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The Answer Guy

By James T. Dennis, answerguy@ssc.com
Starshine Technical Services, http://www.starshine.org/

Conflict: Num-Lock, X Window Managers, and pppd

From Victor J. McCoy on 11 Oct 1998

Please publish this. After the original question, I received a number of inquiries indicating that I'm not the only one with this problem.

Last year LG22 (Oct97) I asked a question regarding window manager and pppd anomaly.

Quick answer: Num-Lock key activation.

Long answer:

I finally got fed up with the problem, so I tore my machine apart, down to a single SCSI controller (with only my root drive), keyboard, modem.

The problem continued. I upgraded to redhat 5.0 since, and the problem persisted, different Window managers also exhibit problems (just differently). I even changed to Caldera lite 1.2, and I still had the problem.

Believe it or not, it turned out to be my NUM-LOCK key. If NL is active, then the WM screws up EVERY TIME; different WMs just screw up differently. I would turn on Num-lock to ping a host IP addr and that would be all it took.

I have a MS natural keyboard (Of all the products MS has, software sucks, but I love the hardware [KB and Mouse].) I'm sure that's not the problem, because I've only recently acquired the KB and the problem has been around for a couple of years.

I would like to know if this is a widespread problem. Surely, I'm not one of very few people to use the numeric keypad.

Victor J. McCoy

I'll just let this message speak for itself. I'm not really sure what it's saying but it sounds like a call for other people to do some testing. What happens if you have your NumLock key active when you start up and user your ppp link from within an X session.

As for ways to try to alleviate the problem:

• Change to a newer (2.1.x) kernel and a new pppd (must do that to use PPP under the new kernels anyway).
• Try a different X server. If you're currentlly using XFree86, consider tying Xig or Metro-X (one of the commercial X suites for Linux).

... I don't know of good ways to troubleshoot or isolate this, off hand. Look in your syslog (/var/log/messages) for "ooops" or similar messages from the kernel. Try strace on the X server and the window managers, the pppd (also run it under full debugging and kdegug). Try adding ipfwadm (or ipchains) rules with the -o switch (to "output" details of every packet to your syslogs). You could also capture tcpdump's from the ppp0 interface during the whole affair.

It's probably something specific to your hardware --- since you've changed your software completely. I'll be curious if you can isolate the problem to a specific library function or system call.

Copyright © 1998, James T. Dennis
Published in Linux Gazette Issue 34 November 1998

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