Question about Computers & Internet

1 Answer

Firewall is not configered is linux centos

How to configer squid and iptables in linux centos pls, give me a help for
step by step configer on linux

Posted by on


1 Answer

  • Level 1:

    An expert who has achieved level 1.


    An expert who has answered 20 questions.


    An expert that hasĀ over 10 points.


    An expert whose answer gotĀ voted for 2 times.

  • Contributor
  • 39 Answers

Try and go for it..all d best...

Use yum command as follows:
# yum install squid
Loading "installonlyn" plugin Setting up Install Process Setting up repositories Reading repository metadata in from local files Parsing package install arguments Resolving Dependencies --> Populating transaction set with selected packages. Please wait. ---> Package squid.i386 7:2.6.STABLE6-4.el5 set to be updated --> Running transaction check Dependencies Resolved ============================================================================= Package Arch Version Repository Size ============================================================================= Installing: squid i386 7:2.6.STABLE6-4.el5 updates 1.2 M Transaction Summary ============================================================================= Install 1 Package(s) Update 0 Package(s) Remove 0 Package(s) Total download size: 1.2 M Is this ok [y/N]: y Downloading Packages: Running Transaction Test Finished Transaction Test Transaction Test Succeeded Running Transaction Installing: squid ######################### [1/1] Installed: squid.i386 7:2.6.STABLE6-4.el5 Complete! Squid Basic Configuration Squid configuration file located at /etc/squid/squid.conf. Open file using a text editor:
# vi /etc/squid/squid.conf
At least you need to define ACL (access control list) to work with squid. The defaults port is TCP 3128. Following example ACL allowing access from your local networks and Make sure you adapt to list your internal IP networks from where browsing should be allowed:
acl our_networks src
http_access allow our_networks
Save and close the file. Start squid proxy server:
# chkconfig squid on
# /etc/init.d/squid start
init_cache_dir /var/spool/squid... Starting squid: . [ OK ] Verify port 3128 is open:
# netstat -tulpn | grep 3128
tcp 0 0* LISTEN 20653/(squid) Open TCP port 3128 Finally make sure iptables is allowing to access squid proxy server. Just open /etc/sysconfig/iptables file:
# vi /etc/sysconfig/iptables
Append configuration:
-A RH-Firewall-1-INPUT -m state --state NEW,ESTABLISHED,RELATED -m tcp -p tcp --dport 3128 -j ACCEPT
Restart iptables based firewall:
# /etc/init.d/iptables restart
Flushing firewall rules: [ OK ] Setting chains to policy ACCEPT: filter [ OK ] Unloading iptables modules: [ OK ] Applying iptables firewall rules: [ OK ] Loading additional iptables modules: ip_conntrack_netbios_n[ OK ] Client configuration Open a webbrowser > Tools > Internet option > Network settings > and setup Squid server IP address and port # 3128.
See also You may find our previous squid tips useful:

Posted on Jun 22, 2009


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

2 Answers

Drivers for canon lbp2900b in linux for ubuntu and centos

how can i instal canon lbp2900 in cent os pls tell me any one step by step

Feb 21, 2011 | Canon LASER SHOT LBP-2900 Printer


How to configure your squid in linux

To configure squid proxy go to
/etc/squid/squid.conf file and then change its port no. from 3128 to 8080.
this is the http port that squid proxy listen for .

Then create your own access list
acl_access name_access_list src networkaddress

Then finally u have the power to allow or deny the particular network

http_access allow name_access_list

Just follow the above three steps to let squid work properly.

You must enable ip forwarding also.

for this go to


in it on the line
net_ipv4 forwarding=0
change it to 1
this will enable the ip forwarding

you can check ip forwarding by

sysctl -p

on Apr 24, 2010 | fedora Linux Operating System

1 Answer

How t format a pc with centos os?

The formatting and installing the PC with the centos is similar to the other Linux operating systems .
Initially insert installation cd and boot the computer and with the help of GUI you can perform the formatting and installation .
Installing centos is similar to rest of Linux operating systems

The detailed steps can be found from tyhe following link

May 05, 2010 | Red Hat Enterprise Linux ES Basic Edition

1 Answer

How to create subinterfaces on a 3845 series cisco router? I am trying to setup a trunk port for VLAN configuration. Thanks

Its like router on stick configuration??enter the interface which you have to configure and in that interface as mentioned below
Hostname(config)#interface FastEthernet0/1
Hostname(config-if)#no ip address
Hostname(config-if)#no shutdown
Hostname(config)#interface FastEthernet0/1.1
Hostname(config-if)#encapsulation dot1Q 1 native
Hostname(config-if)#ip address x.x.y.y < subnet mask >
interface FastEthernet0/1.2
Hostname(config-if)#encapsulation dot1Q 2
Hostname(config-if)#ip address x.x.y.y < subnet mask >

Apr 09, 2010 | Cisco 3845 Integrated Services Router...

1 Answer

How to counfugre asa 5505 cisco Router

Use the Cisco ASDM or SDM software, that will give you an easy graphical interface to configure the ASA. One of them would have been shipped with the device.

Don't forget the ASA has to pre-configured, just a simple config. Have HTTPS enabled and telnet/SSH helps as well if you dont have a serial port or the console cable.

Cisco's website will give you quite a lot of info for free...

