Academic Tutorials

English | French | Portugese | German | Italian
Home Advertise Payments Recommended Websites Interview Questions FAQs
News Source Codes E-Books Downloads Jobs Web Hosting

IP Masquerading Intorduction
IP Masquerading Setting Up
IP Masquerading Setting Up - Part 2
IP Masquerading Easy Links
IP Masquerading Linux Networking
IP Masquerading Network Address
IP Masquerading IPCHAINS 101
IP Masquerading IP_MASQ 101
IP Masquerading Setting Up The Router
IP Masquerading Caveats

HTML Tutorials
HTML Tutorial
XHTML Tutorial
CSS Tutorial
TCP/IP Tutorial
CSS 1.0
CSS 2.0
XML Tutorials
XML Tutorial
XSL Tutorial
XSLT Tutorial
DTD Tutorial
Schema Tutorial
XForms Tutorial
XSL-FO Tutorial
XML DOM Tutorial
XLink Tutorial
XQuery Tutorial
XPath Tutorial
XPointer Tutorial
RDF Tutorial
SOAP Tutorial
WSDL Tutorial
RSS Tutorial
WAP Tutorial
Web Services Tutorial
Browser Scripting
JavaScript Tutorial
VBScript Tutorial
DHTML Tutorial
HTML DOM Tutorial
WMLScript Tutorial
E4X Tutorial
Server Scripting
ASP Tutorial
PERL Tutorial
SQL Tutorial
ADO Tutorial
Apple Script
PL/SQL Tutorial
SQL Server
.NET (dotnet)
.Net Mobile
C# : C Sharp
SVG Tutorial
Flash Tutorial
Media Tutorial
SMIL Tutorial
Photoshop Tutorial
Gimp Tutorial
Gnuplot Programming
GIF Animation Tutorial
Scientific Visualization Tutorial
Web Building
Web Browsers
Web Hosting
W3C Tutorial
Web Building
Web Quality
Web Semantic
Web Careers
Weblogic Tutorial
Web Site Hosting
Domain Name
Java Tutorials
Java Tutorial
JSP Tutorial
Servlets Tutorial
Struts Tutorial
EJB Tutorial
JMS Tutorial
JMX Tutorial
Programming Langauges
C Tutorial
C++ Tutorial
Visual Basic Tutorial
Data Structures Using C
Assembly Language
Forth Programming
Lisp Programming
Data Warehousing
CGI Programming
Emacs Tutorial
Soft Skills
Communication Skills
Time Management
Project Management
Team Work
Leadership Skills
Corporate Communication
Negotiation Skills
Database Tutorials
Operating System
Software Testing
SAP Module
Business Warehousing
SAP Basis
Material Management
Sales & Distribution
Human Resource
Customer Relationship Management
Production and Planning
Networking Programming
Corba Tutorial
Networking Tutorial
Microsoft Office
Microsoft Word
Microsoft Outlook
Microsoft PowerPoint
Microsoft Publisher
Microsoft Excel
Microsoft Front Page
Microsoft InfoPath
Microsoft Access
Financial Accounting
Managerial Accounting
Network Sites

Setting Up IP-Masquerading

Previoushome Next

Setting up IP-Masquerading



IP-Masquerading provides the possibility to connect several computers to the Internet using a computer running Linux with just one public IP address. This means you can connect a whole private network to the Internet, and your Internet Service provider thinks you are still connecting just one single computer. This article will explain how to configure IP-Masquerading with a 2.2.x Kernel. It does not explain how to build a network.


To use IP-Masquerading as explained in this article you need at least one Linux box with a 2.2.x Kernel. This machine is used to set up the connection to the Internet. Using Linux as your connection-sharing box doesn't mean that you have run Linux in your internal network. In fact, Linux works well with Windows, Macs, and other flavours of Unix.
This connection-sharing box is what we are concerned about in this article. It connects on one side to the Internet and on the other side to your private network. The machine has therefore at least 2 interfaces and also at least 2 IP addresses. One of the IP addresses is a public IP address which can be routed in the Internet. This IP address is usually assigned to you by your Internet Service Provider the very moment you setup your modem connection (or what ever you use). The other IP addresses is a private address which you can assign from one of these ranges:

  • -
  • -
  • - (we use this range in this article)

This article does not explain how to set up your network. I assume that your private network is already in place and configured.  

IP-Masquerading principles

Basically IP-Masquerading translates internal IP addresses into external IP addresses. This is called network address translation and Linux does this by using something called port-numbers. From the outside world, all connections will seem to be originating from your Linux box.

Sometimes, IP packets are special in nature and IP-Masquerading may not work for all applications, but it works in most cases. There are modules for ICQ, ftp, and quake that need to be inserted in the Kernel in order for those special applications to run correctly from the internal network. In general though, anything that uses only the HTTP (web browsers), telnet, ssh, or smtp (email) will work fine.  

