Use ebpf program to find PID of new connections. (#397)

* Use ebpf program to find PID of new connections. before running the branch you have to compile ebpf_prog/opensnitch.c opensnitch.c is an eBPF program. Compilation requires getting kernel source. cd opensnitch wget https://github.com/torvalds/linux/archive/v5.8.tar.gz tar -xf v5.8.tar.gz patch linux-5.8/tools/lib/bpf/bpf_helpers.h < ebpf_prog/file.patch cp ebpf_prog/opensnitch.c ebpf_prog/Makefile linux-5.8/samples/bpf cd linux-5.8 && yes "" | make oldconfig && make prepare && make headers_install # (1 min) cd samples/bpf && make objdump -h opensnitch.o #you should see many section, number 1 should be called kprobe/tcp_v4_connect llvm-strip -g opensnitch.o #remove debug info sudo cp opensnitch.o /etc/opensnitchd cd ../../../daemon --opensnitchd expects to find opensnitch.o in /etc/opensnitchd/ --start opensnitchd with: opensnitchd -rules-path /etc/opensnitchd/rules -process-monitor-method ebpf Co-authored-by: themighty1 <you@example.com> Co-authored-by: Gustavo Iñiguez Goia <gooffy1@gmail.com>
2025-03-04 00:24:40 +01:00 · 2021-04-05 09:28:16 +00:00 · 2021-04-05 09:28:16 +00:00 · 9497cf8394
commit 9497cf8394
parent 148526e527
14 changed files with 1319 additions and 93 deletions
--- a/daemon/conman/connection.go
+++ b/daemon/conman/connection.go
@ -13,6 +13,7 @@ import (
 	"github.com/evilsocket/opensnitch/daemon/netlink"
 	"github.com/evilsocket/opensnitch/daemon/netstat"
 	"github.com/evilsocket/opensnitch/daemon/procmon"
+	"github.com/evilsocket/opensnitch/daemon/procmon/ebpf"
 	"github.com/evilsocket/opensnitch/daemon/ui/protocol"

 	"github.com/google/gopacket/layers"
@ -81,24 +82,47 @@ func newConnectionImpl(nfp *netfilter.Packet, c *Connection, protoType string) (
 		INode:   -1,
 	}

-	// 0. lookup uid and inode via netlink. Can return several inodes.
-	// 1. lookup uid and inode using /proc/net/(udp|tcp|udplite)
-	// 2. lookup pid by inode
-	// 3. if this is coming from us, just accept
-	// 4. lookup process info by pid
-	uid, inodeList := netlink.GetSocketInfo(c.Protocol, c.SrcIP, c.SrcPort, c.DstIP, c.DstPort)
-	if len(inodeList) == 0 {
-		if c.Entry = netstat.FindEntry(c.Protocol, c.SrcIP, c.SrcPort, c.DstIP, c.DstPort); c.Entry == nil {
-			return nil, fmt.Errorf("Could not find netstat entry for: %s", c)
+	pid := -1
+	var uid int
+	if procmon.MethodIsEbpf() {
+		pid, uid, err = ebpf.GetPid(c.Protocol, c.SrcPort, c.SrcIP, c.DstIP, c.DstPort)
+		if err != nil {
+			log.Warning("ebpf warning: %v", err)
+			return nil, nil
 		}
-		if c.Entry.INode > 0 {
-			log.Debug("connection found in netstat: %v", c.Entry)
-			inodeList = append([]int{c.Entry.INode}, inodeList...)
+	} 
+	// sometimes when using eBPF the connection is not found, but falling back to legacy
+	// methods helps to find it and avoid "unknown/kernel pop-ups". TODO: investigate
+	if pid == -1 {
+		// 0. lookup uid and inode via netlink. Can return several inodes.
+		// 1. lookup uid and inode using /proc/net/(udp|tcp|udplite)
+		// 2. lookup pid by inode
+		// 3. if this is coming from us, just accept
+		// 4. lookup process info by pid
+		var inodeList []int
+		uid, inodeList = netlink.GetSocketInfo(c.Protocol, c.SrcIP, c.SrcPort, c.DstIP, c.DstPort)
+		if len(inodeList) == 0 {
+			if c.Entry = netstat.FindEntry(c.Protocol, c.SrcIP, c.SrcPort, c.DstIP, c.DstPort); c.Entry == nil {
+				return nil, fmt.Errorf("Could not find netstat entry for: %s", c)
+			}
+			if c.Entry.INode > 0 {
+				log.Debug("connection found in netstat: %v", c.Entry)
+				inodeList = append([]int{c.Entry.INode}, inodeList...)
+			}
+		}
+		if len(inodeList) == 0 {
+			log.Debug("<== no inodes found, applying default action.")
+			return nil, nil
+		}
+
+		for n, inode := range inodeList {
+			pid = procmon.GetPIDFromINode(inode, fmt.Sprint(inode, c.SrcIP, c.SrcPort, c.DstIP, c.DstPort))
+			if pid != -1 {
+				log.Debug("[%d] PID found %d", n, pid)
+				c.Entry.INode = inode
+				break
+			}
 		}
-	}
-	if len(inodeList) == 0 {
-		log.Debug("<== no inodes found, applying default action.")
-		return nil, nil
 	}

 	if uid != -1 {
@ -107,26 +131,18 @@ func newConnectionImpl(nfp *netfilter.Packet, c *Connection, protoType string) (
 		c.Entry.UserId = int(nfp.UID)
 	}

-	pid := -1
-	for n, inode := range inodeList {
-		if pid = procmon.GetPIDFromINode(inode, fmt.Sprint(inode, c.SrcIP, c.SrcPort, c.DstIP, c.DstPort)); pid == os.Getpid() {
-			// return a Process object with our PID, to be able to exclude our own connections
-			// (to the UI on a local socket for example)
-			c.Process = procmon.NewProcess(pid, "")
-			return c, nil
-		}
-		if pid != -1 {
-			log.Debug("[%d] PID found %d", n, pid)
-			c.Entry.INode = inode
-			break
-		}
+	if pid == os.Getpid() {
+		// return a Process object with our PID, to be able to exclude our own connections
+		// (to the UI on a local socket for example)
+		c.Process = procmon.NewProcess(pid, "")
+		return c, nil
 	}
+
 	if c.Process = procmon.FindProcess(pid, showUnknownCons); c.Process == nil {
 		return nil, fmt.Errorf("Could not find process by its pid %d for: %s", pid, c)
 	}

 	return c, nil
-
 }

 // NewConnection creates a new Connection object, and returns the details of it.
--- a/daemon/main.go
+++ b/daemon/main.go
@ -21,6 +21,7 @@ import (
 	"github.com/evilsocket/opensnitch/daemon/log"
 	"github.com/evilsocket/opensnitch/daemon/netfilter"
 	"github.com/evilsocket/opensnitch/daemon/procmon"
+	"github.com/evilsocket/opensnitch/daemon/procmon/monitor"
 	"github.com/evilsocket/opensnitch/daemon/rule"
 	"github.com/evilsocket/opensnitch/daemon/statistics"
 	"github.com/evilsocket/opensnitch/daemon/ui"
@ -62,7 +63,7 @@ var (
 func init() {
 	flag.BoolVar(&showVersion, "version", debug, "Show daemon version of this executable and exit.")

-	flag.StringVar(&procmonMethod, "process-monitor-method", procmonMethod, "How to search for processes path. Options: ftrace, audit (experimental), proc (default)")
+	flag.StringVar(&procmonMethod, "process-monitor-method", procmonMethod, "How to search for processes path. Options: ftrace, audit (experimental), ebpf (experimental), proc (default)")
 	flag.StringVar(&uiSocket, "ui-socket", uiSocket, "Path the UI gRPC service listener (https://github.com/grpc/grpc/blob/master/doc/naming.md).")
 	flag.StringVar(&rulesPath, "rules-path", rulesPath, "Path to load JSON rules from.")
 	flag.IntVar(&queueNum, "queue-num", queueNum, "Netfilter queue number.")
@ -156,7 +157,7 @@ func setupWorkers() {
 func doCleanup(queue, repeatQueue *netfilter.Queue) {
 	log.Info("Cleaning up ...")
 	firewall.Stop(&queueNum)
-	procmon.End()
+	monitor.End()
 	uiClient.Close()
 	queue.Close()
 	repeatQueue.Close()
@ -387,7 +388,7 @@ func main() {
 	if procmonMethod != "" {
 		procmon.SetMonitorMethod(procmonMethod)
 	}
-	procmon.Init()
+	monitor.Init()

 	// queue is ready, run firewall rules
 	firewall.Init(&queueNum)
--- a/daemon/procmon/activepids.go
+++ b/daemon/procmon/activepids.go
@ -23,10 +23,10 @@ var (
 	activePidsLock = sync.RWMutex{}
 )

