MITE 062

VISVESVARAYA TECHNOLOGICAL UNIVERSITY Jnana Sangam, Belgaum-590018

COMPUTER NETWORKS LABORATORY (15CSL57)

MANGALORE INSTITUTE OF TECHNOLOGY AND ENGINEERING (An ISO 9001:2008 Certified Institution)

DEPARTMENT OF COMPUTER SCIENCE & ENGINEERING Badaga Mijar, Moodbidri – 574225, Karnataka

Computer Network Laboratory

15CSL57

COMPUTER NETWORK LABORATORY [As per Choice Based Credit System (CBCS) scheme] (Effective from the academic year 2017 -2018) SEMESTER – V Subject Code

15CSL57

IA Marks

20

Number of Lecture Hours/Week

01I + 02P

Exam Marks

80

Total Number of Lecture Hours

40

Exam Hours

03

Course Outcome Course Outcome

Cognitive Level An,Ap

Class Sessions 13

CO1

Analyze and Compare various networking protocols (Exp No. 9,10,1,2)

CO2

Demonstrate the working of different concepts of networking (Exp No. 7,8,11,12)

U,Ap

13

CO3

Implement, analyze and evaluate networking protocols in NS2 / NS3 (Exp No. 3,4,5,6)

U,An

13

POs PO1-2h, PO2-2h PO3-1h, PO4-3h, PO5-2h PO12-1h, PSO2-2h PO3-3h, PO23h, PO3-2h PO4-2h, PO12-1h, PSO2-2h PO1-3h, PO23h, PO3-1h PO4-3h, PO12-1h, PSO2-2h

Cognitive Level : R-Remember, U-Understand, Ap-Apply, An-Analyze, E-Evaluate, C-Create

Dept of CSE, MITE, Moodabidri

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SYLLABUS PART A 1. Implement three nodes point – to – point network with duplex links between them. Set the queue size, vary the bandwidth and find the number of packets dropped. 2. Implement transmission of ping messages/trace route over a network topology consisting of 6 nodes and find the number of packets dropped due to congestion. 3. Implement an Ethernet LAN using n nodes and set multiple traffic nodes and plot congestion window for different source / destination. 4. Implement simple ESS and with transmitting nodes in wire-less LAN by simulation and determine the performance with respect to transmission of packets. 5. Implement and study the performance of GSM on NS2/NS3 (Using MAC layer) or equivalent environment. 6. Implement and study the performance of CDMA on NS2/NS3 (Using stack called Call net) or equivalent environment. PART B Implement the following in Java: 7. Write a program for error detecting code using CRC-CCITT (16- bits). 8. Write a program to find the shortest path between vertices using bellman-ford algorithm. 9. Using TCP/IP sockets, write a client – server program to make the client send the file name and to make the server send back the contents of the requested file if present. Implement the above program using as message queues or FIFOs as IPC channels. 10. Write a program on datagram socket for client/server to display the messages on client side, typed at the server side. 11. Write a program for simple RSA algorithm to encrypt and decrypt the data. 12. Write a program for congestion control using leaky bucket algorithm.

STEPS FOR EXECUTION OF PROGRAMS 1. Open the terminal 2. Move to the directory /home/mite/Desktop/ns-allinone-2.35/ns-2.35 cd /home/mite/Desktop/ns-allinone-2.35/ns-2.35 3. Create a directory with your USN mkdir USN 4. Change directory to USN cd USN 5. Create files using gedit editor.  gedit program1.tcl 6. command to execute the program  ns program1.tcl

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PROGRAM-1 TITLE Implement three nodes point – to – point network with duplex links between them. Set the queue size, vary the bandwidth and find the number of packets dropped. AIM analyzing the traffic between the nodes using different bandwidth ,propagation delay and queue size of point to point duplex link and its effects on packet transmission. DESCRIPTION Ns2(network simulator2) is used for this experiment, in which point to point duplex link is created between the node with varying queuing capacity of node. Bandwidth, propagation delay of a point to point link and queuing capacity of a node is very important to minimize the affect on packet transmission. Ns2 simulated data traffic analyzed by setting the different bandwidth, propagation delay and queuing capacity of a link and corresponding its affect on packet transmission is noted. Awk script is used for analyzing the out.tr trace log file generated upon executing the ns2 simulation script for determining the packet drops.

INPUT Different Bandwidth, propagation delay & queuing capacity of node of duplex link awk scripts for analyzing the out.tr trace log file for determining the number of packet drop.

EXPECTED OUTPUT (a) generate the out.tr trace log file and out.nam network animation file. (b) number of packet drop

PROGRAM (1) # This script is created by NSG2 beta1 # #=================================== #

Simulation parameters setup

#=================================== set val(stop) 30.0

;# time of simulation end

#=================================== Dept of CSE, MITE, Moodabidri

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#

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Initialization

#=================================== #Create a ns simulator set ns [new Simulator] #Open the NS trace file set tracefile [open out.tr w] $ns trace-all $tracefile #Open the NAM trace file set namfile [open out.nam w] $ns namtrace-all $namfile #=================================== #

Nodes Definition

#=================================== #Create 3 nodes set n0 [$ns node] set n1 [$ns node] set n2 [$ns node] #=================================== #

Links Definition

#=================================== #Createlinks between nodes $ns duplex-link $n0 $n1 100.0Mb 10ms DropTail $ns queue-limit $n0 $n1 02 $ns duplex-link $n1 $n2 1.0Mb 50ms DropTail $ns queue-limit $n1 $n2 02

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#Give node position (for NAM) $ns duplex-link-op $n0 $n1 orient right $ns duplex-link-op $n1 $n2 orient right #=================================== #

Agents Definition

#=================================== #Setup a TCP connection set tcp0 [new Agent/TCP] $ns attach-agent $n0 $tcp0 set sink1 [new Agent/TCPSink] $ns attach-agent $n2 $sink1 $ns connect $tcp0 $sink1 $tcp0 set packetSize_ 1500 #=================================== #

Applications Definition

#=================================== #Setup a FTP Application over TCP connection set ftp0 [new Application/FTP] $ftp0 attach-agent $tcp0 $ns at 1.0 "$ftp0 start" $ns at 20.0 "$ftp0 stop" #=================================== #

Termination

#=================================== #Define a 'finish' procedure proc finish {} { Dept of CSE, MITE, Moodabidri

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global ns tracefile namfile $ns flush-trace close $tracefile close $namfile exec nam out.nam & exit 0 } $ns at $val(stop) "$ns nam-end-wireless $val(stop)" $ns at $val(stop) "finish" $ns at $val(stop) "puts \"done\" ; $ns halt" $ns run RESULT

Illustration 1: AWK Script for counting number of packets drop

Drawing 1: NAM Output

Dept of CSE, MITE, Moodabidri

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PROGRAM -2 TITLE (a)Implement transmission of ping messages/trace route over a network topology consisting of 6 nodes and find the number of packets dropped due to congestion.

