linux - Duplicate packets when crafted from a VM with host OSX -


i'm getting strange results when crafting packets linux vm osx host (using virtualbox 4.3.20).

basically using script below reply icmp packets. when use wireshark both in vm , in osx different amount of packets , i'm interested in reason this. in vm expect, icmp request , associated reply, when capture same 'session' in osx see icmp request , 2 icmp replies...!

i'm filtering legitimate replies vm using following iptable rule:

iptables -a input -p ip -i eth0 -j drop

in terms of vm setup i'm using virtualbox v4.3.20, using host adapter.

sorry code quality i'm been hammering @ while , didn't cleanup!

#!/usr/bin/python  import socket, sys, commands multiprocessing import process, queue scapy.all import sniff, send, ether, ip, conf, raw, icmp   conf.verbose = 0  def start_procs(iface, bpf):      pkt_pipe = queue()      pkt_cap_th = process(target=pkt_cap, args=(iface, bpf, pkt_pipe,))     pkt_cap_th.start()      pkt_play_th = process(target=pkt_play, args=(iface, pkt_pipe,))     pkt_play_th.start()   def pkt_cap(iface, bpf, pkt_pipe):      while true:          try:             sniff(iface=iface, filter=bpf, prn=lambda pkt:pkt_pipe.put(str(pkt[ip])), count=0, store=0, timeout=none)         except exception, error:             print 'error in pkt_cap: ' + str(error.message)   def pkt_play(iface, pkt_pipe):       try:         s = socket.socket(socket.af_inet, socket.sock_raw, socket.ipproto_raw)     except socket.error , msg:         print 'socket not created. error code : ' + str(msg[0]) + ' message ' + msg[1]      count = 1      while true:          pkt = pkt_pipe.get()         pkt = ip(pkt)          pkt = modpkt(pkt)         dest_ip = pkt[ip].dst          print 'pkt_play ****** s: ' + str(count)          print 'pkt_play - ' + pkt.summary()         print pkt.show2()          pkt_hex = str(pkt)          try:             #send(pkt, iface=iface, verbose=0)             s.sendto(pkt_hex, (dest_ip , 0))         except exception, e:             print 'error sending packet: ' + str(e.message)          print 'pkt_play ****** e :' + str(count)          count += 1  def modpkt(pkt):      ipdst = pkt[ip].dst     ipsrc = pkt[ip].src      pkt[ip].src = ipdst     pkt[ip].dst = ipsrc      pkt[icmp].type = 0      del pkt[ip].chksum     del pkt[ip].len     del pkt[icmp].chksum      return pkt   def main():      iface = 'eth0'     srcmac = commands.getoutput('ifconfig ' + iface + ' | grep hwaddr | awk \'{print $5}\'')     bpf = '(ether dst ' + srcmac + ') , ip'      print bpf      start_procs_th = process(target=start_procs, args=(iface, bpf))     start_procs_th.start()  if __name__ == '__main__':     main()

tia!


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