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Ethereal

Ethereal. The Technology Firm. What is Ethereal (From Docs.). Ethereal is a GUI network protocol analyzer. It lets you interactively browse packet data from a live network or from a previously saved capture file.

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Ethereal

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  1. Ethereal The Technology Firm

  2. What is Ethereal (From Docs.) • Ethereal is a GUI network protocol analyzer. It lets you interactively browse packet data from a live network or from a previously saved capture file. • Ethereal knows how to read libpcap capture files, including those of tcpdump, snoop (including Shomiti) and atmsnoop, LanAlyzer, Sniffer (compressed or uncompressed), Microsoft Network Monitor, AIX's iptrace, NetXray, Sniffer Pro, Etherpeek, RADCOM's WAN/LAN analyzer, Lucent/Ascend router debug output, HP-UX's nettl, the dump output from Toshiba's ISDN routers, the output from i4btrace from the ISDN4BSD project, the output in IPLog format from the Cisco Secure Intrusion Detection System, and pppd logs (pppdump format). • Display filters in Ethereal are very powerful; more fields are filterable in Ethereal than in other protocol analyzers, and the syntax you can use to create your filters is richer. As Ethereal progresses, expect more and more protocol fields to be allowed in display filters. • Packet capturing is performed with the pcap library. The capture filter syntax follows the rules of the pcap library. This syntax is different from the display filter syntax.

  3. Ethereal Screen Layout The summary line, briefly describing what the packet is. A protocol tree is shown, allowing you to drill down to exact protocol or field that you interested in. a hex dump shows you exactly what the packet looks like when it goes over the wire. Filename Of Current File

  4. Edit -> Preferences -> Columns This screen allows you to add or move columns around. For consistency, I always recommend you name your columns the same as the descriptions noted in the ‘pull down’ menu.

  5. Neat Feature – ‘Sorting Columns’ Output is Sorted By Frame No By Default Click Info Header After Sorting By Info

  6. Neat Feature – ‘Drag and Drop’ • You can now drag and drop a file from Windows Explorer directly into Ethereal.

  7. Neat Feature – ‘Follow TCP Stream’ See the next slide for the results,

  8. Neat Feature – ‘Conversation List’ • You can now see a list of all the TCP, IP or MAC addresses.

  9. Results for Follow TCP Stream • By default the red text is the data received by the client. • This color/feature may be modified via the Edit->Preferences->TCP Streams menu.

  10. How To Use The ‘Decode As’ Feature

  11. How To Rebuild A Captured Web Page Using Ethereal

  12. 1. Select ‘Follow TCP Stream’

  13. 2. Select Save As And Provide A HTML Extension

  14. 3. Open Newly Created file

  15. Capture Filters • Seems complicated at best. • The capture filter syntax follows the rules of the pcap library • This syntax is different from the display filter syntax. • Ethereal documentation asks you to check the manual page of tcpdump • Sample filters • src ip 192.168.1.1 • ether src 00:50:BA:48:B5:EF

  16. More On Capture Filters • A capture filter for HTTP than captures traffic to and from a particular host • tcp port 80 and host 10.10.10.5 • A capture filter for HTTP than captures traffic not from a particular host • tcp port 80 and not host 10.10.10.5 • A capture filter to and from an ethernet address • ether 00:00:01:01:02:22

  17. Display Filter Comparison Operators • The comparison operators can be expressed either through C-like symbols, or through English-like abbreviations: • eq, == Equal • ne, != Not equal • gt, > Greater than • lt, < Less Than • ge, >= Greater than or Equal to • le, <= Less than or Equal to

  18. GUI Display Filter

  19. Match Selected – Quick Display Filter Quick Way to Learn Display Filter Commands

  20. Save Selected Frames - OPE • Go to File -> Save Capture. • In the next screen, select the From Frame ID# radio button and enter the frame number range. • Provide location and File Name. 1 2 3

  21. How To Define A Capture FilterUsingEthereal

  22. Figure Out Your MAC Address • Go to your command prompt and type “ipconfig /all” (without the quotes). • The resulting display will contain the following info: 1 Ethernet Adapter : Description . . . . . . . . : Xircom CardBus Ethernet 10/100 Adapter Physical Address. . . . . . : 00-10-A4-E4-43-02 DHCP Enabled. . . . . . . . : Yes

  23. The Correct Way…

  24. The Wrong Way…

  25. References • http://www.ethereal.com. • ….\ethereal.html • .….\editcap.html • .….\tethereal.html • .….\text2pcap.html

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