AIM to understand the working principle of ICMP Ping message and deeper insights into the congestion scenario caused by successive ping message among nodes. DESCRIPTION Ping is the one of popular mechanism for internet control messaging protocol. Ping message is used for determining the reach ability and aliveness of the remote/ destination machine in a network. In this experiment, network simulator2 is used for creating network topology consisting of 6 nodes interconnected by point to point duplex link. Nodes on the created topology issues ping command to the other nodes in the network and generate traffic. Node upon receiving the ping message will respond by sending a ping reply message to the requesting node and generate return traffic in the network. Successive ping message by different nodes generates huge traffic on the network and cause packet drop scenario.

INPUT  ping message from nodes.  awk scripts for analyzing the out.tr trace log file for determining the number of packet drop. EXPECTED OUTPUT 1. Ping response from corresponding nodes. 2. Generate the out.tr trace log file and out.nam network animation file. 3. Number of packet drop

PROGRAM (2) #Create a simulator object set ns [new Simulator] #Open a trace file set nf [open exp4.nam w] $ns namtrace-all $nf set nd [open exp4.tr w] Dept of CSE, MITE, Moodabidri

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$ns trace-all $nd $ns color 1 Red $ns color 2 Green #Define a 'finish' procedure proc finish {} { global ns nf nd $ns flush-trace close $nf close $nd exec nam exp4.nam & exit 0 } #Create six nodes set n0 [$ns node] set n1 [$ns node] set n2 [$ns node] set n3 [$ns node] set n4 [$ns node] set n5 [$ns node] #Connect the nodes with two links $ns duplex-link $n0 $n1 0.1Mb 10ms DropTail $ns duplex-link $n1 $n2 0.1Mb 10ms DropTail $ns duplex-link $n2 $n3 0.1Mb 10ms DropTail $ns duplex-link $n3 $n4 0.1Mb 10ms DropTail $ns duplex-link $n4 $n5 0.1Mb 10ms DropTail

Dept of CSE, MITE, Moodabidri

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$ns duplex-link-op $n0 $n1 orient right $ns duplex-link-op $n1 $n2 orient right $ns duplex-link-op $n2 $n3 orient down $ns duplex-link-op $n3 $n4 orient left $ns duplex-link-op $n4 $n5 orient left #Define a 'recv' function for the class 'Agent/Ping' Agent/Ping instproc recv {from rtt} { $self instvar node_ puts "node [$node_ id] received ping answer from \ #$from with round-trip-time $rtt ms." } #Create two ping agents and attach them to the nodes n0 and n2 set p0 [new Agent/Ping] $ns attach-agent $n0 $p0

$p0 set fid_ 1

set p1 [new Agent/Ping] $ns attach-agent $n5 $p1 $p1 set fid_ 2 #Connect the two agents $ns connect $p0 $p1 #Schedule events $ns at 0.2 "$p0 send" $ns at 0.4 "$p1 send"

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$ns at 0.6 "$p0 send" $ns at 0.8 "$p1 send" $ns at 1.0 "finish" #Run the simulation $ns run

RESULT

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PROGRAM-3 TITLE Implement an Ethernet LAN using n nodes and set multiple traffic nodes and plot congestion window for different source / destination. AIM To understand the working principle of Ethernet LAN and congestion scenarios using multiple data traffic. DESCRIPTION 

Ethernet LAN denoted by IEEE 802.3 is one of the popular computer networking technology. In this experiment, ns2 simulator is used for creating Ethernet LAN and set the two different data traffic between pair of nodes using TCP as transport layer agent. Simulated data traffic between pair of nodes is analyzed for determining the packet drop due to congestion in the network. Congestion window for each TCP traffic is plotted on graph using xgraph tool.

INPUT    

Ethernet LAN Bandwidth, propagation delay, Queue Type and channel type two TCP traffic between pair of nodes initial Congestion window for both the traffic. awk scripts for analyzing the out.tr trace log file for determining the number of packet drop.

EXPECTED OUTPUT    

generate the out.tr trace log file, winfile0, winfile1 and out.nam network animation file. Generate Windowsize_file0, WindowSize_file1 holding congestion window size of both the traffic at different instance of time. number of packet drop. Xgraph plotted graph of depicting the congestion window of both the traffic.

PROGRAM (3) set ns [new Simulator] #Use colors to differentiate the traffics $ns color 1 Blue $ns color 2 Red #Open trace and NAM trace file set ntrace [open prog7.tr w] $ns trace-all $ntrace

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set namfile [open prog7.nam w] $ns namtrace-all $namfile #Use some flat file to create congestion graph windows set winFile0 [open WinFile0 w] set winFile1 [open WinFile1 w] #Finish Procedure proc Finish {} { #Dump all trace data and Close the files global ns ntrace namfile $ns flush-trace close $ntrace close $namfile #Execute the NAM animation file exec nam prog7.nam & #Plot the Congestion Window graph using xgraph exec xgraph WinFile0 WinFile1 & exit 0 } #Plot Window Procedure proc PlotWindow {tcpSource file} { global ns set time 0.1 set now [$ns now] set cwnd [$tcpSource set cwnd_] puts $file "$now $cwnd"

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$ns at [expr $now+$time] "PlotWindow $tcpSource $file" } #Create 6 nodes for {set i 0} {$i<6} {incr i} { set n($i) [$ns node] } #Create duplex links between the nodes $ns duplex-link $n(0) $n(2) 2Mb 10ms DropTail $ns duplex-link $n(1) $n(2) 2Mb 10ms DropTail $ns duplex-link $n(2) $n(3) 0.6Mb 100ms DropTail #Nodes n(3) , n(4) and n(5) are considered in a LAN set lan [$ns newLan "$n(3) $n(4) $n(5)" 0.5Mb 40ms LL Queue/DropTail MAC/802_3 Channel] #Orientation to the nodes $ns duplex-link-op $n(0) $n(2) orient right-down $ns duplex-link-op $n(1) $n(2) orient right-up $ns duplex-link-op $n(2) $n(3) orient right #Setup queue between n(2) and n(3) and monitor the queue $ns queue-limit $n(2) $n(3) 20 $ns duplex-link-op $n(2) $n(3) queuePos 0.5 #Set error model on link n(2) to n(3) set loss_module [new ErrorModel] $loss_module ranvar [new RandomVariable/Uniform] $loss_module drop-target [new Agent/Null] $ns lossmodel $loss_module $n(2) $n(3) #Set up the TCP connection between n(0) and n(4)

