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Write the Linux Gazette at gazette@ssc.com. Send technical questions to the Answer Gang at linux-questions-only@ssc.com.

Help Wanted -- Article Ideas

These questions have been selected among the hundreds the Gazette recieves each month. Article submissions on these topics will be eagerly accepted at gazette@ssc.com, and posted in the next issue.

Answers to these questions should be sent directly to the e-mail address of the inquirer with or without a copy to gazette@ssc.com. Answers that are copied to LG will be printed in the next issue -- in the Tips column if simple, the Answer Gang if more complex and detailed.

Before asking a question, please check the Linux Gazette FAQ to see if it has been answered there. The AnswerGuy "past answers index" may also be helpful (if a bit dusty).

Internet Cafe Management Software

Wed, 27 Dec 2000 08:39:31 -0600 (CST)
From: Alan Pater <alan@celasmaya.edu.gt>

Hi Folks.

I've taken a quick look around the web for Linux based Internet Cafe Software, with no luck. There's a few windows based packages around, but that will just not do. What I'm looking for is something which can record when people login and logoff and calculate how much they should pay. Have you seen anything like that? Even a set of instructions on how to do it with a set of scripts would be cool.

Alan Pater


Can any of our fair readers find some good internet cafe or "walk in ISP" software? We can only offer the following leads:

Try looking around including the keyword Coffeenet. That was a Linux based cafe in the S.F. area; he closed shop when he had his lease end, but it was successful before that, the building owner just didn't want to renew. I'm pretty sure he open sourced the distro he created, but note, it depends on having a serious NFS server in the back.

I know the VA Linux "mail garden" machines and his, had a similar feature of cleaning up after anything local, so the machines never have any interesting leftovers from previous clients. xdm or gdm have control files for stuff to do before and after a session, so it should be possible to add accounting functions to logging in and out, and to add cleanup to logging out, quite easily. Keeping people from accessing text mode is a little more work, but I don't think Coffeenet was preventing that.

Neither of these actually kick someone out when their time is up, so you still have some work to do if your shop is too big to merely keep an eye on people and rely on a popup "you've been on for awhile" note.
-- Heather

I don't know of any scripts, but "last" gives you login/logout times by user. Should be possible to dump the output into a database via some pretty simple awk, perl, python, or even sh scripts.

Last reads wtmp, so watch out for when your wtmp gets rotated. Most log rotation scripts will move wtmp to a backup, for example wtmp.1, and "last" will take a filename as a parameter.

Sample output from "last":

[ ... ]
dlong    ttyp3        passenger.ssc.co Fri Dec  1 09:21 - 09:22  (00:00)
carrie   ttyp5        catnip.ssc.com   Fri Dec  1 08:48 - 17:04  (08:15)
fax_inc  ttyS0              +39 45 877 Fri Dec  1 08:43 - 08:44  (00:01)
annie    ttyp4        passenger.ssc.co Fri Dec  1 08:42 - 14:48  (06:06)
dlong    ttyp3        passenger.ssc.co Fri Dec  1 08:20 - 09:03  (00:42)
[ ... ]

See "man last".
-- Dan Wilder

geforce card

Mon, 25 Dec 2000 12:27:50 +1100
From: "Ron Nicholls" <nykysle@bigpond.com>

I have RH 7.0 which has XFree86 4.0.1 which does not support Geforce 2 chips yet. Is there a patch or update or howto to install the necessary support.

Regards RonN

Any developer types want to help him out here? Xfree86 4.0.2 came out, but it still has no special support for this card, so unless it works in VESA mode, he's out of luck for now...

And, we'll galdly take articles on adding support for new cards to X version 4! -- Heather

Hiding samba shares across multiple networks

Fri, 15 Dec 2000 10:07:36 -0800 (PST)
From: Faber Fedor <faberfedor@yahoo.com>

Hi guys (and Heather :-)!

I've got an interesting little problem with Samba and hiding shares when multiple networks are involved. I'm hoping one of you can help out, or maybe one of the Gentle Readers has already done this.

I have one Samba box with two network interfaces (on one NIC using virtual lans), say and Two companies sit on each network and can't learn about the other. Let's call them "Acme, Limited" ( and "Coyotes-R-Us" ( They, of course, use Another Operating System.

What I want to do is to create shares on the Samba box for Acme and Coyote to store their files. That's easy enough, the problem is in restricting what they see.

If I create Acme and Coyote as users and share the home directories via the [homes] default share, Acme will not see Coyote's share and vice versa. This is good. However, if the CEO of "Coyotes-R-Us", Mr. Wiley, logs onto the Acme network, he will see the Coyote [home] share appear on the Acme network. This is NOT a Good Thing.

(I tested this by placing a Windows box on Acme's network via a port on a Cisco switch that was set up to handle only Acme's vlan.)

If, OTOH, I set them up as separate shares and restrict them via IP addresses a la "allowed_hosts=", both companies can see the other's share, which is Not A Good Thing, even though they cannot access the other's share (always a good thing).

I've been hacking at this for several days trying to figure something out, as well as surfing Google, Deja.com, the samba mailing lists, and any other place I could think of. You are my Last Great Hope. :-)


===== Sincerely, Faber Fedor

It looks like the Answer Gang could stand to be joined by a serious Samba expert. Anyone care to jump in?