-//monitorActivePids checks that each process in activePids
+//MonitorActivePids checks that each process in activePids
 //is still running and if not running (or another process with the same pid is running),
 //removes the pid from activePids
-func monitorActivePids() {
+func MonitorActivePids() {
 	for {
 		time.Sleep(time.Second)
 		activePidsLock.Lock()
--- a/daemon/procmon/cache.go
+++ b/daemon/procmon/cache.go
@ -110,7 +110,7 @@ func deleteInodeEntry(pid int) {
 	}
 }

-func cacheCleanerTask() {
+func CacheCleanerTask() {
 	for {
 		select {
 		case <-cacheTicker.C:
--- a/daemon/procmon/ebpf/ebpf.go
+++ b/daemon/procmon/ebpf/ebpf.go
@ -0,0 +1,535 @@
+package ebpf
+
+import (
+	"encoding/binary"
+	"fmt"
+	"net"
+	"os/exec"
+	"strconv"
+	"sync"
+	"syscall"
+	"time"
+	"unsafe"
+
+	"github.com/evilsocket/opensnitch/daemon/log"
+	"github.com/evilsocket/opensnitch/daemon/procmon"
+	"github.com/vishvananda/netlink"
+
+	daemonNetlink "github.com/evilsocket/opensnitch/daemon/netlink"
+	elf "github.com/iovisor/gobpf/elf"
+)
+
+//contains pointers to ebpf maps for a given protocol (tcp/udp/v6)
+type ebpfMapsForProto struct {
+	counterMap    *elf.Map
+	bpfmap        *elf.Map
+	lastPurgedMax uint64 // max counter value up to and including which the map was purged on the last purge
+}
+
+var (
+	m        *elf.Module
+	mapSize  = 12000
+	ebpfMaps map[string]*ebpfMapsForProto
+	//connections which were established at the time when opensnitch started
+	alreadyEstablishedTCP   = make(map[*daemonNetlink.Socket]int)
+	alreadyEstablishedTCPv6 = make(map[*daemonNetlink.Socket]int)
+	//stop == true is a signal for all goroutines to stop
+	stop = false
+	// list of local addresses of this machine
+	localAddresses     []net.IP
+	localAddressesLock sync.RWMutex
+	hostByteOrder      binary.ByteOrder
+)
+
+//Start installs ebpf kprobes
+func Start() error {
+	m = elf.NewModule("/etc/opensnitchd/opensnitch.o")
+	if err := m.Load(nil); err != nil {
+		log.Error("Failed to load /etc/opensnitchd/opensnitch.o", err)
+		return err
+	}
+
+	// if previous shutdown was unclean, then we must remove the dangling kprobe
+	// and install it again (close the module and load it again)
+	if err := m.EnableKprobes(0); err != nil {
+		m.Close()
+		if err := m.Load(nil); err != nil {
+			log.Error("Failed to load /etc/opensnitchd/opensnitch.o", err)
+			return err
+		}
+		if err := m.EnableKprobes(0); err != nil {
+			log.Error("Error when enabling kprobes", err)
+			return err
+		}
+	}
+
+	// init all connection counters to 0
+	zeroKey := make([]byte, 4)
+	zeroValue := make([]byte, 8)
+	for _, name := range []string{"tcpcounter", "tcpv6counter", "udpcounter", "udpv6counter"} {
+		err := m.UpdateElement(m.Map(name), unsafe.Pointer(&zeroKey[0]), unsafe.Pointer(&zeroValue[0]), 0)
+		if err != nil {
+			log.Error("Could not init counters to zero", err)
+			return err
+		}
+	}
+
+	//determine host byte order
+	buf := [2]byte{}
+	*(*uint16)(unsafe.Pointer(&buf[0])) = uint16(0xABCD)
+	switch buf {
+	case [2]byte{0xCD, 0xAB}:
+		hostByteOrder = binary.LittleEndian
+	case [2]byte{0xAB, 0xCD}:
+		hostByteOrder = binary.BigEndian
+	default:
+		log.Error("Could not determine host byte order.")
+	}
+
+	ebpfMaps = map[string]*ebpfMapsForProto{
+		"tcp": {lastPurgedMax: 0,
+			counterMap: m.Map("tcpcounter"),
+			bpfmap:     m.Map("tcpMap")},
+		"tcp6": {lastPurgedMax: 0,
+			counterMap: m.Map("tcpv6counter"),
+			bpfmap:     m.Map("tcpv6Map")},
+		"udp": {lastPurgedMax: 0,
+			counterMap: m.Map("udpcounter"),
+			bpfmap:     m.Map("udpMap")},
+		"udp6": {lastPurgedMax: 0,
+			counterMap: m.Map("udpv6counter"),
+			bpfmap:     m.Map("udpv6Map")},
+	}
+
+	// save already established connections
+	socketListTCP, err := daemonNetlink.SocketsDump(uint8(syscall.AF_INET), uint8(syscall.IPPROTO_TCP))
+	if err != nil {
+		log.Error("Could not dump TCP sockets via netlink", err)
+		return err
+	}
+	for _, sock := range socketListTCP {
+		inode := int((*sock).INode)
+		pid := procmon.GetPIDFromINode(inode, fmt.Sprint(inode,
+			(*sock).ID.Source, (*sock).ID.SourcePort, (*sock).ID.Destination, (*sock).ID.DestinationPort))
+		alreadyEstablishedTCP[sock] = pid
+	}
+
+	socketListTCPv6, err := daemonNetlink.SocketsDump(uint8(syscall.AF_INET6), uint8(syscall.IPPROTO_TCP))
+	if err != nil {
+		log.Error("Could not dump TCPv6 sockets via netlink", err)
+		return err
+	}
+	for _, sock := range socketListTCPv6 {
+		inode := int((*sock).INode)
+		pid := procmon.GetPIDFromINode(inode, fmt.Sprint(inode,
+			(*sock).ID.Source, (*sock).ID.SourcePort, (*sock).ID.Destination, (*sock).ID.DestinationPort))
+		alreadyEstablishedTCPv6[sock] = pid
+	}
+
+	go monitorMaps()
+	go monitorLocalAddresses()
+	go monitorAlreadyEstablished()
+	return nil
+}
+
+func Stop() {
+	stop = true
+	if m != nil {
+		m.Close()
+	}
+}
+
+// delete all map's elements which have counter value <= maxToDelete
+func deleteOld(bpfmap *elf.Map, isIPv6 bool, maxToDelete uint64) {
+	var lookupKey []byte
+	var nextKey []byte
+	var value []byte
+	if !isIPv6 {
+		lookupKey = make([]byte, 12)
+		nextKey = make([]byte, 12)
+		value = make([]byte, 24)
+	} else {
+		lookupKey = make([]byte, 36)
+		nextKey = make([]byte, 36)
+		value = make([]byte, 24)
+	}
+	firstrun := true
+	i := 0
+	for {
+		i++
+		if i > 12000 {
+			// there were more iterations than the max amount of elements in map
+			// TODO find out what causes the endless loop
+			// maybe because ebpf prog modified the map while we were iterating
+			log.Error("Breaking because endless loop was detected in deleteOld")
+			break
+		}
+		ok, err := m.LookupNextElement(bpfmap, unsafe.Pointer(&lookupKey[0]),
+			unsafe.Pointer(&nextKey[0]), unsafe.Pointer(&value[0]))
+		if err != nil {
+			log.Error("LookupNextElement error", err)
+			return
+		}
+		if firstrun {
+			// on first run lookupKey is a dummy, nothing to delete
+			firstrun = false
+			copy(lookupKey, nextKey)
+			continue
+		}
+		// last 8 bytes of value is counter value
+		counterValue := hostByteOrder.Uint64(value[16:24])
+		if counterValue > maxToDelete {
+			copy(lookupKey, nextKey)
+			continue
+		}
+		if err := m.DeleteElement(bpfmap, unsafe.Pointer(&lookupKey[0])); err != nil {
+			log.Error("DeleteElement error", err)
+			return
+		}
+		if !ok { //reached end of map
+			break
+		}
+		copy(lookupKey, nextKey)
+	}
+}
+
+// we need to manually remove old connections from a bpf map
+// since when a bpf map is full it doesn't allow any more insertions
+func monitorMaps() {
+	zeroKey := make([]byte, 4)
+	for {
+		time.Sleep(time.Second * 1)
+		if stop {
+			return
+		}
+		for name, ebpfMap := range ebpfMaps {
+			value := make([]byte, 8)
