Network Analyzer Example

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Network Analyzer Example
Internet

• User clicks on http//www.nytimes.com/
• Ethereal network analyzer captures all frames
  observed by its Ethernet NIC
• Sequence of frames and contents of frame can be
  examined in detail down to individual bytes

Ethereal web site, http//www.ethereal.com/
(This material is for self study.))
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Ethereal Protocol Analyzer

• A network protocol analyzer is a tool for
  capturing, displaying, and analyzing the PDUs
  that are exchanged in a network. Current
  analyzers cover a very broad range of protocols
  and are constantly being updated. Protocol
  analyzers are also extremely useful in teaching
  the operation of protocols by providing a means
  of examining traffic from a live network.
• Communication Networks uses the Ethereal open
  source package, which supports an extensive set
  of protocols, including PPP, HDLC, Ethernet,
  MPLS, IP, IPv6, ARP, ICMP, RIP, OSPF, UDP, TCP,
  DNS, HTTP, telnet, FTP, RSVP, RTP, SIP, H.323,
  SSL and TLS, PING, and traceroute.
• Ethereal can be run in two modes. In the first
  mode, the Ethereal application opens existing
  packet capture files for analysis. In the second
  mode the Ethereal application captures a frame
  sequence in real time and then stores the result
  in a packet capture file. In this document we
  provide a number of packet capture files that can
  be used by the instructor to demonstrate and
  analyze protocols in class. In a separate
  document we provide lab experiments for capturing
  these frame sequences.
• The Ethereal package can be downloaded from
  www.ethereal.com. Their web site also contains
  instructions and example screen captures.

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Ethereal windows
Middle Pane shows encapsulation for a given frame
Top Pane shows frame/packet sequence
Bottom Pane shows hex text
4
Top pane frame sequence
TCP Connection Setup
DNS Query
HTTP Request Response
5
Middle pane Encapsulation
Ethernet Frame
Ethernet Destination and Source Addresses
Protocol Type
6
Middle pane Encapsulation
And a lot of other stuff!
IP Packet
IP Source and Destination Addresses
Protocol Type
7
Middle pane Encapsulation
TCP Segment
Source and Destination Port Numbers
GET
HTTP Request