Internet of Things vs Internet of Everything

Internet of things deals with physical objects. Late in the 1990, most of the objects connected to the internet were immovable objects. E.g:- Desktop. In the recent years more number of devices got connected to the network which includes movable devices. E.g:- Mobile phones. The requirement of the data stored, speed and transmitted increased in millionth times. Internet of things is the technology which is planned to bring all the physical objects to the network. Analogy all the physical objects to be made smart devices. Every device will be identified with a unique ID and remotely managed through devices like mobile applications etc.

Internet of everything deals with people, process, things and data. The things here is the Internet of things. the entire system is viewed and managed smartly and remotely. This requires integration of people, process, things and data together. This can be applied to any Industry.

Emulator vs Virtualization

Emulator does emulate a real hardware. This could be board or CPU or any hardware device. There is a cost associated with the performance when an emulator is used as emulator runs on a user space as a program. Qemu is one of the most used emulator to emulate a board or CPU.

Virtualization virtualise the real hardware. The real hardware is virtually shared by the guest operating system. Multiple types of virtualization possible. VMWare ESX is one of the popular virtualization software. With Intel hardware support the virtualization software can perform very similar to a single system and can make use of the system resources to its maximum.

Emulator vs Simulator

A simulator models an application while an emulator replicates the usage of an original system.

A simulator mimics the act of something. e.g:- flight simulator.

An emulator does the same thing as the real system does. The result is the same as the output of the real system. e.g:- Virtual PC.

A good article on modifying the MTU.

The maximum transmission unit (MTU) of a network interface is the size of the largest block of data that can be transmitted as a single unit. Anything larger than the MTU must be broken into smaller units prior to transmission. The following link has a short passage on modifying the MTU.

Change the MTU of a network interface

If you want to change the MTU in the linux kernel source code the macro can be found in

the location

linux/include/uapi/linux/if_ether.h

The macro name is ETH_DATA_LEN and if you are increasing it you need to increase the frame length also. The macro for from length is ETH_FRAME_LEN. I did experiment to modify MTU to 1508. So I modified the ETH_DATA_LEN to 1508 and frame length to 1522.

After the same through ifconfig I was able to set the mtu to 1508.

e.g:- ifconfig eth0 mtu 1508

Setting anything beyond ETH_DATA_LEN the ifconfig will return “SIOCSIFMTU: Invalid argument”. Also changing to any values beyond 1500 ensure your network devices support.

 

How to do ssh autologin

I got a requirement in my project to enable autologin for some build scripts to get some information from remote machine through autologin. My colleagues has given steps to create identiry and rsa files and copy them to the remote machine and rename as authorize files. But that steps didnt work. Browsing the internet I got a good reference to built-in script which Linux had. These are the 2 simple steps to enable autologin.

The machine from which you want to login just type the following commands.

ssh-keygen -q -t rsa -N ” -f ~/.ssh/id_rsa

ssh-copy-id -i ~/.ssh/id_rsa yogindar@yogindar.com

this will ask for password once. Enter the same.

Now try ssh  yogindar@yogindar.com

you will find it wont ask any password.

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