pyPLC/pyPlcHomeplug.py

# Preconditions:
# Library pcap-ct (not libpcap, not pylibpcap, not pypcap)
#
# Version 2022-08-14:
#  - Selection of interfaces ok
#  - Sniffing of the SLAC-request ok
#  - Transmission of a demo message ok
#
# Test results 2022-10-15
# 1. GET_SW.REQ broadcast is answered by both TPlinks, while the first is connected to eth, the other via PLC at the first.
# 2. Step 1 works also, if we use a different MAC address than the original laptop ethernet MAC.
# 3. CM_SET_KEY addressed to the correct destination works, with the following results:
#     - there were cases, when the TPlink responded "negative", but with a "valid" none (each time it used a new mynonce, and correctly
#       reflected our mynonce.
#     - but also there is "positive" response, also with correct nonces.
#     - also the Devolo reponds positive and with correct nonces.
#     - not yet checked, whether the NMK is really set
# 4. CM_GET_KEY with wrong NID is refused by the devolo. But at least it delivers the NID (e.g. d57c1fe9544e01), and if we use this NID in the next
#     request, it responds with KEY_GRANTED, Keytype=NMK, and a key 7f19ba0261892d59b7ea42aed875d2320000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
#     This key delivers exactly the NMK, which we have set in the CM_SET_KEY.
#     But: There are some pitfalls:
#       The CM_SET_KEY responds in some cases (wrong request) positive, but does not apply the NMK.
#       If the CM_SET_KEY is well-formatted, including the correct NID, we get a false-negative response, and
#       we see the LEDs on the adaptor shortly going completely off, completely on, and back to normal state. This
#       is the sign, that the new key was accepted. It means, the
#       adaptor is making a reset, to apply the new key.
# 5. CM_SET_KEY and CM_GET_KEY works also when sent to broadcast address.

import pcap

def twoCharHex(b):
    strHex = "%0.2X" % b
    return strHex

def showAsHex(mybytearray):
    packetlength = len(mybytearray)
    strHex = ""
    for i in range(0, packetlength):
        strHex = strHex + twoCharHex(mybytearray[i]) + " "
    print("len " + str(packetlength) + " data " + strHex)

MAC_BROADCAST = [0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ]
MAC_LAPTOP    = [0xdc, 0x0e, 0xa1, 0x11, 0x67, 0x08 ]
MAC_RANDOM    = [0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff ]
MAC_IONIQ     = [0x04, 0x65, 0x65, 0x00, 0x64, 0xC3 ]
MAC_ALPI      = [0x0A, 0x19, 0x4A, 0x39, 0xD6, 0x98 ] # alpitronics
MAC_TPLINK_E4 = [0x98, 0x48, 0x27, 0x5A, 0x3C, 0xE4 ] # TPlink PLC adaptor
MAC_TPLINK_E6 = [0x98, 0x48, 0x27, 0x5A, 0x3C, 0xE6 ] # TPlink PLC adaptor
MAC_DEVOLO_26 = [0xBC, 0xF2, 0xAF, 0x0B, 0x8E, 0x26 ] # Devolo PLC adaptor


CM_SET_KEY = 0x6008
CM_GET_KEY = 0x600C
CM_SC_JOIN = 0x6010
CM_CHAN_EST = 0x6014
CM_TM_UPDATE = 0x6018
CM_AMP_MAP = 0x601C
CM_BRG_INFO = 0x6020
CM_CONN_NEW = 0x6024
CM_CONN_REL = 0x6028
CM_CONN_MOD = 0x602C
CM_CONN_INFO = 0x6030
CM_STA_CAP = 0x6034
CM_NW_INFO = 0x6038
CM_GET_BEACON = 0x603C
CM_HFID = 0x6040
CM_MME_ERROR = 0x6044
CM_NW_STATS = 0x6048
CM_SLAC_PARAM = 0x6064
CM_START_ATTEN_CHAR = 0x6068
CM_ATTEN_CHAR = 0x606C
CM_PKCS_CERT = 0x6070
CM_MNBC_SOUND = 0x6074
CM_VALIDATE = 0x6078
CM_SLAC_MATCH = 0x607C
CM_SLAC_USER_DATA = 0x6080
CM_ATTEN_PROFILE = 0x6084