+			if err := m.LookupElement(ebpfMap.counterMap,
+				unsafe.Pointer(&zeroKey[0]), unsafe.Pointer(&value[0])); err != nil {
+				log.Error("m.LookupElement", err)
+			}
+			counterValue := hostByteOrder.Uint64(value)
+			if counterValue-ebpfMap.lastPurgedMax > 10000 {
+				ebpfMap.lastPurgedMax = counterValue - 5000
+				deleteOld(ebpfMap.bpfmap, name == "tcp6" || name == "udp6", ebpfMap.lastPurgedMax)
+			}
+		}
+	}
+}
+
+// GetPid looks up process pid in a bpf map. If not found there, then it searches
+// already-established TCP connections.
+func GetPid(proto string, srcPort uint, srcIP net.IP, dstIP net.IP, dstPort uint) (int, int, error) {
+        if hostByteOrder == nil {
+                return -1, -1, fmt.Errorf("eBPF monitoring method not initialized yet")
+        }
+
+	if pid, uid := getPidFromEbpf(proto, srcPort, srcIP, dstIP, dstPort); pid != -1 {
+		return pid, uid, nil
+	}
+	//check if it comes from already established TCP
+	if proto == "tcp" || proto == "tcp6" {
+		if pid, uid, err := findInAlreadyEstablishedTCP(proto, srcPort, srcIP, dstIP, dstPort); err == nil {
+			return pid, uid, nil
+		}
+	}
+	//using netlink.GetSocketInfo to check if UID is 0 (in-kernel connection)
+	if uid, _ := daemonNetlink.GetSocketInfo(proto, srcIP, srcPort, dstIP, dstPort); uid == 0 {
+		return -100, -100, nil
+	}
+	if !findAddressInLocalAddresses(srcIP) {
+		// systemd-resolved sometimes makes a TCP Fast Open connection to a DNS server (8.8.8.8 on my machine)
+		// and we get a packet here with **source** (not detination!!!) IP 8.8.8.8
+		// Maybe it's an in-kernel response with spoofed IP because wireshark does not show neither
+		// resolved's TCP Fast Open packet, nor the response
+		// Until this is better understood, we simply do not allow this machine to make connections with
+		// arbitrary source IPs
+		return -1, -1, fmt.Errorf("Packet with unknown source IP: %s", srcIP)
+	}
+	return -1, -1, nil
+}
+
+// getPidFromEbpf looks up a connection in bpf map and returns PID if found
+// the lookup keys and values are defined in opensnitch.c , e.g.
+//
+// struct tcp_key_t {
+// 	u16 sport;
+// 	u32 daddr;
+// 	u16 dport;
+//  u32 saddr;
+// }__attribute__((packed));
+
+// struct tcp_value_t{
+// 	u64 pid;
+//  u64 uid;
+// 	u64 counter;
+// }__attribute__((packed));;
+
+func getPidFromEbpf(proto string, srcPort uint, srcIP net.IP, dstIP net.IP, dstPort uint) (pid int, uid int) {
+	var key []byte
+	var value []byte
+	var isIP4 bool = (proto == "tcp") || (proto == "udp") || (proto == "udplite")
+
+	if isIP4 {
+		key = make([]byte, 12)
+		value = make([]byte, 24)
+		copy(key[2:6], dstIP)
+		binary.BigEndian.PutUint16(key[6:8], uint16(dstPort))
+		copy(key[8:12], srcIP)
+	} else { // IPv6
+		key = make([]byte, 36)
+		value = make([]byte, 24)
+		copy(key[2:18], dstIP)
+		binary.BigEndian.PutUint16(key[18:20], uint16(dstPort))
+		copy(key[20:36], srcIP)
+	}
+	hostByteOrder.PutUint16(key[0:2], uint16(srcPort))
+
+	err := m.LookupElement(ebpfMaps[proto].bpfmap, unsafe.Pointer(&key[0]), unsafe.Pointer(&value[0]))
+	if err != nil {
+		// key not found
+		// maybe srcIP is 0.0.0.0 Happens especially with UDP sendto()
+		// TODO: can this happen with TCP?
+		if isIP4 {
+			zeroes := make([]byte, 4)
+			copy(key[8:12], zeroes)
+		} else {
+			zeroes := make([]byte, 16)
+			copy(key[20:36], zeroes)
+		}
+		err = m.LookupElement(ebpfMaps[proto].bpfmap, unsafe.Pointer(&key[0]), unsafe.Pointer(&value[0]))
+	}
+	if err != nil && proto == "udp" && srcIP.String() == dstIP.String() {
+		// very rarely I see this connection. It has srcIP and dstIP == 0.0.0.0 in ebpf map
+		// it is a localhost to localhost connection
+		// srcIP was already set to 0, set dstIP to zero also
+		// TODO try to reproduce it and look for srcIP/dstIP in other kernel structures
+		zeroes := make([]byte, 4)
+		copy(key[2:6], zeroes)
+		err = m.LookupElement(ebpfMaps[proto].bpfmap, unsafe.Pointer(&key[0]), unsafe.Pointer(&value[0]))
+	}
+	if err != nil {
+		// key not found in bpf map
+		return -1, -1
+	}
+	pid = int(hostByteOrder.Uint32(value[0:4]))
+	uid = int(hostByteOrder.Uint32(value[8:12]))
+	return pid, uid
+}
+
+// FindInAlreadyEstablishedTCP searches those TCP connections which were already established at the time
+// when opensnitch started
+func findInAlreadyEstablishedTCP(proto string, srcPort uint, srcIP net.IP, dstIP net.IP, dstPort uint) (int, int, error) {
+	var alreadyEstablished map[*daemonNetlink.Socket]int
+	if proto == "tcp" {
+		alreadyEstablished = alreadyEstablishedTCP
+	} else if proto == "tcp6" {
+		alreadyEstablished = alreadyEstablishedTCPv6
+	}
+	for sock, v := range alreadyEstablished {
+		if (*sock).ID.SourcePort == uint16(srcPort) && (*sock).ID.Source.Equal(srcIP) &&
+			(*sock).ID.Destination.Equal(dstIP) && (*sock).ID.DestinationPort == uint16(dstPort) {
+			return v, int((*sock).UID), nil
+		}
+	}
+	return -1, -1, fmt.Errorf("Inode not found")
+}
+
+//returns true if addr is in the list of this machine's addresses
+func findAddressInLocalAddresses(addr net.IP) bool {
+	localAddressesLock.Lock()
+	defer localAddressesLock.Unlock()
+	for _, a := range localAddresses {
+		if addr.String() == a.String() {
+			return true
+		}
+	}
+	return false
+}
+
+// maintains a list of this machine's local addresses
+func monitorLocalAddresses() {
+	for {
+		addr, err := netlink.AddrList(nil, netlink.FAMILY_ALL)
+		if err != nil {
+			log.Error("Error looking up this machine's addresses via netlink", err)
+			continue
+		}
+		localAddressesLock.Lock()
+		localAddresses = nil
+		for _, a := range addr {
+			localAddresses = append(localAddresses, a.IP)
+		}
+		localAddressesLock.Unlock()
+		time.Sleep(time.Second * 1)
+		if stop {
+			return
+		}
+	}
+}
+
+// monitorAlreadyEstablished makes sure that when an already-established connection is closed
+// it will be removed from alreadyEstablished. If we don't do this and keep the alreadyEstablished entry forever,
+// then after the genuine process quits,a malicious process may reuse PID-srcPort-srcIP-dstPort-dstIP
+func monitorAlreadyEstablished() {
+	for {
+		time.Sleep(time.Second * 1)
+		if stop {
+			return
+		}
+		socketListTCP, err := daemonNetlink.SocketsDump(uint8(syscall.AF_INET), uint8(syscall.IPPROTO_TCP))
+		if err != nil {
+			log.Error("Error in dumping TCP sockets via netlink")
+			continue
+		}
+		for aesock := range alreadyEstablishedTCP {
+			found := false
+			for _, sock := range socketListTCP {
+				if (*aesock).INode == (*sock).INode &&
+					//inodes are unique enough, so the matches below will never have to be checked
+					(*aesock).ID.SourcePort == (*sock).ID.SourcePort &&
+					(*aesock).ID.Source.Equal((*sock).ID.Source) &&
