Reserved DNS TLD's .invalid ?

I (wrongly) assumed that using a .local domain would never bother the root dns servers. It does (about 1500 q/sec).

So I read the relevant rfc's (2606 and 6761) where it clearly states:

...caching DNS servers SHOULD, by
default, generate immediate negative responses for all such
queries.  This is to avoid unnecessary load on the root name
servers and other name servers...
So I did a small test with the most recent bind9 in Debian as a caching only server, and it turns out it sends .local .localhost .example and .invalid to the root name servers ?! Only .test has an immediate response.

root@debian7:~# tcpdump port 53 -l | grep NX &
[1] 5699
root@debian7:~# tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes

root@debian7:~# nslookup
> server
Default server:
> linux-training.local
09:22:15.932194 IP f.root-servers.net.domain > 49328 NXDomain*- 0/6/1 (656)
09:22:15.997731 IP j.root-servers.net.domain > 43556 NXDomain*- 0/6/1 (669)

** server can't find linux-training.local: NXDOMAIN
> linux-training.localhost
09:22:23.099452 IP e.root-servers.net.domain > 22464 NXDomain*- 0/6/1 (673)

** server can't find linux-training.localhost: NXDOMAIN
> linux-training.test

** server can't find linux-training.test: NXDOMAIN
> linux-training.example
09:22:42.124036 IP e.root-servers.net.domain > 8476 NXDomain*- 0/6/1 (661)
09:22:42.141847 IP e.root-servers.net.domain > 31139 NXDomain*- 0/6/1 (671)

** server can't find linux-training.example: NXDOMAIN
> linux-training.invalid
09:22:49.660427 IP e.root-servers.net.domain > 15655 NXDomain*- 0/6/1 (671)
09:22:49.753120 IP l.root-servers.net.domain > 48281 NXDomain*- 0/6/1 (671)

** server can't find linux-training.invalid: NXDOMAIN

So I visit the root dns server stats and notice the top queries (in queries/second):

1 .com 3500
2 .net 2500
3 .local 1400
4 . 1100
5 .home 1100
6. (.com base 64)
7 .org 400
8. .belkin 300

The top five queries for BRU01 (a Belgian root name server) are a surprise:

1 .home 240
2 .localhost 53
3 .local 50
4 .com 19
5 .ru 12

(.be is negligible with 0.4 queries/second)



Coffee or Tea ? Yes!

When people ask me:
"Do you want coffee or tea?" (*)
Then I answer:

... and most assume that I want to be funny, but I don't. I just don't care which of the two (coffee or tea) you give me, I am happy with both.

Turns out I am a hacker.

(*) Do you want spaghetti or rice ? Yes!
(*) Leffe or Chimay ? Yes!
(*) Can I see you tonight or tomorrow ? Yes!

It gets worse when questions contain all possible actions:
(*) Should I stay or should I go?
(*) Can I keep the book or do you want it back ?
(*) With or without sugar ?
 You just gave me all possible options ?! What kind of trickery questions are these ?!



Vagrant: Creating 10 vm's with 6 disks each

Hello lazyweb,

the Vagrantfile below works fine, but can probably be written simpler. I've been struggling to create variables like "servers=10" and "disks=6" to automate creation of 10 servers with 6 disks each.

Drop me a hint if you feel like creating those two loops.

paul@retinad:~/vagrant$ cat Vagrantfile
hosts = [ { name: 'server1', disk1: './server1disk1.vdi', disk2: 'server1disk2.vdi' },
          { name: 'server2', disk1: './server2disk1.vdi', disk2: 'server2disk2.vdi' },
          { name: 'server3', disk1: './server3disk1.vdi', disk2: 'server3disk2.vdi' }]

Vagrant.configure("2") do |config|

  config.vm.provider :virtualbox do |vb|
   vb.customize ["storagectl", :id, "--add", "sata", "--name", "SATA" , "--portcount", 2, "--hostiocache", "on"]

  hosts.each do |host|

    config.vm.define host[:name] do |node|
      node.vm.hostname = host[:name]
      node.vm.box = "chef/centos-6.5"
      node.vm.network :public_network
      node.vm.synced_folder "/srv/data", "/data"
      node.vm.provider :virtualbox do |vb|
        vb.name = host[:name]
        vb.customize ['createhd', '--filename', host[:disk1], '--size', 2 * 1024]
        vb.customize ['createhd', '--filename', host[:disk2], '--size', 2 * 1024]
        vb.customize ['storageattach', :id, '--storagectl', "SATA", '--port', 1, '--device', 0, '--type', 'hdd', '--medium', host[:disk1] ]
        vb.customize ['storageattach', :id, '--storagectl', "SATA", '--port', 2, '--device', 0, '--type', 'hdd', '--medium', host[:disk2] ]




The grand Windows vs Linux fight

A lot of muggles are convinced there is some big battle going on between Microsoft and Linux. They are wrong.

Truth is that only a minority of very noisy wannabe-Linux users see this as a fight. I imagine this loud minority as people who once installed Ubuntu but actually spend most of their time playing games on Windows.

The reality is that most organizations use Microsoft on the Desktop and a lot of them also have one or more products like MS Active Directory, MS Exchange or MS Sharepoint.

