Notes of a Systems Administrator

Tuesday, 28 April 2015

Add http/https access to iptables - CentOS 6

Edit iptables:

vi /etc/sysconfig/iptables

Add the following lines:

-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 443 -j ACCEPT

Restart iptables:

service iptables restart

Tuesday, 10 March 2015

Installing Hyper-V Daemons on CentOS 7

[root@its-webmon ~]# yum search hyperv
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.coreix.net
 * epel: mirror.vorboss.net
 * extras: mirror.ox.ac.uk
 * updates: mirror.ox.ac.uk
============================= N/S matched: hyperv ==============================
hyperv-daemons.x86_64 : HyperV daemons suite
hyperv-daemons-license.noarch : License of the HyperV daemons suite
hypervkvpd.x86_64 : HyperV key value pair (KVP) daemon
hypervvssd.x86_64 : HyperV VSS daemon
perl-Sys-Virt.x86_64 : Represent and manage a libvirt hypervisor connection

  Name and summary matches only, use "search all" for everything.
[root@its-webmon ~]# yum install hyperv-daemons
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.coreix.net
 * epel: mirror.vorboss.net
 * extras: mirrors.coreix.net
 * updates: mirror.sov.uk.goscomb.net
Resolving Dependencies
--> Running transaction check
---> Package hyperv-daemons.x86_64 0:0-0.24.20130826git.el7 will be installed
--> Processing Dependency: hypervvssd = 0-0.24.20130826git.el7 for package: hyperv-daemons-0-0.24.20130826git.el7.x86_64
--> Processing Dependency: hypervkvpd = 0-0.24.20130826git.el7 for package: hyperv-daemons-0-0.24.20130826git.el7.x86_64
--> Running transaction check
---> Package hypervkvpd.x86_64 0:0-0.24.20130826git.el7 will be installed
--> Processing Dependency: hyperv-daemons-license = 0-0.24.20130826git.el7 for package: hypervkvpd-0-0.24.20130826git.el7.x86_64
---> Package hypervvssd.x86_64 0:0-0.24.20130826git.el7 will be installed
--> Running transaction check
---> Package hyperv-daemons-license.noarch 0:0-0.24.20130826git.el7 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================
 Package                   Arch      Version                      Repository
                                                                           Size
================================================================================
Installing:
 hyperv-daemons            x86_64    0-0.24.20130826git.el7       base    3.7 k
Installing for dependencies:
 hyperv-daemons-license    noarch    0-0.24.20130826git.el7       base     11 k
 hypervkvpd                x86_64    0-0.24.20130826git.el7       base     18 k
 hypervvssd                x86_64    0-0.24.20130826git.el7       base    9.9 k

Transaction Summary
================================================================================
Install  1 Package (+3 Dependent packages)

Total download size: 43 k
Installed size: 60 k
Is this ok [y/d/N]: y
Downloading packages:
(1/4): hyperv-daemons-0-0.24.20130826git.el7.x86_64.rpm    | 3.7 kB   00:00     
(2/4): hyperv-daemons-license-0-0.24.20130826git.el7.noarc |  11 kB   00:00     
(3/4): hypervvssd-0-0.24.20130826git.el7.x86_64.rpm        | 9.9 kB   00:00     
(4/4): hypervkvpd-0-0.24.20130826git.el7.x86_64.rpm        |  18 kB   00:00     
--------------------------------------------------------------------------------
Total                                              103 kB/s |  43 kB  00:00     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : hyperv-daemons-license-0-0.24.20130826git.el7.noarch         1/4 
  Installing : hypervkvpd-0-0.24.20130826git.el7.x86_64                     2/4 
  Installing : hypervvssd-0-0.24.20130826git.el7.x86_64                     3/4 
  Installing : hyperv-daemons-0-0.24.20130826git.el7.x86_64                 4/4 
  Verifying  : hyperv-daemons-license-0-0.24.20130826git.el7.noarch         1/4 
  Verifying  : hyperv-daemons-0-0.24.20130826git.el7.x86_64                 2/4 
  Verifying  : hypervkvpd-0-0.24.20130826git.el7.x86_64                     3/4 
  Verifying  : hypervvssd-0-0.24.20130826git.el7.x86_64                     4/4 

