github.com/AkihiroSuda/go-netfilter-queue

go-netfilter-queue

Go bindings for libnetfilter_queue

Forked from openshift/geard@be0423a for supporting recent environments.

This library provides access to packets in the IPTables netfilter queue (NFQUEUE). The libnetfilter_queue library is part of the Netfilter project.

Example

use IPTables to direct all outgoing Ping/ICMP requests to the queue 0:

iptables -A OUTPUT -p icmp -j NFQUEUE --queue-num 0

You can then use go-netfilter-queue to inspect the packets:

package main

import (
        "fmt"
        "github.com/AkihiroSuda/go-netfilter-queue"
        "os"
)

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.SetVerdict(netfilter.NF_ACCEPT)
                }
        }
}

To inject a new or modified packet in the place of the original packet, use:

p.SetVerdictWithPacket(netfilter.NF_ACCEPT, byte_slice)

Instead of:

p.SetVerdict(netfilter.NF_ACCEPT)

To undo the IPTables redirect. Run:

iptables -D OUTPUT -p icmp -j NFQUEUE --queue-num 0