Setting up the Kernel

People who use an out of the box Kernel from one of the major Linux distributions (Redhat, Mandrake, Debian, Suse...) can skip this chapter as their kernel is already prepared to use IP-Masquerading.

I usually make a backup of /usr/src/linux/.config after I have compiled a successfully working Kernel. Next time I need to compile a Kernel I just load this configuration and I have already the configuration of my previous Kernel in place. It is then relatively simple to configure minor changes such as IP-Masquerading.

To use IP-Masquerading say yes to the following when configuring the Kernel. These are just the components you need for IP Masquerade, select whatever other options you need for your specific setup.


  • Prompt for development and/or incomplete code/drivers
    (this will allow you to select experimental IP Masquerade code compiled into the kernel)
  • Enable loadable module support
  • Networking support
  • Network firewalls
  • TCP/IP networking
  • IP: forwarding/gatewaying
  • IP: firewalling
  • IP: masquerading
  • IP: ipportfw masq support
  • IP: ipautofw masquerade support
  • IP: ICMP masquerading
  • IP: always defragment CONFIG_IP_ALWAYS_DEFRAG
  • Dummy net driver support
  • IP: ip fwmark masq-forwarding support

Configure IP-Masquerading

We will write a little script to automate IP-Masquerading configuration. You should put the the following script into /etc/rc.d/init.d/ and call it ipmasq. Change permissions with chmod 755 ipmasq to make it executable. The script below assumes that you have used the static IP address on the interface towards your internal network (ifconfig eth0 netmask Please change the script if you are using something else. This picture shows the network plan of the network that we are using.

echo "Setting up IP masquerading ..."
# People still using windows to surf the web must convert this
# to a UNIX text file before using it.
# Support masquerading of FTP file transfer.
/sbin/modprobe ip_masq_ftp
# Note: the modules below are commented out from loading. Remove the
# comment sign if you want to use the corresponding applications form
# one of the computers inside your internal network.
# Support masquerading of RealAudio over UDP.
#/sbin/modprobe ip_masq_raudio
# Supports the masquerading of IRC DCC file transfers
#/sbin/modprobe ip_masq_irc
# Support masquerading of Quake and QuakeWorld
# Quake I / QuakeWorld (ports 26000 and 27000)
#/sbin/modprobe ip_masq_quake
# Quake I/II/III / QuakeWorld (ports 26000, 27000, 27910, 27960)
#/sbin/modprobe ip_masq_quake ports=26000,27000,27910,27960
# Support masquerading of the CuSeeme video conferencing software
#/sbin/modprobe ip_masq_cuseeme
#Support masquerading of the VDO-live video conferencing software
#/sbin/modprobe ip_masq_vdolive
# Important: Enable IP forwarding. It is disabled by default in
# the 2.2.x Kernels
echo "1" > /proc/sys/net/ipv4/ip_forward
# NOTE: This is an example for an internal Network address of
# 192.168.0.x The sub netmask is or "24" bit
# Please change this if you use different internal IP addresses.
/sbin/ipchains -P forward DENY
/sbin/ipchains -A forward -s -j MASQ
#--- end of file

To test it make sure you have configured all your computers in your private network to have a default gateway route (!!!) to (the masquerading Linux host). Then run the script as root on the masquerading host. After that send a ping from one machine inside your network to a host in the Internet (e.g ping
If this works then masquerading works. Try also ping This should give the same results as the above ping. If it does not work then check the /etc/resolv.conf file on your clients. It should exist on every computer inside your network and should list the DNS server of your ISP.
With Windows 9x-Clients you need to bind the network configuration of the TCP/IP-Stack to the Networkcard and DNS needs to be activated by adding the DNS server of the ISP under 'search order for DNS Server'.
Once the pings work everything else (e.g web browsing) will also work.

Now it is time to change your configuration such that your /etc/rc.d/init.d/ipmasq script will be executed automatically every time you boot your Linux connection-box. The best way to do this is in my opinion to edit the /etc/rc.d/init.d/network file (this file should already exist) and execute /etc/rc.d/init.d/ipmasq AT THE END of the start section in the init.d/network file. Look for a case statement and then for the "start)".  


As you saw it is not difficult to setup IP-Masquerading. It is basically just ip forwarding enabled and 2 ipchains commands. IP-Masquerading is a very powerful application for small home networks schools small business networks etc....

Be the first one to comment on this page.

  IP-Masquerading eBooks

No eBooks on IP-Masquerading could be found as of now.

 IP-Masquerading FAQs
More Links » »
 IP-Masquerading Interview Questions
More Links » »
 IP-Masquerading Articles

No IP-Masquerading Articles could be found as of now.

 IP-Masquerading News

No News on IP-Masquerading could be found as of now.

 IP-Masquerading Jobs

No IP-Masquerading Articles could be found as of now.

