[HECnet] Effects of Rogue Duplicate HECnet Node?

[Johnny Billquist]

On 2020-03-04 00:57, Thomas DeBellis wrote:
> However, as I've said before (viz., the NFT: device and FTS), there are 
> parts of Tops-20 DECnet that strike me as not fully productized.  One 
> example is that there is no way for /anybody/ to extract the area and 
> number of a node once it is the monitor.  You can (and should) verify 
> that the node is 'legitimate' by using .NDVFY function of the NODE% 
> JSYS, which will also tell you some interesting things about it.  
> However, it will not divulge the aforementioned numbers.  It annoyed me 
> enough so that I modified the monitor to do just that with an additional 
> function, .NDVFX and I use this in DAP (but don't depend on it) and in 
> the mailer (where I do).
> 
> I haven't posted the changes anywhere because I can't make up my mind 
> whether this was fixing an oversight or breaking a design decision or 
> indeed, whether that should even matter.

In RSX there is no documented way to map between node names and 
addresses, in either direction.
There is an interface for it, but it's not documented. Internally, 
DECnet have a separate device and ACP which handles the nodename 
database. If you just have the specifications for this device, you can 
do lookups yourself, but DEC never intended that anyone should use it, 
except DECnet internally does.

> Another example is that, once a node is inserted into the monitor data 
> base, there is *no* documented way to remove it.  As I was implementing 
> .NDVFX, I was looking at the in-area hashing code and noticed that it 
> appears that the monitor will remove a node marked as -1 (36 bits).  I 
> have yet to test this.  Certainly SETNOD gives no hint (another reason 
> I'm toying with a rewrite).
> 
> Curiouser and curiouser.  Do the above two functionalities exist in 
> other operating systems?

The ability to remove nodes from the nodename database works fine in 
pretty much all OSes I know of, except for the PDP-10 world.
In VMS and RSX, it's NCP CLEAR NODE node ALL, for example, for the 
current running system. In VMS you use PURGE in NCP for the permanent 
database, while in RSX, you use PURGE, but in CFE, which is the 
configuration file editor, for the permanent database.

I think RSTS/E does it all through NCP, like in VMS, but I guess Paul 
can tell for sure.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol