How to implement remote forwarding in golang

In network transmission, remote forwarding is often involved, and golang language is a very suitable language for remote forwarding. This article will introduce the relevant content of golang remote forwarding.

1. Remote forwarding

Remote forwarding is also called port mapping. In short, it is to forward the data packets of one port on the host to the designated port of another host. On the network, each host will open multiple ports for internal communication, while external access requires specific ports to communicate with the corresponding services.

2. Golang remote forwarding

1. Characteristics of golang

Golang is a special language, its concurrency is very strong, and it is IO is also very well managed, which makes it easy for Go, as a language close to the network server, to implement various rich functions in many network applications.

2. The basic principle of port forwarding

The basic principle of port forwarding is to establish a connection between the client and the server, and the client forwards the data packet sent to The server side performs processing, and the data packet flow is shown in the figure below.

3. Implementation code

Remote forwarding in golang is quite simple, you only need to use Dial, Listen, etc. in the net package function, the specific code is as follows.

package main

import (
    "fmt"
    "log"
    "net"
)

func main() {
    ln, err := net.Listen("tcp", ":8844")
    if err != nil {
        log.Fatal("error binding to socket")
    }

    fmt.Println("listen on port ：8844 ...")
    for {
        conn, err := ln.Accept()
        if err != nil {
            log.Fatal("error accepting connection")
        }
        go forward(conn)
    }
}

func forward(conn net.Conn) {
    remote, err := net.Dial("tcp", "serverIP:serverPort")
    if err != nil {
        log.Fatal("error connecting to server")
    }

    defer remote.Close()
    defer conn.Close()

    go func() {
        _, err := copy(remote, conn)
        if err != nil {
            log.Printf("error copying into remote: %s", err)
        }
    }()

    _, err = copy(conn, remote)
    if err != nil {
        log.Printf("error copying into local: %s", err)
    }
}

4. Summary
Golang’s remote forwarding implementation is simple and efficient, and is very suitable for applications in high-concurrency scenarios. Through the above code demonstration and introduction, the implementation of golang remote forwarding may bring some inspiration and reference for your application development.

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