Host group based access restriction - Nagios

This is useful especially when you have different host groups belongs to different entities and you need to have access separation.

The basic idea is to use the same login user name in the contact groups. I assume that you have Apache htaccess authentication or LDAP authentication in place.

You may create new contact group of use the already existing one , just make sure your username and contact_name matches.

- Create a contact group
define contactgroup {

 contactgroup_name customer1
 alias Customer1 Servers
 members customer1
}

- Create the contact
define contact {
 contact_name customer1 #make sure this matches with the username
 alias Customer1 Contact
 service_notification_period 24x7
 host_notifications_enabled 0
 host_notification_period 24x7
 service_notification_options w,u,c,r
 host_notification_options d,u,r
 service_notification_commands notify-by-email
 host_notification_commands host-notify-by-email
 email customer1@example.com
}

- Use this contact group in host definition

define host {
 use generic-alerted-host
 host_name customer1-host
 address 8.8.8.8
 contact_groups customer1 # make sure this matches with the contactgroup_name
 max_check_attempts 3
}

Just restart nagios and try to login with the new user account. You may give more privileges to this user if required from cgi.cfg

./run

Delete mailman archieves

If required take backup of the archives

$ cp -a /var/lib/mailman/archives/private/<listname>/* <backup_directory>

Remove the archives

$ rm -rf <listname>/*

Once it is removed recreate the html archive files

$ mailman/bin/arch <listname>

./arun

Detected bug in an extension! Hook FCKeditor_MediaWiki

Detected bug in an extension! Hook FCKeditor_MediaWiki::onCustomEditor failed to return a value; should return true to continue hook processing or false to abort.

Backtrace:

#0 mediawiki/includes/Wiki.php(497): wfRunHooks('CustomEditor', Array)
 #1 mediawiki/includes/Wiki.php(63): MediaWiki->performAction(Object(OutputPage), Object(Article), 
Object(Title), Object(User), Object(WebRequest))
 #2 mediawiki/index.php(114): MediaWiki->initialize(Object(Title), Object(Article), Object(OutputPage), 
Object(User), Object(WebRequest))
 #3 {main}

Edit the following file to fix this issue:

"FCKeditor/FCKeditor.body.php"
 -- public function onCustomEditor(&$article, &$user) {
 ++ public function onCustomEditor($article, $user) {

reference: http://dev.ckeditor.com/ticket/3530
./arun

svn: Can't convert string from 'UTF-8' to native encoding:

"svn: Can't convert string from 'UTF-8' to native encoding:"

This usually happens with special characters in the file name, which the client cannot understand.

Just set proper locale in the client to fix this issues,

$ export LC_CTYPE=en_US.UTF-8
// make sure the locale is properly set.
$ locale
LC_CTYPE=en_US.UTF-8

./arun

Fix categories and tags in wordpress custom post_type

By default word press does not look in to custom post_types for categories and tags, even though the category names are visible you get a NOT FOUND page when you click on the category.

A work around found for this issue is :

Edit : functions.php

add_filter('pre_get_posts', 'query_post_type');
function query_post_type($query) {
if(is_category() || is_tag()) {
$post_type = get_query_var('post_type');
if($post_type)
$post_type = $post_type;
else
$post_type = array('post','custom_post_type_name','nav_menu_item'); // replace custom_post_type_name with your post_type, and keep nav_menu_item to display menu in category page.
$query->set('post_type',$post_type);
return $query;
}
}

Reference: http://wordpress.org/support/topic/custom-post-type-tagscategories-archive-page

Thanks to paranoid  for guiding to the fix . ;)

./arun

 

Replace broken hard drive in software RAID1

This scenario assumes that you have two hard disk with RAID1 setup and one of them is broken (say sdb).

To check the status of RAID:

$ cat /proc/mdstat

Personalities : [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md2 : active raid1 sda3[1]
730202368 blocks [2/1] [U_]
md1 : active raid1 sda2[1]
264960 blocks [2/1] [U_]
md0 : active (auto-read-only) raid1 sda1[1]
2102464 blocks [2/1] [U_]

you will see [_U] or [U_] if there is a broken RAID.

If required remove the broken hardrive from RAID from all md devices.

# mdadm --manage /dev/md0 --fail /dev/sdb1

# mdadm --manage /dev/md1 --fail /dev/sdb2

# mdadm --manage /dev/md2 --fail /dev/sdb3

Shutdown the machine and replace the hard drive.

Once the server is booted, you will see the new device (either sda or sdb depends on what drive is broken)

# ls -l /dev/sd*

Now we need to replicate the partition schema on the new drive.

sfdisk -d /dev/sda | sfdisk /dev/sdb

// -d     Dump the partitions of a device

We can add the partition to the RAID now, you could verify the partitions with fdisk -l.

# mdadm --manage /dev/md0 --add /dev/sdb1

# mdadm --manage /dev/md1 --add /dev/sdb2

# mdadm --manage /dev/md2 --add /dev/sdb3

It will start sync the data and will be ready once completed.

You may verify the mdstat

# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md2 : active raid1 sda3[0] sdb3[1]
7302023 blocks [2/2] [UU]

md1 : active raid1 sda2[0] sdb2[1]
2649 blocks [2/2] [UU]

md0 : active (auto-read-only) raid1 sda1[0] sdb1[1]
21024 blocks [2/2] [UU]

./arun

Enable IPv6 on Direct Admin

It was rather easy to get IPv6 working with DA if you have the IPv6 subnet allocated for your server.

