This article was posted to the Usenet group alt.hackers in
1995; any technical information is probably outdated.
Re: Tell me
Article: 7659 of alt.hackers From: dilatush@sccs.swarthmore.edu (Jeremy Dilatush) Newsgroups: alt.hackers Subject: Re: Tell me Date: 14 Apr 1995 20:38:31 GMT Organization: (none) Lines: 54 Approved: If you can read this...yes. Message-ID: 3mmmg7$cq@larch.cc.swarthmore.edu NNTP-Posting-Host: ginger.cs.swarthmore.edu Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Status: RO
> Exactly, I doubt it. Someone let me know if you read this.
I didn't read the message quoted above, so I won't.
If I'm interpreting things correctly, your post is a 'first try'. Well, you
succeeded in posting. And if anybody's reading this, so did I. :')
One thing I'm afraid your forgot about posting here is your
ObHack (April-Fools type)
This year was great for AFJ's ... I participated in three and
witnessed two. One I engineered myself:
Our CS department keeps a cluster of Sun SPARC machines running
SunOS Unix -- nice systems.
Anyway, from about 9:30pm on March 31 (I kinda jumped the gun)
to 11:00pm on April 1, everyone who sat down at the machines and logged
in (remote logins are not involved here) got a message to their terminal.
The message started in their console window (an 'xterm') with a sequence
of beeps (separated by fraction-of-a-second pauses so they wouldn't
blend together). Then that window cleared, a black border was drawn
around it, and text started appearing, with boldface, beeps, pauses,
etc. The gist of the text was this:
"Yo bub -- this is the computer. I'm tired of compiling those CS
assignments you think so important, I'm bored of those WWW pages you
think so interesting; I think I'll go out and get a beer -- April Fools!"
As an AFJ it wasn't too great (Saturday is a bad day for
that sort of hack, damn it!) but I think it's a cool ObHack 'cuz:
- I did it all under my own uid.
- I used the fact that /dev/console is world-writable
on these machines -- there's good reasons for it to be, in fact, but
nobody ever _thinks_ of it being writable.
- I used the VT100 control sequences (xterm emulates a VT102)
Nobody ever thinks about them being there. People are
too used to GUIs to think about _how_ windows, etc, get put up within
their text screens. So I just looked at TERMCAP (using the man page
for translation) did some experimenting, and tailored my message with
lots of cheap-but-wizardly-looking text formatting.
The thing was implemented in two parts, a C program that did the actual
message output. And a Bourne shell script that, every 120 seconds,
used 'finger' to find out who was logged in, used 'grep' to find out
who was actually at the console, used some hack I don't clearly remember
to figure out who was _new_, shelled to the machine and ran the message
program. (Sorry about the run-on sentence)
I know, I could have done that last part in Perl in seconds but I haven't
gotten around to learning it yet...
OK so you had to be there. (preferably not expecting it and having no
idea how anybody could do it w/out root access)
And Mark -- I'm looking forward to reading your ObHack.