Analyzing DDoS Attack with Nginx log

In this small post I would like to show a few useful commands to use if someone is experiencing a DDoS attack. In my case, there is an nginx as a front-end server. The access log format looks like this:

log_format main '$remote_addr — $remote_user [$time_local] "$host" "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for" -> $upstream_response_time';

In the log file we’ll see something like this:

188.142.8.61 — - [14/Sep/2014:22:51:03 +0400] «www.mysite.com» «GET / HTTP/1.1» 200 519 «kiloccnp.com.vn/» «Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.191602; .NET CLR 3.5.191602; .NET CLR 3.0.191602» "-" -> 0.003

Sử dụng log Apache để phân tích DDos

Nguồn : http://pastebin.com/raw/MLHtJ7fQ

[root@kiloccnp~]# cat kilo.txt  | cut -d ' ' -f 9 | sort | uniq -c | sort -nr

    698 404
    691 HTTP/1.1"
    168 HTTP/1.0"
     27 403

[root@kiloccnp~]# grep " 404 " kilo.txt  | cut -d ' ' -f 7 | sort | uniq -c | sort -nr

    674 /
    672 "POST
     23 //
      1 /balancer?&data=

[root@kiloccnp~]# grep " 404 " kilo.txt   | cut -d '"' -f 6 | sort | uniq -c | sort -nr

    136 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; SV1; .NET CLR 2.0.50727; InfoPath.2)
    132 Mozilla/5.0 (Windows; U; Windows NT 6.1; en; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729)
    131 Mozilla/4.0 (compatible; MSIE 6.1; Windows XP)
    118 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.1 (KHTML, like Gecko) Chrome/4.0.219.6 Safari/532.1
    117 Mozilla/5.0 (Windows; U; MSIE 7.0; Windows NT 6.0; en-US)
    113 Opera/9.80 (Windows NT 5.2; U; ru) Presto/2.5.22 Version/10.51
    109 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; InfoPath.2)
    106 Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729)
    102 Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.3) Gecko/20090913 Firefox/3.5.3
     98 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.2; Win64; x64; Trident/4.0)
     94 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 1.1.4322; .NET CLR 3.5.30729; .NET CLR 3.0.30729)
     92 Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.1) Gecko/20090718 Firefox/3.5.1
     21 Mozilla/5.0 (KHTML, like Gecko) Safari/537.36
      1 MyClient/1.0

Install MySQL Enterprise Monitor

1 . Install MySQL Monitor center

[root@Kilo-MySQL-Monitor ~]# unzip V790192-01-MySQL_Enterprise_Monitor_Service_Manager_3.3.1.zip

Archive:  V790192-01-MySQL_Enterprise_Monitor_Service_Manager_3.3.1.zip

 inflating: mysqlmonitor-3.3.1.1112-linux-x86_64-installer.bin  

 inflating: mysqlmonitor-3.3.1.1112-linux-x86_64-update-installer.bin  

 inflating: README_en.txt           

 inflating: READ_ME_ja.txt         

[root@Kilo-MySQL-Monitor ~]# chmod +x mysqlmonitor-3.3.1.1112-linux-x86_64-installer.bin

[root@Kilo-MySQL-Monitor ~]# ./mysqlmonitor-3.3.1.1112-linux-x86_64-installer.bin --mode text

Language Selection

MySQL Enterprise Backup & Restore - Full and Incrimental

1. Create bash script 

#!/bin/bash

#creates and maintains MySQL Enterprise Backup (MEB) backups

#prints usage
usage()
{
    echo "$VERSION"
    echo "
Usage: `basename $0` [command] [MEB options]

Commands:
    full                                make full backup
    incremental                         make incremental backup
    incremental-with-redo-log-only      make incremental backup with redo log only
    verify-to-tape                      verify backup images, then copy to tape
    prepare                             prepare backups
    remove-old                          remove old backups
    "
}

Full Backup using MySQL Enterprise Backup

Install the software

Before we can configure backups and the like, you’ll need to install the MySQL Enterprise Backup software:

