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import ctypes
import signal
import datetime
import threading
# This is a Python 3 demo of how to interact with the Nethogs library via Python. The Nethogs
# library operates via a callback. The callback implemented here just formats the data it receives
# and prints it to stdout. This must be run as root (`sudo python3 python-wrapper.py`).
# By Philip Semanchuk (psemanchuk@caktusgroup.com) November 2016
# Copyright waived; released into public domain as is.
# The code is multi-threaded to allow it to respond to SIGTERM and SIGINT (Ctrl+C). In single-
# threaded mode, while waiting in the Nethogs monitor loop, this Python code won't receive Ctrl+C
# until network activity occurs and the callback is executed. By using 2 threads, we can have the
# main thread listen for SIGINT while the secondary thread is blocked in the monitor loop.
#######################
# BEGIN CONFIGURATION #
#######################
# You can use this to monitor only certain devices, like:
# device_names = ['enp4s0', 'docker0']
device_names = []
# LIBRARY_NAME has to be exact, although it doesn't need to include the full path.
# The version tagged as 0.8.5 (download link below) builds a library with this name.
# https://github.com/raboof/nethogs/archive/v0.8.5.tar.gz
LIBRARY_NAME = 'libnethogs.so.0.8.5'
# EXPERIMENTAL: Optionally, specify a capture filter in pcap format (same as
# used by tcpdump(1)) or None. See `man pcap-filter` for full information.
# Note that this feature is EXPERIMENTAL (in libnethogs) and may be removed or
# changed in an incompatible way in a future release.
# example:
# FILTER = 'port 80 or port 8080 or port 443'
FILTER = None
#####################
# END CONFIGURATION #
#####################
# Here are some definitions from libnethogs.h
# https://github.com/raboof/nethogs/blob/master/src/libnethogs.h
# Possible actions are NETHOGS_APP_ACTION_SET & NETHOGS_APP_ACTION_REMOVE
# Action REMOVE is sent when nethogs decides a connection or a process has died. There are two
# timeouts defined, PROCESSTIMEOUT (150 seconds) and CONNTIMEOUT (50 seconds). AFAICT, the latter
# trumps the former so we see a REMOVE action after ~45-50 seconds of inactivity.
class Action():
SET = 1
REMOVE = 2
MAP = {SET: 'SET', REMOVE: 'REMOVE'}
class LoopStatus():
"""Return codes from nethogsmonitor_loop()"""
OK = 0
FAILURE = 1
NO_DEVICE = 2
MAP = {OK: 'OK', FAILURE: 'FAILURE', NO_DEVICE: 'NO_DEVICE'}
# The sent/received KB/sec values are averaged over 5 seconds; see PERIOD in nethogs.h.
# https://github.com/raboof/nethogs/blob/master/src/nethogs.h#L43
# sent_bytes and recv_bytes are a running total
class NethogsMonitorRecord(ctypes.Structure):
"""ctypes version of the struct of the same name from libnethogs.h"""
_fields_ = (('record_id', ctypes.c_int),
('name', ctypes.c_char_p),
('pid', ctypes.c_int),
('uid', ctypes.c_uint32),
('device_name', ctypes.c_char_p),
('sent_bytes', ctypes.c_uint64),
('recv_bytes', ctypes.c_uint64),
('sent_kbs', ctypes.c_float),
('recv_kbs', ctypes.c_float),
)
def signal_handler(signal, frame):
print('SIGINT received; requesting exit from monitor loop.')
lib.nethogsmonitor_breakloop()
def dev_args(devnames):
"""
Return the appropriate ctypes arguments for a device name list, to pass
to libnethogs ``nethogsmonitor_loop_devices``. The return value is a
2-tuple of devc (``ctypes.c_int``) and devicenames (``ctypes.POINTER``)
to an array of ``ctypes.c_char``).
:param devnames: list of device names to monitor
:type devnames: list
:return: 2-tuple of devc, devicenames ctypes arguments
:rtype: tuple
"""
devc = len(devnames)
devnames_type = ctypes.c_char_p * devc
devnames_arg = devnames_type()
for idx, val in enumerate(devnames):
devnames_arg[idx] = (val + chr(0)).encode('ascii')
return ctypes.c_int(devc), ctypes.cast(
devnames_arg, ctypes.POINTER(ctypes.c_char_p)
)
def run_monitor_loop(lib, devnames):
# Create a type for my callback func. The callback func returns void (None), and accepts as
# params an int and a pointer to a NethogsMonitorRecord instance.
# The params and return type of the callback function are mandated by nethogsmonitor_loop().
# See libnethogs.h.
CALLBACK_FUNC_TYPE = ctypes.CFUNCTYPE(
ctypes.c_void_p, ctypes.c_int, ctypes.POINTER(NethogsMonitorRecord)
)
filter_arg = FILTER
if filter_arg is not None:
filter_arg = ctypes.c_char_p(filter_arg.encode('ascii'))
if len(devnames) < 1:
# monitor all devices
rc = lib.nethogsmonitor_loop(
CALLBACK_FUNC_TYPE(network_activity_callback),
filter_arg
)
else:
devc, devicenames = dev_args(devnames)
rc = lib.nethogsmonitor_loop_devices(
CALLBACK_FUNC_TYPE(network_activity_callback),
filter_arg,
devc,
devicenames,
ctypes.c_bool(False)
)
if rc != LoopStatus.OK:
print('nethogsmonitor_loop returned {}'.format(LoopStatus.MAP[rc]))
else:
print('exiting monitor loop')
def network_activity_callback(action, data):
print(datetime.datetime.now().strftime('@%H:%M:%S.%f'))
# Action type is either SET or REMOVE. I have never seen nethogs send an unknown action
# type, and I don't expect it to do so.
action_type = Action.MAP.get(action, 'Unknown')
print('Action: {}'.format(action_type))
print('Record id: {}'.format(data.contents.record_id))
print('Name: {}'.format(data.contents.name))
print('PID: {}'.format(data.contents.pid))
print('UID: {}'.format(data.contents.uid))
print('Device name: {}'.format(data.contents.device_name.decode('ascii')))
print('Sent/Recv bytes: {} / {}'.format(data.contents.sent_bytes, data.contents.recv_bytes))
print('Sent/Recv kbs: {} / {}'.format(data.contents.sent_kbs, data.contents.recv_kbs))
print('-' * 30)
############# Main begins here ##############
signal.signal(signal.SIGINT, signal_handler)
signal.signal(signal.SIGTERM, signal_handler)
lib = ctypes.CDLL(LIBRARY_NAME)
monitor_thread = threading.Thread(
target=run_monitor_loop, args=(lib, device_names,)
)
monitor_thread.start()
done = False
while not done:
monitor_thread.join(0.3)
done = not monitor_thread.is_alive()
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