why doesn't cat | tb work properly?

[aasutossh]

Just after entering first line it gives the link out. Shouldn't it wait for all to be typed and ctrl + d then only pipe to the termbin?

[holdenrohrer]

Because default netcat behavior (maybe only on bsd-netcat) is to not close the socket on EOF, the server closes after a 5-second timeout. You can patch this out if you're okay with using nc -N on your client.