69 lines
2.8 KiB
Plaintext
69 lines
2.8 KiB
Plaintext
# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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DOC = """\
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lansim is a LAN simulator that runs over a TAP network interface and
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allows to simulate network traffic on that interface from Python code.
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A TAP interface is a virtual network kernel device that acts as any
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other network interface, except that instead of sending and receiving
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the traffic through a hardware interface it allows a given program to
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handle that traffic through a socket. It is essentially a
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bi-directional pipe where one side is a network interface and the
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other side is a socket on a program.
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The lansim Simulator class allows a Python function to attend all the
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outbound traffic matching certain rules and take an action over that
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like send back a packet to this interface. The kernel network stack
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will see this packet as an inbound packet from the fake interface.
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These actions can also be time driven, like a simulation timeout or
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send a ping packet every second.
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This simulator is useful on situations where you can't fake a network
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service using the normal kernel network stack. For example, if you
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need to fake a network of several hosts publishing services via mDNS
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with multicast you can write those services using this simulator but
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it's more complicated to do the same using the system's network stack
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since an outbound multicast packet will be sent out on the real
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interface.
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The Simulator class requires a TAP network interface and allows other
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Python classes to subscribe to its traffic. The TAP interface needs to
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be up when the Simulator runs.
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For example, to create a tap interface you can do the following:
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tap = tuntap.TunTap(tuntap.IFF_TAP, name="faketap")
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print "Interface running on", tap.name
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This will create a TAP interface with a name like "faketap0". You can
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then configure it manually, or just bring it up without an IP address
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if you have a Python class implementing a fake DHCP server to
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configure it later. To set the IP address manually, you can use any
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system command like "ip" or "ifconfig", or from Python in this way:
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tap.set_addr("192.168.0.123")
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tap.up()
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A very simple example of the usage of this simulator is the
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following, where three hosts are created on the faketap0 interface
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and will respond to ARP requests. Running the command
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"arping -I faketap0 192.168.0.4" will show two responses for that
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given IP address:
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simu = simulator.SimulatorThread(tap)
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host_a = host.SimpleHost(simu, '12:34:56:78:90:AB', '192.168.0.3')
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host_b = host.SimpleHost(simu, '12:34:56:78:90:CD', '192.168.0.4')
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host_c = host.SimpleHost(simu, '12:34:56:78:90:EF', '192.168.0.4')
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simu.start() # Run the thread.
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print "Press enter to stop the simulation."
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raw_input()
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simu.stop()
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simu.join()
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"""
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job.setup_dep(['lansim'])
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