$ tar xvzf meb-3.9.0-linux2.6-x86-64bit.tar.gz 
meb-3.9.0-linux2.6-x86-64bit/
meb-3.9.0-linux2.6-x86-64bit/bin/
meb-3.9.0-linux2.6-x86-64bit/bin/mysqlbackup
meb-3.9.0-linux2.6-x86-64bit/README.txt
meb-3.9.0-linux2.6-x86-64bit/LICENSE.mysql
meb-3.9.0-linux2.6-x86-64bit/manual.html
meb-3.9.0-linux2.6-x86-64bit/mysql-html.css

I then placed the mysqlbackup binary in my MySQL “bin” directory :

$ cp meb-3.9.0-linux2.6-x86-64bit/bin/mysqlbackup /usr/local/mysql/bin/
$ which mysqlbackup 
/usr/local/mysql/bin/mysqlbackup

Now we’ve installed the software, we can go on and prepare our database for backup.

How to Back Up MySQL Server using MySQL Enterprise Backup (MEB)

 In order to be able to use MySQL Enterprise Backup to perform a backup of a MySQL Server instance, the following MySQL options must be specified in the configuration file of the server instance, under the [mysqld] section (substitute ... with any valid values):

datadir=...
innodb_data_home_dir=...
innodb_data_file_path=...
innodb_log_group_home_dir=...
innodb_log_files_in_group=...
innodb_log_file_size=...

Alternately you can use a new configuration file, that contains just the options above, and pass it to MySQL Enterprise Backup.

My.cnf examples

[root@kiloccnp ~]# cat /etc/my.cnf
# On Linux you can copy this file to /etc/my.cnf to set global options,
# mysql-data-dir/my.cnf to set server-specific options
# (@localstatedir@ for this installation) or to
# ~/.my.cnf to set user-specific options.

[mysqld]
datadir=/usr/local/mysql/data
#tmpdir=/var/log/mysqld/
tmpdir=/db/mytmp
log-error=/var/log/mysqld/mysqld.err
# as of MySQL 5.1.29, log-slow-queries is deprecated, use the 2 options below
#log-slow-queries=/var/log/mysqld/mysqld-slow.log
slow-query-log=1
slow-query-log-file=/var/log/mysqld/mysqld-slow.log
performance_schema_consumer_events_statements_history_long = ON

How to Automate Backups on Linux/UNIX Using MySQL Enterprise Backup (MEB)

Goal

Backups should be made regularly.  The easiest way to do so on Linux/UNIX is to write a cron job. In this article MEB users will find two crontab templates: one for weekly full backups and another for daily incremental backups.

Solution

Although MEB allows for the creation of incremental backups, it is still best practice to run full backups periodically.   Below you will find a schedule which makes weekly full backups and daily incremental backups.

Weekly full backup can be done using following crontab command:

Create example data MySQL

1. Create tables 

DROP TABLE IF EXISTS `City`;
CREATE TABLE `City` (
  `ID` int(11) NOT NULL auto_increment,
  `Name` char(35) NOT NULL default '',
  `CountryCode` char(3) NOT NULL default '',
  `District` char(20) NOT NULL default '',
  `Population` int(11) NOT NULL default '0',
  PRIMARY KEY  (`ID`)
) ENGINE=NDBCLUSTER DEFAULT CHARSET=latin1;

INSERT INTO `City` VALUES (1,'Kabul','AFG','Kabol',1780000);
INSERT INTO `City` VALUES (2,'Qandahar','AFG','Qandahar',237500);
INSERT INTO `City` VALUES (3,'Herat','AFG','Herat',186800);

2. Shell insert 
#!/bin/bash
max=1000
for (( i=11; i <= $max; ++i ))
do
    /usr/bin/mysql -uroot -p123456 -hA.A.A.B -e "use test; INSERT INTO City VALUES ($i,'Kabul','AFG','Kabol',1780000);"

done

Installing PHP and the Oracle Instant Client

PHP OCI8 is the PHP extension for connecting PHP to Oracle Database. OCI8 is open source and included with PHP. The name is derived from Oracle's C "call interface" API first introduced in version 8 of Oracle Database. PHP OCI8 links with Oracle C client libraries, which are included in the Oracle Database software and also in Oracle Instant Client.
Oracle Instant Client is a free set of easily installed libraries that allow programs to connect to local or remote Oracle Database instances. To use Instant Client an existing database is needed because Instant Client does not include one. Typically the database will be on another machine. If the database is local then Instant Client, although convenient and still usable, is generally not needed because PHP OCI8 can be built using the database libraries.

