How to set MTU manually to avoid problem while trasferring large data files in Linux boxes?

We've gigabit networks, and large maximum transmission units (MTU) sizes (JumboFrames) can provide better network performance.

 If you want to transfer large amounts of data at gigabit speeds, increasing the default MTU size can provide significant performance gains.

Whenever using multiple different networks its bandwidth should be consistent with the systems which are connected ,& It is mostly managed by router end.
  
MTU : the maximum transmission unit (MTU) of a communications protocol of a layer is the size (in bytes) of the largest protocol data unit that the layer can pass onwards. MTU parameters usually appear in association with a communications interface (NIC, serial port, etc.)

But Sometimes we are unable to make changes from router end but we need to send large data files which fails due to inconsistent bandwidth on 3 or multiple PPPoE networks.Problems might occur while sending data in Unix/Linux systems as its MTU (maximum transmission unit) default value is 1500.

1492 = Max for PPPoE (Point-to-Point Protocol over Ethernet)
1500 = Max for PPPoA  (Point-to-Point Protocol over ATM )

way to change MTU manually if you are facing large packet drop :

To change the MTU size, use /sbin/ifconfig command as follows:

ifconfig ${Interface} mtu ${SIZE} up 

ifconfig eth1 mtu 1492 up

Note: Its only if supported by both the network interface card and the network components such as switch.

Changing the MTU size permanently :

Edit /etc/sysconfig/network-scripts/ifcfg-eth0,

# vi /etc/sysconfig/network-scripts/ifcfg-eth0

Add MTU, :

MTU="1492"

Save and close the file. Restart networking:

# service network restart

Note for IPV6 set dedicated MTU as follows:

IPV6_MTU="1492"

Installing Mozilla Firefox Browser in Kali Linux ...

If you wish to remove default browser Iceweasel from kali linux 

 apt-get remove iceweasel

#echo -e "\ndeb http://downloads.sourceforge.net/project/ubuntuzilla/mozilla/apt all main" | tee -a /etc/apt/sources.list > /dev/null
#apt-key adv --recv-keys --keyserver keyserver.ubuntu.com C1289A29
#apt-get update
#apt-get install firefox-mozilla-build 

RIP Whatsapp Plus... "Legends may sleep, but they never die ! "

"Now what i'm gonna do ? my whatsapp (plus) has been showing that i've been banned for 24 hours & now it went for 72 hours !! ... " A panicked husky voice came from other side of my cellphone one fine morning ... I calmly said , "Enjoy the silence !!  :) "

Then i understood ; finally the whatsapp plus which was illegal modified version [MOD] of Whatsapp has been come to an abnormal death due to strict user policies of Whatsapp.Inc

It had so many great customization's & rich features than the original one.

WhatsApp Plus provided some extra features compared to original WhatsApp like:

• Disabling your last seen status and still being able to see others last seen time
• Hiding and pausing your last seen time
• 1000+ new Themes
• Extra new animated emoticons
• You can edit file sharing options i.e . file size to be sent
• we can change font & color 
• rich GUI

Q. I am banned by whatsapp.inc for 24/72 Hours , Now what should i do ? 
->  Here are some ways to tackle this :
First take backup of all data of whatsapp plus by using following steps :

1.Go to Whatsapp > Settings >Chat Settings >Backup conversations
and take the backup of all the data, we can restore it later .

2.Ideally you should wait till the ban gets levied but if you are so eager to get it un-banned you might want to follow the steps as below :

3.Keep your data connection off (Airplane mode) & your android phone should be rooted to get un-banned 
(How do i root my android phone ?)

Step 1. First you need to Download and Install XMod games on your device.

Step 2. After Installing XMod games, open it and tap on "More" in right corner.

Step 3. In the opened Menu section tap on Accelerator.

Step 4. Scroll down and find the WhatsApp app switch ON the option before it.

Step 5. After that close the XMod games App and get back to your WhatsApp Application.

Step 6. Now you will find a small icon on your screen after opening WhatsApp App.

Step 7. Click on that icon and accelerate your time, this is the trick now you unban yourself in minutes.

Ideally you should be patient enough to get it un-banned  and then un-install & reinstall original Whatsapp.

How to track suspicious Email ?

Here one user approached me regarding an anonymous / unknown mail which he found suspicious & threat to security & he was concerned about theft of his data .
In process of investigations I had great help of one tool developed by C-DAC Thiruvananthapuram for Email forensics.

Here's the WebLink for that application :
C-DAC OnlineEmailTracer

In its simple minimalist GUI you just have to paste an Email Header of your suspicious email as an input in this tool.
& this tool will generate a route information about the email and so many other important information with which we can trace the culprits location & other vital information.

I found some other great online tools :
Here are the links :

http://whatismyipaddress.com/trace-email
http://www.ip2location.com/free/email-tracer
http://www.iptrackeronline.com/email-header-analysis.php

How to fix Yum repository's Most common Error :" File contains no section headers."

Q. What the Hell is Repository ?& why do we care about it ?
A.-> So the idea of a repository in terms of a distro is: A central area for users to collect RPMs/DEBs/etc from.

These benefit for you by allowing you to get all your favourite programs from some defined source. Otherwise you would need to hunt the web to find the right site that would have the right RPM for your system. Even then you would need that RPM to be compatible to your system and not install ontop of other RPMs files.
  (thank you wikipedia )


Sometimes you might get following error while playing with Yum Repositories
"Error: File contains no section headers.
file: file://///etc/yum.repos.d/fedora-cinnamon.repo, line: 1 

The quick fix should be :
1. Navigate to above said .repo file which is containing errors
i.e #cd /etc/yum.repos.d/fedora-cinnamon.repo

2.open it with Text editor like Vi or nano .I prefer vi
i.e. #vi /etc/yum.repos.d/fedora-cinnamon.repo

3.As it was dictated an error on line no. 1 ,You'll have to  scan line no. 1 for any typographic errors
#vi /etc/yum.repos.d/fedora-cinnamon.repo

Just fix those typing errors in words contained in .repo file

& you're set to go with using Yum repository again !!!