Combine and send data from stdin and fifo to a tcp socket.
I use radare2's rarun2 for CTFs.
Rarun2 has a neat little feature, which allows binding std{in,out} of the debugged binary to a tcp socket, to which i can connect via nc from another terminal.
It is perfect, but you won't be able to send binary input (like addresses, etc.).
With tcpcombo, you can connect to a listening tcp socket, transfer text data via stdin/stdout AND transfer binary data by writing to a pipe.