Install HP ArcSight

[root@Kilo~]# useradd kilo_arc

[root@Kilo~]# vim /etc/security/limits.d/90-nproc.conf

    # Default limit for number of user's processes to prevent

    # accidental fork bombs.

    # See rhbz #432903 for reasoning.

    * soft nproc 1024

    root soft nproc unlimited

    * soft nproc 10240

Installing PDO_OCI and OCI8 PHP extensions on CentOS

I am currently working on a PHP project that requires using an Oracle server as the database. I
This tutorial assumes that you have already installed php and other packages (e.g. php-pdo) you normally need. This was also tested with an installation of Oracle 11g Express. I’m not sure if this will work for higher versions.

Dependencies

Development packages

$ sudo yum install php-pear php-devel zlib zlib-devel bc libaio glibc
$ sudo yum groupinstall "Development Tools"

InstantClient

Apache Web Server Security and Hardening Tips

1. How to hide Apache Version and OS Identity from Errors

When you install Apache with source or any other package installers like yum, it displays the version of your Apache web server installed on your server with the Operating system name of your server in Errors. It also shows the information about Apache modules installed in your server.

Troubleshoot with Apache Logs

$ cat access.log | cut -d ' ' -f 9 | sort | uniq -c | sort -nr
     941 200
     292 500
     290 404
     50 401
     20 400
$ grep " 404 " access.log | cut -d ' ' -f 7 | sort | uniq -c | sort -nr
     17 /manager/html
      3 /robots.txt
      3 /phpMyAdmin/scripts/setup.php
      3 //myadmin/scripts/setup.php
      3 /favicon.ico
$ cat access.log.1 | cut -d '"' -f 6 | sort | uniq -c | sort -nr

Install PHP & Apache from sourcecode

[root@kiloccnp httpd-2.4.23]# yum install libxml2-static.x86_64 libxml2.x86_64 libxml2-devel.x86_64
[root@kiloccnp php-5.6.28]# yum install gsm.x86_64 gsm-devel.x86_64 gsm-tools.x86_64 libxslt.x86_64
[root@kiloccnp php-5.6.28]# yum install icu.x86_64 libicu.x86_64 libicu-devel.x86_64 libicu-doc.noarch
[root@kiloccnp php-5.6.28]# yum install unixODBC.x86_64 unixODBC-devel.x86_64
[root@kiloccnp curl]# yum install libcurl-devel.x86_64 libcurl.x86_64
[root@kiloccnp gd]# yum install dvipng.x86_64 libpng.x86_64 libpng-devel.x86_64 libpng-static.x86_64 gd.x86_64
http://www.oracle.com/technetwork/topics/linuxx86-64soft-092277.html  (download for oci8 )
[root@kiloccnp ~]# rpm -Uvh oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64.rpm
[root@kiloccnp ~]# rpm -Uvh oracle-instantclient11.2-devel-11.2.0.4.0-1.x86_64.rpm

CÔNG NGHỆ LƯU TRỮ CEPH

Ceph là giải pháp mã nguồn mở để xây dựng hạ tầng lưu trữ phân tán, ổn định, độ tin cậy và hiệu năng cao, dễ dàng mở rộng. Với hệ thống lưu trữ được điều khiển bằng phần mềm, Ceph cung cấp giải pháp lưu trữ theo đối tượng (Object), khối (Block) và tệp dữ liệu (File) trong một nền tảng đơn nhất. Ceph chạy trên nền tảng điện toán đám mây với các thiết bị phần cứng ổn định và tiên tiến nhất, giúp tiết kiệm chi phí và sử dụng dễ dàng với Linux Kernel.

1. Lưu trữ Ceph là gì?

How to Configure a Proxmox VE 4 Multiple Node Cluster

Prerequisites

• 3 Proxmox server

    pve1
        IP          : 192.168.1.114
        FQDN     : pve1.myproxmox.co
        SSH port: 22

    pve2
        IP          : 192.168.1.115
        FQDN     : pve2.myproxmox.co
        SSH port: 22

    pve3
        IP           : 192.168.1.116
        FQDN      : pve3.myproxmox.co
        SSH port : 22

• 1 CentOS 7 server as NFS storage with IP 192.168.1.101
• Date and time mus be synchronized on each Proxmox server.

