I am trying to add a metadata field to the pkt by Scapy. I use mininet as a platform to launch my network simulation.
from scapy.all import *
from datetime import datetime
class Metadata(Packet):
name = "Metadata"
fields_desc = [ XByteField("metadata", 1) ]
def generatePackets():
if len(sys.argv) != 4:
print "Usage: arping2tex <net>\n eg: arping2text 192.168.1.0/24"
sys.exit(1)
src= sys.argv[1]
dst= sys.argv[2]
x = int(sys.argv[3])
ip=IP(src= src, dst= dst)
metadata = Metadata(metadata = 200)
udp=UDP(sport= 2235, dport=5546)#,
data = datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f')[:-3]
pkt = (ip/udp/metadata/data)
print pkt.show()
send(pkt, count = x)
if __name__ == '__main__':
generatePackets()
when I send the pkt I can see the metadata field on the sender(xterm) Xterm for the sender with new field
But, I do not see the metadata field on the controller, Wireshark or the destination host. Xterm for the receiver without the new field
please, I need an explanation, or what is the mistake I have done.
your metadata is present on the other side. you can see it on the payload of your receiving side
you sent: metadata: c8 / raw: "a date" you received: raw: c8 "a date"
now let's dig on what is going on. your receiver receive a UDP frame with a some data. Since no protocol has been registered, it cannot know that the 1st 2 bytes are metedata, then assumes it is part of the normal payload.
you can confirm that simply by reuning that command before sending: pkt.show2() instead of running pkt.show()
The difference is that show2() rebuild and re-decode the packet before printing, while show() only prints the packet. Then you will see that you sent what the receiver got.