[HECnet] How much should you be allowed to shoot yourself in the foot?

[Paul Koning]

> On Oct 13, 2020, at 10:01 AM, Johnny Billquist <bqt at softjar.se> wrote:
> 
>>> ...
>> In RSTS, it isn't a privilege but rather a quota (for "message receive blocks" which are somewhat like Unix sockets).  If your quota for those is 0 you can't do networking.  There are also login terminal flags that control (a) any interactive login, (b) any login on a dialup line (modem controlled line) and (c) login via DECnet.  So it's possible to set up an account that can't be accessed via SET HOST.
> 
> I thought the message receive blocks were only used for interprocess communication, and not for anything DECnet related. But then again, DECnet under RSTS/E is not something I ever was exposed to.

No, DECnet uses an extension of the IPC feature.  A receive block allows you do to either, subject to quotas.  Local messages and the various DECnet messages are all queued to the receive block, with a type code indicating what sort of message it is.

The "with privilege mask" message I mentioned is a variation on the local IPC message, with a distinct function code and a portion of the payload dedicated to the masks and PPN.  Those fields are all set by the kernel, so the receiving program can use and trust those values.

	paul