Wireshark Rahul Hiran TDTS11Computer Networks and Internet Protocols 1 Note T he slides are adapted and modified based on slides from the books companion Web site as well as modified slides by ID: 329225
Download Presentation The PPT/PDF document "Protocol layers and" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Protocol layers and
Wireshark
Rahul HiranTDTS11:Computer Networks and Internet Protocols
1
Note: The slides are adapted and modified based on slides from the book’s companion Web site, as well as modified slides by Niklas Carlsson
Textbook: “Computer Networking: A Top Down Approach”, by Jim Kurose and Keith Ross. Slide2
What will I talk about?Short description from lecture 1 about computer networksInternet protocol stackHow to see what different stack layer doesUsing network analysis tool called wireshark2Slide3
What’s the Internet: Slide from lecture 1millions of connected computing devices: hosts = end systems
running network apps
Home network
Institutional network
Mobile network
Global ISP
Regional ISP
router
PC
server
wireless
laptop
cellular
handheld
wired
links
access
points
communication links
fiber, copper, radio,
satellite
routers:
forward packets (chunks of data)
Introduction 1-
3
3Slide4
What’s a protocol?(slide from lecture 1)human protocols:“what’s the time?”
“I have a question”introductions… specific msgs sent… specific actions taken when msgs received, or other events
network protocols:machines rather than humansall communication activity in Internet governed by protocolsprotocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt
Introduction 1-
4
4Slide5
More about protocolsThere are many protocols that are involved in working of computer networkThere is a internet protocol stack. A protocol normally belongs to one of the layers in the stack.Let us look at the airline functionality
5Slide6
ticket (purchase)
baggage (check)gates (load)
runway (takeoff)airplane routing
departure
airportarrival
airport
intermediate air-traffic
control centers
airplane routing
airplane routing
ticket (complain)
baggage (claim
gates (unload)
runway (land)
airplane routing
ticket
baggage
gate
takeoff/landing
airplane routing
Layering of airline functionality
Layers:
each layer implements a service
via its own internal-layer actions
relying on services provided by layer below
Introduction 1-
6
6Slide7
Internet protocol stack
application: supporting network applicationsFTP, SMTP, HTTPtransport: process-process data transfer
TCP, UDPnetwork: routing of datagrams from source to destinationIP, routing protocolslink: data transfer between neighboring network elementsEthernet, 802.111 (WiFi), PPPphysical: bits “on the wire”
application
transportnetwork
link
physical
Introduction 1-
7
7Slide8
Encapsulation
8Slide9
wiresharkHow can we analyze the network data?Using tools such as wiresharkWireshark: a network packet analyzer. A network packet analyzer will try to capture network packets and tries to display that packet data as detailed as possible.Let us start wireshark….!
9Slide10
Start screen of wireshark
10Slide11
Make your own capture or open existing trace files
11Slide12
Graphical User Interface12Slide13
Reduce clutterDisable the checksum error messages from Views->Coloring rules…menu itemEnter data in the filter to show only http packetsLet us look at the example13Slide14
After unnecessary data is removed14Slide15
Let us look at the application level data15Slide16
Internet protocol stack
application: supporting network applicationsFTP, SMTP, HTTPtransport:
process-process data transferTCP, UDP TCP is responsible for the establishment of a TCP connection, the sequencing and acknowledgment of packets sent, and the recovery of packets lost during transmissionnetwork: routing of datagrams from source to destinationIP, routing protocolslink: data transfer between neighboring network elementsEthernet, 802.111 (WiFi), PPP
physical: bits “on the wire”
application
transport
network
Link
physical
Introduction 1-
16
16Slide17
Encapsulation
17Slide18
TCP header18Slide19
TCP header data in our packet19Slide20
How to look at time/sequence plotSelect tcp-ethereal-trace-1Filter by entering tcpSelect TCP segmentGo to statistics-> TCP streamgraph -> Time-sequence graph (stevens)
20Slide21
Internet protocol stack
application: supporting network applicationsFTP, SMTP, HTTPtransport:
process-process data transferTCP, UDP network: routing of datagrams from source to destinationIP, routing protocolsThe Internet layer is responsible for addressing, packaging, and routing functions.link: data transfer between neighboring network elementsEthernet, 802.111 (WiFi), PPP
physical: bits “on the wire”
application
transport
network
Link
physical
Introduction 1-
21
21Slide22
Encapsulation
22Slide23
Internet layerLet us first open ip-ethereal-trace-1And look at the first ICMP messageWe also look at the IP protocol header format23Slide24
IP header24Slide25
IP header in collected traces25Slide26
Internet protocol stack
application: supporting network applicationsFTP, SMTP, HTTPtransport:
process-process data transferTCP, UDP network: routing of datagrams from source to destinationIP, routing protocols.link: data transfer between neighboring network elementsEthernet, 802.111 (WiFi), PPPphysical: bits “on the wire”
application
transport
network
Link
physical
Introduction 1-
26
26Slide27
What’s the Internet: Slide from lecture 1
Home network
Institutional network
Mobile network
Global ISP
Regional ISP
Introduction 1-
27
27
Network layers job is end-to-end movement of data from source to destination
Link layers job is node-to-node movement of network-layer datagrams over a single link in the path
Ethernet is quite popular protocol
Let us look at the headerSlide28
Ethernet header and trailer
28Slide29
Conclusion
application: supporting network applicationsFTP, SMTP, HTTPtransport:
process-process data transferTCP, UDPnetwork: routing of datagrams from source to destinationIP, routing protocolslink: data transfer between neighboring network elementsEthernet, 802.111 (WiFi), PPPphysical: bits “on the wire”
application
transportnetwork
link
physical
Introduction 1-
29
29Slide30
Conclusion
30Slide31
31Questions…?Slide32
www.liu.se
32