+					(*aesock).ID.Destination.Equal((*sock).ID.Destination) &&
+					(*aesock).ID.DestinationPort == (*sock).ID.DestinationPort &&
+					(*aesock).UID == (*sock).UID {
+					found = true
+					break
+				}
+			}
+			if !found {
+				delete(alreadyEstablishedTCP, aesock)
+			}
+		}
+
+		socketListTCPv6, err := daemonNetlink.SocketsDump(uint8(syscall.AF_INET6), uint8(syscall.IPPROTO_TCP))
+		if err != nil {
+			log.Error("Error in dumping TCPv6 sockets via netlink")
+			continue
+		}
+		for aesock := range alreadyEstablishedTCPv6 {
+			found := false
+			for _, sock := range socketListTCPv6 {
+				if (*aesock).INode == (*sock).INode &&
+					//inodes are unique enough, so the matches below will never have to be checked
+					(*aesock).ID.SourcePort == (*sock).ID.SourcePort &&
+					(*aesock).ID.Source.Equal((*sock).ID.Source) &&
+					(*aesock).ID.Destination.Equal((*sock).ID.Destination) &&
+					(*aesock).ID.DestinationPort == (*sock).ID.DestinationPort &&
+					(*aesock).UID == (*sock).UID {
+					found = true
+					break
+				}
+			}
+			if !found {
+				delete(alreadyEstablishedTCPv6, aesock)
+			}
+		}
+	}
+}
+
+//Not in use, ~4usec faster lookup compared to m.LookupElement()
+
+//mimics union bpf_attr's anonymous struct used by BPF_MAP_*_ELEM commands
+//from <linux_headers>/include/uapi/linux/bpf.h
+type bpf_lookup_elem_t struct {
+	map_fd uint64 //even though in bpf.h its type is __u32, we must make it 8 bytes long
+	//because "key" is of type __aligned_u64, i.e. "key" must be aligned on an 8-byte boundary
+	key   uintptr
+	value uintptr
+}
+
+//make bpf() syscall with bpf_lookup prepared by the caller
+func makeBpfSyscall(bpf_lookup *bpf_lookup_elem_t) uintptr {
+	BPF_MAP_LOOKUP_ELEM := 1 //cmd number
+	syscall_BPF := 321       //syscall number
+	sizeOfStruct := 24       //sizeof bpf_lookup_elem_t struct
+
+	r1, _, _ := syscall.Syscall(uintptr(syscall_BPF), uintptr(BPF_MAP_LOOKUP_ELEM),
+		uintptr(unsafe.Pointer(bpf_lookup)), uintptr(sizeOfStruct))
+	return r1
+}
+
+// print map contents. used only for debugging
+func dumpMap(bpfmap *elf.Map, isIPv6 bool) {
+	var lookupKey []byte
+	var nextKey []byte
+	var value []byte
+	if !isIPv6 {
+		lookupKey = make([]byte, 12)
+		nextKey = make([]byte, 12)
+		value = make([]byte, 24)
+	} else {
+		lookupKey = make([]byte, 36)
+		nextKey = make([]byte, 36)
+		value = make([]byte, 24)
+	}
+	firstrun := true
+	i := 0
+	for {
+		i++
+		ok, err := m.LookupNextElement(bpfmap, unsafe.Pointer(&lookupKey[0]),
+			unsafe.Pointer(&nextKey[0]), unsafe.Pointer(&value[0]))
+		if err != nil {
+			log.Error("LookupNextElement error", err)
+			return
+		}
+		if firstrun {
+			// on first run lookupKey is a dummy, nothing to delete
+			firstrun = false
+			copy(lookupKey, nextKey)
+			continue
+		}
+		fmt.Println("key, value", lookupKey, value)
+
+		if !ok { //reached end of map
+			break
+		}
+		copy(lookupKey, nextKey)
+	}
+}
+
+//PrintEverything prints all the stats. used only for debugging
+func PrintEverything() {
+	bash, _ := exec.LookPath("bash")
+	//get the number of the first map
+	out, err := exec.Command(bash, "-c", "bpftool map show | head -n 1 | cut -d ':' -f1").Output()
+	if err != nil {
+		fmt.Println("bpftool map dump name tcpMap ", err)
+	}
+	i, _ := strconv.Atoi(string(out[:len(out)-1]))
+	fmt.Println("i is", i)
+
+	//dump all maps for analysis
+	for j := i; j < i+14; j++ {
+		_, _ = exec.Command(bash, "-c", "bpftool map dump id "+strconv.Itoa(j)+" > dump"+strconv.Itoa(j)).Output()
+	}
+
+	for sock1, v := range alreadyEstablishedTCP {
+		fmt.Println(*sock1, v)
+	}
+	fmt.Println("---------------------")
+	for sock1, v := range alreadyEstablishedTCPv6 {
+		fmt.Println(*sock1, v)
+	}
+	fmt.Println("---------------------")
+	sockets, _ := daemonNetlink.SocketsDump(syscall.AF_INET, syscall.IPPROTO_TCP)
+	for idx := range sockets {
+		fmt.Println("socket tcp: ", sockets[idx])
+	}
+	fmt.Println("---------------------")
+	sockets, _ = daemonNetlink.SocketsDump(syscall.AF_INET6, syscall.IPPROTO_TCP)
+	for idx := range sockets {
+		fmt.Println("socket tcp6: ", sockets[idx])
+	}
+	fmt.Println("---------------------")
+	sockets, _ = daemonNetlink.SocketsDump(syscall.AF_INET, syscall.IPPROTO_UDP)
+	for idx := range sockets {
+		fmt.Println("socket udp: ", sockets[idx])
+	}
+	fmt.Println("---------------------")
+	sockets, _ = daemonNetlink.SocketsDump(syscall.AF_INET6, syscall.IPPROTO_UDP)
+	for idx := range sockets {
+		fmt.Println("socket udp6: ", sockets[idx])
+	}
+
+}
--- a/daemon/procmon/monitor/init.go
+++ b/daemon/procmon/monitor/init.go
@ -0,0 +1,77 @@
+package monitor
+
+import (
+	"net"
+
+	"github.com/evilsocket/opensnitch/daemon/log"
+	"github.com/evilsocket/opensnitch/daemon/procmon"
+	"github.com/evilsocket/opensnitch/daemon/procmon/audit"
+	"github.com/evilsocket/opensnitch/daemon/procmon/ebpf"
+)
+
+var (
+	cacheMonitorsRunning = false
+)
+
+// monitor method supported types
+const (
+	MethodFtrace = "ftrace"
+	MethodProc   = "proc"
+	MethodAudit  = "audit"
+	MethodEbpf   = "ebpf"
+)
+
+// End stops the way of parsing new connections.
+func End() {
+	if procmon.MethodIsAudit() {
+		audit.Stop()
+	} else if procmon.MethodIsEbpf() {
+		ebpf.Stop()
+	} else if procmon.MethodIsFtrace() {
+		go func() {
+			if err := procmon.Stop(); err != nil {
+				log.Warning("procmon.End() stop ftrace error: %v", err)
+			}
+		}()
+	}
+}
+
+// Init starts parsing connections using the method specified.
+func Init() (err error) {
+	if cacheMonitorsRunning == false {
+		go procmon.MonitorActivePids()
+		go procmon.CacheCleanerTask()
+		cacheMonitorsRunning = true
+	}
+
+	if procmon.MethodIsEbpf() {
+		err = ebpf.Start()
+		if err == nil {
+			log.Info("Process monitor method ebpf")
+			return nil
+		}
+		log.Warning("error starting ebpf monitor method: %v", err)
+	} else if procmon.MethodIsFtrace() {
+		err = procmon.Start()
+		if err == nil {
+			log.Info("Process monitor method ftrace")
+			return nil
+		}
+		log.Warning("error starting ftrace monitor method: %v", err)
+
+	} else if procmon.MethodIsAudit() {
+		var auditConn net.Conn
+		auditConn, err = audit.Start()
+		if err == nil {
+			log.Info("Process monitor method audit")
+			go audit.Reader(auditConn, (chan<- audit.Event)(audit.EventChan))
+			return nil
+		}
+		log.Warning("error starting audit monitor method: %v", err)
+	}
+
+	// if any of the above methods have failed, fallback to proc
+	log.Info("Process monitor method /proc")
+	procmon.SetMonitorMethod(MethodProc)
+	return err
+}
--- a/daemon/procmon/parse.go
+++ b/daemon/procmon/parse.go
@ -58,12 +58,12 @@ func GetPIDFromINode(inode int, inodeKey string) int {
 		return cachedPid
 	}

