luv-main May 2013

luv-main@luv.asn.au

54 participants
48 discussions

by Andrew Worsley

Just got what looks to be a pretty good deal on what appears to have GPL version of the code made available. Got this D-Link Modem - hopes weren't high but it appears pretty reasonable 802.11bgn + 8 LAN ports switch + WAN router. I noticed that it contained a "D-LINK GPL Code Statement" with link http://tsd.dlink.com.tw/GPL.asp which turns out to be their GPL web interface which lists masses of products and a download links to source code which includes my DIR-632 (took a little time to find it amongst the massive number of items). I am downloading it now - 185Mb. See what you actually get in that. The modem itself is rather nice - it has most features you could think of (no CLI though, Web interface) and has a built in manual that explains each feature in detail! I suspect they are letting them go at that price because the new 802.11ac modems have arrived. See http://www.msy.com.au/images/ADbanner/eletter/04042013/online/html.html for the original promotion. Anyway thought others might be interested in this and perhaps an example of GPL compliance that seems pretty good... Andrew

8 years, 11 months

anyone running Jessie yet?

by James Harper

Is anyone running Debian Jessie yet? Previously I was running Wheezy with a few packages from Sid and experimental, but in the past it's taken a month or two for the new testing release to reach some form of stability. Thanks James

9 years, 2 months

alternate OS voids warranty

by James Harper

Not necessarily Linux related, but I just got off the phone with a certain large computer manufacture trying to resolve a failed harddisk on a 3 month old computer, and they claim that installing an alternate OS has voided the warranty. In this case the computer shipped with Win7 and the "alternate OS" was XP, but I find the claim ludicrous as I install Linux on all sorts of PC's and the warranty callcenter has never skipped a beat as long as I can demonstrate the fault in an obvious way. This particular computer is a different brand though... What's my best avenue to force the issue? Or are they within their rights to say that I have voided my warranty? Thanks James

9 years, 2 months

Statistical spam filters

by Jason White

This issue arose in conversation recently, thus I thought it worth asking here. Which tools are state of the art these days in statistical spam filtering? (Free/open-source and running on Linux are both assumed.) When I last looked (some years ago), the top options appeared to be, in no particular order: Spamassassin (rules + statistical classifier). It works well for many people; the statistical classifier used to be very memory-intensive and I know people for whom SpamAssassin didn't give accurate results even after training. CRM114: this is what I am currently using for my incoming mail. It appears to be in the midst of a rewrite as a library with support for various scripting languages. My initial experiences with it weren't good, but I tried it again several years ago and, this time, it quickly surpassed SpamAssassin when trained to classify my mail. Dspam: also has a good reputation, seems to be maintained to some extent. When last I looked at it in detail, a number of years ago, there were plans to add interesting features for allowing users to share filters so that a new user wouldn't have to train it from an empty database and one user's training could affect other users' filters. There were other projects around, but the above appeared to be the most sophisticated. So it's now 2013... Any changes? Comments?

9 years, 2 months

Samba 4 and LDAP

by Peter

Hi all, I just play around with Samba 4. At the moment, there is no official support for external LDAP (e.g. OpenLDAP). My original understanding was: We want Samba 4 "out" as fast as possible so we concentrate on "core functionality" (e.g. using internal LDAP, DNS etc.), and look at issues related to external sources later. Yesterday I found this: ---- http://us.generation-nt.com/re-samba-windows-8-pro-no-domain-logon-possible… (20th Sep 2012) We spent considerable effort over a period of years in attempting to make this possible. It is not. Even if it was, it would not involve 'simply' reading the companies LDAP server, it would be a very intrusive change no more acceptable than using our own built-in LDAP server. Andrew Bartlett ---- I wonder whether it means: Samba will not use external LDAP at all (that would rule it out for me here) "Very intrusive changes".. to Samba or LDAP? Does anybody has insight of the "roadmap", especially about the future of external LDAP sources? I know that you can make it work, somehow, now. But if it does not have support by the Samba team it will be fiddly and fragile and you have to worry about future releases all the time. I am not really keen on that. Regards Peter

