Can ubt0 be a slave or a passive listener, and not a master?

[Yuri]

I am trying to do some troubleshooting of BlueTooth connectivity and 
wouild like to see the packets, or maybe make a simple slave (like GPS 
slave).

I have this BlueTooth USB dongle:
ubt0: <vendor 0x0a12 product 0x0001, class 224/1, rev 2.00/19.15, addr 
3> on usbus1
Then I stop bluetooth (master) stack, so that ubt0 has no hooks.
Then I direct all packets to ng_hole node:
ngctl mkpeer ubt0: hole hook hhook

Then I run DTrace script showing when some msg or data comes:
#!/usr/sbin/dtrace -s
fbt::ngh_rcvmsg:entry
{
   printf("ngh_rcvmsg * ");
}
fbt::ngh_rcvdata:entry
{
   printf("ngh_rcvdata * ");
}

Attaching the hook to ubtN causes it to start bulk and interrupt 
transfers (according to the code).

Then I turn the cellphone (master) into discovery mode. But nothing 
comes to the ng_hole at all. Supposedly, master in discovery mode should 
announce itself to slaves.

Why no messages arrive to the hole? Where is the problem?

Yuri