-	if methodIsAudit() {
+	if MethodIsAudit() {
 		if aPid, pos := getPIDFromAuditEvents(inode, inodeKey, expect); aPid != -1 {
 			log.Debug("PID found via audit events: %v, position: %d", time.Since(start), pos)
 			return aPid
 		}
-	} else if methodIsFtrace() && IsWatcherAvailable() {
+	} else if MethodIsFtrace() && IsWatcherAvailable() {
 		forEachProcess(func(pid int, path string, args []string) bool {
 			if inodeFound("/proc/", expect, inodeKey, inode, pid) {
 				found = pid
@ -85,6 +85,9 @@ func GetPIDFromINode(inode int, inodeKey string) int {
 // If it exists in /proc, a new Process{} object is returned with  the details
 // to identify a process (cmdline, name, environment variables, etc).
 func FindProcess(pid int, interceptUnknown bool) *Process {
+	if pid == -100 {
+		return NewProcess(-100, "Linux kernel")
+	}
 	if interceptUnknown && pid < 0 {
 		return NewProcess(0, "")
 	}
@ -93,7 +96,7 @@ func FindProcess(pid int, interceptUnknown bool) *Process {
 		return proc
 	}

-	if methodIsAudit() {
+	if MethodIsAudit() {
 		if aevent := audit.GetEventByPid(pid); aevent != nil {
 			audit.Lock.RLock()
 			proc := NewProcess(pid, aevent.ProcPath)
--- a/daemon/procmon/process.go
+++ b/daemon/procmon/process.go
@ -1,11 +1,7 @@
 package procmon

 import (
-	"net"
 	"time"
-
-	"github.com/evilsocket/opensnitch/daemon/log"
-	"github.com/evilsocket/opensnitch/daemon/procmon/audit"
 )

 var (
@ -73,14 +69,21 @@ func SetMonitorMethod(newMonitorMethod string) {
 	monitorMethod = newMonitorMethod
 }

-func methodIsFtrace() bool {
+func MethodIsEbpf() bool {
+	lock.RLock()
+	defer lock.RUnlock()
+
+	return monitorMethod == MethodEbpf
+}
+
+func MethodIsFtrace() bool {
 	lock.RLock()
 	defer lock.RUnlock()

 	return monitorMethod == MethodFtrace
 }

-func methodIsAudit() bool {
+func MethodIsAudit() bool {
 	lock.RLock()
 	defer lock.RUnlock()

@ -93,49 +96,3 @@ func methodIsProc() bool {

 	return monitorMethod == MethodProc
 }
-
-// End stops the way of parsing new connections.
-func End() {
-	if methodIsAudit() {
-		audit.Stop()
-	} else if methodIsFtrace() {
-		go func() {
-			if err := Stop(); err != nil {
-				log.Warning("procmon.End() stop ftrace error: %v", err)
-			}
-		}()
-	}
-}
-
-// Init starts parsing connections using the method specified.
-func Init() (err error) {
-	if cacheMonitorsRunning == false {
-		go monitorActivePids()
-		go cacheCleanerTask()
-		cacheMonitorsRunning = true
-	}
-
-	if methodIsFtrace() {
-		err = Start()
-		if err == nil {
-			log.Info("Process monitor method ftrace")
-			return nil
-		}
-		log.Warning("error starting ftrace monitor method: %v", err)
-
-	} else if methodIsAudit() {
-		var auditConn net.Conn
-		auditConn, err = audit.Start()
-		if err == nil {
-			log.Info("Process monitor method audit")
-			go audit.Reader(auditConn, (chan<- audit.Event)(audit.EventChan))
-			return nil
-		}
-		log.Warning("error starting audit monitor method: %v", err)
-	}
-
-	// if any of the above methods have failed, fallback to proc
-	log.Info("Process monitor method /proc")
-	SetMonitorMethod(MethodProc)
-	return err
-}
--- a/daemon/procmon/watcher.go
+++ b/daemon/procmon/watcher.go
@ -14,6 +14,7 @@ const (
 	MethodFtrace = "ftrace"
 	MethodProc   = "proc"
 	MethodAudit  = "audit"
+	MethodEbpf   = "ebpf"
 )

 const (
--- a/daemon/ui/notifications.go
+++ b/daemon/ui/notifications.go
@ -13,6 +13,7 @@ import (
 	"github.com/evilsocket/opensnitch/daemon/firewall"
 	"github.com/evilsocket/opensnitch/daemon/log"
 	"github.com/evilsocket/opensnitch/daemon/procmon"
+	"github.com/evilsocket/opensnitch/daemon/procmon/monitor"
 	"github.com/evilsocket/opensnitch/daemon/rule"
 	"github.com/evilsocket/opensnitch/daemon/ui/protocol"
 	"golang.org/x/net/context"
@ -95,7 +96,7 @@ func (c *Client) handleActionChangeConfig(stream protocol.UI_NotificationsClient
 	// in such case close the current method, and start the new one.
 	procMonitorEqual := c.isProcMonitorEqual(newConf.ProcMonitorMethod)
 	if procMonitorEqual == false {
-		procmon.End()
+		monitor.End()
 	}