MMTYPE_REQ = 0x0000
MMTYPE_CNF = 0x0001
MMTYPE_IND = 0x0002
MMTYPE_RSP = 0x0003

 
class pyPlcHomeplug():    
    def showIpAddresses(self, mybytearray):
        addr = lambda pkt, offset: '.'.join(str(pkt[i]) for i in range(offset, offset + 4))
        print('SRC %-16s\tDST %-16s' % (addr(mybytearray, self.sniffer.dloff + 12), addr(mybytearray, self.sniffer.dloff + 16)))

    def showMacAddresses(self, mybytearray):
        strDestMac = ""
        for i in range(0, 6):
            strDestMac = strDestMac + twoCharHex(mybytearray[i]) + ":"
        strSourceMac = ""
        for i in range(5, 12):
            strSourceMac = strSourceMac + twoCharHex(mybytearray[i]) + ":"
        lastThreeOfSource = mybytearray[6]*256*256 + mybytearray[7]*256 + mybytearray[8]
        strSourceFriendlyName = ""
        if (lastThreeOfSource == 0x0a663a):
            strSourceFriendlyName="Fritzbox"
        if (lastThreeOfSource == 0x0064c3):
            strSourceFriendlyName="Ioniq"
            
        print("From " + strSourceMac + strSourceFriendlyName + " to " + strDestMac)

    def isHomeplug(self, mybytearray):
        blIsHomePlug=False
        if len(mybytearray)>(6+6+2):
            protocol=mybytearray[12]*256 + mybytearray[13]
            if (protocol == 0x88E1):
                blIsHomePlug=True
                print("HomePlug protocol")
        return blIsHomePlug
        
    def fillSourceMac(self, mac):
        self.mytransmitbuffer[6]=mac[0]
        self.mytransmitbuffer[7]=mac[1]
        self.mytransmitbuffer[8]=mac[2]
        self.mytransmitbuffer[9]=mac[3]
        self.mytransmitbuffer[10]=mac[4]
        self.mytransmitbuffer[11]=mac[5]
        
    def fillDestinationMac(self, mac):
        self.mytransmitbuffer[0]=mac[0]
        self.mytransmitbuffer[1]=mac[1]
        self.mytransmitbuffer[2]=mac[2]
        self.mytransmitbuffer[3]=mac[3]
        self.mytransmitbuffer[4]=mac[4]
        self.mytransmitbuffer[5]=mac[5]
        
    def cleanTransmitBuffer(self):
        for i in range(0, len(self.mytransmitbuffer)):
            self.mytransmitbuffer[i]=0

    def setNwkAt(self, index):
        # sets the Network Key (NMK) at a certain position in the transmit buffer
        for i in range(0, 16):
            self.mytransmitbuffer[index+i]=self.NWK[i] # NWK 

    def setNidAt(self, index):
        # (b0f2e695666b03 was NID of TPlink)
        # copies the network ID (NID) into the wished position in the transmit buffer
        for i in range(0, 7):
            self.mytransmitbuffer[index+i]=self.NID[i]
        
    def getManagementMessageType(self):
        # calculates the MMTYPE (base value + lower two bits), see Table 11-2 of homeplug spec
        return (self.myreceivebuffer[16]<<8) + self.myreceivebuffer[15]

    def composeTestFrameGetSwReq(self):
		# GET_SW.REQ request, as used by the win10 laptop
        self.mytransmitbuffer = bytearray(60)
        self.cleanTransmitBuffer()
        # Destination MAC
        self.fillDestinationMac(MAC_BROADCAST)
        # Source MAC
        self.fillSourceMac(MAC_RANDOM)
        # Protocol
        self.mytransmitbuffer[12]=0x88 # Protocol HomeplugAV
        self.mytransmitbuffer[13]=0xE1
        self.mytransmitbuffer[14]=0x00 # version
        self.mytransmitbuffer[15]=0x00 # GET_SW.REQ
        self.mytransmitbuffer[16]=0xA0 # 
        self.mytransmitbuffer[17]=0x00 # Vendor OUI
        self.mytransmitbuffer[18]=0xB0 # 
        self.mytransmitbuffer[19]=0x52 # 