9 years, 2 months

uncorrectable read errors

by James Harper

I've had a few disks fail with uncorrectable read errors just recently, and in the past my process is that any disk with any sort of error gets discarded and replaced, especially in a server. I did some reading though (see previous emails about SMART vs actual disk failures) and read that simply writing back over those sectors is often enough to clear the error and allow them to be remapped, possibly extending the life of the disk, depending on the cause of the error. In actual fact after writing the entire failed disk with /dev/zero the other day, all the SMART attributes are showing a healthy disk - no pending reallocations and no reallocated sectors, yet, so maybe it wrote over the bad sector and determined it was good again without requiring a remap. I'm deliberately using some old hardware to test ceph to see how it behaves in various failure scenarios, and has been pretty good so far despite 3 failed disks over the few weeks I've been testing. What can cause these unrecoverable read errors? Is losing power mid-write enough to cause this to happen? Or maybe a knock while writing? I grabbed these 1TB disks out of a few old PC's and NAS's I had lying around the place so their history is entirely uncertain. I definitely can't tell if they were already present when I started using ceph on them. Is Linux MD software smart enough to rewrite a bad sector with good data to clear this type of error (keeping track of error counts to know when to eject the disk from the array)? What about btrfs/zfs? Trickier with something like ceph where ceph runs on top of a filesystem which isn't itself redundant... Thanks James

9 years, 3 months

Re: Screen Res. Was alternate OS voids warranty

by mjones11

-------- Original message -------- From: Russell Coker <russell(a)coker.com.au> Date: 30/05/2013 11:25 (GMT+10:00) To: luv-main(a)luv.asn.au Cc: muzza <mjones11(a)tpg.com.au> Subject: Re: Screen Res. Was alternate OS voids warranty On Wed, 29 May 2013, muzza <mjones11(a)tpg.com.au> wrote: > woefully pitiful especially considering that some MS Windows configuration > windows often have the OK and cancel buttons below the bottom of the > screen and you have to tab to them and hope you know which one you > selected. This is even worse in linux for some reason. OK I digress - the > point is why are they Hold down the ALT key, then you can click the mouse anywhere in a Window to drag it around. This allows you to get access to the bottom of a window which is larger than the screen resolution. Yes this works and it is possible to get around those problems in windows as well. Its just a pita that developers don't consider and testers are slack

9 years, 3 months

Re: fast fail on specific entries not defined in /etc/hosts

by andrewv＠melbpc.org.au

Hi, Thanks for the feedback. See my responses below: > andrewv(a)melbpc.org.au writes: > > > Assume I have (at most), all of these entries in /etc/hosts > > > > custom1.company.com nnn.nnn.nnn.nnn > > custom2.company.com nnn.nnn.nnn.nnn > > default.company.com nnn.nnn.nnn.nnn > > That won't work. It's > > <address> <canonical name> [<alias> ...] > Sorry, you're right - my typo :) > > where nnn is some specific IPv4 address number > > > > I want to lookup the hosts in say this order: > > > > custom2.company.com > > custom1.company.com > > default.company.com > > It doesn't work that way, sorry. > I wasn't clear enough - I meant the application will specifically attempt to look up custom2.company.com, and if not found, will try to look up custom1.company.com, then if not found, will lastly try default.company.com. I wasn't trying to say that this search order had anything to do with how the lookup/resolving will be done for me by the lookup service. > > If the custom2 entry is not found, I want to try custom1, and if not ok, > > then I want to try default. > > You're talking about reverse resolution (IP to FQDN)? > No, I mean this is what my application will explicitly attempt, in that order. > > Importantly, I do _not_ want _any_ DNS lookup to be performed for > > _these_ _specific_ host lookups, because I want an immediate failure > > if the entry is not defined in /etc/hosts. > > I don't think you can have that, at least not on a per-host basis. > ok > The way different name services (such as flat files and DNS) are used is > governed by nsswitch on eglibc/glibc-using (and most other) systems. > > You can probably add > > 1.2.3.4 canthappen.invalid > > And if nsswitch has "hosts: files dns" then it will hit that first, and > not try DNS. You can't have an absence in /etc/hosts -- hosts(5) has no > support for the equivalent of an authoritative NX RR. > ok > > Note: I want an _immediate_ failure initially, _and_ for every lookup > > thereafter - an initial DNS lookup that fails after a DNS lookup > > timeout, and then perhaps caches that failure result is no good, > > because every lookup must respond immediately (and of course > > /etc/hosts and DNS service entries can change at any time so even > > then, cacheing is not useful). > > You can't have this with hosts(5). > ok > Your best bet is probably to point resolv.conf at a local DNS resolver > that is configured to return spoof results for particular domains > (including, obviously, the C.B.A.in-addr.arpa for the PTR RR). > This one sounds like the most viable option for me. I can run a DNS resolver on the same host as the application is running on, and configure it just for this application, and change the DNS search order to consult this local DNS service first (and then the ones it currently uses). I can use multiple domains if needed (not just company.com). > You could, alternatively, disable DNS altogether and ensure that all > hosts you need to reach are hard-coded in /etc/hosts. > Not an option, because many other lookups are performed aside from those servicing this application. > > Assume that I am using software that I cannot change, and so workarounds > > like actually reading the /etc/hosts file to see which entries exist, > > cannot be wired into the software. > > LD_PRELOAD might still be a viable option, though I don't recommend it. > Considered that one, I see it as last resort stuff, but yes, viable if nothing else hits the mark. > > I am thinking of something functionally like a like /etc/disable_dns_lookup > > that I can also copy all 3 of the above entries to, and linux will _never_ > > try DNS if the entries appear in /etc/disable_dns_lookup. > > AFAIK no such feature exists. > > This all sounds like an xyproblem; what is the ACTUAL problem you're > trying to solve? > I want to be able to use the configuration entered in /etc/hosts, as the sole data driven means of configuring host selection order, assuming the hosts are always going to be on an internal network, with well known addresses. > _______________________________________________ > luv-main mailing list > luv-main(a)luv.asn.au > http://lists.luv.asn.au/listinfo/luv-main Message sent using MelbPC WebMail Server

