dnsdiag/dnstraceroute.py

374 lines
11 KiB
Python
Executable File

#!/usr/bin/env python3
#
# Copyright (c) 2016, Babak Farrokhi
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import concurrent.futures
import getopt
import ipaddress
import os
import pickle
import signal
import socket
import sys
import time
import dns.rdatatype
import dns.resolver
from cymruwhois import cymruwhois
__author__ = 'Babak Farrokhi (babak@farrokhi.net)'
__license__ = 'BSD'
__version__ = 1.3
def test_import():
# passing this test means imports were successful
pass
# Constants
__PROGNAME__ = os.path.basename(sys.argv[0])
WHOIS_CACHE = 'whois.cache'
class Colors(object):
N = '\033[m' # native
R = '\033[31m' # red
G = '\033[32m' # green
O = '\033[33m' # orange
B = '\033[34m' # blue
def __init__(self, mode):
if not mode:
self.N = ''
self.R = ''
self.G = ''
self.O = ''
self.B = ''
# Globarl Variables
shutdown = False
def whoisrecord(ip):
try:
currenttime = time.time()
ts = currenttime
if ip in whois:
ASN, ts = whois[ip]
else:
ts = 0
if ((currenttime - ts) > 36000):
c = cymruwhois.Client()
ASN = c.lookup(ip)
whois[ip] = (ASN, currenttime)
return ASN
except Exception as e:
return e
try:
pkl_file = open(WHOIS_CACHE, 'rb')
try:
whois = pickle.load(pkl_file)
except EOFError:
whois = {}
except IOError:
whois = {}
def usage():
print('%s version %1.1f\n' % (__PROGNAME__, __version__))
print('usage: %s [-h] [-q] [-a] [-s server] [-p port] [-c count] [-t type] [-w wait] hostname' % __PROGNAME__)
print(' -h --help Show this help')
print(' -q --quiet Quiet')
print(' -e --expert Print expert hints if available')
print(' -a --asn Turn on AS# lookups for each hop encountered')
print(' -s --server DNS server to use (default: first system resolver)')
print(' -p --port DNS server port number (default: 53)')
print(' -c --count Maximum number of hops (default: 30)')
print(' -w --wait Maximum wait time for a reply (default: 5)')
print(' -t --type DNS request record type (default: A)')
print(' -C --color Print colorful output')
print(' ')
exit()
def signal_handler(sig, frame):
global shutdown
if shutdown: # pressed twice, so exit immediately
exit(0)
shutdown = True # pressed once, exit gracefully
def expert_report(trace_path, color_mode):
color = Colors(color_mode)
print("\n%s=== Expert Hints ===%s" % (color.B, color.N))
if len(trace_path) == 0:
print(" [*] empty trace - should not happen")
return
prev_hop = None
if len(trace_path) > 1:
prev_hop = trace_path[-2]
if len(trace_path) < 2:
print(
" %s[*]%s path too short (possible DNS hijacking, unless it is a local DNS resolver)" % (color.R, color.N))
return
if prev_hop == '*':
print(" %s[*]%s public DNS server is next to an invisible hop (probably a firewall)" % (color.R, color.N))
return
if prev_hop and ipaddress.ip_address(prev_hop).is_private:
print(" %s[*]%s public DNS server is next to a private IP address (possible hijacking)" % (color.R, color.N))
return
if prev_hop and ipaddress.ip_address(prev_hop).is_reserved:
print(" %s[*]%s public DNS server is next to a reserved IP address (possible hijacking)" % (color.R, color.N))
return
## no expert info available
print(" %s[*]%s No expert hint available for this trace" % (color.G, color.N))
def ping(resolver, hostname, dnsrecord, ttl):
reached = False
try:
resolver.query(hostname, dnsrecord, ipttl=ttl)
except dns.resolver.NoNameservers as e:
if not quiet:
print("no or bad response:", e)
exit(1)
except dns.resolver.NXDOMAIN as e:
if not quiet:
print("Invalid hostname:", e)
exit(1)
except dns.resolver.Timeout:
pass
except dns.resolver.NoAnswer:
if not quiet:
print("invalid answer")
pass
except SystemExit:
pass
except:
print("unxpected error: ", sys.exc_info()[0])
exit(1)
else:
reached = True
return reached
def main():
global quiet
try:
signal.signal(signal.SIGTSTP, signal.SIG_IGN) # ignore CTRL+Z
signal.signal(signal.SIGINT, signal_handler) # custom CTRL+C handler
