Roundtable

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2555 discussions

Re: [RndTbl] Roundtable Digest, Vol 137, Issue 1
by Vijay Sankar 01 May '16

01 May '16

Quoting roundtable-request(a)muug.mb.ca: > Send Roundtable mailing list submissions to > roundtable(a)muug.mb.ca > > To subscribe or unsubscribe via the World Wide Web, visit > http://www.muug.mb.ca/mailman/listinfo/roundtable > or, via email, send a message with subject or body 'help' to > roundtable-request(a)muug.mb.ca > > You can reach the person managing the list at > roundtable-owner(a)muug.mb.ca > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Roundtable digest..." > > Today's Topics: > > 1. IPv6 in Manitoba (Vijay Sankar) > 2. Re: IPv6 in Manitoba (Robert Keizer) > 3. Re: IPv6 in Manitoba (Adam Thompson) > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sun, 01 May 2016 10:55:51 -0500 > From: Vijay Sankar <vsankar(a)foretell.ca> > To: roundtable(a)muug.mb.ca > Subject: [RndTbl] IPv6 in Manitoba > Message-ID: > <20160501105551.Horde.74GXIMIcwaEZgxNlNJBLU4-(a)server3.foretell.ca> > Content-Type: text/plain; charset="utf-8"; Format="flowed"; > DelSp="Yes" > > I have had an IPv6 tunnel working through Hurricane Electric since 2011 or > so but increasingly it is not usable due to changes in security stances at > the destination sites. Ideally I would like to have a /48 subnet with > addresses that allow use of DNS etc.. Checked with tech support at MTS and > Shaw but both said IPv6 is not available through them. > > So I am wondering what others are doing. Really appreciate any advice or > suggestions about IPv6 providers in Winnipeg. > > Thank you very much, > > Vijay > -- > Vijay Sankar, M.Eng., P.Eng. > ForeTell Technologies Limited > vsankar(a)foretell.ca >

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process accouting, fields meaning?
by Grigory Shamov 27 Apr '16

27 Apr '16

Hi All, Following up on the Adam's old presentation on Linux process accounting. Does anyone know the meaning of fields in the pacct file? The utility dump-acct dumps it in a plaintext lines separated by | . Like this: sh | 0.0| 0.0| 11.0| 0| 0|107328.0| 19284 3258|Tue Apr 26 04:17:07 2016 First three floats are runtimes, then UID|GID; last is the date it ended. Googling brought me "memory" and "io" for the two other fields but I am still at loss. What is memory here? And why io is two numbers (read/write? Which is which?) Does anyone know? (I am trying to avoid reading the sources of dump-acct or system headers). Thanks! -- Grigory Shamov Westgrid/ComputeCanada Site Lead University of Manitoba E2-588 EITC Building, (204) 474-9625

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web access abuse of lisa
by Trevor Cordes 26 Apr '16

26 Apr '16

I noticed stomething strange. Lisa's web hits (as per access logs) were through the roof since around the site changeover date. Weird. I glanced at them and noticed we're getting tons of hits from just 1 user: 216.98.56.20 - - [24/Apr/2016:05:20:11 -0500] "GET /pub/epel/6/x86_64/repodata/repomd.xml HTTP/1.1" 301 332 "-" "urlgrabber/3.9.1 yum/3.2.29" All the same! Of 8434659 total current access.log hits, 8243763 (97.7%) were this same guy! Many per second! For a couple of weeks now (but not before that!). An ip lookup says this is Ubisoft in Montreal. Looks like someone has a misconfig on their box. Should we contact them about fixing this? If have added that IP to an iptables DROP rule on lisa. I just did this now and they sent 49 more hits and then stopped. Their runaway ps must have been looking for success before continuing. I guess I'll leave it in for a while then we can take it out? Looks like this IP has hit the new server but only a few times; i.e. normal looking access. Perhaps when the switchover occurred and the redirects were put in place it made their client go mental... Maybe it never dropped its http connection this whole time! Lastly, fail2ban-server is often in the top 5 ps's in top on lisa, but I don't see any fail2ban rule in iptables? Does it only create a rule once it gets something to put in? I thought it made a blank table that it filled up as needed, not no table at all. Maybe it's not working?

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Re: [RndTbl] [Board] muug.ca hostname?
by Trevor Cordes 17 Apr '16

