In Linux, nc stands for netcat, which is a simple utility used to read from and write to network connections using TCP or
UDP. It is a versatile tool that can be used for a variety of network-related tasks, such as debugging and testing network
connectivity, sending files across the network, and creating custom network applications.
The nc program provides a command-line interface that allows users to specify various parameters to control the behavior of
the tool, such as the type of connection to use, the port number to connect to or listen on, and the data to be sent or received.
Here are a few examples of how nc can be used:
Debugging network connectivity:
The nc program can be used to test network connectivity between two hosts by connecting to a specific port and sending a
test message. For example, the command:
nc -vz example.com 80
will attempt to connect to port 80 on the host example.com and report whether the connection was successful or not.
Sending files over the network:
The nc program can be used to transfer files over the network by piping the file contents to the nc command on one end,
and receiving the data on the other end using the nc command. For example, to send a file file.txt from one host to another,
you can use the command:
cat file.txt | nc -q 5 host2 1234
on the sending end, and
nc -l -p 1234 > file.txt
on the receiving end.
Creating custom network applications: The nc program can be used as a building block for custom network applications that
need to establish TCP or UDP connections. By using nc in conjunction with other Unix utilities, it is possible to
create custom network clients and servers that perform specific tasks.