Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!uwm.edu!zaphod.mps.ohio-state.edu!samsung!munnari.oz.au!metro!news From: dawes@suphys.physics.su.OZ.AU (David Dawes) Newsgroups: comp.unix.sysv386 Subject: Re: 2-user systems Message-ID: <1990Nov29.122330.10550@metro.ucc.su.OZ.AU> Date: 29 Nov 90 12:23:30 GMT References: <28370@usc> <2391@sixhub.UUCP> <1990Nov26.113040.1865@metro.ucc.su.OZ.AU> Reply-To: dawes@suphys.physics.su.OZ.AU (David Dawes) Organization: School of Physics, Uni of Sydney, Australia. Lines: 29 Nntp-Posting-Host: suphys.physics.su.oz.au In article pcg@cs.aber.ac.uk (Piercarlo Grandi) writes: >On 26 Nov 90 11:30:40 GMT, dawes@suphys.physics.su.OZ.AU (David Dawes) said: >dawes> Nntp-Posting-Host: suphys.physics.su.oz.au > >dawes> For what its worth: On DEC's Ultrix with a 2 user license, a max >dawes> of 2 users may be logged in at a time. These 2 users may however >dawes> be logged in any number of times (from ethernet, serial lines, >dawes> console or wherever). root is also able to login when two other >dawes> users are logged in. This to me seems the most logical way of >dawes> implementing a 2-user system. > >No, it's a famous and catastrophic bug of some old release of Ultrix. >It is catastrophic because the limit is not two logins, but two UIDs, as >you say; so it can be easily circumvented by using the same uid for >multiple users, and more nastily, if you have something like uucp or the >printer spooler or other daemon running under its own UID, the number od >UIDs is reduced even if nobody is logged in. As I recall, with Ultrix 2.2, the limit was two UIDs logged in. It worked on entries in /etc/utmp. Sure this can be overcome by people sharing UIDs, but (at least with this version of Ultrix) the number of UIDs was not reduced by any background or daemon processes that might be running. David -- ------------------------------------------------------------------------------ David Dawes (dawes@suphys.physics.su.oz.au) DoD#210 | Phone: +612 692 2639 School of Physics, University of Sydney, Australia | Fax: +612 660 2903 ------------------------------------------------------------------------------