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Advice required on implementing, configuring and managing a large number (> 500) of networked desktops
by Ashley T. Howes, Ph.D. 01 Nov '05

01 Nov '05

Hi all, I'm looking for some advice and hints on how to go about installing and managing a large group of desktop machines, with shared file stores and resources such as applications, printers, etc. By large, I mean more than 500 machines. Think of a large university lab or internet cafe, where people can login to any machine, do their 'work', access their files independent of terminal used, etc. Based on my knowledge so far, under Debian GNU/Linux, the actual installation of all the machines is relatively straight-forward. Once I have setup the roles and machine groupings (based on tasks and application needs), I can use the FAI (Fully Automated Installer) which hold master 'settings' to assign each machine to a group and watch the install take place. As and when machines fail, I can just configure a new one for a specific group and then let it install and put it on the network. My confusion comes when I want to work out how to get central authentication, shared file stores, and where the line should be drawn for local/network storing of applications, files, etc. There is also the problem of scaling to 500+ machines. I know this is possible, as I used to see it in action at UEA when I studied in SYS. xdm used to talk to something (LDAP?) before allowing login. The directory of users/passwords was shared between nearly all machines so you could login to any machine using your assigned userid. So: 1) How do I do central authentication? 2) Could I use NFS for shared file access with user /home being mounted as r/w at login, or would this cause a denial of service attack on the server? Are there more scalable alternatives with intermediate caching, etc? 3) Will > 500 desktops require more than one server for shared file access? What are the preferred replication procedures in this case? 4) What the best way to network that many machines? I can run switches and bridges between the machines. Should I load-balance or shape the traffic in some way to ensure fair and fast access to the shared file store? How do I check for network saturation other than looking at blinking coloured lights :) 5) Security. I would assume standard unix security would stop one user fiddling with another's files, but how does that work over a network file store? 6) Am I correct to assume that it is best to have applications installed locally on the machines given the number of machines? 7) Is there a way to sandbox the user, so they don't enter parts of the system they aren't supposed to? I know that there is the normal root access restriction, but what about forcing them to use their network file store, rather than leaving stuff in /tmp. I know quite a bit of this depends on what the machines will be actually used for. At present, I am looking for more general advice from people who have done this before to help guide my research into this topic. In fact, I am also interested on how this would work on non-linux machines, e.g. Windows and Macs. Do these need to run separatedly, or could non-Linux based machines authenticate against a shared profile directory? I know there are many large windows based deployments. For example the Norfolk Library Services runs one for internet and application access. In fact, they seems to run a reduced version of Windows that limits what the user can and can't do. Does anyone know how that actually works? To keep this on topic, please email me off-list for non-linux based discussions. -- Ashley T. Howes, Ph.D. http://www.ashleyhowes.com "The philosophers have only interpreted the world in different ways; the point is to change it." - Karl Marx

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Linux.com article: Hardware emulation with QEMU
by Keith Watson 01 Nov '05

01 Nov '05

http://www.linux.com/article.pl?sid=05/10/24/1845248 Regards, Keith ____________ You can never turn your back on reality, it surrounds you. - Stanislaw J. Lec

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Re: [ALUG] Hunt the Swap Hog
by Ted.Harding＠nessie.mcc.ac.uk 01 Nov '05

01 Nov '05

On 01-Nov-05 Maz Walker wrote: > On 11/1/05, Ted Harding <Ted.Harding(a)nessie.mcc.ac.uk> wrote: >> >> What might be the best way to find out what could be >> hogging swap-space? > > > Hi Ted > > Try running top and then press the f key to add another field, > then the p key to add the swap size. You can change the sort > order of top on the latest versions, press h for help to see > if yours can do that. Hope that helps, > Maz. Thanks, yes it does a bit! Unfortunately swap is not one of the variables I can sort on in my 'top'. A:age M:resident memory usage N:pid T:time (or cumulative time) P:CPU usage only! Tried getting 'ps' to show me, but it's confusing and I'm not sure whether it did or not. Cheers, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding(a)nessie.mcc.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 01-Nov-05 Time: 20:44:26 ------------------------------ XFMail ------------------------------

