31 lines
768 B
Python
31 lines
768 B
Python
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#!/usr/bin/env python3
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"""UDP sport 8001 round trip via DNS query to 8.8.8.8."""
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import socket
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import sys
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PORT = int(sys.argv[1]) if len(sys.argv) > 1 else 8001
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s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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s.bind(("0.0.0.0", PORT))
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# DNS query: txn ID 0x1234, standard query for example.com A
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query = (
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b"\x12\x34\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00"
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b"\x07example\x03com\x00\x00\x01\x00\x01"
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)
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s.sendto(query, ("8.8.8.8", 53))
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s.settimeout(5)
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try:
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resp, addr = s.recvfrom(512)
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print(f"OK {len(resp)} bytes from {addr[0]}:{addr[1]}")
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except socket.timeout:
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print("TIMEOUT")
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sys.exit(1)
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except Exception as e:
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print(f"ERROR {e}")
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sys.exit(1)
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finally:
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s.close()
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