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...
Here in this post, I am going to explain the basic Linux networking command Ifconfig
Ifconfig Command Use:
One can know or configure the interfaces in the system using Ifconfig. Let us know what information about an interface is displayed using ifconfig command
The sample interfaces information is shown above:
The Link encap indicates that the packets are encapsulated and connected to Ethernet. The HWaddr shows the address of physical adapter associated with interface. First three octets of HWaddr determines the manufacturer of the adapter.
The second line may contain inet addr or inet6 addr based on the type of interface and has corresponding IP address. There will be some flags shown when ifconfig is used. Some of them are explained below:
- UP: Interface is in the active state
- RUNNING: Interface is ready to accept data
- BROADCAST: Interface supports broadcasting
- MULTICAST: Interface supports multicasting (Send packets only to a group of people)
BCAST denotes the broadcast address of the interface.
MTU which means the Maximum Transmission Unit indicated the largest size of the packet that can be handled by interface.
RX and TX indicate the packets count received and sent through an interface since system is in active state. For example, pinging localhost (ping 127.0.0.1) increase RX and TX of the lo interface (Loopback interface)
Usually errors, dropped, overruns, and the carrier will be zero. If not, there may be some problem with the interface. collisions should be either zero or small number. If not, the interface is facing a lot of traffic.
txqueuelen indicates that the maximum number of packets supported in the transmission queue. RX bytes and TX bytes indicate the total amount of data sent and received through the interface since system is in active state.
Ifconfig Command Variations:
Some of the variants of using the command and its purpose can be seen here:
1) ifconfig – Command used to display active interfaces in the system at a given time
2) ifconfig <interface-name> down – Command used to make an interface to go to inactive state
3) ifconfig -a - Command used to display both active and inactive interfaces in the system at a given time
4) ifconfig <interface-name> up – Command used to make an interface to go to active state
5) ifconfig <interface-name> <IP address> - Command that assigns a static IP address to the given interface and brings back it to active state in case it is inactive
6) ifconfig <interface-name> <IP address> up - Command that assigns a static IP address to the given interface and brings back it to active state
7) ifconfig <interface-name> - Command that is used to get a particular interface which can be active or inactive
8) ifconfig -s - Command used to get only some information on active interfaces in a table like format
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