client-reverse-proxy

This program allows you to accept requests and send responses to the server that is located behind the NAT. This is made possible by a one-time connection of the proxy-client to the destination server and to the gateway-server. The Gateway server must have an external IP address and be located, for example, on a rented VPS. The client-reverse-proxy program can help in cases where there is no trust in the VPS server, and therefore to the storage of private keys, user database, etc.

How it works

Warning

This program is written in order to provide an understanding of how reverse-proxy can be implemented using the client side. Therefore, in this example, there is no authorization of the client to the gateway service, which, nevertheless, is a VERY important criterion on the security side.

1. tcp connection: client -> gateway
2. http request: producer -> [gateway -> client] -> server
3. http response: server -> [client -> gateway] -> producer

This work scenario has a limitation in the need to constantly generate connections from the proxy-client side. If there are not enough connections to successfully maintain communication, then manufacturers will receive errors from the gateway service.

Example

$ make

gateway-1    | gateway is listening...
server-1     | server is listening...
client-2     | client is listening...
client-1     | client is listening...
server-1     | [192.168.48.3:47488]: ping
producer-10  | pong
server-1     | [192.168.48.3:47488]: ping
producer-10  | pong
server-1     | [192.168.48.3:47488]: ping
producer-10  | pong
...

You can also open browser page on http://localhost:9000/ping.

Docker-Compose

version: "3"
services:
  producer:
    build:
      context: ./
      dockerfile: cmd/producer/Dockerfile
    depends_on:
      - client
    deploy:
      mode: replicated
      replicas: 1
    networks:
      - producer-gateway
  gateway:
    build:
      context: ./
      dockerfile: cmd/gateway/Dockerfile
    ports:
      - 9000:9000
    networks:
      - producer-gateway      
      - gateway-client
  client:
    build:
      context: ./
      dockerfile: cmd/client/Dockerfile
    depends_on:
      - server
      - gateway
    deploy:
      mode: replicated
      replicas: 2
    networks:
      - gateway-client
      - client-server
  server:
    build:
      context: ./
      dockerfile: cmd/server/Dockerfile
    depends_on:
      - gateway
    networks:
      - client-server
networks:
  gateway-client:
    driver: bridge
  producer-gateway:
    driver: bridge
  client-server:
    driver: bridge