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Commands used in Dockefile - Part4

  Docker is an opensource tool used for virtualization and deliver software in the form of packages called Containers. It is one of the most important tools used in networking domain.  Dockerfile  is a template for building the image which contains commands needed to package the software. In this post, I am going to explain the commands ADD & COPY used in  Dockerfile .   ADD Command:   ADD command is used to copy files, directories or files from remote URLS to destination path in the image. The source paths can contain wildcards.   If the destination has relative path, it is relative to the Working directory of the image. Note that source path is always relative to the Docker build context.   ADD command will not support authentication. So, if there are any protected files to be added in  Dockerfile  building, use other tools like curl or  wget   Dockerfile  copying Single & Multiple files, directory using ADD inst...
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Virtual Interface Creation and deletion in Linux Operating System

Virtual interfaces are the interfaces that allows physical connection to have more than one interface. These help in tagging the LAN packet with ID’s that may be used to segregate the traffic or customer. This article focuses on the creation and removal of Virtual Interfaces using Open Source tool Vlan and command ip link in Linux Operating system. All the commands are prefixed with sudo to run commands as a root user
Vlan:
Vlan is an open source tool that helps in creating and removing the virtual interfaces over a physical interface.
To use Vlan, one needs to install vlan using sudo apt-get install vlan on Linux Operating System

Adding Virtual Interface using Vlan tool:
Assume you have a physical interface named enp0s4. To create a Virtual Lan or Sub interface, the command is vconfig add <Physical_Interface_Name> <tag_number>. For an interface with tag 903, the tag_name in command is replaced with 903 and Physical_Interface_name with enp0s4. By default, the interface created will be in downstate and name will be Physical_Interface_Name.tag_number
To bring that to up state use command ifconfig <Physical_Interface_Name.tag_number> up

Removing Virtual Interface using Vlan tool:
To remove a virtual interface created using Vlan tool, first down the interface using command ifconfig <Physical_Interface_Name.tag_number> down. Then remove the same using command sudo vconfig add <Physical_Interface_Name.tag_numbeer>

IP Link Command:
IP Link is an inbuilt Linux command used to create virtual interfaces and is an alternative to Vlan tool.

Adding Virtual Interface using ip link Command:
Assume you have a physical interface named enp0s4. To create a Virtual Lan or Sub interface, the command is ip link add link <Physical_Interface_Name> <Physical_Interface_Name.tag> type vlan id <tag_number>.Then up the interface using command ip link set dev < Physical_Interface_Name.tag_number> up

Removing Virtual Interface using ip link Command:
To remove the virtual interface using ip link comand, first down It using ip link set dev < Physical_Interface_Name.tag_number> down. Then delete the same using command ip link delete < Physical_Interface_Name.tag_number>

Note:
The tag for Virtual Interface can be in the range of 0-4094. Also, it is not advisable to use tag 0 and 1 which may be reserved sometimes for specific purposes 

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