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set tcp0 [new Agent/TCP/Newreno] $tcp0 set fid_ 1 $tcp0 set window_ 8000 $tcp0 set packetSize_ 552 $ns attach-agent $n(0) $tcp0 set sink0 [new Agent/TCPSink/DelAck] $ns attach-agent $n(4) $sink0 $ns connect $tcp0 $sink0 #Apply FTP Application over TCP set ftp0 [new Application/FTP] $ftp0 attach-agent $tcp0 $ftp0 set type_ FTP #Set up another TCP connection between n(5) and n(1) set tcp1 [new Agent/TCP/Newreno] $tcp1 set fid_ 2 $tcp1 set window_ 8000 $tcp1 set packetSize_ 552 $ns attach-agent $n(5) $tcp1 set sink1 [new Agent/TCPSink/DelAck] $ns attach-agent $n(1) $sink1 $ns connect $tcp1 $sink1 #Apply FTP application over TCP set ftp1 [new Application/FTP] $ftp1 attach-agent $tcp1 $ftp1 set type_ FTP

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#Schedule Events $ns at 0.1 "$ftp0 start" $ns at 0.1 "PlotWindow $tcp0 $winFile0" $ns at 0.5 "$ftp1 start" $ns at 0.5 "PlotWindow $tcp1 $winFile1" $ns at 25.0 "$ftp0 stop" $ns at 25.1 "$ftp1 stop" $ns at 25.2 "Finish" #Run the simulation $ns run RESULT

Dept of CSE, MITE, Moodabidri

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PROGRAM-4 TITLE Implement simple ESS and with transmitting nodes in wire-less LAN by simulation and determine the performance with respect to transmission of packets.

AIM To understand how Extended Service Set is created and works by providing services to nodes in wirlesess LAN and analyzing the wireless traffic for determining packet drops. DESCRIPTION In this experiment, network simulator2 is used to create a IEEE 802.11 Wireless LAN consisting of mobile nodes and Extended Service set. An extended service set (ESS) is one or more interconnected basic service sets (BSSs) and their associated LANs. Each BSS consists of a single access point (AP) together with all wireless client devices (stations, also called STAs) creating a local or enterprise 802.11 wireless LAN (WLAN). Wireless mobile nodes INPUT  

two TCP traffic between pair of nodes awk scripts for analyzing the out.tr trace log file for determining the number of packet drop.

EXPECTED OUTPUT  

generate the out.tr trace log file, and generate the out.nam network animation file depicting the IEEE 802.3 Wireless LAN.

#=================================== # Simulation parameters setup #=================================== set val(chan) Channel/WirelessChannel ;# channel type set val(prop) Propagation/TwoRayGround ;# radio-propagation model set val(netif) Phy/WirelessPhy ;# network interface type set val(mac) Mac/802_11 ;# MAC type set val(ifq) Queue/DropTail/PriQueue ;# interface queue type set val(ll) LL ;# link layer type set val(ant) Antenna/OmniAntenna ;# antenna model set val(ifqlen) 50 ;# max packet in ifq set val(nn) 5 ;# number of mobilenodes set val(rp) AODV ;# routing protocol set val(x) 939 ;# X dimension of topography set val(y) 558 ;# Y dimension of topography Dept of CSE, MITE, Moodabidri

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15CSL57 ;# time of simulation end

#=================================== # Initialization #=================================== #Create a ns simulator set ns [new Simulator] #Setup topography object set topo [new Topography] $topo load_flatgrid $val(x) $val(y) create-god $val(nn) #Open the NS trace file set tracefile [open out.tr w] $ns trace-all $tracefile #Open the NAM trace file set namfile [open out.nam w] $ns namtrace-all $namfile $ns namtrace-all-wireless $namfile $val(x) $val(y) set chan [new $val(chan)];#Create wireless channel #=================================== # Mobile node parameter setup #=================================== $ns node-config -adhocRouting $val(rp) \ -llType $val(ll) \ -macType $val(mac) \ -ifqType $val(ifq) \ -ifqLen $val(ifqlen) \ -antType $val(ant) \ -propType $val(prop) \ -phyType $val(netif) \ -channel $chan \ -topoInstance $topo \ -agentTrace ON \ -routerTrace ON \ -macTrace ON \ -movementTrace ON #=================================== # Nodes Definition #=================================== #Create 5 nodes set n0 [$ns node] $n0 set X_ 261 $n0 set Y_ 85 $n0 set Z_ 0.0 $ns initial_node_pos $n0 20 Dept of CSE, MITE, Moodabidri

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set n1 [$ns node] $n1 set X_ 388 $n1 set Y_ 288 $n1 set Z_ 0.0 $ns initial_node_pos $n1 20 set n2 [$ns node] $n2 set X_ 544 $n2 set Y_ 458 $n2 set Z_ 0.0 $ns initial_node_pos $n2 20 set n3 [$ns node] $n3 set X_ 699 $n3 set Y_ 284 $n3 set Z_ 0.0 $ns initial_node_pos $n3 20 set n4 [$ns node] $n4 set X_ 839 $n4 set Y_ 105 $n4 set Z_ 0.0 $ns initial_node_pos $n4 20 #=================================== # Agents Definition #=================================== #Setup a TCP connection set tcp0 [new Agent/TCP] $ns attach-agent $n0 $tcp0 set sink1 [new Agent/TCPSink] $ns attach-agent $n4 $sink1 $ns connect $tcp0 $sink1 $tcp0 set packetSize_ 1500

#=================================== # Applications Definition #=================================== #Setup a FTP Application over TCP connection set ftp0 [new Application/FTP] $ftp0 attach-agent $tcp0 $ns at 1.0 "$ftp0 start" $ns at 5.0 "$n0 setdest 700 151 10" $ns at 100.0 "$ftp0 stop"

#=================================== # Termination #=================================== #Define a 'finish' procedure proc finish {} { global ns tracefile namfile Dept of CSE, MITE, Moodabidri

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$ns flush-trace close $tracefile close $namfile exec nam out.nam & exit 0 } for {set i 0} {$i < $val(nn) } { incr i } { $ns at $val(stop) "\$n$i reset" } $ns at $val(stop) "$ns nam-end-wireless $val(stop)" $ns at $val(stop) "finish" $ns at $val(stop) "puts \"done\" ; $ns halt" $ns run

RESULT

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PROGRAM-5 TITLE Implement and study the performance of GSM on NS2/NS3 (Using MAC layer) or equivalent environment. . AIM To understand the GSM TDMA Mac layer functionality under different traffic scenario and mobility of nodes. DESCRIPTION GSM stands for Global System for Mobile Communication. It is a digital cellular technology used for transmitting mobile voice and data services. GSM uses narrowband Time Division Multiple Access (TDMA) for providing voice and text based services over mobile phone networks. Radio spectrum being a limited resource that is consumed and divided among all the users, GSM devised a combination of TDMA/FDMA as the method to divide the bandwidth among the users. In this process, the FDMA part divides the frequency of the total 25 MHz bandwidth into 124 carrier frequencies of 200 kHz bandwidth. Each BS is assigned with one or multiple frequencies, and each of this frequency is divided into eight timeslots using a TDMA scheme. Each of these slots are used for both transmission as well as reception of data. These slots are separated by time so that a mobile unit doesn’t transmit and receive data at the same time. In this experiment, network simulator2 is used for simulating GSM network using TDMA as a MAC layer for nodes and performance of data communication is analyzed under different scenario.

