Hi everyone,
While reading through the list I got interested on the subject of being
able (or not) to move a program to a different TTY. So I started
experimenting. I ran "man", I can't remember on which manpages now, and
then I did Ctrl+Z to freeze the process. I then logged out. I logged back
in and did a "jobs" to see if it was still there, and it wasn't. "Never
mind" I thought, and got on with something else.
Then I started to notice my HDD going fairly regularly. "Eek", I thought,
"what's going on?". So I ran "top" to see what was happening. To my
surprise "man" was still running, using around 15% CPU time, and
continually absorbing memory at a rate of around 256K/sec. "Strange..." I
thought, and exited "top", waited for a while (swapping had kicked in bad
by this time), and I ran "kill" on the process, ps'd and the process was
still there. I tried logging in at a different console, and it locked,
with HDD on constantly. I could enter a command on the already logged on
console but it didn't execute it, just locked. Suddenly the HDD
stopped...."ooh", I thought, "it must have died", so I tried logging in
both locally and remotely, still locked. And after a few more secs the HDD
kicked in again. "Nooo!" I thought, "I'll have to reset without shutting
down", (Ctrl+Alt+Del had no effect) though my confidence of course was
much greater in Linux than it would be if I had to do the same in
Winslozes. And everything rebooted fine. Checked the /var/log/messages,
and it had reported the following:
nexus: kernel: swap_in:
nexus: Out of memory for mingetty (I guess one of my login attempts)
nexus: Unable to load interpreter (" " " " " " " )
"Well," I thought, "that's a reasonable response". Anyway, that happened
as the root user.
"So," I pondered, "let's find out if this was a one off". So, I fired up
my other machine into Linux (systems explained below), thinking as it
isn't using swap memory it won't be so painful. Anyway, I logged in as a
normal user. Ran "man" on a different page, did Ctrl+Z, logged out (this
time I got a message saying that a process was still running, tried logout
again and it let me), logged back in, ps'd and "man" was still there, I
brought up "top", and again around 15% CPU and slowly increasing memory
usage. Anyway, did a "man" on kill, and worked out to do "kill -s 9 pid",
which put it to rest and released the resources.
So, what's the point of this random ramblings? Well, I thought it'd be an
easy way to crash a server if all a user had to do is log in, start a
process, halt it, and log out. By the time it is discovered, it'd probably
be too late. Not so much a security risk, but a big nuisence. Perhaps this
has already been resolved, or is only specific to me (though on two
different systems?).
OK, my setup is this....
Cyrix M-II 300 32Mb RAM as my Linux Server (where I discovered the
problem)
AMD K6-2 300MHz 128Mb as my Win98 (working on removing
it)/Linux Workstation, remote booting via nfs-root and
loadlin from the above mentioned server.
Both using SuSE Linux 5.2, Kernel 2.0.34.
This brings me to my next problem (if anyone is reading this far down).
I've setup NIS/YP server on my Server machine, which seems fine. I've set
the workstation up to use YP client. Config seems OK, but when I log in on
the client with one of the servers username, it don't like it, "login
incorrect". So I run ypserv on the server in debug mode to see what's
happening. Attempt another login, the server validates the user, bring up
name and everything on the server's display, but again "login incorrect"
on the client. Any ideas? Let me know if you want anymore details. (home
directories are being pulled off the server onto the clients /home by NFS,
to maintain them across both machines).
I've been using Linux for a while now, and love it a bit more everyday. I
installed NT Server on a system the other day, just to revisit it (having
used it some time ago), and I couldn't believe how bad it was as server
(let alone anything else). After getting used to Linux it just seemed
really unflexible and lacking. (Sorry, I had to tell someone)!
Thanks for any assistance any of you may offer,
Stephen Newey.