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Hunt the Swap Hog
by Ted.Harding＠nessie.mcc.ac.uk 01 Nov '05

01 Nov '05

What might be the best way to find out what could be hogging swap-space? Best wishes to all, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding(a)nessie.mcc.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 01-Nov-05 Time: 19:29:43 ------------------------------ XFMail ------------------------------

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RE: [ALUG] Help for UEA student
by Keith Watson 01 Nov '05

01 Nov '05

> Quoting Laurie Brown < >: > > > I'm pretty sure one or two subscribers to this list work > at/in UEA... > > A friend of mine's daughter has just started there and has been > > obliged to put McAfee on her (XP Pro) laptop. The problem is, > > everytime she joins the UEA net, the machine slows to a > crawl. Would > > anyone be so kind as to take a look at it for her please? > > > > Cheers, Laurie. > > From: Simon Sent: 31 October 2005 16:59 > > This is true and also some-what annoying. Windows users > *have* to install McAfee anti-virus 8 before they can connect > to the network. A friend of mine had to uninstall McAfee 10 - > seems silly but I suppose it's a good thing in a way. I have > McAfee on my Windows 2000 installation, I haven't noticed > that it slows down. The only thing I would put it down to, > would be scanning all the files on the disc for virii which > would slow the machine down but you can't really stop it doing that. > Yes, we use McAfee here at work and it seems to run ok on my HP laptop (Win XP Pro). You do get an initial hit as it insists on doing a full scan of all the local disks which does hammer the machine at first. It may be worth her just starting up and leaving it for a couple of hours (days?). Other than that, Simon may be right in suspecting something else that's doing a lot of disk i/o, that may also cause McAfee to do a lot of work if it involves disk writes. I'm going to shut up now as this is way of topic for an ALUG post - sorry folks! Regards, Keith ____________ The shortest answer is doing. - George Herbert

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Weekly IRC reminder
by Brett Parker 31 Oct '05

31 Oct '05

This is the automated ALUG IRC meeting reminder sent to remind you that there is an IRC meeting tonight (Monday) at 8.00pm. Historically, these used to be the only time a lot of us would be about, now the channel has some usual faces that are there most of the time (except at silly o'clock, when we might be sleeping, or on the second thursday of the month, where we might be drinking in the Reindeer), so don't feel limited to visit during this time, come visit us when ever you feel like it! The meeting takes place on the irc server irc.alug.org.uk in the #alug channel. Most IRC clients should allow you to get there with the commands "/server irc.alug.org.uk" and "/join #alug". Popular IRC clients include xchat, irssi and EPIC on Unix, and Mirc under windows. Here are some links to help you get started with irc. Unix http://www.xchat.org/ http://www.irssi.org/ http://www.epicsol.org/ Windows http://www.mirc.com (loads of help with irc for newbies!)

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PHP / MySQL web developer Job
by David Reynolds 30 Oct '05

30 Oct '05

Hi, I've been asked to post this job application here, in case anyone is interested: Job Type: Permanent Job Title: PHP MySQL Website Developer Location: North Norwich, Norfolk Salary: Negotiable Details: We are looking for a team player to join our development team. We have an excellent track record in delivering a diverse range of web projects to small and medium sized business across Norfolk. Ideally you will have commercial experience developing websites using PHP and MySQL preferably in a Linux environment. Ideally you'll also have an ability to create graphic designs for a web environment. Please forward a covering letter and CV to paul(a)paston.co.uk Cheers, David -- David Reynolds david(a)reynoldsfamily.org.uk

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/var/log/lastlog
by Ted.Harding＠nessie.mcc.ac.uk 30 Oct '05

