Not the law, but a good idea.
Port knocking: a stealthy system for network authentication across closed ports
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port knocking > knocklab > knock_lab

Port Knocking Lab

Perl prototype: v0.30

  • pcaplib support added; daemon no longer requires firewall log file

2004-Nov-14 18:59 | ...more

new Net::Pcap support added to sniff packets directly ...more

Try creating your own encrypted knock sequences. Use the knock sequence maker to experiment with encryption and decryption of the type of information that might be contained in a typical knock sequence. This application does not try to knock or connect to any hosts. Experiment at will.
required for encryptionrequired for encryption | optional for encryptionoptional for encryption | required for decryptionrequired for decryption
ip(e.g., 66.35.1.10, 66.35/16)
required for encryption
mask(include IP mask in knock sequence)
optional for encryption
port(choose a port)
required for encryption
custom porte.g. 119 (must be <256)
optional for encryption
time flag(0-255)
required for encryption
min knock port(0-65535)
required for decryption required for encryption
cipher
required for decryption required for encryption
IV (use initalization vector)
optional for encryption
password
required for decryption required for encryption
encrypted port knock sequence
decrypted port knock sequence
IP1 IP2 IP3 IP4 MASK(optional) PORT TIME CRC

   
last updated 2009-Dec-09 14:01
Port Knocking (c) 2002-2017 Martin Krzywinski