But every other computer runs a form of Unix, very often this is Linux:
- the millions of servers from Facebook, Google, Twitter, ...
- millions of DSL modems
- more than a billion Android phones
- 98 percent of the 500 largest supercomputers in the world
- Lego robots
- space station laptops
- (in Belgium specifically stuff like the bbox and digibox etc)
- tablets, routers, firewalls, NAS devices (aka "external harddisks"), stock exchanges, radar control, gps navigation and much more

There was no battle, there is no fight, there will never be a Linux vs Windows. They are just different things, Microsoft is used for end user intranet, Linux for servers and all other devices.

(*) Sure there is also iPad, iPhone and Mac, I know that.


nieuwe laptop kopen ?

Ik zou een nieuwe laptop willen kopen, graag advies:
- moet uiteraard Debian kunnen draaien zonder proprietary binary drivers (dus radeon hd?)
- liefst zonder Microsoft of Apple tax
- kleine harde schijf (ik gebruik amper 50GB)
- rond de 8GB ram
- snelle cpu i5 of i7
- maar wil vooral dus dat Debian er op werkt...
- us qwerty!

Ik was tevreden over de macbook pros die ik heb, maar vind online amper informatie over Debian op die retina Macbook Pro.

Heel wat laptops komen met Intel hd 4000 video, werkt die vlot onder Linux ?

Zou je vandaag nog Lenovo Thinkpad aanraden ? Zo ja welke ?


independent Raspberry Pi

The Raspberry Pi is great, but by default it needs usb for power and utp for network.

Luckily there is the Smart Power Base to provide power and the Netgear (I use the wna1100 for obvious reasons) for wireless, both making the Pi a lot more independent.


Recovering lvm2 on degraded mdadm raid 1

An mdadm raid 1 had one disk crash, the other was moved to a new computer (/dev/sdb2).

Step 1: Does fdisk see the disk: yes

root@debian6~# fdisk -l /dev/sdb

Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00060f19

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1         254     2040254+  83  Linux
/dev/sdb2             255      121602   974722329   83  Linux 

Step 2: Gently look with fsck, yes it is part of mdadm
root@debian6~# fsck -n /dev/sdb2
fsck from util-linux-ng 2.17.2
fsck: fsck.linux_raid_member: not found
fsck: Error 2 while executing fsck.linux_raid_member for /dev/sdb2

Step 3: Let's see what mdadm says

root@debian6~# mdadm --examine /dev/sdb2
          Magic : a92b4efc
        Version : 1.0
    Feature Map : 0x0
     Array UUID : e8221214:354aaaf1:e9e15d78:075bfc18
           Name : storage:1
  Creation Time : Thu May  6 20:00:16 2010
     Raid Level : raid1
   Raid Devices : 2

 Avail Dev Size : 1949444384 (929.57 GiB 998.12 GB)
     Array Size : 1949444384 (929.57 GiB 998.12 GB)
   Super Offset : 1949444640 sectors
          State : clean
    Device UUID : 0c265a25:cc3f2ddd:ae7a1511:f447c74e

    Update Time : Tue May  1 23:09:11 2012
       Checksum : 498b9bd4 - correct
         Events : 33039098

   Device Role : Active device 0
   Array State : A. ('A' == active, '.' == missing) 

Step 4: Let's fix the md device

root@debian6~# mdadm --assemble --scan
mdadm: /dev/md/storage:1 has been started with 1 drive (out of 2).
mdadm: /dev/md/0_0 has been started with 1 drive (out of 2).

root@debian6~# cat /proc/mdstat 
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
md126 : active (auto-read-only) raid1 sdb1[0]
      2040128 blocks [2/1] [U_]
md127 : active (auto-read-only) raid1 sdb2[0]
      974722192 blocks super 1.0 [2/1] [U_]
unused devices:  

root@debian6~# fdisk -l
Disk /dev/md127: 998.1 GB, 998115524608 bytes
2 heads, 4 sectors/track, 243680548 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/md127 doesn't contain a valid partition table 

Step 5: Gently look with mount and lvs/pvs

root@debian6~# mount /dev/md127 /mnt
mount: unknown filesystem type 'LVM2_member'

root@debian6~# lvs
  No volume groups found
root@debian6~# pvs

Step 6: Fix the lvm2 device

root@debian6~# vgscan
  Reading all physical volumes.  This may take a while...
  Found volume group "md1_vg" using metadata type lvm2

root@debian6~# vgs
  VG     #PV #LV #SN Attr   VSize   VFree
  md1_vg   1   1   0 wz--n- 929.57g    0 
root@debian6~# pvs
  PV         VG     Fmt  Attr PSize   PFree
  /dev/md127 md1_vg lvm2 a-   929.57g    0 
root@debian6~# lvs
  LV      VG     Attr   LSize   Origin Snap%  Move Log Copy%  Convert
  md1vol1 md1_vg -wi--- 929.57g 
Step 7: The lvm2 device is not activated, yet

root@debian6~# lvdisplay 
  --- Logical volume ---
  LV Name                /dev/md1_vg/md1vol1
  VG Name                md1_vg
  LV UUID                qSpslc-nO70-8jjX-5lBl-ge20-fFdR-dSEnWk
  LV Write Access        read/write
  LV Status              NOT available
  LV Size                929.57 GiB
  Current LE             475938
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto 
Step 8: Activate lvm2 device and mount

root@debian6~# vgchange -a y
  1 logical volume(s) in volume group "md1_vg" now active

root@debian6~# mount /dev/md1_vg/md1vol1 /mnt

root@debian6~# mount | grep mnt
/dev/mapper/md1_vg-md1vol1 on /mnt type xfs (rw)