Knock

Jul 20, 2023

Flexible port-knocking server and client

knockd is a port-knock server. It listens to all traffic on an ethernet or PPP interface, looking for special “knock” sequences of port-hits.

A client makes these port-hits by sending a TCP or UDP packet to a port on the server. This port need not be open – since knockd listens at the link-layer level, it sees all traffic even if it’s destined for a closed port. When the server detects a specific sequence of port-hits port-hits, it runs a command defined in its configuration file. This can be used to open up holes in a firewall for quick access.



Checkout these related ports:
  • Zzuf - Transparent application input fuzzer
  • Zlint - X.509 certificate linter
  • Zeronet - Decentralized websites using Bitcoin crypto and BitTorrent network
  • Zenmap - GUI frontend for the Nmap scanning utility
  • Zeek - System for detecting network intruders in real-time
  • Zaproxy - The OWASP zed attack proxy
  • Yubioath-desktop - GUI for displaying OATH codes with a Yubikey
  • Yubikey-personalization-gui - Graphical YubiKey personalization tool
  • Yubikey-manager-qt - Cross-platform application for configuring any YubiKey
  • Yubikey-agent - Seamless ssh-agent for YubiKeys
  • Yubico-piv-tool - Yubico PIV tool
  • Ylva - Command line password manager and file encryption program
  • Ykpers - Library and tool for personalization of Yubico's YubiKey
  • Ykclient - Yubico C client library
  • Yersinia - Layer 2 vulnerability scanner (switches, spanning tree, 802.1q ...)