17 Apr '16

> On April 16, 2016 12:50:43 AM CDT, Trevor Cordes > <trevor(a)tecnopolis.ca> wrote: > >on muug.ca (new server): > > > >#hostname > >muug > > > >This valid? Done for a reason? Should it be muug.ca? On 2016-04-16 Adam Thompson wrote: > Hostname is - and always has - been specified as the bare name, not > the FQDN. Hmm, that's opposite to what I've understood for 25 years, and what I've done on every machine I've ever been responsible for (all of which that have "worked"). But you made me think about it a bit, and why I do it this way. Thinking back I distinctly recall that my personal AIX box in '95 would freak out (like not boot, or take forever to boot) when the hostname wasn't FQDN. Back then it was tricky because I didn't actually own a domain name to use, so I had to make something up. I've done it this way ever since. Thinking more about what is right/wrong *now*, I find: http://serverfault.com/questions/331936/setting-the-hostname-fqdn-or-short-… Which basically hints that it's a) vendor specific (i.e. RH vs Deb), and b) personal preference. No consensus (there or elsewhere) by a mile, but it appears there is a bias towards hostname NOT being FQDN. For me, being an all-Fedora guy, if "RHEL deployment guide" says use FQDN, then that's a good enough excuse for me! And I've never had any issues... I would do a survey of machines I can access, but all I can access are ones I've built, along with lisa.muug.mb.ca, and lisa says: #hostname lisa.muug.mb.ca I'd be interested to see how the computers at, say, the U of M answer that question... (Strangely, much of my computing preference to this very day stems from interesting quirks of U of M's setup from my long days as a student.) > YP/NIS domain, not DNS. Any apps that break this way are broken, > period. The reason I brought it up is that apache on new muug.ca was guessing its host/domainname wrong and doing wonky things with rewrites until I added a ServerName directive to make it explicit. But that might have been a red herring with regards to this whole question. Final note, maybe the One Systemd To Rule Them All will settle this once and for all, as I'm pretty sure hostname is now under systemd purview (gobbled up like everything else)...

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Fwd: [MBIX-Members] MBIX AGM May 4th, 2016
by Adam Thompson 16 Apr '16

16 Apr '16

FYI. -Adam (one of the outgoing directors) -------- Forwarded Message -------- Subject: [MBIX-Members] MBIX AGM May 4th, 2016 Date: Tue, 12 Apr 2016 21:12:56 -0500 From: Bill Reid <billreid(a)shaw.ca> Reply-To: MBIX Members <members(a)lists.mbix.ca> To: members(a)lists.mbix.ca <members(a)lists.mbix.ca> *Manitoba Internet Exchange Annual General Meeting* Wednesday May 4^th , 2016 4 to 6 p.m. AGM to start at 4:30 p.m. King's Head Pub <http://www.kingshead.ca/> Open to all interested in IXs MBIX will be holding its 4^th AGM next month. There are 4 Board of Director positions open for election. Jacques Latour from CIRA will give an update on Canadian IXs. We will have a social time before and after the meeting. Drinks and snacks will be provided by CIRA and MBIX. Look forward to seeing you on May 4^th , Bill

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poor drive/array performance
by Trevor Cordes 14 Apr '16

14 Apr '16

I have an new SSD in a system setup as linux md RAID-1 but with the 2nd drive missing at the moment. No LVM. FS is ext4, very recently created and less than half full. ext4 creation had no tweaks (just default options). md creation had no tweaks. I'm getting extremely bizarre low FS performance. cd /tmp dd if=/dev/zero of=zzzz conv=fdatasync bs=1M count=250 262144000 bytes (262 MB) copied, 21.3281 s, 12.3 MB/s again... 262144000 bytes (262 MB) copied, 35.6929 s, 7.3 MB/s again... 262144000 bytes (262 MB) copied, 26.1413 s, 10.0 MB/s This SSD is rated at 450MB/s write. Sites on the net say I may only realize 100MB/s. I would be overjoyed with 100MB/s. I'm not looking for blazing speed, just not garbage speed. The system had a rust drive previously that had the same problem. When I replaced that, I also recreated the RAID, and the FS. Strangely, this drive is also part of another array for /boot, and that one has 2 drives, one of them spinning rust. And that array/FS is faster!? Huh? : 262144000 bytes (262 MB) copied, 14.6355 s, 17.9 MB/s 262144000 bytes (262 MB) copied, 13.4979 s, 19.4 MB/s 262144000 bytes (262 MB) copied, 9.99149 s, 26.2 MB/s I'm baffled. I really am. hdparm's speed tests show it to behave super fast for reads: Timing buffered disk reads: 1010 MB in 3.00 seconds = 336.32 MB/sec Timing cached reads: 26774 MB in 2.00 seconds = 13412.64 MB/sec I've checked hdparm -i: Model=KINGSTON SV300S37A480G, FwRev=603ABBF0, SerialNo=50026B7763021118 Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4 BuffType=unknown, BuffSize=unknown, MaxMultSect=1, MultSect=1 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=937703088 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio1 pio2 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 AdvancedPM=yes: unknown setting WriteCache=enabled Drive conforms to: unknown: ATA/ATAPI-2,3,4,5,6,7 udma6 is the correct mode for something like this I do believe. smartctl shows correct sata speeds: ATA Version is: ATA8-ACS, ACS-2 T13/2015-D revision 3 SATA Version is: SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s) Kernel is fairly new: 4.4.6-200.fc22.i686+PAE Hardware is server class Intel Xeon E3 with S1200V3RP board, a fairly new model. My only thoughts now are firmware problems, bios setting problems, or cable problem. I need to go onsite to check all three. Anything I am missing? I have lots of extremely similar systems out there *without SSDs* and they all show FS write speeds of no slower than 60MB/s! Weird!!

