Port Knocking
To create a port knocking program in Go, you need to create a few files: main.go for the main logic and optionally, a knock.go file for the port knocking functionality. Here is a step-by-step guide:
Step 1: Initialize the Go Module
First, create a new directory for your project and initialize the Go module.
mkdir portknocking
cd portknocking
go mod init github.com/username/portknocking
Step 2: Create the knock.go File
Create a portknocking/portknocking.go file to handle the port knocking functionality.
// portknocking.go
package portknocking
import (
"fmt"
"net"
"time"
)
// Knock sends a sequence of packets to the specified ports.
func Knock(host string, ports []int, delay time.Duration) error {
for _, port := range ports {
address := fmt.Sprintf("%s:%d", host, port)
conn, err := net.Dial("udp", address)
if err != nil {
return err
}
conn.Close()
time.Sleep(delay)
}
return nil
}
Step 3: Create the main.go File
Create a main.go file to use the port knocking functionality.
// main.go
package main
import (
"fmt"
"os"
"strconv"
"time"
portknocking "github.com/username/portknocking/knocking"
)
func main() {
if len(os.Args) < 4 {
fmt.Println("Usage: portknocking <host> <delay_ms> <port1> <port2> ... <portN>")
os.Exit(1)
}
host := os.Args[1]
delayMs, err := strconv.Atoi(os.Args[2])
if err != nil {
fmt.Printf("Invalid delay: %v\n", err)
os.Exit(1)
}
delay := time.Duration(delayMs) * time.Millisecond
var ports []int
for _, arg := range os.Args[3:] {
port, err := strconv.Atoi(arg)
if err != nil {
fmt.Printf("Invalid port: %v\n", err)
os.Exit(1)
}
ports = append(ports, port)
}
if err := portknocking.Knock(host, ports, delay); err != nil {
fmt.Printf("Port knocking failed: %v\n", err)
os.Exit(1)
}
fmt.Println("Port knocking sequence completed.")
}
Step 4: Run the Program
Run the program using the go run command.
go run main.go example.com 500 1234 5678 91011
This will send a port knocking sequence to example.com with a 500ms delay between each knock on ports 1234, 5678, and 91011.
Last modified: 08 January 2025