redirect package to a different IP

[bonifaido]

I have the following example, which tries to redirect my pings to 8.8.8.8 address instead of the original request:

package main

import (
	"fmt"
	"net"
	"os"

	"github.com/AkihiroSuda/go-netfilter-queue"
	"github.com/google/gopacket/layers"
)

func main() {
	var err error

	nfq, err := netfilter.NewNFQueue(0, 100, netfilter.NF_DEFAULT_PACKET_SIZE)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	defer nfq.Close()
	packets := nfq.GetPackets()

	for true {
		select {
		case p := <-packets:
			fmt.Println(p.Packet)

			p.Packet.NetworkLayer().(*layers.IPv4).DstIP = net.IPv4(8, 8, 8, 8)

			fmt.Println("new ->", p.Packet)

			p.SetVerdictWithPacket(netfilter.NF_ACCEPT, p.Packet.Data())
		}
	}
}

I think from the logs, that it doesn't work, since even if I change the IP to a bad address instead I still get a response in ping CLI, where am I doing it wrong?

I used sudo iptables -A OUTPUT -p icmp -j NFQUEUE to setup the queue.

[terrbear]

You'll want to re-serialize the packet after changing the dest that way. See https://pkg.go.dev/github.com/google/gopacket#SerializePacket