Jan 18, 2010 | Cisco ASA 5505 Firewall

1 Answer


Dear Friend....
The examples below are based on the discussion of Linux iptables in Chapter 14, "Linux Firewalls Using iptables". Additional commands may be necessary for you particular network topology.
In both cases below, the firewall is connected to the Internet on interface eth0 and to the home network on interface eth1. The firewall is also the default gateway for the home network and handles network address translation on all the network's traffic to the Internet.
Only the Squid server has access to the Internet on port 80 (HTTP), because all HTTP traffic, except that coming from the Squid server, is redirected.
If the Squid server and firewall are the same server, all HTTP traffic from the home network is redirected to the firewall itself on the Squid port of 3128 and then only the firewall itself is allowed to access the Internet on port 80.
iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 \
-j REDIRECT --to-port 3128
iptables -A INPUT -j ACCEPT -m state \
--state NEW,ESTABLISHED,RELATED -i eth1 -p tcp \
--dport 3128
iptables -A OUTPUT -j ACCEPT -m state \
--state NEW,ESTABLISHED,RELATED -o eth0 -p tcp \
--dport 80
iptables -A INPUT -j ACCEPT -m state \
--state ESTABLISHED,RELATED -i eth0 -p tcp \
--sport 80
iptables -A OUTPUT -j ACCEPT -m state \
--state ESTABLISHED,RELATED -o eth1 -p tcp \
--sport 80
Note: This example is specific to HTTP traffic. You won't be able to adapt this example to support HTTPS web browsing on TCP port 443, as that protocol specifically doesn't allow the insertion of a "man in the middle" server for security purposes. One solution is to add IP masquerading statements for port 443, or any other important traffic, immediately after the code snippet. This will allow non HTTP traffic to access the Internet without being cached by Squid.
If the Squid server and firewall are different servers, the statements are different. You need to set up iptables so that all connections to the Web, not originating from the Squid server, are actually converted into three connections; one from the Web browser client to the firewall and another from the firewall to the Squid server, which triggers the Squid server to make its own connection to the Web to service the request. The Squid server then gets the data and replies to the firewall which then relays this information to the Web browser client. The iptables program does all this using these NAT statements:
iptables -t nat -A PREROUTING -i eth1 -s ! \
-p tcp --dport 80 -j DNAT --to
iptables -t nat -A POSTROUTING -o eth1 -s \
-d -j SNAT --to
iptables -A FORWARD -s -d \
-i eth1 -o eth1 -m state
-p tcp --dport 3128 -j ACCEPT
iptables -A FORWARD -d -s \
-i eth1 -o eth1 -m state --state ESTABLISHED,RELATED \
-p tcp --sport 3128 -j ACCEPT
In the first statement all HTTP traffic from the home network except from the Squid server at IP address is redirected to the Squid server on port 3128 using destination NAT. The second statement makes this redirected traffic also undergo source NAT to make it appear as if it is coming from the firewall itself. The FORWARD statements are used to ensure the traffic is allowed to flow to the Squid server after the NAT process is complete. The unusual feature is that the NAT all takes place on one interface; that of the home network (eth1).
You will additionally have to make sure your firewall has rules to allow your Squid server to access the Internet on HTTP TCP port 80 as covered in Chapter 14, "Linux Firewalls Using iptables".

Good Luck!

Jun 22, 2009 | Computers & Internet

1 Answer

Cisco ASA 5505 Firewall

1. Change your PCs default gateway to your firewalls' internal IP

2. configure the nameservers on your ASA

Then internet will work fine.

May 23, 2009 | Cisco ASA 5510 Anti-X Edition...

1 Answer

I can not install linux from my m2n68-am asus mb ,how to solve

1. please refer to the following links u will overcome your problems .

2. u have to install the x server in linux

Mar 30, 2009 | Computers & Internet

3 Answers

Obtain low bandwidh in linux

Sorry, I have no idea about Linux. Could be the software that is causing this issue..
I have forwarded this request to other Experts here who have more knowledge on this subject. Hopefully they should respond to your query within the next couple of hours..

Jun 13, 2008 | Computers & Internet

1 Answer

Nvidia Quadro4 (128MB RAM) driver required for linux

hi there..

here is the link for your Quadro 4 Graphics for linux 32 Bit

To download and install the drivers, follow the steps below:

STEP 1: Review the NVIDIA Software License.
You will need to accept this license prior to downloading any files.
STEP 2: Download the Driver File

Download -
SuSE users: please read the SuSE NVIDIA Installer HOWTO before downloading the driver.
STEP 3: Install
Type "sh" to install the driver. NVIDIA now provides a utility to assist you with configuration of your X config file. Please see Chapter 3 of the README or run 'man nvidia-xconfig' for details on usage. Instructions for those wishing to edit their X config file by hand can also be found in the README.


here is the link for your Quadro 4 Graphics for linux 64 Bit

To download and install the drivers, follow the steps below:
STEP 1: Review the NVIDIA Software License.
You will need to accept this license prior to downloading any files.
STEP 2: Download the Driver File
Download -
SuSE users: please read the SuSE NVIDIA Installer HOWTO before downloading the driver.
STEP 3: Install
Type "sh" to install the driver, then edit your X config file as appropriate. If you are using a Linux 2.6 based system, type "modprobe -q agpgart", first. See the text README for more detailed instructions.

All the Best.

Was this solution helpful? Show your Appreciation by rating it:

Feb 19, 2008 | Nvidia Quadro NVS 280 (64 MB) Graphic Card

Not finding what you are looking for?
Computers & Internet Logo

Related Topics:

388 people viewed this question

Ask a Question

Usually answered in minutes!

Top Computers & Internet Experts

Doctor PC
Doctor PC

Level 3 Expert

7733 Answers


Level 3 Expert

102366 Answers

David Payne
David Payne

Level 3 Expert

14162 Answers

Are you a Computer and Internet Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides