08-18-2010
Nothing bad happens when you write to both ends at the same time. What precisely happens when depends on a lot of things like buffers, framing, and transit time, but two-way traffic is still just business as usual. If the data has arrived by the time one of them finishes a write(), yes, a read() may be able to get it.
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LEARN ABOUT DEBIAN
guessnet-scan
GUESSNET-SCAN(8) System Manager's Manual GUESSNET-SCAN(8)
NAME
guessnet-scan - guess network configuration data by looking at network traffic
SYNOPSIS
guessnet-scan [options] [ethernet_interface]
DESCRIPTION
Guessnet-scan tries to deduce network configuration data by watching network traffic at a given Ethernet interface.
After scanning network traffic for some time, guessnet-scan prints a configuration string suitable for inclusion in /etc/network/inter-
faces.
Note that guessnet-scan uses heuristics and wild guesses and that the resulting data is not guaranteed to be accurate. The program is
intended to be used as a first try at getting network configuration data without bothering anyone.
OPTIONS
Options follow the usual GNU conventions,
--debug
Print debugging messages.
--help Show a brief summary of commandline options.
--init-time=int
Time in seconds to wait for the interface to initialize when it is not found already up at program startup. Default: 3 seconds.
-t, --timeout=int
Time in seconds to watch for network traffic. Default: 5 seconds.
-v, --verbose
Operate verbosely.
--version
Show the version number of the program.
SCANNING REQUIREMENTS
To correctly identify all data of the local network, guessnet-scan needs to see traffic related to a host in the local network and to the
local gateway, if any.
To be able to identify the network gateway, guessnet-scan also needs to see some traffic directed to the external network: you can help the
detection by generating some outbound IP traffic during the scan, for example by browsing a web page (without proxy) or using telnet to
open a connection to some remote host.
Note that if you are connected to a switch, guessnet-scan won't probably be able to work, since the switch will isolate it from the network
traffic that the other machines are generating.
SEE ALSO
guessnet(8), interfaces(5).
AUTHOR
Guessnet-scan was written by Enrico Zini <enrico@debian.org>.
10 October 2004 GUESSNET-SCAN(8)