Rishikesh Sharma's Blog

Destination NAT on Cisco Routers

2011-11-28T08:56:00.000+05:30

Destination-NAT, it turns out is not as self-explanatory as Source-NAT when it comes to CLI commands. And, the materials I found on CCO and Google searches did not clearly explain how to do this simple task in Cisco IOS. So, I think it warrants a quick article in case others need!

Why would you want to Destination-NAT? It is needed when a service provider assigns private addressing (RFC 1918) to a service you need to target and you already have a route in your network for that subnet, which goes elsewhere. Or, you need to direct certain lines of business (LOB) to use one circuit over another, to reach the same service. In this case, you can have one LOB target the real IP to reach the service over a specific circuit, and another LOB would target the Destination-NAT IP. This way, the two LOBs don’t have to share the circuit.

If you are translating one IP to one IP, there is no need for a pool, or an ACL, for either source OR destination-NAT. You would use the “ip nat inside source static” or “ip nat outside source static”. I’ll explain which one to use for which scenario. I just depends of the direction the session is initiated. I usually assign the interface for my network (the one closer to the network core) as the “inside” interface using the “ip nat inside”. And the interface facing the other network as “outside” using the “ip nat outside” command. This also happens to be the way zone based firewalls work, although NAT has nothing to do with security or firewalls, and you could very well do the opposite.

Before I give a Destination-NAT example, let’s do a Source-NAT because that’s more common. Here is the topology:

Core network where sessions get initiated (10.1.1.0/24) –> NAT router –> Other network (172.16.1.0/24)

In this scenario, we hide the core network’s real host IP address (10.1.1.1) for that flow with the NAT range IP address of 192.168.1.1. So, the “other network” sees our traffic coming from the NAT address.

The IOS CLI command to do this is:

ip nat inside source static 10.1.1.1 192.168.1.1

Of course, you have to ensure there is a route for the translated address in the routing tables along the path for any router to reach that destination.

Now, let’s say we also need to use this NAT router to translate the destination of our packet. In other words, there is a LOB who needs to reach 172.16.1.1 via a different path, or we simply cannot advertise 172.16.1.0/24 into our core, for various reasons. We need the host on our core to be able to target 172.16.1.1 by using destination address 172.18.222.222.

At the NAT router, you can’t use “ip nat inside destination static” because there is no such command in IOS. Instead, you would use the following:

ip nat outside source static 172.18.222.222 172.16.1.1 add-route

As you can see, we are dealing with the outside NAT interface, which means we NAT in the return direction, which is why we have to reverse the order of the translation and use “source” instead of “destination”!

The “add-route” keyword may be needed if there is no route (or a route with an incorrect next-hop) in the routing table for the old “not-translated” destination.

Again, you have to ensure the 172.18.222.222 route is advertised inside your core, so the hosts can reach it.

Note- not all applications are tolerant to NAT, so make sure you test!

Make Money Online

2011-11-11T14:19:00.001+05:30

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Access Your Android SD Card From Another Device

2011-08-22T19:12:00.000+05:30

Here’s how to access the content of your SD card from another device or computer; XDA member jhonnyx1000 shows us that using File Expert on your Android device will let you channel your SD card through your wireless router making it accessible while connected to the same network. The application lets you do all basic file operations like copy, paste, move, create, and rename your files and folders. If that wasn’t enough, the app also features:

-FTP/HTTP Server – Share & Manage your files without a USB cable.
- Web & FTP transferring support.
- Web management featuring a Windows style interface.
- Root access to system folders and files like Root Explorer.
- SMB & FTP Client – Access your host computer from your phone, using your phone to manage your PC
via WIFI with SMB or FTP.
- Bluetooth – Share your files over Bluetooth OBEX FTP.

And more. The application can be found for free on the usual place. Please let us know your comments.

Limited Edition: Macallan's Rs7.2 Lakh Whisky

2011-01-08T08:04:00.003+05:30

The Macallan, the famous producer of Scotch whisky, is selling a very limited edition 64-year-old whisky as part of its Macallan's Masters of Photography series.

