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Life & fun · May 17, 2017

TB

TOTP Based Port Knocking -- two factor firewall

Introduction This is a proof of concept for using TOTP with a shared key between client and server to gain access to a normally closed secure...

TOTP Based Port Knocking -- two factor firewall launched on May 17, 2017 with 5 votes and more than 50% of that year's launches. The site was still online in September 2026, 9 years on.

Visit dhj.io ↗Alternatives

What it does

This is a proof of concept for using TOTP with a shared key between client and server to gain access to a normally closed secure shell (ssh) port. Port knocking is typically implemented as a series of connection attempts to a "secret" sequence of ports. When the correct sequence of connetions are attempted (none of which form a complete connection) the firewall identifies this sequence and opens the desired port (typically ssh, port 22). The effect of this is that the sensitive ssh port can remain silent, not responding to any connection attempt, until the knock sequence occurs. This is helpful because attack probes will generally not be able to identify that ssh is available for connection…from dhj.io

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