A very simple TCP echo server written in go
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A (very) simple TCP echo server written in golang


By default, the server will listen on port 7. You can override this via either an environment variable or command-line switch.


From a command prompt, build the docker image

$> docker build -t echo .

This will build two docker images. The first is an untagged Golang image for building the code. The second docker image will contain the echo server in an image tagged echo. This technique is taken from Adriaan de Jonge's article

You can then run the docker image. You'll need to bind the port to your host. For example, to bind localhost:7000 to port 7 on the container (the default port)

$> docker run --rm -p 7000:7 echo


From a command prompt, run the main.go file

$> go run main.go

This will start the TCP server listening on port 7.

You can specify another port using the -p switch

$> go run main.go -p 8080

Or, set the environment variable PORT. In Powershell, you would run

$> $env:PORT = 7000
$> go run main.go

This will start the TCP server on port 7000

Note, if you are on Windows, you will be prompted to allow network access. Select yes.


On Windows, use a telnet client like PuTTY. If you're using PuTTY, be sure to connect using the Raw connection type. You'll be greeted with a blank window after connecting. Type in some text and press <enter>; your message will be repeated back to you.

Connecting with PuTTY

Attack surface

All connects are passed off to a goroutine. There is no connection pooling or throttling.

Text from the client is copied directly back to the client's connection. Memory safety is left to golang.

Text is sent back to the client without processing. Text from the client is not logged.


This software is release free and unencumbered under the unlicense. Details in LICENSE