INPUT  Two TCP traffic between pair of nodes  Awk scripts for analyzing the out.tr trace log file for determining the number of packet drop. EXPECTED OUTPUT (a) Generate the out.tr trace log file, and (b) Generate the out.nam network animation file depicting the GSM Nework by creating base station node and mobile nodes. #=================================== # Simulation parameters setup #=================================== set val(chan) Channel/WirelessChannel ;# channel type set val(prop) Propagation/TwoRayGround ;# radio-propagation model Dept of CSE, MITE, Moodabidri

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set val(netif) Phy/WirelessPhy ;# network interface type set val(mac) Mac/Tdma ;# MAC type set val(ifq) Queue/DropTail/PriQueue ;# interface queue type set val(ll) LL ;# link layer type set val(ant) Antenna/OmniAntenna ;# antenna model set val(ifqlen) 50 ;# max packet in ifq set val(nn) 7 ;# number of mobilenodes set val(rp) AODV ;# routing protocol set val(x) 1478 ;# X dimension of topography set val(y) 100 ;# Y dimension of topography set val(stop) 90.0 ;# time of simulation end #=================================== # Initialization #=================================== #Create a ns simulator set ns [new Simulator] #Setup topography object set topo [new Topography] $topo load_flatgrid $val(x) $val(y) create-god $val(nn) #Open the NS trace file set tracefile [open out.tr w] $ns trace-all $tracefile #Open the NAM trace file set namfile [open out.nam w] $ns namtrace-all $namfile $ns namtrace-all-wireless $namfile $val(x) $val(y) set chan [new $val(chan)];#Create wireless channel #=================================== # Mobile node parameter setup #=================================== Phy/WirelessPhy set freq_ 2.472e6 $ns node-config -adhocRouting $val(rp) \ -llType $val(ll) \ -macType $val(mac) \ -ifqType $val(ifq) \ -ifqLen $val(ifqlen) \ -antType $val(ant) \ -propType $val(prop) \ -phyType $val(netif) \ -channel $chan \ -topoInstance $topo \ -agentTrace ON \ -routerTrace ON \ -macTrace ON \ Dept of CSE, MITE, Moodabidri

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-movementTrace ON #=================================== # Nodes Definition #=================================== #Create 7 nodes set n0 [$ns node] $n0 set X_ 271 $n0 set Y_ 58 $n0 set Z_ 0.0 $ns initial_node_pos $n0 20 set n1 [$ns node] $n1 set X_ 458 $n1 set Y_ 214 $n1 set Z_ 0.0 $ns initial_node_pos $n1 20 set n2 [$ns node] $n2 set X_ 666 $n2 set Y_ 344 $n2 set Z_ 0.0 $ns initial_node_pos $n2 20 set n3 [$ns node] $n3 set X_ 877 $n3 set Y_ 229 $n3 set Z_ 0.0 $ns initial_node_pos $n3 20 set n4 [$ns node] $n4 set X_ 1103 $n4 set Y_ 150 $n4 set Z_ 0.0 $ns initial_node_pos $n4 20 Phy/WirelessPhy set freq_ 2.472e9 $ns node-config -phyType $val(netif) set n5 [$ns node] $n5 set X_ 616 $n5 set Y_ 55 $n5 set Z_ 0.0 $ns initial_node_pos $n5 20 set n6 [$ns node] $n6 set X_ 722 $n6 set Y_ 55 $n6 set Z_ 0.0 $ns initial_node_pos $n6 20 #=================================== # Agents Definition #=================================== #Setup a TCP connection set tcp1 [new Agent/TCP] $ns attach-agent $n5 $tcp1 Dept of CSE, MITE, Moodabidri

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set sink3 [new Agent/TCPSink] $ns attach-agent $n6 $sink3 $ns connect $tcp1 $sink3 $tcp1 set packetSize_ 1500 #Setup a TCP connection set tcp5 [new Agent/TCP] $ns attach-agent $n0 $tcp5 set sink6 [new Agent/TCPSink] $ns attach-agent $n4 $sink6 $ns connect $tcp5 $sink6 $tcp5 set packetSize_ 1500

#=================================== # Applications Definition #=================================== #Setup a FTP Application over TCP connection set ftp1 [new Application/FTP] $ftp1 attach-agent $tcp5 $ns at 1.0 "$ftp1 start" $ns at 80.0 "$ftp1 stop" #Setup a FTP Application over TCP connection set ftp2 [new Application/FTP] $ftp2 attach-agent $tcp1 $ns at 1.0 "$ftp2 start" $ns at 80.0 "$ftp2 stop"

#=================================== # Termination #=================================== #Define a 'finish' procedure proc finish {} { global ns tracefile namfile $ns flush-trace close $tracefile close $namfile exec nam out.nam & exit 0 } for {set i 0} {$i < $val(nn) } { incr i } { $ns at $val(stop) "\$n$i reset" } $ns at $val(stop) "$ns nam-end-wireless $val(stop)" $ns at $val(stop) "finish" $ns at $val(stop) "puts \"done\" ; $ns halt" $ns run

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RESULT

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PROGRAM-6 TITLE (a) Implement and study the performance of CDMA on NS2/NS3 (Using stack called Call net) or equivalent environment.

AIM To understand the CDMA Mac layer functionality under different traffic scenario and mobility of nodes. DESCRIPTION LTE is the latest high- speed cellular transmission network.LTE is a 4G technology with download speeds that run the gamut from 3 to 28 Mbps worldwide.4G LTE is one of several competing 4G standards along with Ultra Mobile Broadband (UMB) and WiMax (IEEE 802.16).Ns3 is the best choice among network simulator for simulating LTE framework. We provide customized NS3 LTE Simulation Projects based on customer Requirements.

INPUT  Two TCP traffic between pair of nodes  Awk scripts for analyzing the out.tr trace log file for determining the number of packet drop. EXPECTED OUTPUT (a) Generate the out.tr trace log file, and (b) Generate the out.nam network animation file depicting the GSM Nework by creating base station node and mobile nodes. PROGRAM – 6A.PL

#include "ns3/core module.h" #include "ns3/network module.h" #include "ns3/mobility module.h" #include "ns3/lte module.h" #include "ns3/config store Dept of CSE, MITE, Moodabidri

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module.h" using namespace ns3; int main (int argc, char *argv[]) { CommandLine cmd; cmd.Parse (argc, argv) ; ConfigStore inputConfig; inputConfig.ConfigureDefaults (); cmd.Parse (argc, argv); Ptr lteHelper = CreateObject (); lteHelper >SetAttribute ("PathlossModel", StringValue ("ns3::FriisSpectrumPropagationLossModel")); NodeContainer enb Nodes; NodeContainer ueNodes; enbNodes.Create (1); ueNodes.Create (3); MobilityHelper mobility; mobility.SetMobilityModel ("ns3::ConstantPositionMobilityModel"); mobility.Install (enbNodes); mobility.SetMobilityModel ("ns3::ConstantPositionMobilityModel"); mobility.Install (ueNodes); NetDeviceContainer enbDevs; NetDeviceContainer ueDevs; enbDevs = lteHelper >InstallEnbDevice (enbNodes); ueDevs = lteHelper >InstallUeDevice (ueNodes); lteHelper >Attach (ueDevs, enbDevs. Get (0)); enum EpsBearer::Qci q = EpsBearer::GBR_CONV_VOICE; EpsBearer bearer (q); Dept of CSE, MITE, Moodabidri

