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46 lines
1.3 KiB
Python
46 lines
1.3 KiB
Python
"""Sniff for network packets using tcpdump/tshark"""
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import os
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import signal
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import subprocess
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import tempfile
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import time
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class Sniffer:
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"""Helper class for tcpdump"""
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def __init__(self, netns, expr):
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self.pcap = tempfile.NamedTemporaryFile(suffix=".pcap", delete=False)
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self.expr = expr
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self.netns = netns
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self.proc = None
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def __del__(self):
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self.pcap.close()
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os.unlink(self.pcap.name)
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def __enter__(self):
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cmd = f"tshark -lni iface -w {self.pcap.name} {self.expr}"
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arg = cmd.split(" ")
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self.proc = self.netns.popen(arg, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
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def __exit__(self, _, __, ___):
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if not self.proc:
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return False
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self.proc.send_signal(signal.SIGINT)
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time.sleep(1)
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if not self.proc.poll():
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try:
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self.proc.kill()
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except OSError:
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pass
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self.proc.wait()
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def output(self):
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"""Return PCAP output"""
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return self.netns.runsh(f"tcpdump -n -r {self.pcap.name}")
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def packets(self):
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"""Filtered text output, skipping tcpdump "reading from file" initial line"""
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lines = self.output().stdout.split('\n')
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return '\n'.join(lines[1:])
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