NAME
arp-fingerprint - Fingerprint a system using ARP
SYNOPSIS
arp-fingerprint [options] target
The target should be specified as a single IP address or hostname. You
cannot specify multiple targets, IP networks or ranges.
If you use an IP address for the target, you can use the -o option to
pass the --numeric option to arp-scan, which will prevent it from
attempting DNS lookups. This can speed up the fingerprinting process,
especially on systems with a slow or faulty DNS configuration.
DESCRIPTION
arp-fingerprint fingerprints the specified target host using the ARP
protocol.
It sends various different types of ARP request to the target, and
records which types it responds to. From this, it constructs a
fingerprint string consisting of "1" where the target responded and "0"
where it did not. An example of a fingerprint string is 01000100000.
This fingerprint string is then used to lookup the likely target
operating system.
Many of the fingerprint strings are shared by several operating
systems, so there is not always a one-to-one mapping between
fingerprint strings and operating systems. Also the fact that a
system’s fingerprint matches a certain operating system (or list of
operating systems) does not necessarily mean that the system being
fingerprinted is that operating system, although it is quite likely.
This is because the list of operating systems is not exhaustive; it is
just what I have discovered to date, and there are bound to be
operating systems that are not listed.
The ARP fingerprint of a system is generally a function of that
system’s kernel (although it is possible for the ARP function to be
implemented in user space, it almost never is).
Sometimes, an operating system can give different fingerprints
depending on the configuration. An example is Linux, which will
respond to a non-local source IP address if that IP is routed through
the interface being tested. This is both good and bad: on one hand it
makes the fingerprinting task more complex; but on the other, it can
allow some aspects of the system configuration to be determined.
Sometimes the fact that two different operating systems share a common
ARP fingerprint string points to a re-use of networking code. One
example of this is Windows NT and FreeBSD.
arp-fingerprint uses arp-scan to send the ARP requests and receive the
replies.
There are other methods that can be used to fingerprint a system using
arp-scan which can be used in addition to arp-fingerprint. These
additional methods are not included in arp-fingerprint either because
they are likely to cause disruption to the target system, or because
they require knowledge of the target’s configuration that may not
always be available.
arp-fingerprint is still being developed, and the results should not be
relied on. As most of the ARP requests that it sends are non-standard,
it is possible that it may disrupt some systems, so caution is advised.
If you find a system that arp-fingerprint reports as UNKNOWN, and you
know what operating system it is running, could you please send details
of the operating system and fingerprint to arp-scan@nta-monitor.com so
I can include it in future versions. Please include the exact version
of the operating system if you know it, as fingerprints sometimes
change between versions.
OPTIONS
-h Display a brief usage message and exit.
-v Display verbose progress messages.
-o <option-string>
Pass specified options to arp-scan. You need to enclose the
options string in quotes if it contains spaces. e.g. -o "-I
eth1". The commonly used options are --interface (-I) and
--numeric (-N).
EXAMPLES
$ arp-fingerprint 192.168.0.1
192.168.0.1 01000100000 Linux 2.2, 2.4, 2.6
$ arp-fingerprint -o "-N -I eth1" 192.168.0.202
192.168.0.202 11110100000 FreeBSD 5.3, Win98, WinME, NT4, 2000, XP, 2003
NOTES
arp-fingerprint is implemented in Perl, so you need to have the Perl
interpreter installed on your system to use it.
AUTHOR
Roy Hills <Roy.Hills@nta-monitor.com>
SEE ALSO
arp-scan(1)
http://www.nta-monitor.com/wiki/ The arp-scan wiki page.
April 5, 2007