TsharkService

Create a service that inherits from TsharkService and override the packetReceived method to handle incoming packets:

from twisted.python import log
from txshark import TsharkService


class SnifferService(TsharkService):

    def packetReceived(self, packet):
        """Override the TsharkService method"""
        log.msg("Packet received: {}".format(packet)

The interfaces to listen to should be given as a list of {"name": <name>, "filter": <filter>}. This allows to give a specific filter to each interface:

service = SnifferService(
    [{"name": "eth0", "filter": "tcp and port 8521"},
     {"name": "eth1", "filter": "tcp and port 8522"}])

To read packets from a captured file, just give the name of the file instead of the interface. If a filter is used in this case, it should be a display filter (syntax different from a capture filter):

service = SnifferService(
    [{"name": "test.pcap", "filter": "tcp.port == 8501"}])

The filter is optional in both case.

The service can be started with the startService method:

service.startService()

But as a Twisted Service, it is designed to be started automatically by a Twisted Application. Refer to Twisted documentation for more information.

Accessing packet data

Data can be accessed in multiple ways. Packets are divided into layers, first you have to reach the appropriate layer and then you can select your field.

All of the following work:

packet['ip'].dst
>>> 192.168.0.1
packet.ip.src
>>> 192.168.0.100
packet[2].src
>>> 192.168.0.100