Port knocking and using ports based on IP

My latest trick for deciding on external ports to forward is to combine the service port and the device’s internal IP address. If my desktop was 10.0.1.36 and the service was SSH on port 22, the external port would be 22136. So far it’s worked well, but it only really works if you force your router to only give out 10.0.1.2 through 10.0.1.99. (snazz @ Port knocking | Hacker News)

Also: Port knocking is a method of externally opening ports on a firewall by generating a connection attempt on a set of prespecified closed ports. Once a correct sequence of connection attempts is received, the firewall rules are dynamically modified to allow the host which sent the connection attempts to connect over specific port(s). ¹

Random / Interesting

I’ve noticed a similar way of counting that’s still quite common today in China. They point with their thumb to each segment of their four fingers to count up to 12 on one hand. The other hand tracks the number of 12 counts, which lets you keep track all the way up to 144 with both hands. (modo_ at Roman Finger Counting | Hacker News)

English

All thumbs - Fig. very awkward and clumsy, especially with one’s hands.

uncouth - clumsy, awkward, unrefined, crude.