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Port knocking

Port knocking

Port knocking definition

Port knocking is a technique for externally opening ports that by default, the firewall keeps locked. It operates by demanding connection attempts to several predefined closed ports. When the proper sequence of port “knocks“ (connection attempts) is received using a straightforward port knocking approach, the firewall opens a specific port or several ports to permit a connection. This technique is used for port protection.

Benefits of port knocking

  • Preventing an attacker’s attempt to port scan your system in search of exploitable services.
  • Making your devices immune to random cyberattacks, which are constantly probing them for weak spots.
  • Offering protection from viruses and script kiddies by functioning as an extra layer of security to the already existing ones in your system.
  • Allowing time to fix any flaws or vulnerabilities that put your devices at risk.
  • Preventing or slowing down a cyberattack by obscuring open ports.
  • Integrating additional features like cryptographically safe hashes, allowlists, blocklists, and dynamic attack responses in order to increase system capability.

Disadvantages of port knocking

  • Can’t be used as a standalone security mechanism.
  • A minor glitch can cut off an entire system.

Further reading

Ultimate digital security