Simple Alpine image for running netcat (nc).
Use this when you don't have netcat installed on your system or you want to use this image as a base for simple service demos.
Start a netcat server in one terminal
$ docker run -t --rm --network=host --name=ncs subfuzion/netcat -vl 8888
Note: we use the host network stack (host) which means that port 8888 in the
container is available on port 8888 of the host machine. Since we are using the host
network stack directly it is not necessary to explicitly "publish" the port to the host
network (using the -p|--publish option). In any case, the netcat command itself still
needs to be told which port it is supposed to listen to, so 8888 is supplied as the
argument to the default process for the container (which is netcat) created by the
subfuzion/netcat image at the end of the docker run command.
Send a message to the server from another terminal
$ docker run -i --rm --network=host subfuzion/netcat localhost 8888
hello # will see hello echoed at the other terminal
Here, supply localhost and 8888 as the host and port arguments to the default
command running in the container (netcat) created from the subfuzion/netcat
image. Remember, the host is localhost (or 127.0.0.1) because we started a netcat listener in
another container attached to the host network.
You can set aliases in your shell configuration to reduce typing:
$ alias ncs="docker run -t --rm --network=host --name=ncs subfuzion/netcat -vl"
$ alias nc="docker run -i --rm --network=host --name=nc subfuzion/netcat localhost"
Then the example above looks like this:
Start netcat server in one terminal
$ ncs 8888
Send a message from another terminal
$ echo "hello world" | nc 8888
To kill both containers from yet another terminal
$ docker rm -f nc ncs
Create a bridge network
We will use a dedicated network for two containers to communicate with each other using netcat
for this example. By using a dedicated network, it is not necessary to publish ports on localhost.
$ docker network create --driver bridge demonet
Start a netcat server in one terminal
$ docker run -t --rm --network=demonet --name=ncs subfuzion/netcat -vl 8888
Note that although we did not publish the port to localhost (docker run -p option),
netcat itself still needs to be told which port to listen on (in this case, port 8888).
Send a message to the server from another terminal
$ docker run -i --rm --network=demonet subfuzion/netcat ncs 8888
hello # will see hello echoed at the other terminal
Note that when we run the container using the subfuzion/netcat image, the default
entrypoing is the nc command, for which we supply both the host to connect to (ncs on the bridget network) and the port (8888).
You can set aliases in your shell configuration to reduce typing:
alias ncs="docker run -t --rm --network=demonet --name=ncs subfuzion/netcat -vl"
alias nc="docker run -i --rm --network=demonet --name=nc subfuzion/netcat ncs"
Then the example above looks like this:
Start netcat server in one terminal
$ ncs 8888
Send a message from another terminal
$ echo "hello world" | nc 8888
To kill both containers from yet another terminal
$ docker rm -f nc ncs