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lteHelper >ActivateDataRadioBearer (ueDevs, bearer); Simulator::Stop (Seconds (0.5)); lteHelper >EnablePhyTraces (); lteHelper >EnableMacTraces (); lteHelper >EnableRlcTrac es (); double distance_temp [] = { 1000,1000,1000}; std::vector userDistance; userDistance.assign (distance_temp, distance_temp + 3); for (int i = 0; i < 3; i++) { Ptr mm = ueNodes.Get (i) >GetObject< ConstantPositionMobilityModel> (); mm >SetPosition (Vector (userDistance[i], 0.0, 0.0)); } Simulator::Run (); Simulator::Destroy (); return 0; } RESULT

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PART B STEPS FOR EXECUTION OF PROGRAMS 1. Start Eclipse 2. Create a new java project 3. Create a new java class Dept of CSE, MITE, Moodabidri

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4. Run the program

PROGRAM-1 TITLE Write a program for error detecting code using CRC-CCITT (16-bits). AIM To detect the error at receiver side DESCRIPTION CRC is an error detection mechanism. CRC is based on binary division. In this a sequence of redundant bits, called CRC remainder is appended to the end of a data unit so that the resulting data unit becomes exactly divisible by a second predetermined binary number. At its destination, the incoming data unit is divided by the same number. If at this step there is no reminder, the data unit is assumed to be intact and therefore accepted. A remainder indicates that the data unit has been changed in transit and therefore must be rejected. The generalized technique can be explained as follows. If a k bit message is to be transmitted, the transmitter generates an r-bit sequence, known as Frame Check Sequence (FCS) so that the (k +r) bits are actually being transmitted. Now this r-bit FCS is generated by dividing the original number, appended by r zeros, by a predetermined number. This number, which is (r+1) bit in length, can also be considered as the coefficients of a polynomial, called Generator Polynomial. The remainder of this division process generates the r-bit FCS. On receiving the packet, the receiver divides the (k+r) bit frame by the same predetermined number and if it produces no remainder, it can be assumed that no error has occurred during the transmission.

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INPUT a) Enter the Data word b) Enter the position where error has to be inserted EXPECTED OUTPUT Dept of CSE, MITE, Moodabidri

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Print the Generating Polynomial Print the modified Bits Print the checksum Print the Final Code word Print the error occurred data

PROGRAM: CRC package crcsender; import java.util.Scanner; public class CRCSender { public static void main(String[] args) { // TODO code application logic here Scanner scan = new Scanner(System.in); String msg, crc, encoded = " "; System.out.println("Enter the message"); msg = scan.next(); System.out.println("Enter the crc generator polynomial"); crc = scan.next(); int m = msg.length(), n = crc.length(); encoded+= msg ; //************************ Logic to generate the codeword ***********************// char[] generatorPolyArray = crc.toCharArray(); for(int i=1; i<=n-1;i++)encoded+='0'; System.out.println("E:"+encoded); char[] encodedArray = encoded.toCharArray(); for(int i=0;i<=encodedArray.length-n;){ for(int j=0;j
//************************ Choice 1: Check for Validity 2:Induce error and cross check ***************// Dept of CSE, MITE, Moodabidri

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if(i==1){ for(int k =0;k
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RESULT

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PROGRAM-2 TITLE Write a program to find the shortest path between vertices using bellman-ford algorithm. AIM To find the shortest path to all the different nodes from a source. DESCRIPTION The Bellman–Ford algorithm is an algorithm that computes shortest paths from a single source vertex to all of the other vertices in a weighted digraph.[1] It is slower than Dijkstra's algorithm for the same problem, but more versatile, as it is capable of handling graphs in which some of the edge weights are negative numbers. Negative edge weights are found in various applications of graphs, hence the usefulness of this algorithm.[3] If a graph contains a "negative cycle" (i.e. a cycle whose edges sum to a negative value) that is reachable from the source, then there is no cheapest path: any path that has a point on the negative cycle can be made cheaper by one more walk around the negative cycle. In such a case, the Bellman–Ford algorithm can detect negative cycles and report their existence 1) This step initializes distances from source to all vertices as infinite and distance to source itself as 0. Create an array dist[] of size |V| with all values as infinite except dist[src] where src is source vertex. 2) This step calculates shortest distances. Do following |V|-1 times where |V| is the number of vertices in given graph. Do following for each edge u-v If dist[v] > dist[u] + weight of edge uv, then update dist[v] dist[v] = dist[u] + weight of edge uv 3) This step reports if there is a negative weight cycle in graph. Do following for each edge u-v If dist[v] > dista) Do [u] + weight of edge uv, then “Graph contains negative weight cycle” The idea of step 3 is, step 2 guarantees shortest distances if graph doesn’t contain negative weight cycle. If we iterate through all edges one more time and get a shorter path for any vertex, then there is a negative weight cycle.

INPUT a) Enter the number of nodes b) Enter the adjacent matrix EXPECTED OUTPUT a) Print the routing table with shortest distance from each source to sink. PROGRAM: BELLMAN FORD package bellmanford; import java.util.Scanner;

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public class BellmanFord { private int distances[]; private int numberofvertices; public static final int MAX_VALUE = 999; public BellmanFord(int numberofvertices) { this.numberofvertices = numberofvertices; distances = new int[numberofvertices + 1]; } public void BellmanFordEvaluation(int source, int adjacencymatrix[][]) { for (int node = 1; node <= numberofvertices; node++) { distances[node] = MAX_VALUE; } distances[source] = 0; for (int node = 1; node <= numberofvertices - 1; node++) { for (int sourcenode = 1; sourcenode <= numberofvertices; sourcenode++) { for (int destinationnode = 1; destinationnode <= numberofvertices; destinationnode++) { if (adjacencymatrix[sourcenode][destinationnode] != MAX_VALUE) { if (distances[destinationnode] > distances[sourcenode] + adjacencymatrix[sourcenode][destinationnode]) distances[destinationnode] = distances[sourcenode] + adjacencymatrix[sourcenode][destinationnode]; Dept of CSE, MITE, Moodabidri

