2 ms·

You don't even need netcat or socat for that, probing /dev/tcp/<host>/<port> from the shell is enough.

• hibbelig 9mo ago
  Telnet was available in the 90s. I reckon /dev/tcp is way more recent. GP did say a long time ago.
• geocar 9mo ago
  That's some gnu bash shenanigans. There is no /dev/tcp in unix Lots of shops didn't have gnu installed: telnet was what we had.