DHCP Server

To create a DHCP server program in Go, follow these steps:

Step 1: Initialize the Go Module

First, create a new directory for your project and initialize the Go module.

mkdir dhcpserver
cd dhcpserver
go mod init github.com/username/dhcpserver

Step 2: Install Dependencies

You will need the insomniacslk/dhcp library for DHCP server functionality.

go get github.com/insomniacslk/dhcp

Step 3: Create the `dhcpserver.go` File

Create a dhcpserver.go file to handle the DHCP server functionality.

// dhcpserver.go
package main

import (
    "github.com/insomniacslk/dhcp/dhcpv4"
    "github.com/insomniacslk/dhcp/dhcpv4/server4"
    "log"
    "net"
)

// handleDHCPRequest handles incoming DHCP requests.
func handleDHCPRequest(conn net.PacketConn, peer net.Addr, req *dhcpv4.DHCPv4) {
    log.Printf("Received DHCP request from %v", peer)

    // Create a DHCP offer packet
    offer, err := dhcpv4.New()
    if err != nil {
        log.Printf("Failed to create DHCP offer: %v", err)
        return
    }

    offer.OpCode = dhcpv4.OpcodeBootReply
    offer.YourIPAddr = net.IPv4(192, 168, 1, 100) // Example IP address
    offer.ServerIPAddr = net.IPv4(192, 168, 1, 1) // Example server IP address
    offer.BootFileName = "bootfile"

    // Send the DHCP offer
    if _, err := conn.WriteTo(offer.ToBytes(), peer); err != nil {
        log.Printf("Failed to send DHCP offer: %v", err)
    }
}

// StartDHCPServer starts the DHCP server on the specified interface.
func StartDHCPServer(iface string) {
    handler := server4.HandlerFunc(handleDHCPRequest)
    server, err := server4.NewServer(iface, nil, handler)
    if err != nil {
        log.Fatalf("Failed to start DHCP server: %v", err)
    }

    log.Printf("Starting DHCP server on interface %s", iface)
    if err := server.Serve(); err != nil {
        log.Fatalf("Failed to serve: %v", err)
    }
}

Step 4: Create the `main.go` File

Create a main.go file to use the DHCP server functionality.

// main.go
package main

import (
    "fmt"
    "log"
    "os"
)

func main() {
    if len(os.Args) != 2 {
        fmt.Println("Usage: dhcpserver <network_interface>")
        os.Exit(1)
    }

    iface := os.Args[1]

    fmt.Printf("Starting DHCP server on interface %s...\n", iface)
    StartDHCPServer(iface)
}

Step 5: Run the Program

Run the program using the go run command.

go run main.go <network_interface>

Replace <network_interface> with the name of the network interface you want to use (e.g., eth0 on Linux or en0 on macOS). This will start the DHCP server on the specified network interface.

Last modified: 19 December 2024