Enabling IP Forwarding

In the arp cache poisoning it is important for attacker to enable ip forwarding so the end user will not know that his packet actually peeped by attacker and attacker can do his job without any doubt by end user.


check forwarding enabled or not:
                       root@bt:~# sysctl net.ipv4.ip_forward
            net.ipv4.ip_forward = 0

                                  or

            root@bt:~# cat /proc/sys/net/ipv4/ip_forward
            0

o- ip forwarding is not enabled
1- enabled

changing ip forwarding:
                  root@bt:~# sysctl -w net.ipv4.ip_forward=1
                                 or

         root@bt:~# echo 1 > /proc/sys/net/ipv4/ip_forward

                                                                or

we can change in /etc/sysctl.conf fil e and add
                  net.ipv4.ip forward = 1

and then run
                    #sysctl -p /etc/sysctl.conf

                                   or

          #service procps restart

done... put ur black hat on ur head.....

a simple code for ns2

following code is a good example to understand how to write a simple tcl script for ns2 simulation.

#simulator object
set ns [new Simulator]

#colouring the class 1 packet
$ns color 1 Blue
$ns color 2 Red

#open a file to write and attaching it to ns object
set nf [open out.nam w]
$ns namtrace-all $nf

#process finish called at the last
proc finish {} {
          global ns nf
          $ns flush-trace
          close $nf
          exec nam out.nam &
          exit 0
           }

#creation of node       
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]

#creation of link
$ns duplex-link $n0 $n2 1Mb 10ms DropTail
$ns duplex-link $n1 $n2 1Mb 10ms DropTail
#we created a stochastic fair queu between 2 and 
$ns duplex-link $n2 $n3 0.5Mb 10ms SFQ

#for layout of links
$ns duplex-link-op $n0 $n2 orient right-down     
$ns duplex-link-op $n1 $n2 orient right-up
$ns duplex-link-op $n2 $n3 orient right

#setting udp agent
set udp0 [new Agent/UDP]
set udp1 [new Agent/UDP]

$ns attach-agent $n0 $udp0
$ns attach-agent $n1 $udp1

#setting traffic agent then it will attach to udp agent
set cbr0 [new Application/Traffic/CBR]
$cbr0 set packetSize_ 500
$cbr0 set interval 0.005
$udp0 set class_ 1
#attaching cbr agent to udp agent
$cbr0 attach-agent $udp0

set cbr1 [new Application/Traffic/CBR]
$cbr1 set packetSize_ 500
$cbr1 set interval 0.005
$udp1 set class_ 2
$cbr1 attach-agent $udp1

#this is sink
set null3 [new Agent/Null]
$ns attach-agent $n3 $null3

$ns connect $udp0 $null3
$ns connect $udp1 $null3

# to make a queu at a node
$ns duplex-link-op $n3 $n2 queuePos 0.5
#monitor a queu

$ns at 0.5 "$cbr0 start"
$ns at 4.5 "$cbr0 stop"
$ns at 1.5 "$cbr1 start"
$ns at 4.0 "$cbr1 stop"
#$ns duplex-link-op $n0 $n1 orient right-down
#$ns duplex-link-op $n1 $n2 orient right
#$ns duplex-link-op $n2 $n0 orient right-up

$ns at 5.0 "finish"
$ns run

save this with any *.tcl name and run it simply #ns *.tcl
.... enjoy coding

Installation of NS2 in ubuntu

I tried to install ns2 and downloaded its code to install it in my ubuntu10.10 system but it was tedious task.
And then i found that following steps were the most simplest way to install ns2.

step 1: make sure that u don't have any previous installation of ns2.

step 2: export the key for ppa
           #sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys B3F3334F

step 3: add ppa to your source. You can get this file /etc/apt/source.list. Simply append these line to source.list file.
       
             deb http://ppa.launchpad.net/wouterh/ppa/ubuntu karmic main

             deb-src http://ppa.launchpad.net/wouterh/ppa/ubuntu karmic main

step 4: now reload your apt-cache 

            #sudo apt-get update 

            or simply reload your synaptic package manager

step 5: install ns2

             #sudo apt-get install ns nam xgraph

      now ns2 installed.

Test run:

download sample code that is tcl file.

run this code

         # ns example1b.tcl

for more help

done......  enjoy coding..