68 lines
1.4 KiB
Python
68 lines
1.4 KiB
Python
#!/usr/bin/env python3
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"""Minimal NFQUEUE example: randomly drop packets by percentage."""
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import random
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import signal
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import sys
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from netfilterqueue import NetfilterQueue
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DEFAULT_LOSS_PERCENT = 10.0
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nfq = NetfilterQueue()
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loss_percent = DEFAULT_LOSS_PERCENT
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def _handle_packet(packet) -> None:
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if random.random() < (loss_percent / 100.0):
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packet.drop()
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return
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packet.accept()
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def _stop(_sig, _frame) -> None:
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raise SystemExit(0)
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def main() -> int:
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global loss_percent
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if len(sys.argv) not in (2, 3):
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print("Usage: packet_loss.py <qnum> [loss_percent]", file=sys.stderr)
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return 1
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try:
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qnum = int(sys.argv[1])
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except ValueError:
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print("qnum must be an integer", file=sys.stderr)
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return 1
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if len(sys.argv) == 3:
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try:
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loss_percent = float(sys.argv[2])
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except ValueError:
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print("loss_percent must be a number between 0 and 100", file=sys.stderr)
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return 1
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if not 0.0 <= loss_percent <= 100.0:
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print("loss_percent must be between 0 and 100", file=sys.stderr)
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return 1
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signal.signal(signal.SIGINT, _stop)
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signal.signal(signal.SIGTERM, _stop)
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nfq.bind(qnum, _handle_packet)
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try:
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nfq.run()
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except KeyboardInterrupt:
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pass
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finally:
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nfq.unbind()
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return 0
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if __name__ == "__main__":
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raise SystemExit(main())
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