    def composeTestFrameSetKey(self, variation=0):
		# CM_SET_KEY.REQ request
        # From example trace from catphish https://openinverter.org/forum/viewtopic.php?p=40558&sid=9c23d8c3842e95c4cf42173996803241#p40558
        # Table 11-88 in the homeplug_av21_specification_final_public.pdf
        self.mytransmitbuffer = bytearray(60)
        self.cleanTransmitBuffer()
        # Destination MAC
        #self.fillDestinationMac(MAC_DEVOLO_26)
        #self.fillDestinationMac(MAC_TPLINK_E4)
        self.fillDestinationMac(MAC_BROADCAST)
        # Source MAC
        #self.fillSourceMac(MAC_LAPTOP)
        self.fillSourceMac(MAC_RANDOM)
        # Protocol
        self.mytransmitbuffer[12]=0x88 # Protocol HomeplugAV
        self.mytransmitbuffer[13]=0xE1
        self.mytransmitbuffer[14]=0x01 # version
        self.mytransmitbuffer[15]=0x08 # CM_SET_KEY.REQ
        self.mytransmitbuffer[16]=0x60 # 
        self.mytransmitbuffer[17]=0x00 # frag_index
        self.mytransmitbuffer[18]=0x00 # frag_seqnum
        self.mytransmitbuffer[19]=0x01 # 0 key info type

        self.mytransmitbuffer[20]=0xaa # 1 my nonce
        self.mytransmitbuffer[21]=0xaa # 2
        self.mytransmitbuffer[22]=0xaa # 3
        self.mytransmitbuffer[23]=0xaa # 4

        self.mytransmitbuffer[24]=0x00 # 5 your nonce
        self.mytransmitbuffer[25]=0x00 # 6
        self.mytransmitbuffer[26]=0x00 # 7
        self.mytransmitbuffer[27]=0x00 # 8
        
        self.mytransmitbuffer[28]=0x04 # 9 nw info pid
        
        self.mytransmitbuffer[29]=0x00 # 10 info prn
        self.mytransmitbuffer[30]=0x00 # 11
        self.mytransmitbuffer[31]=0x00 # 12 pmn
        self.mytransmitbuffer[32]=0x00 # 13 cco cap
        #self.setNidAt(33) # 14-20 nid  7 bytes from 33 to 39
        self.mytransmitbuffer[40]=0x01 # 21 peks (payload encryption key select) Table 11-83. 01 is NMK. We had 02 here, why???
                                       # with 0x0F we could choose "no key, payload is sent in the clear"
        self.setNwkAt(41)
        self.mytransmitbuffer[41]+=variation # to try different NMKs
        # and three remaining zeros

    def composeTestFrameGetKey(self):
		# CM_GET_KEY.REQ request
        # from https://github.com/uhi22/plctool2/blob/master/listen_to_eth.c
        # and homeplug_av21_specification_final_public.pdf
        self.mytransmitbuffer = bytearray(60)
        self.cleanTransmitBuffer()
        # Destination MAC
        #self.fillDestinationMac(MAC_DEVOLO_26)
        #self.fillDestinationMac(MAC_TPLINK_E4)
        self.fillDestinationMac(MAC_BROADCAST)
        # Source MAC
        #self.fillSourceMac(MAC_LAPTOP)
        self.fillSourceMac(MAC_RANDOM)
        # Protocol
        self.mytransmitbuffer[12]=0x88 # Protocol HomeplugAV
        self.mytransmitbuffer[13]=0xE1
        self.mytransmitbuffer[14]=0x01 # version
        self.mytransmitbuffer[15]=0x0C # CM_GET_KEY.REQ https://github.com/uhi22/plctool2/blob/master/plc_homeplug.h
        self.mytransmitbuffer[16]=0x60 #
        self.mytransmitbuffer[17]=0x00 # 2 bytes fragmentation information. 0000 means: unfragmented.
        self.mytransmitbuffer[18]=0x00 #
        
        self.mytransmitbuffer[19]=0x00 # 0 Request Type 0=direct
        self.mytransmitbuffer[20]=0x01 # 1 RequestedKeyType only "NMK" is permitted over the H1 interface.
                                       #    value see HomeplugAV2.1 spec table 11-89. 1 means AES-128.
                                       
        self.setNidAt(21)# NID starts here (table 11-91 Homeplug spec is wrong. Verified by accepted command.)
        self.mytransmitbuffer[28]=0xaa # 10-13 mynonce. The position at 28 is verified by the response of the devolo.
        self.mytransmitbuffer[29]=0xaa # 
        self.mytransmitbuffer[30]=0xaa # 
        self.mytransmitbuffer[31]=0xaa # 
        self.mytransmitbuffer[32]=0x04 # 14 PID. According to  ISO15118-3 fix value 4, "HLE protocol"
        self.mytransmitbuffer[33]=0x00 # 15-16 PRN Protocol run number
        self.mytransmitbuffer[34]=0x00 # 
        self.mytransmitbuffer[35]=0x00 # 17 PMN Protocol message number

    def composeTestFrameSlacReq(self):
		# SLAC request, as it was recorded 2021-12-17 WP charger 2
        self.mytransmitbuffer = bytearray(60)
        self.cleanTransmitBuffer()
        # Destination MAC
        self.fillDestinationMac(MAC_BROADCAST)