Installed:
  hyperv-daemons.x86_64 0:0-0.24.20130826git.el7                                

Dependency Installed:
  hyperv-daemons-license.noarch 0:0-0.24.20130826git.el7                        
  hypervkvpd.x86_64 0:0-0.24.20130826git.el7                                    
  hypervvssd.x86_64 0:0-0.24.20130826git.el7                                    

Complete!

[root@its-webmon init.d]# service hypervkvpd start
Redirecting to /bin/systemctl start  hypervkvpd.service
[root@its-webmon init.d]# service hypervvssd start
Redirecting to /bin/systemctl start  hypervvssd.service
[root@its-webmon init.d]# systemctl|grep hyper
hypervkvpd.service                                                                                                        loaded active running   Hyper-V KVP daemon
hypervvssd.service                                                                                                        loaded active running   Hyper-V VSS daemon

Friday, 6 March 2015

Registering networker ports

echo "Registering networker ports 7937-7999 with backup server"
/usr/bin/nsrports -s backupserver.domain.com -S 7937-7999
/usr/bin/nsrports -S 7937-7999
/usr/bin/nsrports -s backupserver.domain.com -C 10001-30000
/usr/bin/nsrports -C 10001-30000

Thursday, 5 March 2015

Changing a Ganeti node's group

# gnt-group list
Group    Nodes Instances AllocPolicy NDParams
tier1     5        78 last_resort (empty)
tier2     3       118 preferred   (empty)
mvb       4        74 last_resort (empty)
# gnt-group assign-nodes cc-tier2 sever
# gnt-group list
Group    Nodes Instances AllocPolicy NDParams
tier1     5        78 last_resort (empty)
tier2     4       124 preferred   (empty)
mvb       3        68 last_resort (empty)

Tuesday, 3 March 2015

Extract text string in brackets

grep -oP '\(\K[^\)]+' file

\K means that use look around regex advanced feature. More precisely, it's a positive look-behind assertion, you can do it like this too :

grep -oP '(?<=\()[^\)]+' file

if you lack the -P option, you can do this with perl :

perl -lne '/\(\K[^\)]+/ and print $&' file

Another simpler approach using awk

awk -F'[()]' '{print $2}' file

Monday, 23 February 2015

LVM Metadatasize too small

Too small:

# vgs --units k -o vg_mda_count,vg_mda_free,vg_mda_size,vg_name
  #VMda VMdaFree  VMdaSize  VG
      1    91.50k   188.00k volg0
      2    73.50k   188.00k volg1

OK:

#  vgs --units k -o vg_mda_count,vg_mda_free,vg_mda_size,vg_name
  #VMda VMdaFree  VMdaSize  VG
      1    91.50k   188.00k volg0
      4  8091.00k 16384.00k volg1

Friday, 20 February 2015

Starting a Ganeti VM to reset root password

# gnt-instance start -H kernel_args="rw init=/bin/sh" INSTANCE
Waiting for job 1333533 for INSTANCE ...
# gnt-instance console INSTANCE
Initializing cgroup subsys cpuset
Initializing cgroup subsys cpu
Linux version 2.6.32-358.23.2.el6.x86_64 (mockbuild@c6b9.bsys.dev.centos.org) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC) ) #1 SMP Wed Oct 16 18:37:12 UTC 2013
Command line: ro root=LABEL=root rhgb noquiet root=/dev/xvda rw init=/bin/sh

[cut]

sh: cannot set terminal process group (-1): Inappropriate ioctl for device
sh: no job control in this shell
sh-4.1# passwd
Changing password for user root.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.
sh-4.1# exit

# gnt-instance reboot INSTANCE