir’
I have configure transparent squid proxy server but https site is not working and sites blocking issue.
Reply
ajay
August 5, 2014 at 1:58 pm
Dear Sir’
I have configure transparent squid proxy server but https site is not working and sites blocking issue.
Reply
ajay mishra
August 5, 2014 at 2:01 pm
Hi Krizana’
We are configure squid transparent proxy server s but https site is not working
So Please help.
Reply
ajay mishra
August 5, 2014 at 2:01 pm
Hi Krizana’
We are configure squid transparent proxy server s but https site is not working
So Please help.
Reply