P0F(1)P0F(1)NAMEp0f - identify remote systems passively
SYNOPSISp0f p0f [ -f file ] [ -i device ] [ -r file ] [ -o file ] [ -s socket ]
[ -u user ] [ -S limit ] [ -t c,h ] [ -m c,h ] [ -pdL ] [ 'filter rule'
]
DESCRIPTIONp0f uses a fingerprinting technique based on analyzing the structure of
a TCP/IP packet to determine the operating system and other configura‐
tion properties of a remote host. The process is completely passive and
does not generate any suspicious network traffic. The other host has to
either:
- connect to your network - either spontaneously or in an induced man‐
ner, for example when trying to establish a ftp data stream, returning
a bounced mail, performing auth lookup, using IRC DCC, external html
mail image reference and so on,
- or be contacted by some entity on your network using some standard
means (such as a web browsing); it can either accept or refuse the con‐
nection.
The method can see thru packet firewalls and does not have the restric‐
tions of an active fingerprinting. The main uses of passive OS finger‐
printing are attacker profiling (IDS and honeypots), visitor profiling
(content optimization), customer/user profiling (policy enforcement),
pen-testing, etc.
OPTIONS-f file
read fingerprints from file; by default, p0f reads signatures
from ./p0f.fp or /etc/p0f/p0f.fp (the latter on Unix systems
only). You can use this to load custom fingerprint data. Speci‐
fying multiple -f values will NOT combine several signature
files together.
-i device
listen on this device; p0f defaults to whatever device libpcap
considers to be the best (and which often isn't). On some newer
systems you might be able to specify 'any' to listen on all
devices, but don't rely on this. Specifying multiple -i values
will NOT cause p0f to listen on several interfaces at once.
-r file
read packets from tcpdump snapshot; this is an alternate mode of
operation, in which p0f reads packet from pcap data capture
file, instead of a live network. Useful for forensics (this will
parse tcpdump -w output, for example).
You can use Ethereal's text2pcap to convert human-readable
packet traces to pcap files, if needed.
-o file
write to this logfile. This option is required for -d and
implies -t.
-s socket
listen on a specified local stream socket (a filesystem object,
for example /var/run/p0f-sock) for queries. One can later send a
packet to this socket with p0f_query structure from p0f-query.h,
and wait for p0f_response. This is a method of integrating p0f
with active services (web server or web scripts, etc). P0f will
still continue to report signatures the usual way - but you can
use -qKU combination to suppress this. Also see -c notes.
A sample query tool (p0f-client) is provided in the tools/ sub‐
directory.
NOTE: The socket will be created with permissions corresponding
to your current umask. If you want to restrict access to this
interface, use caution.
-u user
this option forces p0f to chroot to this user's home directory
after reading configuration data and binding to sockets, then to
switch to his UID, GID and supplementary groups.
This is a security feature for the paranoid - when running p0f
in daemon mode, you might want to create a new unprivileged user
with an empty home directory, and limit the exposure when p0f is
compromised. That said, should such a compromise occur, the
attacker will still have a socket he can use for sniffing some
network traffic (better than rm -rf /).
-p switch card to promiscuous mode; by default, p0f listens only to
packets addressed or routed thru the machine it runs on. This
setting might decrease performance, depending on your network
design and load. On switched networks, this usually has little
or no effect.
Note that promiscuous mode on IP-enabled interfaces can be
detected remotely, and is sometimes not welcome by network
administrators.
-d go into daemon mode (detach from current terminal and fork into
background). Requires -o or -s.
-L lists all available interfaces, then quits. Particularly useful
on Windows, where the system-generated interface names are
impossible to memorize.
-S limit
Limit number of parallel API connections (default: 20)
-t c,h Set connection / host cache age limits (default: 30s,120m)
-m c,h Limit the number of active connections / hosts (default:
1000,10000)
FILTERS
The last part, 'filter rule', is a bpf-style filter expression for
incoming packets. It is very useful for excluding or including certain
networks, hosts, or specific packets, in the logfile. See man tcpdump
for more information, few examples:
´src port ftp-data´
´not dst net 10.0.0.0 mask 255.0.0.0´
´dst port 80 and ( src host 195.117.3.59 or src host 217.8.32.51 )´
BUGS
You need to consult the documentation for an up-to-date list of issues.
FILES
/etc/p0f/p0f.fp
default fingerprint database file
AUTHORp0f was written by Michal Zalewski <lcamtuf@coredump.cx>. This man
page was originally written by William Stearns <wstearns@pobox.com>,
then adopted for p0f v2 by Michal Zalewski, and p0f v3 by Pierre Chif‐
flier.
P0F(1)