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} } } } for (int sourcenode = 1; sourcenode <= numberofvertices; sourcenode++) { for (int destinationnode = 1; destinationnode <= numberofvertices; destinationnode++) { if (adjacencymatrix[sourcenode][destinationnode] != MAX_VALUE) { if (distances[destinationnode] > distances[sourcenode] + adjacencymatrix[sourcenode][destinationnode]) System.out.println("The Graph contains negative egde cycle"); } } } for (int vertex = 1; vertex <= numberofvertices; vertex++) { System.out.println("distance of source " + source + " to " + vertex + " is " + distances[vertex]); } } public static void main(String... arg) { int numberofvertices = 0; int source; Dept of CSE, MITE, Moodabidri

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Scanner scanner = new Scanner(System.in); System.out.println("Enter the number of vertices"); numberofvertices = scanner.nextInt(); int adjacencymatrix[][] = new int[numberofvertices + 1][numberofvertices + 1]; System.out.println("Enter the adjacency matrix"); for (int sourcenode = 1; sourcenode <= numberofvertices; sourcenode++) { for (int destinationnode = 1; destinationnode <= numberofvertices; destinationnode++) { adjacencymatrix[sourcenode][destinationnode] = scanner.nextInt(); if (sourcenode == destinationnode) { adjacencymatrix[sourcenode][destinationnode] = 0; continue; } if (adjacencymatrix[sourcenode][destinationnode] == 0) { adjacencymatrix[sourcenode][destinationnode] = MAX_VALUE; } } } System.out.println("Enter the source vertex"); source = scanner.nextInt(); BellmanFord bellmanford = new BellmanFord(numberofvertices); bellmanford.BellmanFordEvaluation(source, adjacencymatrix); scanner.close(); } }

RESULT

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TITLE Using TCP/IP sockets, write a client-server program to make client sending the file name and the server to send back the contents of the requested file if present.

AIM To demonstrate client server {Request and Reply} concept by using socket programming DESCRIPTION Unix sockets is just like two way FIFO's. All data communication will take place through the socket's interface, instead of through the file interface. Although unix socket's are a special file in the file system(just like FIFO's), there's usage of socket(), bind(), recv(),etc and not open(), read(). When programming with socket's, usually there's creation of server and client programs. The server will sit listening for incoming connections from clients and handling. This is similar to the situation that exists with internet sockets but with fine differences. For instance, when describing which unix socket that has to be used(i.e the path to the special file that is the socket). The structure “struct sockaddr_un” has the following fields: struct sockaddr_un { unsigned short sa_family; char sa_data;

// Address family,AF_XXXX

// 14 bytes of protocol address

}; This is the structure you will be passing to the bind() function, which associates a socket descriptor(a file descriptor) with a certain file(the name for which is in the sun_path field). The structure “struct sockaddr_in” is used when we need IP address and Port number to be binded to the Sockets. It has following fields: struct sockaddr_in { short int sin_family;

// Address family

unsigned short int sin_port; struct in_addr sin_addr;

// Port number // Internet address

unsigned char sin_zero[8] // Same size as struct sockaddr };

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// Internet adress struct in_addr { unsigned long s_addr;

// 32 bits or 4 bytes long

}; ii. BACKGROUND REQUIRED: 1. UNIX File I/O system calls 2. UNIX IPC system calls 3. UNIX socket programming

iii. THEORETICAL CONCEPTS: Most interprocess communication uses the client server model. These terms refer to the two processes which will be communication with each other. One of the two processes , the client , connects to the other process, the server, typiceally to make a request for information. A good analogy is a person who makes a phone call to another person. Notice that the client needs to know of the existence of and the address of the server, but the server does not need to know the adresss of(or even the existence of) the client prior to the connection being established. Notice also that once a connection is established, both sides can send and receive information. The system calls for establishing a connection are somewhat different for the client and the server, but both involve the basic construct of a socket. A socket is one end of an interprocess communication channel. The two processes each establish their own socket. The steps involved in establishing a socket on the client side are as follows1. Create a socket with the socket() system call . 2. Connect the socket to the address of the server using the connect() system call. 3. Send and receive data. There are a number of ways to do this, but the simplest is to use the read() and write() systen calls. The steps involved in establishing a socket on the server side are as follows1. Create a socket with the socket() system call. 2. Bind the socket to an address using the bind() system call. For a server socket on the internet, an address consists of a port number on the host machine. 3. Listen for connections with the listen() system call. 4. Acept a connection with the accept() system call. This call typically blocks until a client connects with the server. 5. Send and receive the data. Dept of CSE, MITE, Moodabidri

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Socket Types: When a socket is created, the program has to specify the address domain and the socket type. Two processes can communicate with each other only if their sockets are of the same type and in the same domain, in which two processes running on any two hosts on the Internet communicate. Each of these has it's own adress format. The address of a socket in the Unix domain is a character string which is basically an entry in the file system. The address of a socket in the Internet domain consists of the Internet address of the host machine (every computer on the Internet has a unique 32 bit address, often reffered to as it's IP address). In addition , each socket needs a port number on that host. Port numbers are 16 bit unsigned integers. The lower numbers are reserved in Unix for standard services. For eg, the port number for the FTP server is 21. There are two widely used socket types, stream sockets , and datgram sockets. Stream sockets treat communications as a continuous stream of characters, while datagram sockets have to read entire messages at once. Each uses it's own communications protocol. Stream sockets use TCP , which is a reliable , stream oriented protocol, and datagram sockets use UDP, which is unreliable and message oriented. The primary socket calls are as follows:1. socket() - Create a new socket and return it's descriptor. 2. bind() - Associate a socket with a port and address . 3. Listen() -Establish a queue for connection requests. 4. Accept()- Accepts a connection request. 5. Connect()- Initiate a connection to a remote host. 6. Recv() - Receive data from a socket descriptor. 7. Send() - Send data to a socket descriptor. 8. Close() - “one-way” close of a socket descriptor, The other system calls used are as follows:1. gethostbyname- given a hostname , returns a structure which specifies it's DNS name(s) and IP address(es). 2. getservbyname – given service name and protocol , returns a structure which specifies its name(s) and its port address. The socket utility functions are as follows:1. htons/ntohl- convert short/long from host byte order to network byte order. 2. inet_ntoa/inet_addr- converts 32 bit IP address (network byte order to/from a dotted decimal string) The header files used in order are:Dept of CSE, MITE, Moodabidri

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1. -prerequisite typedefs. 2. -names for “erno” values (error numbers) 3. - struct sock addr ;system prototypes and constants . 4. - network info lookup prototypes and structures. 5. - struct sockaddr_in; byte ordering macros. 6. - utility function prototypes. The two key classes from the java.net package used in creation of server and client programs are: 

ServerSocket



Socket

A server program creates a specific type of socket that is used to listen for client requests (server socket), In the case of a connection request, the program creates a new socket through which it will exchange data with the client using input and output streams. The socket abstraction is very similar to the file concept: developers have to open a socket, perform I/O, and close it.