9 years, 3 months

fast fail on specific entries not defined in /etc/hosts

by andrewv＠melbpc.org.au

Hi, I wanted to know if the following was possible on a linux (in particular) box: Assume I have (at most), all of these entries in /etc/hosts custom1.company.com nnn.nnn.nnn.nnn custom2.company.com nnn.nnn.nnn.nnn default.company.com nnn.nnn.nnn.nnn where nnn is some specific IPv4 address number I want to lookup the hosts in say this order: custom2.company.com custom1.company.com default.company.com Now sometimes, I may only have the default entry, and sometimes I may have the custom1 and / or custom2 entries also in /etc/hosts. So, any combination from 0 to all 3 entries is possible at any point in time. This configuration would not change often, but any combination of entries is possible. If the custom2 entry is not found, I want to try custom1, and if not ok, then I want to try default. Importantly, I do _not_ want _any_ DNS lookup to be performed for _these_ _specific_ host lookups, because I want an immediate failure if the entry is not defined in /etc/hosts. Note: I want an _immediate_ failure initially, _and_ for every lookup thereafter - an initial DNS lookup that fails after a DNS lookup timeout, and then perhaps caches that failure result is no good, because every lookup must respond immediately (and of course /etc/hosts and DNS service entries can change at any time so even then, cacheing is not useful). Assume that I am using software that I cannot change, and so workarounds like actually reading the /etc/hosts file to see which entries exist, cannot be wired into the software. I am thinking of something functionally like a like /etc/disable_dns_lookup that I can also copy all 3 of the above entries to, and linux will _never_ try DNS if the entries appear in /etc/disable_dns_lookup. Any solutions / ideas ? Thanks Andrew Message sent using MelbPC WebMail Server

9 years, 3 months

Re: Screen Res. Was alternate OS voids warranty

by mjones11

-------- Original message -------- From: Toby Corkindale <toby.corkindale(a)strategicdata.com.au> Date: 30/05/2013 10:54 (GMT+10:00) To: luv-main(a)luv.asn.au Subject: Re: Screen Res. Was alternate OS voids warranty On 29/05/13 21:16, muzza wrote: > In the past yoiu could get decent res:- 1280x1024 or above and quite commonly > 1600x1200 and at 2ms response times. However it seems that some idiot > somewhere decided that we only watch videos on our computers so we only need > 1920x1080 at 5ms response times, and for crappy lappies only 1366x768. 27" Dell Ultra Sharp ultra U2713H - 2560x1440 - $799 27" X-Star DP2710 (Samsung panel) - 2560x1440 - $295 I would consider the ultra Sharp to be expensive. Never heard of the X-Star so can't comment Murray

9 years, 3 months

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luv-main May 2013