Script utility to check public routability of udp/tcp ports

[easye]

Use Case

Operators often have local browsers going through VPN, proxies etc. They are really interested if the "user on the command line" has access, rather than if they can visit a given site on the web.

Prototype: Linux Bourne shell script with minimal pkg adds

With something like nc installed, we can handle checking the UDP traffic as well.

[easye]

For the right ip "reflection" service, nc might be part of a solution, but it seems better to use some of the nicely hosted free services around. For instance

curl ifconfig.co/port/8080 

will return a true/false response for the public routability of packets to 8080 locally.

The code for ifconfig.co is supposedly Open Source https://github.com/mpolden/echoip, so we could potentially modify for UDP ports, if we were willing to host somewhere.

[veaceslavdoina]

We discussed a way to implement something like

• port.codex.storage/tcp/8070
• port.codex.storage/udp/8090

So, people can check their port availability. For TCP it can be implemented not so hard but for UDP nc will not work most probably:
man nc

CAVEATS
UDP port scans will always succeed (i.e. report the port as open), rendering the -uz combination of flags relatively useless.

nc -uz 1.1.1.1 22222
Connection to 1.1.1.1 22222 port [udp/*] succeeded!

And we started to think about something like "DHT pinger".