ech0

A raw TCP echo server that reflects HTTP requests exactly as received. Built on raw TCP sockets, so headers and body are echoed exactly as received.

Usage

docker run -p 8421:8421 aykhans/ech0

curl http://localhost:8421/hello

Remote-Addr: 172.17.0.1:54321

GET /hello HTTP/1.1

--- Headers ---
Host: localhost:8421
User-Agent: curl/8.5.0
Accept: */*

JSON output

curl "http://localhost:8421/hello?format=json"

{
  "method": "GET",
  "path": "/hello?format=json",
  "proto": "HTTP/1.1",
  "remote_addr": "172.17.0.1:54321",
  "headers": [
    "Host: localhost:8421",
    "User-Agent: curl/8.5.0",
    "Accept: */*"
  ],
  "query_params": {
    "format": [
      "json"
    ]
  }
}

Custom status code

curl -w "\n%{http_code}" "http://localhost:8421/?status=404"

POST with body

curl -X POST http://localhost:8421/ -d '{"key": "value"}' -H "Content-Type: application/json"

Remote-Addr: 172.17.0.1:54321

POST / HTTP/1.1

--- Headers ---
Host: localhost:8421
User-Agent: curl/8.5.0
Accept: */*
Content-Type: application/json
Content-Length: 16

--- Body (16 bytes) ---
{"key": "value"}

Query Parameters

Parameter	Description
format	Set to json for JSON output, otherwise plain text
status	Set the response status code (any integer)

Environment Variables

Variable	Default	Description
PORT	8421	Port to listen on
REMOTE_ADDR_HEADER		Header to read the client IP from (e.g. X-Forwarded-For, X-Real-IP). When set, the header is removed from the echoed response.

Install

Docker

docker run -p 8421:8421 aykhans/ech0

Behind a reverse proxy:

docker run -p 8421:8421 -e REMOTE_ADDR_HEADER=X-Forwarded-For aykhans/ech0

Binary

Download from releases.

./ech0