This works:

Remote:

  $ socat TCP-LISTEN:4321,reuseaddr,fork EXEC:"bash -li",pty,stderr,setsid,sigint,rawer&
  $ dumbpipe listen-tcp --host 127.0.0.1:4321
  using secret key fe82...7efd
  Forwarding incoming requests to '127.0.0.1:4321'.
  To connect, use e.g.:
  dumbpipe connect-tcp nodeabj...wkqay

  $ dumbpipe connect-tcp --addr 127.0.0.1:4321 nodeabj...wkqay&
  using secret key fe82...7efd
  $ nc 127.0.0.1 4321
  root@localhost:~#