Encapsulating all traffic with a GRE header - go

Question

Summary
I am attempting to GRE encapsulate all traffic from server1 to server2 and I am testing this by pinging the IP address 10.1.1.1 on server2. I have also set up tcpdump on server2 to verify that the traffic is indeed being encapsulated.
However, I am observing the same behavior(I'm able to ping) before and after running the binary, which it is that the traffic is not being encapsulated.
Diagram
Server1<-.3-------->172.16.241.0<---.2-->Server2
I'm running the go code in Server1 and I'm running a ping on server1
code:
package main
import (
"log"
"net"
"github.com/google/gopacket"
"github.com/google/gopacket/layers"
"github.com/google/gopacket/pcap"
)
func main() {
// Open a network interface in promiscuous mode
handle, err := pcap.OpenLive("eth0", 65535, true, pcap.BlockForever)
if err != nil {
log.Fatal(err)
}
defer handle.Close()
// Set a capture filter that drops all packets
err = handle.SetBPFFilter("ip")
if err != nil {
log.Fatal(err)
}
// Start capturing packets
packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
for packet := range packetSource.Packets() {
// Check if the packet is an IPv4 packet
ipv4Layer := packet.Layer(layers.LayerTypeIPv4)
if ipv4Layer != nil {
ipv4 := ipv4Layer.(*layers.IPv4)
// Extract the Ethernet layer from the received packet
ethLayer := packet.Layer(layers.LayerTypeEthernet)
if ethLayer == nil {
log.Printf("Error extracting Ethernet layer")
continue
}
eth := ethLayer.(*layers.Ethernet)
greLayer := &layers.GRE{
Protocol: layers.EthernetTypeIPv4,
}
newIpv4 := &layers.IPv4{
Version: 4,
SrcIP: net.IP{192, 168, 1, 1},
DstIP: net.IP{192, 168, 1, 2},
Protocol: layers.IPProtocolGRE,
Flags: layers.IPv4DontFragment,
TTL: 64,
Id: 33852,
IHL: 5,
}
// Update the checksums
options := gopacket.SerializeOptions{
ComputeChecksums: true,
}
buf := gopacket.NewSerializeBuffer()
err := gopacket.SerializeLayers(buf, options,
eth,
greLayer,
newIpv4,
ipv4,
gopacket.Payload(ipv4.BaseLayer.LayerPayload()),
)
if err != nil {
log.Printf("Error serializing layers: %v", err)
}
// Send the modified packet
err = handle.WritePacketData(buf.Bytes())
if err != nil {
log.Printf("Error sending packet: %v", err)
}
}
}
}
It looks like the ping is not being captured.