 	// this save operation triggers a re-loadConfiguration()
@ -103,7 +104,7 @@ func (c *Client) handleActionChangeConfig(stream protocol.UI_NotificationsClient
 	if err != nil {
 		log.Warning("[notification] CHANGE_CONFIG not applied %s", err)
 	} else if err == nil && procMonitorEqual == false {
-		if err := procmon.Init(); err != nil {
+		if err := monitor.Init(); err != nil {
 			c.sendNotificationReply(stream, notification.Id, "", err)
 		}
 	}
--- a/ebpf_prog/Makefile
+++ b/ebpf_prog/Makefile
@ -0,0 +1,159 @@
+#taken from /samples/bpf/Makefile and removed all targets 
+
+# SPDX-License-Identifier: GPL-2.0
+
+BPF_SAMPLES_PATH ?= $(abspath $(srctree)/$(src))
+TOOLS_PATH := $(BPF_SAMPLES_PATH)/../../tools
+
+# Libbpf dependencies
+LIBBPF = $(TOOLS_PATH)/lib/bpf/libbpf.a
+
+CGROUP_HELPERS := ../../tools/testing/selftests/bpf/cgroup_helpers.o
+TRACE_HELPERS := ../../tools/testing/selftests/bpf/trace_helpers.o
+
+always-y += opensnitch.o
+
+ifeq ($(ARCH), arm)
+# Strip all except -D__LINUX_ARM_ARCH__ option needed to handle linux
+# headers when arm instruction set identification is requested.
+ARM_ARCH_SELECTOR := $(filter -D__LINUX_ARM_ARCH__%, $(KBUILD_CFLAGS))
+BPF_EXTRA_CFLAGS := $(ARM_ARCH_SELECTOR)
+TPROGS_CFLAGS += $(ARM_ARCH_SELECTOR)
+endif
+
+TPROGS_CFLAGS += -Wall -O2
+TPROGS_CFLAGS += -Wmissing-prototypes
+TPROGS_CFLAGS += -Wstrict-prototypes
+
+TPROGS_CFLAGS += -I$(objtree)/usr/include
+TPROGS_CFLAGS += -I$(srctree)/tools/testing/selftests/bpf/
+TPROGS_CFLAGS += -I$(srctree)/tools/lib/
+TPROGS_CFLAGS += -I$(srctree)/tools/include
+TPROGS_CFLAGS += -I$(srctree)/tools/perf
+TPROGS_CFLAGS += -DHAVE_ATTR_TEST=0
+
+ifdef SYSROOT
+TPROGS_CFLAGS += --sysroot=$(SYSROOT)
+TPROGS_LDFLAGS := -L$(SYSROOT)/usr/lib
+endif
+
+TPROGCFLAGS_bpf_load.o += -Wno-unused-variable
+
+TPROGS_LDLIBS			+= $(LIBBPF) -lelf -lz
+TPROGLDLIBS_tracex4		+= -lrt
+TPROGLDLIBS_trace_output	+= -lrt
+TPROGLDLIBS_map_perf_test	+= -lrt
+TPROGLDLIBS_test_overhead	+= -lrt
+TPROGLDLIBS_xdpsock		+= -pthread
+
+# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
+#  make M=samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
+LLC ?= llc
+CLANG ?= clang
+LLVM_OBJCOPY ?= llvm-objcopy
+BTF_PAHOLE ?= pahole
+
+# Detect that we're cross compiling and use the cross compiler
+ifdef CROSS_COMPILE
+CLANG_ARCH_ARGS = --target=$(notdir $(CROSS_COMPILE:%-=%))
+endif
+
+# Don't evaluate probes and warnings if we need to run make recursively
+ifneq ($(src),)
+HDR_PROBE := $(shell printf "\#include <linux/types.h>\n struct list_head { int a; }; int main() { return 0; }" | \
+	$(CC) $(TPROGS_CFLAGS) $(TPROGS_LDFLAGS) -x c - \
+	-o /dev/null 2>/dev/null && echo okay)
+
+ifeq ($(HDR_PROBE),)
+$(warning WARNING: Detected possible issues with include path.)
+$(warning WARNING: Please install kernel headers locally (make headers_install).)
+endif
+
+BTF_LLC_PROBE := $(shell $(LLC) -march=bpf -mattr=help 2>&1 | grep dwarfris)
+BTF_PAHOLE_PROBE := $(shell $(BTF_PAHOLE) --help 2>&1 | grep BTF)
+BTF_OBJCOPY_PROBE := $(shell $(LLVM_OBJCOPY) --help 2>&1 | grep -i 'usage.*llvm')
+BTF_LLVM_PROBE := $(shell echo "int main() { return 0; }" | \
+			  $(CLANG) -target bpf -O2 -g -c -x c - -o ./llvm_btf_verify.o; \
+			  readelf -S ./llvm_btf_verify.o | grep BTF; \
+			  /bin/rm -f ./llvm_btf_verify.o)
+
+BPF_EXTRA_CFLAGS += -fno-stack-protector
+ifneq ($(BTF_LLVM_PROBE),)
+	BPF_EXTRA_CFLAGS += -g
+else
+ifneq ($(and $(BTF_LLC_PROBE),$(BTF_PAHOLE_PROBE),$(BTF_OBJCOPY_PROBE)),)
+	BPF_EXTRA_CFLAGS += -g
+	LLC_FLAGS += -mattr=dwarfris
+	DWARF2BTF = y
+endif
+endif
+endif
+
+# Trick to allow make to be run from this directory
+all:
+	$(MAKE) -C ../../ M=$(CURDIR) BPF_SAMPLES_PATH=$(CURDIR)
+
+clean:
+	$(MAKE) -C ../../ M=$(CURDIR) clean
+	@find $(CURDIR) -type f -name '*~' -delete
+
+$(LIBBPF): FORCE
+# Fix up variables inherited from Kbuild that tools/ build system won't like
+	$(MAKE) -C $(dir $@) RM='rm -rf' EXTRA_CFLAGS="$(TPROGS_CFLAGS)" \
+		LDFLAGS=$(TPROGS_LDFLAGS) srctree=$(BPF_SAMPLES_PATH)/../../ O=
+
+$(obj)/syscall_nrs.h:	$(obj)/syscall_nrs.s FORCE
+	$(call filechk,offsets,__SYSCALL_NRS_H__)
+
+targets += syscall_nrs.s
+clean-files += syscall_nrs.h
+
+FORCE:
+
+
+# Verify LLVM compiler tools are available and bpf target is supported by llc
+.PHONY: verify_cmds verify_target_bpf $(CLANG) $(LLC)
+
+verify_cmds: $(CLANG) $(LLC)
+	@for TOOL in $^ ; do \
+		if ! (which -- "$${TOOL}" > /dev/null 2>&1); then \
+			echo "*** ERROR: Cannot find LLVM tool $${TOOL}" ;\
+			exit 1; \
+		else true; fi; \
+	done
+
+verify_target_bpf: verify_cmds
+	@if ! (${LLC} -march=bpf -mattr=help > /dev/null 2>&1); then \
+		echo "*** ERROR: LLVM (${LLC}) does not support 'bpf' target" ;\
+		echo "   NOTICE: LLVM version >= 3.7.1 required" ;\
+		exit 2; \
+	else true; fi
+
+$(BPF_SAMPLES_PATH)/*.c: verify_target_bpf $(LIBBPF)
+$(src)/*.c: verify_target_bpf $(LIBBPF)
+
+$(obj)/tracex5_kern.o: $(obj)/syscall_nrs.h
+$(obj)/hbm_out_kern.o: $(src)/hbm.h $(src)/hbm_kern.h
+$(obj)/hbm.o: $(src)/hbm.h
+$(obj)/hbm_edt_kern.o: $(src)/hbm.h $(src)/hbm_kern.h
+
+-include $(BPF_SAMPLES_PATH)/Makefile.target
+
+# asm/sysreg.h - inline assembly used by it is incompatible with llvm.
+# But, there is no easy way to fix it, so just exclude it since it is
+# useless for BPF samples.
+$(obj)/%.o: $(src)/%.c
+	@echo "  CLANG-bpf " $@
+	$(Q)$(CLANG) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(BPF_EXTRA_CFLAGS) \
+		-I$(obj) -I$(srctree)/tools/testing/selftests/bpf/ \
+		-I$(srctree)/tools/lib/ \
+		-D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign \
+		-D__TARGET_ARCH_$(SRCARCH) -Wno-compare-distinct-pointer-types \
+		-Wno-gnu-variable-sized-type-not-at-end \
+		-Wno-address-of-packed-member -Wno-tautological-compare \
+		-Wno-unknown-warning-option $(CLANG_ARCH_ARGS) \
+		-I$(srctree)/samples/bpf/ -include asm_goto_workaround.h \
+		-O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf $(LLC_FLAGS) -filetype=obj -o $@
+ifeq ($(DWARF2BTF),y)
+	$(BTF_PAHOLE) -J $@
+endif
--- a/ebpf_prog/README
+++ b/ebpf_prog/README
@ -0,0 +1,19 @@
+opensnitch.c is an eBPF program. Compilation requires getting kernel source.
+
+sudo apt install clang llvm libelf-dev libzip-dev
+cd opensnitch
+wget https://github.com/torvalds/linux/archive/v5.8.tar.gz
+tar -xf v5.8.tar.gz
+patch linux-5.8/tools/lib/bpf/bpf_helpers.h < ebpf_prog/file.patch
+cp ebpf_prog/opensnitch.c ebpf_prog/Makefile linux-5.8/samples/bpf
+cd linux-5.8 && yes "" | make oldconfig && make prepare && make headers_install # (1 min)
+cd samples/bpf && make
+objdump -h opensnitch.o #you should see many section, number 1 should be called kprobe/tcp_v4_connect
+llvm-strip -g opensnitch.o #remove debug info
+sudo cp opensnitch.o /etc/opensnitchd/ 
+cd ../../../daemon
+
+--opensnitchd expects to find opensnitch.o in /etc/opensnitchd/
+--start opensnitchd with:
+
+opensnitchd -rules-path /etc/opensnitchd/rules -process-monitor-method ebpf
--- a/ebpf_prog/file.patch
+++ b/ebpf_prog/file.patch
@ -0,0 +1,11 @@
+--- linux-5.8/tools/lib/bpf/bpf_helpers.h	2020-08-03 00:21:45.000000000 +0300
+++ linux-5.8/tools/lib/bpf/bpf_helpersnew.h	2021-02-23 18:45:21.789624834 +0300
