Found this out of necessity when a security team didn’t allow the installation of either telnet or nc. I initially thought ssh would work, but it doesn’t really work.
The command is simple. Just do this:
Replace the <host> and <port>. Here’s how it would look if successful:
SV-LT-1361:~ altonyu$ > /dev/tcp/192.168.0.11/2049 SV-LT-1361:~ altonyu$ echo $? 0
Here’s how it would look if unsuccessful:
SV-LT-1361:~ altonyu$ > /dev/tcp/192.168.0.11/2047 -bash: connect: Connection refused -bash: /dev/tcp/192.168.0.11/2047: Connection refused SV-LT-1361:~ altonyu$ echo $? 1
Obviously if the command hangs, it probably means it won’t work either.
Hope this helps someone!