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#!/usr/local/bin/python2.7
# check wether path mtu to dst is 1300
import os
from addr import *
from scapy.all import *
dstaddr=sys.argv[1]
pid=os.getpid()
hdr=IPv6(src=SRC_OUT6, dst=dstaddr)/ICMPv6EchoRequest(id=pid)
payload="a" * (1400 - len(str(hdr)))
ip=hdr/payload
eth=Ether(src=SRC_MAC, dst=PF_MAC)/ip
# work around the broken sniffing of packages with bad checksum
#a=srp1(eth, iface=SRC_IF, timeout=2)
if os.fork() == 0:
time.sleep(1)
sendp(eth, iface=SRC_IF)
os._exit(0)
ans=sniff(iface=SRC_IF, timeout=3, filter=
"ip6 and dst "+SRC_OUT6+" and icmp6")
if len(ans) == 0:
print "no packet sniffed"
exit(2)
a=ans[0]
if a and a.type == ETH_P_IPV6 and \
ipv6nh[a.payload.nh] == 'ICMPv6' and \
icmp6types[a.payload.payload.type] == 'Packet too big':
mtu=a.payload.payload.mtu
print "mtu=%d" % (mtu)
if mtu == 1300:
exit(0)
print "MTU!=1300"
exit(1)
print "MTU=UNKNOWN"
exit(2)
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