+@@ -54,7 +54,7 @@
+  * Helper structure used by eBPF C program
+  * to describe BPF map attributes to libbpf loader
+  */
+-struct bpf_map_def {
+struct bpf_map_defold {
+ 	unsigned int type;
+ 	unsigned int key_size;
+ 	unsigned int value_size;
--- a/ebpf_prog/opensnitch.c
+++ b/ebpf_prog/opensnitch.c
@ -0,0 +1,446 @@
+#define KBUILD_MODNAME "dummy"
+
+//uncomment if building on x86_32
+//#define OPENSNITCH_x86_32
+
+#include <linux/ptrace.h>
+#include <linux/version.h>
+#include <uapi/linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h> 
+#include <net/sock.h>
+#include <net/inet_sock.h>
+
+#define MAPSIZE 12000
+
+//-------------------------------map definitions 
+// which github.com/iovisor/gobpf/elf expects
+#define BUF_SIZE_MAP_NS 256
+
+typedef struct bpf_map_def {
+	unsigned int type;
+	unsigned int key_size;
+	unsigned int value_size;
+	unsigned int max_entries;
+	unsigned int map_flags;
+	unsigned int pinning;
+	char namespace[BUF_SIZE_MAP_NS];
+} bpf_map_def;
+
+enum bpf_pin_type {
+	PIN_NONE = 0,
+	PIN_OBJECT_NS,
+	PIN_GLOBAL_NS,
+	PIN_CUSTOM_NS,
+};
+//-----------------------------------
+
+// even though we only need 32 bits of pid, on x86_32 ebpf verifier complained when pid type was set to u32
+typedef u64 pid_size_t;
+typedef u64 uid_size_t; 
+
+struct tcp_key_t {
+	u16 sport;
+	u32 daddr;
+	u16 dport;
+	u32 saddr;
+}__attribute__((packed));
+
+struct tcp_value_t{
+	pid_size_t pid;
+	uid_size_t uid;
+	u64 counter;
+}__attribute__((packed));
+
+// not using unsigned __int128 because it is not supported on x86_32
+struct ipV6 {
+	u64 part1;
+	u64 part2;
+}__attribute__((packed));
+
+struct tcpv6_key_t {
+	u16 sport;
+	struct ipV6 daddr;
+	u16 dport;
+	struct ipV6 saddr;
+}__attribute__((packed));
+
+struct tcpv6_value_t{
+	pid_size_t pid;
+	uid_size_t uid;
+	u64 counter; 
+}__attribute__((packed));;
+
+struct udp_key_t {
+	u16 sport;
+	u32 daddr;
+	u16 dport;
+	u32 saddr; 
+} __attribute__((packed));
+
+struct udp_value_t{
+	pid_size_t pid;
+	uid_size_t uid;
+	u64 counter; 
+}__attribute__((packed));
+
+struct udpv6_key_t {
+	u16 sport;
+	struct ipV6 daddr;
+	u16 dport;
+	struct ipV6 saddr; 
+}__attribute__((packed));
+
+struct udpv6_value_t{
+	pid_size_t pid;
+	uid_size_t uid;
+	u64 counter;
+}__attribute__((packed));
+
+// on x86_32 "struct sock" is arranged differently from x86_64 (at least on Debian kernels).
+// We hardcode offsets of IP addresses.
+struct sock_on_x86_32_t {
+	 u8 data_we_dont_care_about[40];
+	 struct ipV6 daddr;
+	 struct ipV6 saddr;
+};
+
+
+// Add +1,+2,+3 etc. to map size helps to easier distinguish maps in bpftool's output
+struct bpf_map_def SEC("maps/tcpMap") tcpMap = {
+	.type = BPF_MAP_TYPE_HASH,
+	.key_size = sizeof(struct tcp_key_t),
+	.value_size = sizeof(struct tcp_value_t),
+	.max_entries = MAPSIZE+1,
+};
+struct bpf_map_def SEC("maps/tcpv6Map") tcpv6Map = {
+	.type = BPF_MAP_TYPE_HASH,
+	.key_size = sizeof(struct tcpv6_key_t),
+	.value_size = sizeof(struct tcpv6_value_t),
+	.max_entries = MAPSIZE+2,
+};
+struct bpf_map_def SEC("maps/udpMap") udpMap = {
+	.type = BPF_MAP_TYPE_HASH,
+	.key_size = sizeof(struct udp_key_t),
+	.value_size = sizeof(struct udp_value_t),
+	.max_entries = MAPSIZE+3,
+};
+struct bpf_map_def SEC("maps/udpv6Map") udpv6Map = {
+	.type = BPF_MAP_TYPE_HASH,
+	.key_size = sizeof(struct udpv6_key_t),
+	.value_size = sizeof(struct udpv6_value_t),
+	.max_entries = MAPSIZE+4,
+};
+
+// for TCP the IP-tuple can be copied from "struct sock" only upon return from tcp_connect().
+// We stash the socket here to look it up upon return.
+struct bpf_map_def SEC("maps/tcpsock") tcpsock = {
+	.type = BPF_MAP_TYPE_HASH,
+	.key_size = sizeof(u64),
+	.value_size = sizeof(u64),// using u64 instead of sizeof(struct sock *) 
+							  // to avoid pointer size related quirks on x86_32
+	.max_entries = 100,
+};
+struct bpf_map_def SEC("maps/tcpv6sock") tcpv6sock = {
+	.type = BPF_MAP_TYPE_HASH,
+	.key_size = sizeof(u64),
+	.value_size = sizeof(u64),
+	.max_entries = 100,
+};
+
+// //counts how many connections we've processed. Starts at 0.
+struct bpf_map_def SEC("maps/tcpcounter") tcpcounter = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(u32),
+	.value_size = sizeof(u64),
+	.max_entries = 1,
+};
+struct bpf_map_def SEC("maps/tcpv6counter") tcpv6counter = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(u32),
+	.value_size = sizeof(u64),
+	.max_entries = 1,
+};
+struct bpf_map_def SEC("maps/udpcounter") udpcounter = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(u32),
+	.value_size = sizeof(u64),
+	.max_entries = 1,
+};
+struct bpf_map_def SEC("maps/udpv6counter") udpv6counter = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(u32),
+	.value_size = sizeof(u64),
+	.max_entries = 1,
+};
+struct bpf_map_def SEC("maps/debugcounter") debugcounter = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(u32),
+	.value_size = sizeof(u64),
+	.max_entries = 1,
+};
+
+// size 150 gave ebpf verifier errors for kernel 4.14, 100 is ok
+// we can cast any struct into rawBytes_t to be able to access arbitrary bytes of the struct 
+struct rawBytes_t {
+    u8 bytes[100];
+};
+
+
+//used for debug purposes only
+struct bpf_map_def SEC("maps/bytes") bytes = {
+	.type = BPF_MAP_TYPE_HASH,
+	.key_size = sizeof(u32),
+	.value_size = sizeof(u32),
+	.max_entries = 222,
+};
+
+//used for debug purposes only
+struct bpf_map_def SEC("maps/debug") debug = {
+	.type = BPF_MAP_TYPE_HASH,
+	.key_size = sizeof(struct tcpv6_key_t),
+	.value_size = sizeof(struct rawBytes_t),
+	.max_entries = 555,
+};
+
+
+// initializing variables with __builtin_memset() is required
+// for compatibility with bpf on kernel 4.4
+
+SEC("kprobe/tcp_v4_connect")
+int kprobe__tcp_v4_connect(struct pt_regs *ctx)
+{
+	#ifdef OPENSNITCH_x86_32
+	// On x86_32 platforms I couldn't get function arguments using PT_REGS_PARM1
+	// that's why we are accessing registers directly
+		struct sock *sk = (struct sock *)((ctx)->ax);
+	#else 
+		struct sock *sk = (struct sock *)PT_REGS_PARM1(ctx);
+	#endif
+
+	u64 skp = (u64)sk;
+	u64 pid_tgid = bpf_get_current_pid_tgid();
+    bpf_map_update_elem(&tcpsock, &pid_tgid, &skp, BPF_ANY);
+	return 0;
+};
+
+
+SEC("kretprobe/tcp_v4_connect")
+int kretprobe__tcp_v4_connect(struct pt_regs *ctx)
+{
+	u64 pid_tgid = bpf_get_current_pid_tgid();
+	u64 *skp = bpf_map_lookup_elem(&tcpsock, &pid_tgid);
+	if (skp == NULL) {return 0;}
+
+	struct sock *sk;
+	__builtin_memset(&sk, 0, sizeof(sk));
+	sk = (struct sock *)*skp;
+
+	struct tcp_key_t tcp_key;
+    __builtin_memset(&tcp_key, 0, sizeof(tcp_key));
+	bpf_probe_read(&tcp_key.dport, sizeof(tcp_key.dport), &sk->__sk_common.skc_dport);
+	bpf_probe_read(&tcp_key.sport, sizeof(tcp_key.sport), &sk->__sk_common.skc_num);
+	bpf_probe_read(&tcp_key.daddr, sizeof(tcp_key.daddr), &sk->__sk_common.skc_daddr);
+	bpf_probe_read(&tcp_key.saddr, sizeof(tcp_key.saddr), &sk->__sk_common.skc_rcv_saddr);
+	
+	u32 zero_key = 0;
+	u64 *val = bpf_map_lookup_elem(&tcpcounter, &zero_key);
+	if (val == NULL){return 0;}
+
+	struct tcp_value_t tcp_value;
+	__builtin_memset(&tcp_value, 0, sizeof(tcp_value));
+	tcp_value.pid = pid_tgid >> 32;