The steps for creating a simple server program are: 1. Open the Server Socket: ServerSocket server = new ServerSocket( PORT ); 2. Wait for the Client Request: Socket client = server.accept(); 3. Create I/O streams for communicating to the client DataInputStream is = new DataInputStream(client.getInputStream()); DataOutputStream os = new DataOutputStream(client.getOutputStream()); 4. Perform communication with client Receive from client: String line = is.readLine(); Send to client: os.writeBytes(“Hello\n”); 5. Close socket: client.close();

The steps for creating a simple client program are: 1. Create a Socket Object: Socket client = new Socket(server, port_id); 2. Create I/O streams for communicating with the server. is=newDataInputStream(client.getInputStream()); os = new DataOutputStream(client.getOutputStream()); 3. Perform I/O or communication with the server: Receive data from the server: String line = is.readLine(); Send data to the server: os.writeBytes(“Hello\n”); Dept of CSE, MITE, Moodabidri

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4. Close the socket when done: client.close();

INPUT a) Enter the file name EXPECTED OUTPUT a) Print the file content of the request file b) Print the error condition{requested file does not exit}

PROGRAM: CLIENT SIDE package contentclient; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.io.PrintWriter; import java.net.Socket; public class ContentClient { public static void main(String[] args) throws IOException{ // TODO code application logic here Socket sock = new Socket("127.0.0.1", 4000); System.out.println("Enter the filename "); BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String fname = reader.readLine(); OutputStream ostream = sock.getOutputStream(); PrintWriter pwriter = new PrintWriter(ostream,true); pwriter.println(fname); InputStream istream = sock.getInputStream(); BufferedReader toread = new BufferedReader(new InputStreamReader(istream)); String str ; while((str=toread.readLine())!=null){ System.out.println(str); } pwriter.close();sock.close();toread.close(); } } PROGRAM: SERVER SIDE package server; Dept of CSE, MITE, Moodabidri

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import java.io.BufferedReader; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.io.PrintWriter; import java.net.ServerSocket; import java.net.Socket; public class Server { public static void main(String[] args) throws IOException,FileNotFoundException{ // TODO code application logic here ServerSocket serverSocket = new ServerSocket(4000); System.out.println("Server ready for the connection"); Socket sock = serverSocket.accept(); System.out.println("Connection was successful "); //to Read the file name from the client InputStream istream = sock.getInputStream() ; BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(istream)); String fname = bufferedReader.readLine(); //Reading the contents BufferedReader contentReader = new BufferedReader(new FileReader(fname)); //keeping output stream ready for sending the content OutputStream ostream = sock.getOutputStream(); PrintWriter pwrite = new PrintWriter(ostream,true); String str ; while((str = contentReader.readLine())!=null){ pwrite.println(str); } sock.close();serverSocket.close();pwrite.close(); bufferedReader.close();contentReader.close(); } } RESULT:

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PROGRAM-4 TITLE Write a program on datagram socket for client/server to display the messages on client side, typed at the server side. AIM To demonstrate the client server {Request and Reply} concept by using UDP Datagram. DESCRIPTION A datagram socket is the sending or receiving point for a packet delivery service. Each packet sent or received on a datagram socket is individually addressed and routed. Multiple packets sent from one machine to another may be routed differently, and may arrive in any order. One of the examples where UDP is preferred over TCP is the live coverage of TV channels. In this aspect, we want to transmit as many frames to live audience as possible not worrying about the loss of one or two frames. TCP being a reliable protocol add its own overhead while transmission. Datagram packets are used to implement a connectionless packet delivery service supported by the UDP protocol. Each message is transferred from source machine to destination based on information contained within that packet. That means, each packet needs to have destination address and each packet might be routed differently, and might arrive in any order. Packet delivery is not guaranteed. The format of datagram packet is: Message

length

Host

Server Port

Java supports datagram communication through the following classes: 

DatagramPacket



DatagramSocket

The class DatagramPacket contains several constructors that can be used for creating packet object. One of them is: DatagramPacket(byte[] buf, int length, InetAddress address, int port);

This constructor is used for creating a datagram packet for sending packets of length length to the specifi ed port number on the specifi ed host. The message to be transmitted is indicated in the fi rst argument. The key methods of DatagramPacket class are: 

byte[] getData() Returns the data buffer.



int getLength() Returns the length of the data to be sent or the length of the data received.



void setData(byte[] buf) Sets the data buffer for this packet.



void setLength(int length) Sets the length for this packet.

The class DatagramSocket supports various methods that can be used for transmitting or receiving data a datagram over the network. The two key methods are:

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void send(DatagramPacket p) Sends a datagram packet from this socket. void receive(DatagramPacket p) Receives a datagram packet from this socket. A simple UDP server program that waits for client’s requests and then accepts the message (datagram) and sends back the same message is given below. Of course, an extended server program can manipulate client’s messages/request and send a new message as a response.

INPUT a) Enter the file name EXPECTED OUTPUT a) Print the file content of the request file b) Print the error condition {requested file does not exist} PROGRAM: CLIENTSIDE package udpclient; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.SocketException; import java.net.UnknownHostException; public class UDPClient { public static void main(String[] args) throws SocketException, UnknownHostException, IOException { byte[] sendData = new byte[1024]; byte[] receiveData = new byte[1024]; DatagramSocket mySocket = new DatagramSocket(); System.out.println("Enter the data"); BufferedReader infromUser = new BufferedReader(new InputStreamReader(System.in)); InetAddress myIp = InetAddress.getByName("localhost"); String data = infromUser.readLine(); sendData = data.getBytes(); DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length,myIp,9000); mySocket.send(sendPacket);

DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length); mySocket.receive(receivePacket); String datatoDisplay = new String(receivePacket.getData()); System.out.println("From server"+datatoDisplay); mySocket.close(); }

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} PROGRAM: SERVER SIDE package udpserver; import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.SocketException; import java.util.Scanner; /** * * @author prashanth */ public class UDPServer { public static void main(String[] args) throws SocketException, IOException { DatagramSocket datagramSocket = new DatagramSocket(9000); byte[] receivedata = new byte[1024]; byte[] senddata = new byte[1024]; while(true){ DatagramPacket recievePacket = new DatagramPacket(receivedata,receivedata.length); datagramSocket.receive(recievePacket); String data = new String(recievePacket.getData()); System.out.println("Client Data :"+data);

InetAddress clientIPAddress = recievePacket.getAddress(); int port = recievePacket.getPort();

System.out.println("Enter the data to send to client "); Scanner scan = new Scanner(System.in); String datatosend = scan.next(); senddata = datatosend.getBytes(); DatagramPackettoSendtoClient=new DatagramPacket(senddata,senddata.length,clientIPAddress,port); datagramSocket.send(toSendtoClient); } } }

