@h4890 @sj_zero @amerika @cjd @threalist You can do it in software with just routing. Drop incoming UDP/ICMP/etc., drop incoming SYN packets, just drop everything *except* ACKSYN. Then on one side of the network, it cans end out whatever packets it wants, it can establish connections (but only send data down them, not receive any), and on the other side, the only message that can be sent is the second step of the TCP handshake.