        # Source MAC
        self.fillSourceMac(MAC_IONIQ)

        # Protocol
        self.mytransmitbuffer[12]=0x88 # Protocol HomeplugAV
        self.mytransmitbuffer[13]=0xE1

        self.mytransmitbuffer[14]=0x01 # version
        self.mytransmitbuffer[15]=0x64 # SLAC_PARAM.REQ

        self.mytransmitbuffer[16]=0x60 # 
        self.mytransmitbuffer[17]=0x00 # 
        self.mytransmitbuffer[18]=0x00 # 
        self.mytransmitbuffer[19]=0x00 # 
        self.mytransmitbuffer[20]=0x00 # 
        self.mytransmitbuffer[21]=0x04 # runid 8 bytes
        self.mytransmitbuffer[22]=0x65 # 
        self.mytransmitbuffer[23]=0x65 # 
        self.mytransmitbuffer[24]=0x00 # 
        self.mytransmitbuffer[25]=0x64 # 
        self.mytransmitbuffer[26]=0xC3 # 
        self.mytransmitbuffer[27]=0x00 # 
        self.mytransmitbuffer[28]=0x00 # 
        
        self.mytransmitbuffer[29]=0x00 # rest is 0
        self.mytransmitbuffer[30]=0x00 # 
        self.mytransmitbuffer[31]=0x00 # 
        self.mytransmitbuffer[32]=0x00 # 
        self.mytransmitbuffer[33]=0x00 # 
        self.mytransmitbuffer[34]=0x00 # 
        self.mytransmitbuffer[35]=0x00 # 
        self.mytransmitbuffer[36]=0x00 # 
        self.mytransmitbuffer[37]=0x00 # 
        self.mytransmitbuffer[38]=0x00 # 
        self.mytransmitbuffer[39]=0x00 # 
        self.mytransmitbuffer[40]=0x00 # 
        self.mytransmitbuffer[41]=0x00 # 
        self.mytransmitbuffer[42]=0x00 # 
        self.mytransmitbuffer[43]=0x00 # 
        self.mytransmitbuffer[44]=0x00 # 
        self.mytransmitbuffer[45]=0x00 # 
        self.mytransmitbuffer[46]=0x00 # 
        self.mytransmitbuffer[47]=0x00 #
        self.mytransmitbuffer[48]=0x00 # 
        self.mytransmitbuffer[49]=0x00 # 
        self.mytransmitbuffer[50]=0x00 # 
        self.mytransmitbuffer[51]=0x00 # 
        self.mytransmitbuffer[52]=0x00 # 
        self.mytransmitbuffer[53]=0x00 # 
        self.mytransmitbuffer[54]=0x00 # 
        self.mytransmitbuffer[55]=0x00 # 
        self.mytransmitbuffer[56]=0x00 # 
        self.mytransmitbuffer[57]=0x00 # 
        self.mytransmitbuffer[58]=0x00 # 
        self.mytransmitbuffer[59]=0x00 # 
        
    def composeTestFrameSlacResp(self):
        self.mytransmitbuffer = bytearray(60)
        self.cleanTransmitBuffer()
        # Destination MAC
        self.fillDestinationMac(MAC_IONIQ)

        # Source MAC
        self.fillSourceMac(MAC_ALPI)

        # Protocol
        self.mytransmitbuffer[12]=0x88 # Protocol HomeplugAV
        self.mytransmitbuffer[13]=0xE1

        self.mytransmitbuffer[14]=0x01 # version
        self.mytransmitbuffer[15]=0x65 # SLAC_PARAM.confirm

        self.mytransmitbuffer[16]=0x60 # 
        self.mytransmitbuffer[17]=0x00 # 
        self.mytransmitbuffer[18]=0x00 # 
        self.mytransmitbuffer[19]=0xff # 
        self.mytransmitbuffer[20]=0xff # 
        self.mytransmitbuffer[21]=0xff # 
        self.mytransmitbuffer[22]=0xff # 
        self.mytransmitbuffer[23]=0xff # 
        self.mytransmitbuffer[24]=0xff # 
        self.mytransmitbuffer[25]=0x0A # 
        self.mytransmitbuffer[26]=0x06 # 
        self.mytransmitbuffer[27]=0x01 # 
        self.mytransmitbuffer[28]=0x04 # 
        self.mytransmitbuffer[29]=0x65 # 
        self.mytransmitbuffer[30]=0x65 # 
        self.mytransmitbuffer[31]=0x00 # 

