guessnet - guess which LAN a network interface is connected to

guessnet [options] [network_interface]

Guessnet guesses which LAN a network interface is connected to. Given a list of candidate profiles each of which includes a test description, guessnet runs all the tests in parallel and prints the name of the profile whose test was the first one to succeed. If no test succeeds within a certain timeout period then a default profile name is printed. After printing a profile name, guessnet immediately kills any tests that are still running and exits.

Candidate profiles are read either from a test description file or, in ifupdown mode, from /etc/network/interfaces.

Options follow the usual GNU conventions. In ifupdown mode, options can also be specified on the standard input in the form "<long-option-name>: <value>".

-C, --config-file=filename

Name of the configuration file to use if not specified on command line. Default: standard input or /etc/network/interfaces in ifupdown mode.

--debug

Print debugging messages.

-d, --default=string

Interface name to print if no known networks are found. Default: none.

--help

Show a brief summary of command line options.

-i, --ifupdown-mode

Operate in ifupdown mode: parse the input as if it is in the format of /etc/network/interfaces and read from /etc/network/interfaces instead of the standard input if the configuration filename is not specified. See the ifupdown mode section below for details.

--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

Timeout in seconds used to wait for tests to terminate. Default: 5 seconds.

-v, --verbose

Operate verbosely.

--version

Show the version number of the program.

guessnet takes as input a description of the tests it should perform. The test description file looks like this:

  # Empty lines and lines starting with '#' are ignored.
  # Other lines contain:
  #   <profile-name> <test-method> <parameters>

# At home, look for a host with the given IP and MAC address home peer 192.168.1.1 00:01:02:03:04:05

# At the university, check for the presence of at least one # of the following hosts university peer 130.136.1.1 05:06:03:02:01:0A university peer 130.136.1.2 15:13:B3:A2:2F:CD

# If the peer doesn't reply to ARP packets coming from 0.0.0.0 # then you can additionally specify a source address to use university peer 130.136.1.2 15:13:B3:A2:2F:CD 130.136.1.250

# For the work network use a custom script work command /usr/local/bin/check_work

# Commands are executed by "sh -c" so shell syntax can be used john-irda command grep -q `cat ~enrico/john-irda-id` /proc/net/irda/discovery

# Location name and interface name are exported in NAME and IFACE weirdnet command /usr/local/bin/weirddetect "$NAME" "$IFACE"

# Profile "none" is selected if no network signal is detected # (i.e. there is no cable plugged into the socket) no-net missing-cable

Every non-comment line represents a test to perform.

The first word in the line is the name that will be printed if the test succeeds.

The second word is the test type.

The remainder of the line contains parameters for the selected test; these vary depending on the test type.

ifupdown, Debian's standard network configuration system, permits one to define different "logical interfaces" (ifupdown's name for configuration profiles) and to choose among them when one configures a network interface. The choice can be delegated to an external "mapping" program. guessnet can be used as such a program if it is run in "ifupdown mode". guessnet runs in ifupdown mode if it is invoked as guessnet-ifupdown or if it is given the --ifupdown-mode option.

In ifupdown mode guessnet reads test data directly from the logical interface definitions in /etc/network/interfaces rather than from a separate test description file.

In ifupdown mode if names are passed to guessnet on its standard input then guessnet considers only those logical interface definitions; otherwise it considers them all. You can have ifupdown deliver data to guessnet's standard input using the map directive. See interfaces(5) for more information.

In ifupdown mode options are selected by passing "<long-option-name>: <value>" on guessnet's standard input. This feature is provided because ifupdown cannot pass command line arguments to mapping scripts.

If you prefer you can precede the test keyword in /etc/network/interfaces with the word guessnet.

ifupdown does not allow two option lines in /etc/network/interfaces to start with the same word. To work around this limitation, multiple test (or guessnet) lines can have different numerals suffixed to their initial keywords (test1, test2, or guessnet1, guessnet2, and so on).

Here's an example of an /etc/network/interfaces file that has been set up for guessnet:

auto lo eth0

iface lo inet loopback

mapping eth0 script guessnet-ifupdown # Scan all logical interfaces # More options can be given here, such as: # map timeout: 10 # map verbose: true # map debug: true map default: none

iface home inet static address 192.168.1.2 netmask 255.255.255.0 broadcast 192.168.1.255 gateway 192.168.1.1

# Lines for resolvconf (if you use it: see apt-cache show resolvconf) # dns-search casa # dns-nameservers 192.168.1.1 192.168.2.1

# Two tests, in case one of the two machines is down when we test test1 peer address 192.168.1.1 mac 00:01:02:03:04:05 test2 peer address 192.168.1.3 mac 00:01:02:03:04:06

iface work inet static address 10.1.1.42 netmask 255.255.255.0 broadcast 10.1.1.255 gateway 10.1.1.1 test command /usr/local/bin/check_work

iface work2 inet static address 192.168.2.23 netmask 255.255.255.0 broadcast 192.168.2.255 gateway 192.168.2.1 # A source address has to be specified in case the peer # doesn't reply to ARP packets coming from 0.0.0.0 test peer address 192.168.2.1 mac 00:01:02:03:04:05 source 192.168.2.23

# If nothing else is found, try DHCP iface none inet dhcp

peer

missing-cable

command

pppoe

wireless

Getting remote host MAC addresses

Multiple tests

ifup(8), interfaces(5), arping(8), sh(1), pppoe(8), ifplugd(8), waproamd(8).

Guessnet was written by Enrico Zini <enrico@debian.org> with contributions from Thomas Hood. The ARP network detection code was taken from laptop-netconf by Matt Kern <matt@debian.org>, which in turn in based on divine by Felix von Leitner <felix@fefe.de>.

The Guessnet webpage is at http://guessnet.alioth.debian.org .