Only 36 bottles of the whisky, distilled in 1946, will go on sale this year for $16,000 (approx Rs. 7.2 lakh). Each of the 36 bottles will be sold along with a platinum print photograph by award-winning celebrity/fashion photographer Albert Watson. The Scottish photographer is credited with taking iconic images of director Alfred Hitchcock holding a dead goose for Harper's Bazaar in 1973.

In 2010, The Macallan commissioned Watson to depict the journey, the whisky-maker's sherry oak cask wood makes from the forests of Spain to their "spiritual home" in Speyside, Scotland.

A cheaper, $1,000 (Rs 45,000) bottle of 20-year-old whisky that is also part of the Macallan-Watson collaboration will be on sale too. Only 1,000 of these Macallan whisky bottles will be available.

4X INVESTMENT Forex Trading by Professionals

2011-01-04T12:27:00.002+05:30

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Are you loosing Money badly trading Forex Market after all the hard work you had done?

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Our mission is to help you become a better trader. For those looking for a significant part-time or full-time income, we believe Currency Trading is the Vehicle to use. Our passion is creating superior trading tools to help you achieve your goals—no matter which way the markets move.You can take benefit of our services to grow your capital as well as to become a professional forex trader.

If you do not know how to take profit from the forex market or if you do not have the time to trade your own forex trading account, we are here at your service to mange your forex account and we commit you for monthly consistent profit in your forex trading account.

We offer both individuals and instituational investors an opportunity to benefit from our professional skills. At 4XINVESTMENT.COM, your Forex Trading Account will be traded and managed by our full time experience traders. Our Professional team will work out very profitable for you. Our professional forex manager buys and sells currencies on your behalf in your forex trading account.

Computer Solutions Web Hosting

2010-10-08T14:12:00.002+05:30

Professional Web Hosting Starts @ Rs 1500/- only

Computer Solutions has been continuously offering quality cheap web hosting plans at the low cost. Our main objective is to offer our customers incomparable & low cost cheap web hosting services with best technical support. We always try to provide you with low cost web hosting packages. That’s why we offer new hosting plans & packages more often as we can.

Why Choose Computer Solutions?

* 24x 7 live customer support
* Proven and guaranteed 99.9% uptime
* Robust & reliable servers with premium bandwidth
* RAID 5 Storage for Data Protection and Routine Backups
* No Setup Fees No Hidden Fees or Charges or Trick
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* 30 Day Money Back Guarantee

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500MB Disk Space
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5 Sub Domain
1 FTP Account
1 Mysql Database
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Perl, Python
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WEB DESIGNING
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Contact:
Computer Solutions
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http://www.comsolwebhost.com

Music On Hold for Asterisk

2010-08-23T12:05:00.000+05:30

1.
sip.conf ---------------------
2.

3.
[8888]
4.
type=friend
5.
context=outbound
6.
callerid="UnKnown" <8888>
7.
username=8888
8.
secret=mypassword
9.
host=dynamic
10.
nat=yes
11.
dtmfmode=rfc2833
12.

13.
extensions.conf ---------------------
14.

15.
[outbound]
16.
exten => 121,1,MusicOnHold(10)

Bulk SMS and Short Code in Manipur

2010-08-11T22:22:00.000+05:30

Computer Solutions SMS Sevice website is http://bulksms.comsolonline.com

Computer Solutions is a leading end-to-end provider of Mobile Applications and Online Services to corporate and consumer markets. Our solutions include Bulk Messaging Platform, SMS Marketing, SMS Applications, Two-way SMS, and Premium Short Code Service. It is a flexible platform which is both scalable and extensible. We provide sms at lowest rates with unlimited validity. We deliver your messages to all major Cellular network operators of India. With Computer Solutions SMS solutions, you can keep in touch with your clients, business partner and friends. Start integrating sms to your business now and provide better service to your customers. You can send sms right from your desktop or through your web based software. We also provide http API's to integrate with your web applications.

Our Short Code service is available on 56767 and 542423

Computer Solutions Website Launched

2010-08-11T22:14:00.000+05:30

Computer Solutions Imphal Website has been launched on 9/08/2010. The site is still under construction. You can visit our website at http://www.comsolonline.com.

We have added Two new services, SMS Solutions and Voice Solutions.