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RESULT

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PROGRAM-5 TITLE Write a program for simple RSA algorithm to encrypt and decrypt the data. AIM To demonstrate message encryption and Decryption DESCRIPTION The RSA Public key algorithm was invented in 1977 by Ron Rivest, Adi Shamir and Leonard Adleman (RSA). The algorithm Supports Encryption and Digital Signatures. It is the most widely used public key algorithm. RSA gets its security from the integer factorization problem. The algorithm is relatively easy to understand and implement. It has been patent free since 2000. RSA is used in security protocols such as IPSEC/IKE -IP data security, TLS/SSL -transport data security (web), PGP -email security, SSH -terminal connection security, SILC -conferencing service security. RSA gets its security from the factorization problem. The difficulty of factoring large numbers is the basis of security of RSA.The Integer factorization problem (finding a number's prime factors): For a positive integer n, find its prime factors: n = p1 p2 ... pi where pi is positive distinct prime number Example: 257603 = 41 * 61 * 103 Factorization algorithms can be used to factor faster than brute forcing. Some of them are Trial division, Pollard's rho, Pollard's p-1, Quadratic sieve, elliptic curve factorization, Random square factoring, Number field sieve, etc. A Prime number is a positive integer and is divisible only by itself and 1. Prime numbers are found with primality testing; an algorithm which tests a probable prime for primality. If primality testing returns false prime numbers the cryptographic algorithm may be insecure (or will not function correctly). Key generation: 1)Select random prime numbers p and q, and check that p != q 2)Compute modulus n = pq 3)Compute phi = (p - 1)(q - 1) 4)Select public exponent e, 1 < e < phi such that gcd(e,phi) = 1 5)Compute private exponent d = e^-1 mod phi Dept of CSE, MITE, Moodabidri

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6)Public key is {n, e}, private key is d Encryption: c = me mod n, decryption: m = cd mod The selected public exponent e, which is used as public key with n. It is used to encrypt messages and to verify digital signatures. The e is stored for later with n. The e is usually small number but it can be 1 < e < phi . The e must be relatively prime to phi , hence gcd(e, phi ) = 1. (gcd = greatest common divisor, using the Euclidean algorithm) The private exponent d, is the actual RSA private key. The d must not be disclosed at any time security of the RSA is compromised. The d is found by computing the multiplicative inverse

or the

d = e^-1 mod

phi . The extended Euclidean algorithm is commonly used to compute inverses. The d exponent is used to decrypt messages and to compute digital signatures. Implementations try to find as small d as possible to make decryption faster. This is fine as long as it is assured that d is about the same size as n. If it is only one quarter of size it is not considered safe to be used. It is possible to find a smaller d by using lcm(p-1,q-1) instead of phi (lcm = least common multiple, lcm(p-1,q-1) = phi /gcd(p-1,q-1) ). Example of RSA with small numbers: p = 47, q = 71, compute n = pq = 3337 Compute phi = 46 * 70 = 3220 Let e be 79, compute d = 79-1 mod 3220 = 1019 Public key is n and e, private key d, discard p and q. Encrypt message m = 688, 68879 mod 3337 = 1570 = c. Decrypt message c = 1570, 15701019 mod 3337 = 688 = m. INPUT a) Enter the two large prime number b) Enter the Value of e c) Enter the Message EXPECTED OUTPUT a) Print the cipher Text b) Print the plain Text

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PROGRAM: RSA package rsa; import java.io.DataInputStream; import java.io.IOException; import java.math.BigInteger; import java.util.Random; /** * * @author prashanth */ public class RSA { private BigInteger p; private BigInteger q; private BigInteger N; private BigInteger phi; private BigInteger e; private BigInteger d; private int bitlength = 1024; private Random r; public RSA() { r = new Random(); p = BigInteger.probablePrime(bitlength, r); q = BigInteger.probablePrime(bitlength, r); N = p.multiply(q); phi = p.subtract(BigInteger.ONE).multiply(q.subtract(BigInteger.ONE)); e = BigInteger.probablePrime(bitlength / 2, r); while (phi.gcd(e).compareTo(BigInteger.ONE) > 0 && e.compareTo(phi) < 0) { e.add(BigInteger.ONE); } d = e.modInverse(phi); } public RSA(BigInteger e, BigInteger d, BigInteger N) { this.e = e; this.d = d; this.N = N; } @SuppressWarnings("deprecation") public static void main(String[] args) throws IOException { // TODO code application logic here RSA rsa = new RSA(); DataInputStream in = new DataInputStream(System.in); String teststring; System.out.println("Enter the plain text:"); teststring = in.readLine(); System.out.println("Encrypting String: " + teststring); Dept of CSE, MITE, Moodabidri

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System.out.println("String in Bytes: "+ bytesToString(teststring.getBytes())); // encrypt byte[] encrypted = rsa.encrypt(teststring.getBytes()); // decrypt byte[] decrypted = rsa.decrypt(encrypted); System.out.println("Decrypting Bytes: " + bytesToString(decrypted)); System.out.println("Decrypted String: " + new String(decrypted)); } private static String bytesToString(byte[] encrypted) { String test = ""; for (byte b : encrypted) { test += Byte.toString(b); } return test; } // Encrypt message public byte[] encrypt(byte[] message) { return (new BigInteger(message)).modPow(e, N).toByteArray(); } // Decrypt message public byte[] decrypt(byte[] message) { return (new BigInteger(message)).modPow(d, N).toByteArray(); } } RESULT

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TITLE Write a program for congestion control using Leaky bucket algorithm

.

AIM To control congestion in computer network

DESCRIPTION The main concept of the leaky bucket algorithm is that the output data flow remains constant despite the variant input traffic, such as the water flow in a bucket with a small hole at the bottom. In case the bucket contains water (or packets) then the output flow follows a constant rate, while if the bucket is full any additional load will be lost because of spillover. In a similar way if the bucket is empty the output will be zero. From network perspective, leaky bucket consists of a finite queue (bucket) where all the incoming packets are stored in case there is space in the queue, otherwise the packets are discarded. In order to regulate the output flow, leaky bucket transmits one packet from the queue in a fixed time (e.g. at every clock tick). In the following figure we can notice the main rationale of leaky bucket algorithm, for both the two approaches (e.g. leaky bucket with water (a) and with packets (b)).

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INPUT a) Enter the Bucket Size b) Enter the flow rate c) Enter the no of packets and size EXPECTED OUTPUT a) Print the Bucket Size b) Print the flow rate c) Print the no of packet and size

PROGRAM: LEAKY BUCKET /* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */ package leakybucket; import java.util.Scanner; /** * * @author Kokila */ public class Leakybucket { /** * @param args the command line arguments */ public static void main(String[] args) { Scanner sc= new Scanner(System.in); System.out.println("Enter the bucket size="); int n=sc.nextInt(); int a[]=new int[n]; System.out.println("Enter the number of packets="); int num=sc.nextInt(); System.out.println("Enter the Data rate="); for(int i=0;i
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Computer Network Laboratory

15CSL57

if (a[i]==out) System.out.println("Packet transmited"+a[i]); else if(a[i]>out) { while(a[i]!=0 && a[i]>out) { System.out.println("Packet transmitted "+out); a[i]=a[i]-out; } System.out.println("Packet transmitted "+a[i]); } } }

} RESULT

Dept of CSE, MITE, Moodabidri

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