10 lines
587 B
Plaintext
10 lines
587 B
Plaintext
Knockd and knock are a port-knock server and client,
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respectively. Knockd listens to all traffic on an ethernet (or PPP)
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interface, looking for special "knock" sequences of port-hits. A
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client makes these port-hits by sending a TCP (or UDP) packet to a
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port on the server. This port need not be open -- since knockd listens
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at the link-layer level, it sees all traffic even if it's destined
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for a closed port. When the server detects a specific sequence of
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port-hits, it runs a command defined in its configuration file. This
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can be used to open up holes in a firewall for quick access.
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