Ethereal (software)

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It has been suggested that this article or section be merged into Wireshark. (Discuss)

This article is about the network traffic analyzer. For more general definitions, see the Wiktionary entry. For other uses, see Ethereal.

Ethereal
Image:Ethereal icon.png <tr><td colspan="2" style="text-align: center;">Image:Ethereal Screenshot.png Ethereal on Windows XP</td></tr><tr><th>Developer:</th><td>Ethereal</td></tr><tr><th>Latest release:</th><td>0.99.0 / April 24, 2006</td></tr><tr><th>OS:</th><td>Linux, Solaris, FreeBSD, NetBSD, OpenBSD, Mac OS X and Windows</td></tr>
Use:	Packet sniffer <tr><th>License:</th><td>GNU General Public License</td></tr>
Website:	http://www.ethereal.com/

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In computing, Ethereal is a protocol analyzer, or "packet sniffer" application, used for network troubleshooting, analysis, software and protocol development, and education. It has all of the standard features of a protocol analyzer.

The functionality Ethereal provides is very similar to tcpdump (c.f.), but it has a GUI front-end, and many more information sorting and filtering options. It allows the user to see all traffic being passed over the network (usually an Ethernet network but support is being added for others) by putting the network card into promiscuous mode.

Ethereal is released under an open source license, and it runs on most Unix and Unix-compatible systems, including Linux, Solaris, FreeBSD, NetBSD, OpenBSD, Mac OS X and Windows, as it uses the cross-platform GTK+ widget toolkit (although GTK+ only works with X11 on Mac OS X, so the user will need to run an X server such as X11.app).

Ethereal is software that "understands" the structure of different network protocols. Thus it's able to display encapsulation and single fields and interpret their meaning. Ethereal doesn't have its own code to capture packets. Ethereal uses Pcap to capture packets, so it can only capture on networks supported by Pcap.

1 Status
2 Features
3 Security
4 Author(s)
5 External links

[edit] Status

10 November 2006 -- Ethereal is not actively maintained, and hasn't been since May 2006 when the development team switched to Wireshark (see the following entry). The Ethereal download page and a security advisory recommend using Wireshark instead. The Ethereal mailing lists and source code repository have been shut down.

8 June 2006 -- When creator and lead developer Gerald Combs moved to a new job, his former employer (which holds the Ethereal trademark) would not come to an agreement allowing him to keep or use the trademark. He holds the copyright on the Ethereal source code, so he took the Subversion repository for Ethereal and used it as the basis for the Subversion repository of Wireshark. Because he had no rights to the Ethereal trademark, he could not use it with his new project. The trademark holders of Ethereal have not made any statements about Wireshark, and whether Ethereal continues to be developed separate from Wireshark has yet to be seen.

[edit] Features

Data can be captured "from the wire" from a live network connection or read from a capture file.
Live data can be read from Ethernet, FDDI, PPP, Token Ring, IEEE 802.11, Classical IP over ATM, and loopback interfaces (at least on some platforms; not all of those types are supported on all platforms).
Captured network data can be browsed via a GUI, or via the TTY-mode "tethereal" program.
Captured files can be programmatically edited or converted via command-line switches to the "editcap" program.
Display filters can also be used to selectively highlight and color packet summary information.
Data display can be refined using a display filter.
Hundreds of protocols can be dissected.
And more...
In the past the Ethereal program could run only if WinPcap was installed on the local machine, now WinPcap is already added to the Ethereal program in a complete package.
The terminal (command line) version of the utility is Tethereal, which can be very handy when working on Unix and Unix-like environments (although it's available on Windows as well)

[edit] Security

Capturing raw network traffic from an interface requires special privileges on some platforms. For this reason, Ethereal often runs as root (even on platforms where capturing raw network traffic doesn't require that).

Taking into account the huge number of protocol dissectors, which are called when traffic for their protocol is captured, this can pose a serious security risk given a bug in a dissector. Due to the rather large number of vulnerabilities in the past (of which many even allowed remote code execution) and doubts of developers for better future development, OpenBSD removed Ethereal from its ports tree prior to its 3.6 release.

[edit] Author(s)

Out of necessity, Gerald Combs (a computer science graduate of the University of Missouri-Kansas City) started writing the Ethereal code so that he could have a tool to capture and analyze packets; he released the first version around 1998. Pretty soon, this free software protocol analyzer caught on. As of now there are over 500 contributing authors while Gerald continues to maintain the overall code and issues releases of new versions. The entire list of authors is available from Ethereal's web-site.