30 Oct '05

Hi Folks, It's spring-clean time again ... Been recovering disk space occupied by stuff I don't really want to know about. In particular, /var/log/lastlog is 19MB in size, but the output of 'lastlog' is 2225 bytes on 35 lines, telling me *ALL About the Very Last Time Each User Logged In*.[1] Most of these are, of course "pseudo" users like bin daemon adm lp sync shutdown halt mail news uucp operator games gopher ftp rpm vcsa nscd sshd rpc rpcuser nfsnobody mailnull smmsp pcap apache xfs named ntp gdm who never log in anyway! So that's 19136220/35 = 546749 bytes or half a MB for each "user", and from inspection nearly all of that is bytes with value "00"! (Indeed it gzips down to 18668 bytes, i.e. 1/1000). Now I can use an extra 19MB of space on that partition (whose free space varies from near-0 to about 400MB depending on what I'm up to), so I'm feeling mean about 19MB devoted to totally boring info. Hence I'm wondering (a) what's the best way to suppress this lastlog stuff; (b) would it traumatise the system to suppress it? Thanks for any comments! Best wishes to all, Ted. [1]. E.g. ftp **Never logged in** ted pts/12 brandy Sun Oct 30 10:09:37 +0000 2005 -------------------------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding(a)nessie.mcc.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 30-Oct-05 Time: 10:41:23 ------------------------------ XFMail ------------------------------

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Penguins
by Anthony Anson 30 Oct '05

30 Oct '05

It has been reported that penguins can get avian 'flu as well: Now read on - nicked from a newsgroup: H5N1 BIRD FLU BELIEVED TO BE FIRST VIRUS UNABLE TO SPREAD THROUGH MICROSOFT OUTLOOK Researchers Shocked to Finally Find Virus That Email App Doesn't Like Atlanta, Ga. Scientists at the Center for Disease Control and Symantec's AntiVirus Research Center today confirmed that H5N1 bird flu cannot be spread by Microsoft's Outlook email application, believed to be the first time the program has ever failed to propagate a major virus. "Frankly, we've never heard of a virus that couldn't spread through Microsoft Outlook, so our findings were, to say the least, unexpected," said Clive Sarnow, director of the CDC's infectious disease unit. The study was immediately hailed by British officials, who said it will save millions of pounds. "Up until now we have, quite naturally, assumed that bird flu was spread by Microsoft Outlook," said Sir Liam Donaldson, Britain's Chief Medical Officer. "By eliminating it, we can focus our resources elsewhere." However, researchers in Romania, where bird flu has recently appeared, said they are not yet prepared to disqualify Outlook, which has been the progenitor of viruses such as "I Love You," "Bubbleboy," "Anna Kournikova," and "Naked Wife," to name but a few. Said Andrei Niculescu, director of the Molecular Virology Lab at Bucharest University: "It's not that we don't trust the research, it's just that as scientists, we are trained to be sceptical of any finding that flies in the face of established truth. And this one flies in the face like a blind drunk sparrow." Executives at Microsoft, meanwhile, were equally sceptical, insisting that Outlook's patented Virus Transfer Protocol (VTP) has proven virtually pervious to any virus. The company, however, will issue a free VTP patch if it turns out the application is not vulnerable to bird flu. Such an admission would be embarrassing for the software giant, but Symantec virologist Ariel Kologne insisted that no one is more humiliated by the study than she is. "Only last week, I had a reporter ask if the bird flu spreads through Microsoft Outlook, and I told him, 'Doesn't everything?'" she recalled. "Who would've thought?" -- Tony http://www.users.zetnet.co.uk/hi-fi/

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Southern kit meet - any takers?
by Chris Green 28 Oct '05

28 Oct '05

It was suggested a little while ago that we might have a 'southern' kit meet, somewhere near Ipswich for example. Is there much support for this idea? E.g. how many people would actually come? Assuming that there aren't 500 people coming I could host it if the location was deemed suitable. I'm just about equidistant from Ipswich, Felixstowe and Woodbridge and very easy to get to from the A14, as long as you don't mind narrow lanes. Personally I'd prefer an evening rather than week-end as daylight is a precious resource needed for working outside. -- Chris Green (chris(a)areti.co.uk) "Never ascribe to malice that which can be explained by incompetence."

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