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Warning: OVH VPS 2016 line missing feature
by Adam Thompson 10 Apr '16

10 Apr '16

OVH has a new line of SSD-backed KVM-hosted VPS servers starting at C$4.99/month, with good performance, decent availability, pretty much an all-round good deal. Except for one little thing... No IPv6 support. At all. According to the tech support rep I just spoke to, it's because the new 2016 lineup runs on OpenStack. I'm a little unclear on how this makes it "impossible" to provide IPv6 functionality, but that's their claim. It's 2016: new IPv4 addresses are no longer available. IPv6 is supported by all major content providers (except Twitter, I think)- but OVH doesn't consider this important, apparently. FYI: their SoYouStart and OVH Dedicated Server lines still provide IPv6 service; it's only the new 2016 VPS system that doesn't. Ironically, the older-generation (2014) system *did* support IPv6, but I can't order that any more. Grrr. -Adam

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Re: [RndTbl] programatically determine if DNS is down or blocked?
by wyatt＠prairieturtle.ca 08 Apr '16

08 Apr '16

dig has parameters to force cache bypass. Daryl ----- Reply message ----- From: "Trevor Cordes" <trevor(a)tecnopolis.ca> To: "Robert Keizer" <robert(a)keizer.ca> Cc: "Continuation of Round Table discussion" <roundtable(a)muug.mb.ca> Subject: [RndTbl] programatically determine if DNS is down or blocked? Date: Wed, Apr 6, 2016 15:41 On 2016-04-06 Robert Keizer wrote: > Why don't you use dig+grep+sed in bash? Ya, that's one of the ideas (dig). It looks like dig will differentiate between named down, vs blocked 53, vs simple invalid domain. I'm trying to see if there are other ways also, perhaps ones that don't require a fork. And the dig will send out real queries to real servers, but I guess it will be tempered by the cache? I'll have to test what dig does in the different failure modes when a) resolving a domain that isn't cached vs b) resolving one that is cached. _______________________________________________ Roundtable mailing list Roundtable(a)muug.mb.ca http://www.muug.mb.ca/mailman/listinfo/roundtable

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Fw: [Bug 740188] the --title option is nonfunctional
by Trevor Cordes 07 Apr '16

07 Apr '16

Here's a great example of the snootiness, and complete lack of "getting it", of Gnome/systemd people, and why so many people are at odds with them. Tons of people commented on this bug: how asinine it was that --title was removed. The workarounds are ok if you're interactive *in* the window, but what if you want to launch a bunch of windows from a script, and have each one named? Who are the people being l33t here??? At least (for the first time I can remember when watching the dealings of these people), the "old fart" "unix admins" get their way. Begin forwarded message: Date: Thu, 07 Apr 2016 18:25:09 +0000 From: "gnome-terminal" (GNOME Bugzilla) <bugzilla(a)gnome.org> Subject: [Bug 740188] the --title option is nonfunctional https://bugzilla.gnome.org/show_bug.cgi?id=740188 Debarshi Ray <rishi.is(a)lostca.se> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |rishi.is(a)lostca.se --- Comment #22 from Debarshi Ray <rishi.is(a)lostca.se> --- commit 156b85533f42d8c7e6cf6258ce3e7fe4ec8f1754 Author: Christian Persch <chpe(a)gnome.org> Date: Tue Feb 16 18:59:09 2016 +0100 client: legacy: Reimplement deprecated --title option This reverts commit 0033eca2909ddccf3358c1f089bce05d3473b123. Reimplement the deprecated --title client option. It seems it is absolutely required by all those super l33t unix admins that are above using a lowly command like printf(1) or the even simpler xtermcontrol(1). https://bugzilla.gnome.org/show_bug.cgi?id=740188

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programatically determine if DNS is down or blocked?
by Trevor Cordes 06 Apr '16

06 Apr '16

I have a program that needs to do DNS lookups, etc. Things will go Really Wonky if there's a problem with DNS (from a client perspective). Thus, I'd like the program to be able to check if DNS isn't working. In this particular setup, the box runs its own named with a view setup for resolution/caching. In particular, I want to test that: 1. named is running and answering calls to its port 2. named is getting real answers from the net (i.e. doing its recursive resolution properly; and port 53 to outside NS's isn't being blocked) 3. (rare) root NS's aren't getting DDoS'd / whole world's DNS is down I want to do this inside a perl or php program, but any language pseudo-code will be fine as a template. I don't want to run a full-blown monitoring program separately. Ideally, I'll have some php like: function IsDnsOk() { check named check resolution ok } To be used possibly like: while (!IsDnsOk()) { sleep 10; } $important_dns_result=gethostbyname($host); But I want any check to be fairly lightweight. I don't want to fire off useless DNS lookups to root name servers at a potential rate of thousands a minute. Plus, I guess I have to worry about cached results making things look ok when they are really not. Any solution I implement will probably be designed to only run these tests once a minute or something, which won't catch the instant DNS goes down, but will mitigate the damage caused. I can think of a number of fairly simple tests I can try, but they feel kind of kludgy. Is there a better way? Ideally, the PHP calls, like gethostbyname would be able to return a "down" status, but they decided to lump in to the same return value failure due to no dns record and failure due to any other reason. Thanks!

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