private void startAcceptor() throws ConnectionException {
    int p = port;

    createServerSocket();

    int localPort;
    try {
      localPort = socket.getLocalPort();

      id = new InetSocketAddress(socket.getInetAddress(), localPort);
      stopped = false;
      thread = new LoggingThread("P2P Listener Thread " + id, this);
      try {
        thread.setPriority(Thread.MAX_PRIORITY);
      } catch (Exception e) {
        logger.info("unable to set listener priority: {}", e.getMessage());
      }
      if (!Boolean.getBoolean("p2p.test.inhibitAcceptor")) {
        thread.start();
      } else {
        logger.fatal(
            "p2p.test.inhibitAcceptor was found to be set, inhibiting incoming tcp/ip connections");
        socket.close();
      }
    } catch (IOException io) {
      String s = "While creating ServerSocket on port " + p;
      throw new ConnectionException(s, io);
    }
    port = localPort;
  }
binds the server socket and gets threads going
geode-core/src/main/java/org/apache/geode/internal/tcp/TCPConduit.java