Share And Enjoy:These icons link to social bookmarking sites where readers can share and discover new web pages.
  • blinkbits
  • BlinkList
  • blogmarks
  • co.mments
  • connotea
  • digg
  • Fark
  • feedmelinks
  • Furl
  • LinkaGoGo
  • Ma.gnolia
  • NewsVine
  • Netvouz
  • RawSugar
  • Reddit
  • scuttle
  • Shadows
  • Simpy
  • Smarking
  • Spurl
  • TailRank
  • Wists
  • YahooMyWeb

Previoushome Next

Keywords: Setting up IP-Masquerading, IP-Masquerading, IP-Masquerading, IP-Masquerading tutorial, IP-Masquerading tutorial pdf, history of IP-Masquerading, Custamizing Style Sheet, learn IP-Masquerading

HTML Quizzes
CSS Quiz
CSS 1.0 Quiz
CSS 2.0 Quiz
XML Quizzes
XML Quiz
XSL Quiz
DTD Quiz
Schema Quiz
XForms Quiz
XLink Quiz
XQuery Quiz
XPath Quiz
XPointer Quiz
RDF Quiz
RSS Quiz
WAP Quiz
Web Services Quiz
Browser Scripting Quizzes
JavaScript Quiz
VBScript Quiz
WMLScript Quiz
E4X Quiz
Server Scripting Quizzes
ASP Quiz
SQL Quiz
ADO Quiz
CVS Quiz
Python Quiz
Apple Script Quiz
SQL Server Quiz
PHP Quiz
.NET (dotnet) Quizzes
Microsoft.Net Quiz
ASP.Net Quiz
.Net Mobile Quiz
C# : C Sharp Quiz
VC++ Quiz
Multimedia Quizzes
SVG Quiz
Flash Quiz
Media Quiz
Photoshop Quiz
Gimp Quiz
Matlab Quiz
Gnuplot Programming Quiz
GIF Animation Quiz
Scientific Visualization Quiz
Graphics Quiz
Web Building Quizzes
Web Browsers Quiz
Web Hosting Quiz
W3C Quiz
Web Building Quiz
Web Quality Quiz
Web Semantic Quiz
Web Careers Quiz
Weblogic Quiz
SEO Quiz
Web Site Hosting Quiz
Domain Name Quiz
Java Quizzes
Java Quiz
JSP Quiz
Servlets Quiz
Struts Quiz
EJB Quiz
JMS Quiz
JMX Quiz
Eclipse Quiz
J2ME Quiz
Programming Langauges Quizzes
C Quiz
C++ Quiz
Visual Basic Quiz
Data Structures Using C Quiz
Cobol Quiz
Assembly Language Quiz
Mainframe Quiz
Forth Programming Quiz
Lisp Programming Quiz
Pascal Quiz
Delphi Quiz
Fortran Quiz
OOPs Quiz
Data Warehousing Quiz
CGI Programming Quiz
Emacs Quiz
Gnome Quiz
ILU Quiz
Soft Skills Quizzes
Communication Skills Quiz
Time Management Quiz
Project Management Quiz
Team Work Quiz
Leadership Skills Quiz
Corporate Communication Quiz
Negotiation Skills Quiz
Database Quizzes
Oracle Quiz
MySQL Quiz
Operating System Quizzes
BSD Quiz
Symbian Quiz
Unix Quiz
Internet Quiz
IP-Masquerading Quiz
IPC Quiz
Software Testing Quizzes
Testing Quiz
Firewalls Quiz
SAP Module Quizzes
ERP Quiz
Business Warehousing Quiz
SAP Basis Quiz
Material Management Quiz
Sales & Distribution Quiz
Human Resource Quiz
Netweaver Quiz
Customer Relationship Management Quiz
Production and Planning Quiz
Networking Programming Quizzes
Corba Quiz
Networking Quiz
Microsoft Office Quizzes
Microsoft Word Quiz
Microsoft Outlook Quiz
Microsoft PowerPoint Quiz
Microsoft Publisher Quiz
Microsoft Excel Quiz
Microsoft Front Page Quiz
Microsoft InfoPath Quiz
Microsoft Access Quiz
Accounting Quizzes
Financial Accounting Quiz
Managerial Accounting Quiz
Testimonials | Contact Us | Link to Us | Site Map
Copyright ? 2008. Academic All rights reserved Privacy Policies | About Us
Our Portals : Academic Tutorials | Best eBooksworld | Beyond Stats | City Details | Interview Questions | Discussions World | Excellent Mobiles | Free Bangalore | Give Me The Code | Gog Logo | Indian Free Ads | Jobs Assist | New Interview Questions | One Stop FAQs | One Stop GATE | One Stop GRE | One Stop IAS | One Stop MBA | One Stop SAP | One Stop Testing | Webhosting in India | Dedicated Server in India | Sirf Dosti | Source Codes World | Tasty Food | Tech Archive | Testing Interview Questions | Tests World | The Galz | Top Masala | Vyom | Vyom eBooks | Vyom International | Vyom Links | Vyoms | Vyom World | Important Websites
Copyright ? 2003-2024 Vyom Technosoft Pvt. Ltd., All Rights Reserved.