        self.mytransmitbuffer[32]=0x64 # 
        self.mytransmitbuffer[33]=0xC3 # 
        self.mytransmitbuffer[34]=0x00 # 
        self.mytransmitbuffer[35]=0x00 # 
        self.mytransmitbuffer[36]=0x04 # 
        self.mytransmitbuffer[37]=0x65 # 
        self.mytransmitbuffer[38]=0x65 # 
        self.mytransmitbuffer[39]=0x00 # 
        self.mytransmitbuffer[40]=0x64 # 
        self.mytransmitbuffer[41]=0xC3 # 
        self.mytransmitbuffer[42]=0x0 # 
        self.mytransmitbuffer[43]=0x0 # 
        self.mytransmitbuffer[44]=0x0 # 
        self.mytransmitbuffer[45]=0x0 # 
        self.mytransmitbuffer[46]=0x0 # 
        self.mytransmitbuffer[47]=0x0 #
 
        self.mytransmitbuffer[48]=0x0 # 
        self.mytransmitbuffer[49]=0x0 # 
        self.mytransmitbuffer[50]=0x0 # 
        self.mytransmitbuffer[51]=0x0 # 
        self.mytransmitbuffer[52]=0x0 # 
        self.mytransmitbuffer[53]=0x0 # 
        self.mytransmitbuffer[54]=0x0 # 
        self.mytransmitbuffer[55]=0x0 # 
        self.mytransmitbuffer[56]=0x0 # 
        self.mytransmitbuffer[57]=0x0 # 
        self.mytransmitbuffer[58]=0x0 # 
        self.mytransmitbuffer[59]=0x0 # 

    def composeTestFrameDHCP(self):
		# DHCP discover, to check whether this "normal" package arrives on the other side
        self.mytransmitbuffer = bytearray(379)
        self.cleanTransmitBuffer()
        # Destination MAC
        self.fillDestinationMac(MAC_BROADCAST)
        # Source MAC
        self.fillSourceMac(MAC_LAPTOP)
        self.mytransmitbuffer[12]=0x08 # Protocol IPv4
        self.mytransmitbuffer[13]=0x00
        self.mytransmitbuffer[14]=0x45 # header len
        self.mytransmitbuffer[15]=0x00 # 
        self.mytransmitbuffer[16]=0x01 # 
        self.mytransmitbuffer[17]=0x6D # 
        self.mytransmitbuffer[18]=0x9B # 
        self.mytransmitbuffer[19]=0x30 # 
        self.mytransmitbuffer[20]=0x00 # 
        self.mytransmitbuffer[21]=0x00 # 
        self.mytransmitbuffer[22]=0x40 # 
        self.mytransmitbuffer[23]=0x11 # 
        self.mytransmitbuffer[24]=0xde # 
        self.mytransmitbuffer[25]=0x50 # 
        self.mytransmitbuffer[26]=0x00 # 
        self.mytransmitbuffer[27]=0x00 # 
        self.mytransmitbuffer[28]=0x00 # 
        self.mytransmitbuffer[29]=0x00 # 
        
        self.mytransmitbuffer[30]=0xFF # 
        self.mytransmitbuffer[31]=0xFF # 
        self.mytransmitbuffer[32]=0xFF # 
        self.mytransmitbuffer[33]=0xFF # 

        self.mytransmitbuffer[34]=0x00 # 
        self.mytransmitbuffer[35]=0x44 # 

        self.mytransmitbuffer[36]=0x00 # 
        self.mytransmitbuffer[37]=0x43 # 


    def sendTestFrame(self, selection):
        