+	tcp_value.uid = bpf_get_current_uid_gid() & 0xffffffff;
+	tcp_value.counter = *val;
+	bpf_map_update_elem(&tcpMap, &tcp_key, &tcp_value, BPF_ANY);
+	u64 newval = *val + 1;
+	bpf_map_update_elem(&tcpcounter, &zero_key, &newval, BPF_ANY);
+	bpf_map_delete_elem(&tcpsock, &pid_tgid);
+	return 0;
+};
+
+
+SEC("kprobe/tcp_v6_connect")
+int kprobe__tcp_v6_connect(struct pt_regs *ctx)
+{
+	#ifdef OPENSNITCH_x86_32
+		struct sock *sk = (struct sock *)((ctx)->ax);
+	#else
+		struct sock *sk = (struct sock *)PT_REGS_PARM1(ctx);
+	#endif
+
+	u64 skp = (u64)sk;
+	u64 pid_tgid = bpf_get_current_pid_tgid();
+	bpf_map_update_elem(&tcpv6sock, &pid_tgid, &skp, BPF_ANY);
+	return 0;
+};
+SEC("kretprobe/tcp_v6_connect")
+int kretprobe__tcp_v6_connect(struct pt_regs *ctx)
+{
+	u64 pid_tgid = bpf_get_current_pid_tgid();
+	u64 *skp = bpf_map_lookup_elem(&tcpv6sock, &pid_tgid);
+	if (skp == NULL) {return 0;}
+	struct sock *sk;
+	__builtin_memset(&sk, 0, sizeof(sk));
+	sk = (struct sock *)*skp;
+	
+	struct tcpv6_key_t tcpv6_key;
+    __builtin_memset(&tcpv6_key, 0, sizeof(tcpv6_key));
+	bpf_probe_read(&tcpv6_key.dport, sizeof(tcpv6_key.dport), &sk->__sk_common.skc_dport);
+	bpf_probe_read(&tcpv6_key.sport, sizeof(tcpv6_key.sport), &sk->__sk_common.skc_num);
+	#ifdef OPENSNITCH_x86_32
+		struct sock_on_x86_32_t sock;
+    	__builtin_memset(&sock, 0, sizeof(sock));
+    	bpf_probe_read(&sock, sizeof(sock), *(&sk));
+		tcpv6_key.daddr = sock.daddr;
+		tcpv6_key.saddr = sock.saddr;
+	#else
+		bpf_probe_read(&tcpv6_key.daddr, sizeof(tcpv6_key.daddr), &sk->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
+		bpf_probe_read(&tcpv6_key.saddr, sizeof(tcpv6_key.saddr), &sk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
+	#endif
+
+	u32 zero_key = 0;
+	u64 *val = bpf_map_lookup_elem(&tcpv6counter, &zero_key);
+	if (val == NULL){return 0;}
+
+	struct tcpv6_value_t tcpv6_value;
+    __builtin_memset(&tcpv6_value, 0, sizeof(tcpv6_value));
+	tcpv6_value.pid = pid_tgid >> 32;
+	tcpv6_value.uid = bpf_get_current_uid_gid() & 0xffffffff;
+	tcpv6_value.counter = *val;
+	bpf_map_update_elem(&tcpv6Map, &tcpv6_key, &tcpv6_value, BPF_ANY);
+	u64 newval = *val + 1;
+	bpf_map_update_elem(&tcpv6counter, &zero_key, &newval, BPF_ANY);
+	bpf_map_delete_elem(&tcpv6sock, &pid_tgid);
+	return 0;
+};
+
+
+SEC("kprobe/udp_sendmsg")
+int kprobe__udp_sendmsg(struct pt_regs *ctx)
+{
+	#ifdef OPENSNITCH_x86_32
+		struct sock *sk = (struct sock *)((ctx)->ax);
+		struct msghdr *msg = (struct msghdr *)((ctx)->dx);
+	#else
+		struct sock *sk = (struct sock *)PT_REGS_PARM1(ctx);
+		struct msghdr *msg = (struct msghdr *)PT_REGS_PARM2(ctx);
+	#endif
+
+	u64 msg_name; //pointer
+    __builtin_memset(&msg_name, 0, sizeof(msg_name));
+	bpf_probe_read(&msg_name, sizeof(msg_name), &msg->msg_name);
+	struct sockaddr_in * usin = (struct sockaddr_in *)msg_name;
+
+	struct udp_key_t udp_key;
+    __builtin_memset(&udp_key, 0, sizeof(udp_key));
+	bpf_probe_read(&udp_key.dport, sizeof(udp_key.dport), &usin->sin_port);
+	if (udp_key.dport != 0){ //likely
+		bpf_probe_read(&udp_key.daddr, sizeof(udp_key.daddr), &usin->sin_addr.s_addr);
+	}
+	else {
+		//very rarely dport can be found in skc_dport 
+		bpf_probe_read(&udp_key.dport, sizeof(udp_key.dport), &sk->__sk_common.skc_dport);
+		bpf_probe_read(&udp_key.daddr, sizeof(udp_key.daddr), &sk->__sk_common.skc_daddr);
+	}
+	bpf_probe_read(&udp_key.sport, sizeof(udp_key.sport), &sk->__sk_common.skc_num);
+	bpf_probe_read(&udp_key.saddr, sizeof(udp_key.saddr), &sk->__sk_common.skc_rcv_saddr);
+	
+	u32 zero_key = 0;
+    __builtin_memset(&zero_key, 0, sizeof(zero_key));
+	u64 *counterVal = bpf_map_lookup_elem(&udpcounter, &zero_key);
+	if (counterVal == NULL){return 0;}
+	struct udp_value_t *lookedupValue = bpf_map_lookup_elem(&udpMap, &udp_key);
+	u64 pid = bpf_get_current_pid_tgid() >> 32;
+	if ( lookedupValue == NULL || lookedupValue->pid != pid) {
+		struct udp_value_t udp_value;
+        __builtin_memset(&udp_value, 0, sizeof(udp_value));
+		udp_value.pid = pid;
+		udp_value.uid = bpf_get_current_uid_gid() & 0xffffffff;
+		udp_value.counter = *counterVal;
+		bpf_map_update_elem(&udpMap, &udp_key, &udp_value, BPF_ANY);
+		u64 newval = *counterVal + 1;
+		bpf_map_update_elem(&udpcounter, &zero_key, &newval, BPF_ANY);
+	}
+	//else nothing to do
+	return 0;
+
+};
+
+
+SEC("kprobe/udpv6_sendmsg")
+int kprobe__udpv6_sendmsg(struct pt_regs *ctx)
+{	
+	#ifdef OPENSNITCH_x86_32
+		struct sock *sk = (struct sock *)((ctx)->ax);
+		struct msghdr *msg = (struct msghdr *)((ctx)->dx);
+	#else
+		struct sock *sk = (struct sock *)PT_REGS_PARM1(ctx);
+		struct msghdr *msg = (struct msghdr *)PT_REGS_PARM2(ctx);
+	#endif
+
+	u64 msg_name; //a pointer
+    __builtin_memset(&msg_name, 0, sizeof(msg_name));
+	bpf_probe_read(&msg_name, sizeof(msg_name), &msg->msg_name);
+
+	struct udpv6_key_t udpv6_key;
+    __builtin_memset(&udpv6_key, 0, sizeof(udpv6_key));
+	bpf_probe_read(&udpv6_key.dport, sizeof(udpv6_key.dport), &sk->__sk_common.skc_dport);
+	if (udpv6_key.dport != 0){ //likely
+		bpf_probe_read(&udpv6_key.daddr, sizeof(udpv6_key.daddr), &sk->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
+	}
+	else {
+		struct sockaddr_in6 * sin6 = (struct sockaddr_in6 *)msg_name;
+		bpf_probe_read(&udpv6_key.dport, sizeof(udpv6_key.dport), &sin6->sin6_port);
+		bpf_probe_read(&udpv6_key.daddr, sizeof(udpv6_key.daddr), &sin6->sin6_addr.in6_u.u6_addr32);
+	}
+
+	bpf_probe_read(&udpv6_key.sport, sizeof(udpv6_key.sport), &sk->__sk_common.skc_num);
+	bpf_probe_read(&udpv6_key.saddr, sizeof(udpv6_key.saddr), &sk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
+
+
+	#ifdef OPENSNITCH_x86_32
+		struct sock_on_x86_32_t sock;
+    	__builtin_memset(&sock, 0, sizeof(sock));
+    	bpf_probe_read(&sock, sizeof(sock), *(&sk));
+		udpv6_key.daddr = sock.daddr;
+		udpv6_key.saddr = sock.saddr;
+	#endif
+
+	u32 zero_key = 0;
+	u64 *counterVal = bpf_map_lookup_elem(&udpv6counter, &zero_key);
+	if (counterVal == NULL){return 0;}
+	struct udpv6_value_t *lookedupValue = bpf_map_lookup_elem(&udpv6Map, &udpv6_key);
+	u64 pid = bpf_get_current_pid_tgid() >> 32;
+	if ( lookedupValue == NULL || lookedupValue->pid != pid) {
+		struct udpv6_value_t udpv6_value;
+        __builtin_memset(&udpv6_value, 0, sizeof(udpv6_value));
+		udpv6_value.pid = pid;
+		udpv6_value.uid = bpf_get_current_uid_gid() & 0xffffffff;
+		udpv6_value.counter = *counterVal;
+		bpf_map_update_elem(&udpv6Map, &udpv6_key, &udpv6_value, BPF_ANY);
+		u64 newval = *counterVal + 1;
+		bpf_map_update_elem(&udpv6counter, &zero_key, &newval, BPF_ANY);	
+	}
+	//else nothing to do
+	return 0;
+	
+};
+
+// debug only: increment key's value by 1 in map "bytes"
+void increment(u32 key){
+	u32 *lookedupValue = bpf_map_lookup_elem(&bytes, &key);
+	if (lookedupValue == NULL){
+		u32 zero = 0;
+		bpf_map_update_elem(&bytes, &key, &zero, BPF_ANY);
+	}
+	else {
+		u32 newval = *lookedupValue + 1;
+		bpf_map_update_elem(&bytes, &key, &newval, BPF_ANY);
+	}
+}
+
+char _license[] SEC("license") = "GPL";
+// this number will be interpreted by the elf loader
+// to set the current running kernel version
+u32 _version SEC("version") = 0xFFFFFFFE;