The approach by ssh-mitm differs quite significantly as already mentioned by Manfred Kaiser in the issue linked above. Most significantly, ssh-mitm basically establishes two connections (one as a server, one as a client) and forwards messages between the two. This however requires the client to accept the hostkey from the MitM (or the MitM to get a hold on the private key of the server's hostkey). In comparison, our attack manipulates a single connection, without the attacker knowing the hostkey or a client accepting a malicious hostkey. For more details, see the issue here: https://github.com/ssh-mitm/ssh-mitm/issues/165