netcat_sock.go

package main

// This is a simple program that will connect to a listening netcat server, send a hello, and receive a reply
// This is meant as an example of client-side socket usage

import (
    "fmt"
    "net"
    "bufio"
    "os"
    "time"
    "strings"
)

// IP addr and port number to connect to
var address string = "127.0.0.1:4444" // CHANGE THIS

// dial server and return connection object
func dialServer() net.Conn {
    conn, err := net.Dial("tcp", address)
    if err != nil {
        fmt.Printf("Fatal error: %s", err)
        os.Exit(3)
    }
    return conn
}

func main() {
    // call dialServer
    fmt.Printf("[*] Connecting to server... ")
    conn := dialServer()
    fmt.Println("[DONE]")
    time.Sleep(3 * time.Second)

    // send hello message to netcat server
    fmt.Printf("[*] Sending hello to server... ")
    fmt.Fprintf(conn, "Hello, Netcat!\n")
    fmt.Println("[DONE]")
    time.Sleep(3 * time.Second)

    // receive reply from netcat
    fmt.Printf("[*] Receiving reply from server... ")
    reply, err := bufio.NewReader(conn).ReadString('\n')
    if err != nil {
        fmt.Println("[FAIL]")
        os.Exit(3)
    }
    reply = strings.TrimSpace(reply) // trim leading whitespace and newline
    fmt.Printf("[RECEIVED: %s]\n", reply)
    conn.Close()
}