        if (selection=="1"):
            self.composeTestFrameSlacReq()
            self.addToTrace("transmitting TestFrame SlacReq...")
            self.sniffer.sendpacket(bytes(self.mytransmitbuffer))
        if (selection=="2"):
            self.composeTestFrameSlacResp()
            self.addToTrace("transmitting TestFrame SlacResp...")            
            self.sniffer.sendpacket(bytes(self.mytransmitbuffer))
        if (selection=="S"):
            self.composeTestFrameGetSwReq()
            self.addToTrace("transmitting TestFrame GetSwReq...")
            self.sniffer.sendpacket(bytes(self.mytransmitbuffer))
        if (selection=="s"):
            self.composeTestFrameSetKey(1)
            self.addToTrace("transmitting TestFrame SET_KEY.REQ (key 1)")
            self.sniffer.sendpacket(bytes(self.mytransmitbuffer))
        if (selection=="t"):
            self.composeTestFrameSetKey(2)
            self.addToTrace("transmitting TestFrame SET_KEY.REQ (key 2)")
            self.sniffer.sendpacket(bytes(self.mytransmitbuffer))
        if (selection=="D"):
            self.composeTestFrameDHCP()
            self.addToTrace("transmitting TestFrame broken DHCP")           
            self.sniffer.sendpacket(bytes(self.mytransmitbuffer))
        if (selection=="G"):
            self.composeTestFrameGetKey()
            self.addToTrace("transmitting TestFrame GET_KEY")           
            self.sniffer.sendpacket(bytes(self.mytransmitbuffer))
      
    def evaluateGetKeyCnf(self):
        # The getkey response contains the Network ID (NID), even if the request was rejected. We store the NID,
        # to have it available for the next request.
        s = ""
        for i in range(0, 7):
            self.NID[i] = self.myreceivebuffer[29+i]
            s=s+hex(self.NID[i])+ " "
        print("From GetKeyCnf, got network ID (NID) " + s)
        
    
    def evaluateReceivedHomeplugPacket(self):
        mmt = self.getManagementMessageType()
        print(hex(mmt))
        if (mmt == CM_GET_KEY + MMTYPE_CNF):
            self.evaluateGetKeyCnf()

        #if (pkt[15]==0x64): #SLAC_Request
        
    def findEthernetAdaptor(self):
        self.strInterfaceName="eth0" # default, if the real is not found
        print("Interfaces:\n" + '\n'.join(pcap.findalldevs()))
        for i in range(0, 10):
            strInterfaceName = pcap.ex_name("eth"+str(i))
            if (strInterfaceName == '\\Device\\NPF_{E4B8176C-8516-4D48-88BC-85225ABCF259}'):
                print("This is the wanted Ethernet adaptor.")
                self.strInterfaceName="eth"+str(i)
            print("eth"+ str(i) + " is " + strInterfaceName)

    def __init__(self, callbackAddToTrace=None, callbackShowStatus=None):
        self.mytransmitbuffer = bytearray("Hallo das ist ein Test", 'UTF-8')
        self.nPacketsReceived = 0
        self.callbackAddToTrace = callbackAddToTrace
        self.callbackShowStatus = callbackShowStatus
        #self.sniffer = pcap.pcap(name=None, promisc=True, immediate=True, timeout_ms=50)
        # eth3 means: Third entry from back, in the list of interfaces, which is provided by pcap.findalldevs.
        #  Improvement necessary: select the interface based on the name.
        # For debugging of the interface names, we can patch the file
        # C:\Users\uwemi\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\pcap\_pcap_ex.py,
        # in the function
        #    def name(name: bytes) -> bytes:
        # in the place after
        # if i == idx:
        #           print("index match at " + str(i) + " dev name=" + str(dev.name) + " dev.description=" + str(dev.description))
        # This will print the description of the used interface.
        #
        # Patch for non-blocking read-iteration:
        #   in _pcap.py, function def __next__(self), in the case of timeout (if n==0), we need to "raise StopIteration" instead of "continue".
        #
        self.findEthernetAdaptor()
        self.sniffer = pcap.pcap(name=self.strInterfaceName, promisc=True, immediate=True, timeout_ms=50)
        self.sniffer.setnonblock(True)
        self.NWK = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 ] # a default network key
        self.NID = [ 1, 2, 3, 4, 5, 6, 7 ] # a default network ID
        self.runningCounter=0
        print("sniffer created at " + self.strInterfaceName)

    def addToTrace(self, s):
        self.callbackAddToTrace(s)

    def showStatus(self, s):
        self.callbackShowStatus(s) 
        
    def mainfunction(self):  
        # print("will evaluate self.sniffer")
        for ts, pkt in self.sniffer: # attention: for using this in non-blocking manner, we need the patch described above.
            self.nPacketsReceived+=1
            print('%d' % (ts))
            if (self.isHomeplug(pkt)):
                self.myreceivebuffer = pkt
                #    self.showMacAddresses(pkt)
                self.evaluateReceivedHomeplugPacket()
        self.showStatus("nPacketsReceived=" + str(self.nPacketsReceived))
        
    def close(self):
        self.sniffer.close()

#sn = pyPlcHomeplug()
#while (1):
# print("Press control-C to stop")
# sn.mainfunction()