except AttributeError: # not all signals are supported on all platforms
pass
if len(sys.argv) == 1:
usage()
dnsrecord = 'A'
count = 30
timeout = 1
quiet = False
dnsserver = dns.resolver.get_default_resolver().nameservers[0]
dest_port = 53
hops = 0
as_lookup = False
expert_mode = False
should_resolve = True
color_mode = False
try:
opts, args = getopt.getopt(sys.argv[1:], "aqhc:s:t:w:p:neC",
["help", "count=", "server=", "quiet", "type=", "wait=", "asn", "port", "expert",
"color"])
except getopt.GetoptError as err:
# print help information and exit:
print(err) # will print something like "option -a not recognized"
usage()
if args and len(args) == 1:
hostname = args[0]
else:
usage()
for o, a in opts:
if o in ("-h", "--help"):
usage()
elif o in ("-c", "--count"):
count = int(a)
elif o in ("-e", "--expert"):
expert_mode = True
elif o in ("-s", "--server"):
dnsserver = a
elif o in ("-q", "--quiet"):
quiet = True
elif o in ("-w", "--wait"):
timeout = int(a)
elif o in ("-t", "--type"):
dnsrecord = a
elif o in ("-p", "--port"):
dest_port = int(a)
elif o in ("-C", "--color"):
color_mode = True
elif o in ("-n"):
should_resolve = False
elif o in ("-a", "--asn"):
as_lookup = True
else:
usage()
color = Colors(color_mode)
resolver = dns.resolver.Resolver()
resolver.nameservers = [dnsserver]
resolver.timeout = timeout
resolver.lifetime = timeout
resolver.retry_servfail = 0
icmp = socket.getprotobyname('icmp')
ttl = 1
reached = False
trace_path = []
if not quiet:
print("%s DNS: %s:%d, hostname: %s, rdatatype: %s" % (__PROGNAME__, dnsserver, dest_port, hostname, dnsrecord))
while True:
if shutdown:
break
# some platforms permit opening a DGRAM socket for ICMP without root permission
# if not availble, we will fall back to RAW which explicitly requires root permission
try:
icmp_socket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
except OSError:
try:
icmp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, icmp)
except OSError:
print("Error: Unable to create ICMP socket with unprivileged user. Please run as root.")
exit(1)
icmp_socket.bind(("", dest_port))
icmp_socket.settimeout(timeout)
curr_addr = None
curr_host = None
with concurrent.futures.ThreadPoolExecutor(max_workers=1) as pool: # dispatch dns lookup to another thread
stime = time.time()
thr = pool.submit(ping, resolver, hostname, dnsrecord, ttl)
try: # expect ICMP response
_, curr_addr = icmp_socket.recvfrom(512)
curr_addr = curr_addr[0]
except socket.error:
etime = time.time()
pass
finally:
etime = time.time()
icmp_socket.close()
reached = thr.result()
if reached:
curr_addr = dnsserver
stime = time.time() # need to recalculate elapsed time for last hop without waiting for an icmp error reply
ping(resolver, hostname, dnsrecord, ttl)
etime = time.time()
elapsed = abs(etime - stime) * 1000 # convert to milliseconds
if should_resolve:
try:
if curr_addr:
curr_name = socket.gethostbyaddr(curr_addr)[0]
except socket.error:
curr_name = curr_addr
except SystemExit:
pass
except:
print("unxpected error: ", sys.exc_info()[0])
else:
curr_name = curr_addr
if curr_addr:
as_name = ""
if as_lookup:
ASN = whoisrecord(curr_addr)
as_name = ''
try:
if ASN and ASN.asn != "NA":
as_name = "[%s %s] " % (ASN.asn, ASN.owner)
except AttributeError:
if shutdown:
exit(0)
pass
c = color.N # default
if curr_addr != '*':
IP = ipaddress.ip_address(curr_addr)
if IP.is_private:
c = color.R
if IP.is_reserved:
c = color.B
if curr_addr == dnsserver:
c = color.G
print("%d\t%s (%s%s%s) %s%d ms" % (ttl, curr_name, c, curr_addr, color.N, as_name, elapsed), flush=True)
trace_path.append(curr_addr)
else:
print("%d\t *" % ttl, flush=True)
trace_path.append("*")
ttl += 1
hops += 1
if (hops >= count) or (curr_addr == dnsserver) or reached:
break
if expert_mode and not shutdown:
expert_report(trace_path, color_mode)
if __name__ == '__main__':
try:
main()
finally:
pkl_file = open(WHOIS_CACHE, 'wb')
pickle.dump(whois, pkl_file)