Products and Services available at Computer Solutions are listed below:-

IP Telephony (VOIP)
Security Camera System
Point to Point Wireless Connectivity
Global Positioning System (GPS)
Biometrics Systems
Networking Solutions
Bulk SMS and Short Code Service
Voice Broadcast and IVR Service
Web Hosting and Domain Registration
Website Designing
Computer Repairing and Maintenance

Video Calling via Asterik

2010-08-11T22:10:00.000+05:30

Asterik based system are mainly used for Voice Call over IP. With some modification, it can be also use for Video calling.

In the guide I pasted above, they say to add the following to sip.conf:

In Red Hat Based System, you will find sip.com at /etc/asterik/sip.conf

[general]
videosupport=yes ; enable Asterisk video support

[101]
type=friend
username=101
secret=hidden
host=dynamic
context=internal
callerid=Video Phone <101>
disallow=all ; better for custom-tunning codec selection
allow=ulaw
allow=alaw
allow=gsm
allow=h263 ; H.263 is our video codec
allow=h263p ; H.263p is the enhanced video codec
dtmfmode=rfc2833 ; inband is not supported in compressed codecs like gsm, so we better set it to rfc2833
canreinvite=no ; canreinvite must be set to 'no'

However, with TrixBox you actually just add

[general]
videosupport=yes ; enable Asterisk video support

to sip.conf and the rest,

[101]
type=friend
username=101
secret=hidden
host=dynamic
context=internal
callerid=Video Phone <101>
disallow=all ; better for custom-tunning codec selection
allow=ulaw
allow=alaw
allow=gsm
allow=h263 ; H.263 is our video codec
allow=h263p ; H.263p is the enhanced video codec
dtmfmode=rfc2833 ; inband is not supported in compressed codecs like gsm, so we better set it to rfc2833
canreinvite=no ; canreinvite must be set to 'no'

Unlock hidden Windows 7 Themes

2010-08-11T22:07:00.000+05:30

There are a number of regional themes with multiple unique background images hidden from Windows 7 users. On a Windows 7 install with United States regional settings only the United States theme is shown but there are actually four more themes hidden from view.

All these hidden themes can be accessed once you know where to find them. The trick is to navigate to the C:\Windows\Globalization\MCT directory.

The MCT directory within the Globalization directory is super hidden so it will not display even if show hidden files and folders is enabled.

Just click on the address bar of any folder and manually type in or copy and paste in C:\Windows\Globalization\MCT and hit Enter.

Once you have reached the MCT folder you will see five directories as listed below:

MCT-AU
MCT-CA
MCT-GB
MCT-US
MCT-ZA

To view and use the theme for each region just navigate into each MCT-Region directory, enter the Theme folder and double click the theme file.

Fedora 13 Released

2010-06-10T21:53:00.000+05:30

Fedora 13 Released

The Linux distribution Fedora version 13 is now available for download.
Highlights of this release include:

Automatic installation of printer drivers using PackageKit
Automatic installation of language packages matching the user's language
The GUI enabled application for user account administration has been rewritten
Color management software for calibrating monitors, scanners, and printers
3D support for NVIDIA video cards

Find more details on Fedora announcement page

Fedora 13 can be download from http://fedoraproject.org/get-fedora

Puppy Linux - Small but Powerfull and Feature Rich Distribution

2009-10-04T18:36:00.000+05:30

What is Puppy Linux?

Puppy Linux is an operating system for computers. Other well-known operating systems are Microsoft Windows, Apple OSX, and MS-DOS. Puppy Linux is based on GNU/Linux. It is completely free and open source software.

Puppy really is small, the live-CD typically being 85MB, yet there really is a complete set of GUI applications. Being so small, Puppy usually loads completely into RAM, which accounts for the incredible speed.

To download, just open the link and browse http://puppylinux.com

The documentation is also available at the website.

How is Puppy Different?

Small size, ~100MB! This lends itself to some very useful and unique features.
'Live' booting from CDs, DVDs, USB flash drives, and other portable media.
Runs from RAM, making it unusually fast even in old PCs and in netbooks with solid state storage media.
Very low minimum system requirements.
Boot time is well under a minute, 30-40 seconds in most systems.
Includes a wide range of applications: wordprocessors, spreadsheets, internet browsers, games, image editors and many utilities. Extra software in the form of dotpets. There is a GUI Puppy Software Installer included.
Puppy is easy to use and little technical knowledge is assumed. Most hardware is automatically detected.