Make sure that you have IPv6 enabled on your DA.

# grep ipv6 /usr/local/directadmin/conf/directadmin.conf
ipv6=1

Add the IPv6 Addresses to your direct admin, through IP Management (This will add IPv6 address to the interface).
Enter the IPv6 Address in IP field and keep the Netmask as 255.255.255.0

Add IPv6 address for your name servers,
go to DNS administration --> Select your name server domain --> Add AAAA records for your Name Servers. Make sure you have added the IPv6 addresses already to DA.

Check your name server is resolving/reachable via IPv6.

Now to add IPv6 Address to hosted domains, select the domain --> Modify user --> select the IPv6 address in "Add Additional IP". If the IPv6 address is not visible, make sure it is added to DA and to the reseller account you are editing the domain.

Add the IPv6 address(AAAA) to the corresponding domains DNS configuration.

Here we go, ping666666

 

./arun

Extending LVM disk space

Add the new disk drive to the system, you need to reboot the machine and configure the hardware RAID if required.

Add the new disk to Volume group

For e.g.: if the disk is HP with Smart array

# pvcreate /dev/cciss/c0d1
# vgextend <volume_group_name> /dev/cciss/c0d1

Extend the Logical volume:
# lvextend -L<+mention_the_size> /dev/<volume_group>/<logical_volume>
eg: # lvextend -L+25G /dev/localhost/var
       # lvextend -L+10G /dev/localhost/home

Resize the file system:
# resizefs <file_system>
eg:
# resizefs /dev/mapper/localhost-var
# resizefs /dev/mapper/localhost-home

./arun

Install and configure rsnapshot for central backup (without root privilege)

Download and install RsnapShot
Download the latest package from: http://rsnapshot.org/downloads.html

# wget http://rsnapshot.org/downloads/rsnapshot-1.3.1-1.noarch.rpm
# rpm -Uvh rsnapshot-1.3.1-1.noarch.rpm

Configure public key authentication

- Enable public key authentication with remote hosts with normal user privilege

local# ssh-keygen -t rsa
local# scp id_rsa.pub ssh-remote-server:id_rsa.pub

remote# useradd -c "Backup user" -d /data/home/backup/ backup
remote# su - backup

remote# vi .ssh/authorized_keys

remote# chmod 600 .ssh/authorized_keys

remote# cat id_rsa.pub >> authorized_keys ; rm id_rsa.pub

Add the command allowed to execute in the authorized_keys

command="/home/backup/validate-rsync.sh"

Create the /home/backup/validate-rsync.sh script with following contents

#!/bin/sh
case "$SSH_ORIGINAL_COMMAND" in
  *\&*)
    echo "Rejected 1"
    ;;
  *\;*)
    echo "Rejected 2"
    ;;
    rsync*)
    $SSH_ORIGINAL_COMMAND
    ;;
  *true*)
    echo $SSH_ORIGINAL_COMMAND
    ;;
  *)
    echo "Rejected 3"
    ;;
esac

$ chmod 700 validate-rsync.sh

Create the rsync wrapper script

$ cat  > /usr/local/bin/rsync_wrapper.sh

#!/bin/sh
/usr/bin/sudo /usr/bin/rsync "$@";

# chmod 755 /usr/local/bin/rsync_wrapper.sh

This steps will basically force the ssh connection to execute the rsync as sudo

Grant user to execute rsync as root

backup    ALL=(root) NOPASSWD: /usr/bin/rsync

Configure Rsnapshot

master# cp /etc/rsnapshot.conf.default /etc/rsnapshot.conf

Configure path for cp, rsync, ssh, logger, du etc

set link_dest = 1

change rsync_long_args like

rsync_long_args --rsync-path=rsync_wrapper.sh --delete --numeric-ids --relative --delete-excluded

If you require daily backup for a week,

interval daily 7

More details are on the how to section for rsnapshot website
http://rsnapshot.org/howto/1.2/rsnapshot-HOWTO.en.html

Configure the hosts and file system to backup

backup      backup@remotehost:/etc/     remotehost/

./arun

 

 

 

 

Upgrading php to 5.2 or 5.3 in Redhat EL 5

Unfortunately RHEL 5 does not have php.5.2 package, which is required by most of the applications including latest wordpress and drupal.

First thought of compiling php from source, but hard to keep it uptodate. So decided to make the life easier with EPEL/IUS repositories.

Remove all existing php related packages:

# rpm -e php php-mysql php-cli php-pdo php-common

Download and install the EPEL/IUS RPMs

# wget http://dl.iuscommunity.org/pub/ius/stable/Redhat/5/i386/epel-release-1-1.ius.el5.noarch.rpm

# wget http://dl.iuscommunity.org/pub/ius/stable/Redhat/5/i386/ius-release-1.0-8.ius.el5.noarch.rpm

incase if the list not working just browse and find the rpm.

Install the RPMs

# rpm -Uvh *-release-*.rpm

Now you can install php 5.2 or 5.3 like:

# yum install php52 php52-mysql

./arun