Note that this didn't work historically on Debian, and presumably Debian-derived distros, where the virtual file TCP access was disabled by default. The position was reversed (and the capability enabled) in 2009, AFAIU. There's discussion and links in Bug #146464:
As others have mentioned, there are numerous other ways to directly access network features using shell tools, including curl (noted in TFA's title), wget, the HEAD and GET commands (from Perl), netcat (nc), socat, telnet, and I'm quite sure others.
<https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=146464#37>
As others have mentioned, there are numerous other ways to directly access network features using shell tools, including curl (noted in TFA's title), wget, the HEAD and GET commands (from Perl), netcat (nc), socat, telnet, and I'm quite sure others.