Puppy Linux Screenshot

Blueman - Feature Rich Bluetooth Manager for Linux

2009-01-30T07:33:00.000+05:30

I have been searching for easy to use bluetooth manager for Linux with gprs dial up connection support. Its not so easy for a normal user to connect gprs internet via bluetooth. After i did a lot of googling, I have found Blueman.

For Ubuntu, blueman is already a part of Ubuntu ready to install Package. But for Fedora, no rpm package is available till date. I request Fedora packagers to build a rpm version of Blueman and made it available for Fedora users so that anybody can manage bluetooth connection so easily with the click of mouse. Since I am not from the programming background, i am not able to package it.

Some of the features of Blueman are given here. For more details, please visit http://blueman.tuxfamily.org

Blueman is a GTK+ Bluetooth Manager

Blueman is designed to provide simple, yet effective means for controlling BlueZ API and simplifying bluetooth tasks such as:

Connecting to 3G/EDGE/GPRS via dial-up
Connecting to/Creating bluetooth networks
Connecting to input devices
Connecting to audio devices
Sending/Receiving/Browsing files via OBEX
Pairing

Blueman also integrates with Network Manager 0.7, so any Dialup/Network connections will be made available (via HAL) to Network Manager.

Dependencies:

python-gtk2 (>= 2.12)
bluez-gnome (>= 0.25)
bluez-utils (3.26 <= x <= 3.28)
python-bluez
python-dbus
python-notify
policykit (>= 0.7)
obex-data-server

Build Dependencies:

libbluetooth-dev
python2.5-dev
python-distutils-extra

Manipur Fedora 10 Release Party Pictures

2008-12-07T21:37:00.001+05:30

Enjoy the Event Pictures

On Spot Fedora 10 Installation

Rishikesh Sharma

Rishikesh Sharma on Presentation

Visitors

Installation of Fedora 10

Fedora 10 Presentation

Nupilal Complex, Imphal Event Venue

Visitors with Fedora 10 Desktops

Visitors Watching Fedora 10 Installation

Fedora 10 CD's and DVD's Distribution

Rishikesh Sharma helping Fedora User

Rishikesh Sharma with Volunteers

Rishikesh Sharma with Fedora Desktop

Manipur Fedora 10 Release and Install Fest 2008 at Nupilal Complex, Imphal

2008-12-07T18:49:00.000+05:30

Fedora 10 Release and Install Fest 2008 at Nuplilal Complex Imphal powered by Fedora Project was a grand success. Students and professional from different part of Manipur attended the grand event. We were planning to start the event from 11:00 a.m. onwards but delayed for about 45 minutes. We had a attendance of nearly 150 visitors. We started our event with the presentation on Fedora 10 and Fedora project which was presented by none other then myself, Rishikesh Sharma. After the presentation, we have presented the visitors with on spot installation of Fedora 10 with one of visitors laptop. During the long process installation, we take a break with drinks and snacks. After a short break, we allow visitors to have a look at new features and packages of Fedora 10 with the Fedora Demo workstations provided for the visitors during installation. After the completion of on spot installation, we have a demonstration of all powerfull open source application which comes with Fedora 10. After the demonstration, lots of user came up and ask me further details about the installation and dual booting. After this, we have distributed the Fedora 10 CD's and DVD's which include Fedora 10 Gnome Live CD, 32 bit and 64bit DVD's and allow visitors to see what Fedora 10 can do. I have requested the visitors to contribute to Fedora if they have little time to spare and to built a Fedora operating system in our very own language "Manipuri" using our script "Meitei Mayek".

I personally thanks Computer Solutions and CD BYTE Computer for providing the necesary infrastructure to organise the event and all the visitors for making this event a grand success. I am uploading the event photos soon.

Manipur Fedora 10 Release Party and Install Fest 2008

2008-11-23T20:39:00.000+05:30

Fedora 10 Release Party and Install Fest 2008 will be held at Nupilal Complex, Imphal on 7th December, 2008. Computer Solutions and CD BYTE Computers will provide us Desktop PC's for use in the event. Required permission to use Nupilal Complex is also granted by the Deputy Commissioner of Imphal West. In a few days, we will start our advertisement and promotional activities in Imphal.