Exactly. Its been available for a while now on most distros, I even used it on some legacy AIX systems running Korn shell. Btw, the reason why this works even

Exactly. Its been available for a while now on most distros, I even used it on some legacy AIX systems running Korn shell. Btw, the reason why this works even if you dont see anything in /dev/tcp is because when you try to open a socket in bash using /dev/tcp it doesn't talk with the pseudo-filesystem of /dev. Bash actually intercepts the command and issues a connect() to the remote host.