General Mail

Thank you for your telnet logging screen article

Thu, 21 Dec 2000 17:53:00 -0500
From: chris dillon <thebin@mailandnews.com>

I scoured the net and your article gave me the answer so that might log my telnet session.

Thank you.

I've been doing a lot of abstract painting lately, extremely abstract. No brush, no paint, no canvas, I just think about it. -- Steven Wright


Fri, 1 Dec 2000 18:02:15 +1100
From: "BanDiDo" <bandido@drinkordie.com>

LG is awesome, if you charged for it I would subscribe. When I get some free time one of these I hope to pen a few articles and such.

Thanks. Linux Gazette was established as a free zine and we firmly intend to keep it that way. There are already paid magazines out there (we publish one of them :), but LG fills a unique niche. No other e-zine I know of (Linux or otherwise) is read, not just through a single point of access, but in large part via mirrors or off-line (via FTP files, CD-ROMS, etc).

Also, because LG's articles are written by our readers, you (readers) are truly writing your own magazine. I only put things together and insert a few comments here and there, and occasionally write an article. If it weren't for our volunteer authors, there would be no Linux Gazette. When I first took over editing in June 1999, I used to wonder every month whether there would be enough articles. But every month my mailbox magically fills with enough articles not just for a minimal zine (5-10 technical articles), but for a robust zine with 15+ articles covering a variety of content (for newbies and oldbies, technical articles and cartoons). A year ago, we never predicted there would be cartoons in the Gazette, but the authors just wrote in and offered them, and it's been a great addition. It is truly a privilege to work with such a responsive group of readers, and years from now when I'm retired (hi, Margie!), I'm sure I will remember fondly what an opportunity it was.

Our biggest thanks go to The Answer Gang, especially Heather and Jim, who each spend 20+ hours a month unpaid compiling The Answer Gang, 2-Cent Tips and The Mailbag. This has really made things a lot easier for me.

Awwww, shux. I do get the occasional consulting lead from this, though. -- Heather

we look forward to printing some articles with your name on them. See the Author Info section at http://www.linuxgazette.com/faq/index.html#author

And you other readers who haven't contributed anything yet, get off your asses and send something in! Write a letter for the Mailbag, answer a tech-support question, join The Answer Gang, do a translation for our foreign-language sites, or write an article. What do you wish the Gazette had more of? That's what it needs from you.

-- Mike Orr

Would be lovely if you guys established an EFNET irc channel :)
-- BanDiDo


Sun, 10 Dec 2000 11:10:00 -0500
From: Ben Okopnik <The Answer Gang>

On Sun, Dec 10, 2000 at 07:36:50AM -0000, <Name Snipped> wrote:

<A querent asked that we not publish his email>

If all you meant was not to publish your e-mail address, then please write back with your question and be sure to clarify that. If not, then consider this:

I can't speak for the whole Answer Gang, nor do I set Linux Gazette policy - but I, for one, have absolutely zero interest in being a free one-on-one tutor for the general public, although I'm always willing to help my friends. I enjoy the fact that the effort I expend in answering these questions goes toward helping everyone in the Linux community: even those that don't read the LG benefit from the general dispersion of good, useful Linux knowledge. This is precisely why I expend the effort, or is at least one of my major motivations for doing so.

For anyone wanting one-on-one tech support and tutoring, it's "cash on the barrel" in a "what you get is what you pay for" economy. Cash preferred, bank checks are OK, major credit cards cheerfully accepted.

Ben Okopnik

Security articles

Thu, 28 Dec 2000 09:54:31 -0800
linux-questions-only@ssc.com, Kapil Sharma ,gazette@ssc.com

[A guest commentary from our News Bytes editor. I asked him to summarize the controversy on Slashdot regarding SSH/SSL vulnerabilities, and to assess whether we need an article on it. -Mike]

Date: Thu, 28 Dec 2000 16:55:56 +0000 Subject: Re: Late News Bytes additions
From: Michael Conry michael.conry@softhome.net

Hi Mike, please find attached the <A HREF="lg_bytes61.html">news bytes 61 file</A>. I did go through the SSH issues, and summarised them briefly. I kind of skirted around the SSL because it seemed less clear cut, and very much an issue of implementation and protecting users from themselves. Most discussion in the links focussed on SSH in any case.

I would recommend, not an article on Holes in SSH, but rather an article on security in general. Lots of contradictory messages on Slashdot indicate that people still don't really understand what is going on or how exactly to administer a public key system.

The issues are not new, but are inherent in public key systems. pgp,gnupg is the same (how can i be sure the key i think is yours is really yours?). The biggest issue is probably users (lusers) ignoring warning messages.

The new dsniff software is probably worth commenting on also. I included a link in my short discussion, but have not studied it. What could be very interesting would be for an article to highlight how to use tools like this to strengthen your system/network by scrutinising it and probing it. Focus tends to be on how these tools allow malicious people to break other people's systems.

bye for now

[There were several other messages this month, but it's 10:45pm on New Year's Eve, and I want to publish LG and get to the club by 12. The letters will be printed next month. -Mike.]

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