1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
#!/usr/local/bin/python2.7
print "fragments of a large packet that has to be refragmented by reflector"
# |--------|
# |------------------|
# ...
# |------------------|
# |----|
import os
from addr import *
from scapy.all import *
pid=os.getpid()
eid=pid & 0xffff
payload=100 * "ABCDEFGHIJKLMNOP"
packet=IPv6(src=LOCAL_ADDR6, dst=REMOTE_ADDR6)/ \
ICMPv6EchoRequest(id=eid, data=payload)
request_cksum=ICMPv6Unknown(str(packet.payload)).cksum
print "request cksum=%#x" % (request_cksum)
frag=[]
fid=pid & 0xffffffff
frag.append(IPv6ExtHdrFragment(nh=58, id=fid, m=1)/str(packet)[40:56])
offset=2
chunk=4
while 40+8*(offset+chunk) < len(payload):
frag.append(IPv6ExtHdrFragment(nh=58, id=fid, offset=offset, m=1)/
str(packet)[40+(8*offset):40+8*(offset+chunk)])
offset+=chunk
frag.append(IPv6ExtHdrFragment(nh=58, id=fid, offset=offset)/
str(packet)[40+(8*offset):])
eth=[]
for f in frag:
pkt=IPv6(src=LOCAL_ADDR6, dst=REMOTE_ADDR6)/f
eth.append(Ether(src=LOCAL_MAC, dst=REMOTE_MAC)/pkt)
if os.fork() == 0:
time.sleep(1)
sendp(eth, iface=LOCAL_IF)
os._exit(0)
ans=sniff(iface=LOCAL_IF, timeout=3, filter=
"ip6 and src "+REMOTE_ADDR6+" and dst "+LOCAL_ADDR6+" and proto ipv6-frag")
for a in ans:
if a and a.type == ETH_P_IPV6 and \
ipv6nh[a.payload.nh] == 'Fragment Header' and \
a.payload.payload.offset == 0 and \
ipv6nh[a.payload.payload.nh] == 'ICMPv6' and \
icmp6types[a.payload.payload.payload.type] == 'Echo Reply':
id=a.payload.payload.payload.id
print "id=%#x" % (id)
if id != eid:
print "WRONG ECHO REPLY ID"
exit(2)
reply_cksum=a.payload.payload.payload.cksum
print "reply cksum=%#x" % (reply_cksum)
# change request checksum incrementaly and check with reply
diff_cksum=~(~reply_cksum+~(~request_cksum+~0x8000+0x8100))
if diff_cksum != -1:
print "CHECKSUM ERROR diff cksum=%#x" % (diff_cksum)
exit(1)
exit(0)
print "NO ECHO REPLY"
exit(2)
|
