commit c4aa242795d8d612bf51cf822b7ef73d8cff17ed Author: Arturo Filastò art@fuffa.org Date: Thu Nov 22 15:19:10 2012 +0100

Implement a quick and dirty parasitic TCP traceroute --- nettests/core/parasitictraceroute.py | 124 ++++++++++++++++++++++++++++++++++ 1 files changed, 124 insertions(+), 0 deletions(-)

diff --git a/nettests/core/parasitictraceroute.py b/nettests/core/parasitictraceroute.py new file mode 100644 index 0000000..9d8de16 --- /dev/null +++ b/nettests/core/parasitictraceroute.py @@ -0,0 +1,124 @@ +# -*- encoding: utf-8 -*- +# +# :authors: Arturo Filastò +# :licence: see LICENSE + +from twisted.python import usage +from twisted.internet import defer + +from ooni.templates import scapyt + +from scapy.all import * + +from ooni.utils import log + +class UsageOptions(usage.Options): + optParameters = [['backend', 'b', '8.8.8.8', 'Test backend to use'], + ['timeout', 't', 5, 'The timeout for the traceroute test'], + ['maxttl', 'm', 30, 'The maximum value of ttl to set on packets'], + ['dstport', 'd', 80, 'Set the destination port of the traceroute test'], + ['srcport', 'p', None, 'Set the source port to a specific value']] + + optFlags = [['randomize','r', 'Randomize the source port']] + +class TracerouteTest(scapyt.BaseScapyTest): + name = "Parasitic TCP Traceroute Test" + author = "Arturo Filastò" + version = "0.1" + + usageOptions = UsageOptions + + def setUp(self): + def get_sport(): + if self.localOptions['srcport']: + return int(self.localOptions['srcport']) + elif self.localOptions['randomize']: + return random.randint(1024, 65535) + else: + return 80 + + self.get_sport = get_sport + self.dport = int(self.localOptions['dstport']) + + def max_ttl_and_timeout(self): + max_ttl = int(self.localOptions['maxttl']) + timeout = int(self.localOptions['timeout']) + self.report['max_ttl'] = max_ttl + self.report['timeout'] = timeout + return max_ttl, timeout + + @defer.inlineCallbacks + def test_parasitic_tcp_traceroute(self): + """ + Establishes a TCP stream and send the packets inside of such stream. + Requires the backend to respond with an ACK to our SYN packet. + """ + max_ttl, timeout = self.max_ttl_and_timeout() + + sport = self.get_sport() + dport = self.dport + ipid = int(RandShort()) + + packet = IP(dst=self.localOptions['backend'], ttl=max_ttl, + id=ipid)/TCP(sport=sport, dport=dport, + flags="S", seq=0) + + log.msg("Sending SYN towards %s" % dport) + + try: + answered, unanswered = yield self.sr(packet, timeout=timeout) + except Exception, e: + log.exception(e) + except: + log.exception() + + try: + snd, rcv = answered[0] + synack = rcv[0] + + except IndexError: + print answered, unanswered + log.err("Got no response. Try increasing max_ttl") + return + + except Exception, e: + log.exception(e) + + if synack[TCP].flags == 11: + log.msg("Got back a FIN ACK. The destination port is closed") + return + + elif synack[TCP].flags == 18: + log.msg("Got a SYN ACK. All is well.") + else: + log.err("Got an unexpected result") + + self.report['hops'] = [] + for ttl in range(1, max_ttl): + log.msg("Sending ACK with ttl %s" % ttl) + # We generate an ack for the syn-ack we got with increasing ttl + packet = IP(dst=self.localOptions['backend'], + ttl=ttl, id=ipid)/TCP(sport=synack.dport, + dport=dport, flags="A", + seq=synack.ack, ack=synack.seq + 1) + + answered, unanswered = yield self.sr(packet, timeout=timeout) + try: + snd, rcv = answered[0] + except IndexError: + log.err("Got no response.") + + try: + icmp = rcv[ICMP] + + except IndexError: + report = {'ttl': snd.ttl, + 'address': rcv.src, + 'rtt': rcv.time - snd.time + } + log.debug("%s: %s" % (dport, report)) + self.report['hops'].append(report) + if rcv.src == self.localOptions['backend']: + log.msg("Reached the destination. We have finished the traceroute") + return +