General Iptables Firewall Rules

1. Delete all existing rules
# iptables -F

2. Set default chain policies
# iptables -P INPUT DROP
# iptables -P FORWARD DROP
# iptables -P OUTPUT DROP

3. Block a specific ip-address
BLOCK_THIS_IP=”x.x.x.x”
# iptables -A INPUT -s “$BLOCK_THIS_IP” -j DROP

Apache Optimization: KeepAlive On or Off

Apache is the most widely used web server on the Internet. Knowing how to get the most out of Apache is very important for a systems administrator. Optimizing Apache is always a balancing act. It’s a case of sacrificing one resource in order to obtain savings in another.

What is KeepAlive

HTTP is a session less protocol. A connection is made to transfer a single file and closed once the transfer is complete. This keeps things simple but its not very efficient.
To improve efficiency something called KeepAlive was introduced. With KeepAlive the web browser and the web server agree to reuse the same connection to transfer multiple files.

How to rotate apache logs

/var/log/httpd/access_log.* {
compress
copytruncate
create 644 root root
rotate 30
size 100K
}
/var/log/httpd/dummy-host.example.com-access_log.* {
compress
copytruncate
create 644 root root
rotate 30
size 10M

MySQL Engines: InnoDB vs. MyISAM

The 2 major types of table storage engines for MySQL databases are InnoDB and MyISAM. To summarize the differences of features and performance,

1. InnoDB is newer while MyISAM is older.
2. InnoDB is more complex while MyISAM is simpler.
3. InnoDB is more strict in data integrity while MyISAM is loose.
4. InnoDB implements row-level lock for inserting and updating while MyISAM implements table-level lock.
5. InnoDB has transactions while MyISAM does not.
6. InnoDB has foreign keys and relationship contraints while MyISAM does not.
7. InnoDB has better crash recovery while MyISAM is poor at recovering data integrity at system crashes.
8. MyISAM has full-text search index while InnoDB has not.

How to Reset MySQL Root Password

Method 1. How to Change MySQL Root Password Using mysqladmin Command?
You can change the MySQL root password using mysqladmin command as shown below. Please note that there is no space between -p and currentpassword.
# mysqladmin -u root -pCURRENTPASSWORD password ‘NEWPASSWORD’
Once you’ve changed it make sure you can login with your new password successfully as shown below.
# mysql -u root -pnewpassword
Welcome to the MySQL monitor.  Commands end with ; or g.
Your MySQL connection id is 8
Server version: 5.5.13-rc-community MySQL Community Server (GPL)
mysql>

How to Shrink or reduce size of LVM partitons in RHEL/CentOS

1. Check disk partitions size
# df -hT

Filesystem	Type	Size	Used	Avail	Use%	Mounted on
/dev/mapper/VolGroup00-LogVol00	ext3	34G	6.6G	26G	21%	/
/dev/mapper/VolGroup00-LogVol03	ext3	34G	29G	27G	52%	/usr
/dev/mapper/VolGroup00-LogVol04	ext3	97G	89G	2.7G	98%	/var
/dev/sda1	ext3	99M	27M	67M	29%	/boot
tmpfs	tmpfs	56G	0	56G	0%	/dev/shm
/dev/mapper/VolGroup00-LogVol02	ext3	56G	9.1G	65G	13%	/backup

2. Unmount the partitions that want to shrink or reduce
# umount /dev/mapper/VolGroup00-LogVol02

Difference between RAID and LVM

 S.No.

	RAID	LVM
1.	RAID is used for redundancy.	LVM is a way in which you partition the hard disk logically and it contains its own advantages.
2.	A RAID device is a physical grouping of disk devices in order to create a logical presentation of one device to an Operating System for redundancy or performance or a combination of the two.	LVM is a logical layer that that can be anipulated in order to create and, or expand a logical presentation of a disk device to an Operating System.
3.	RAID is a way to create a redundant or striped block device with redundancy using other physical block devices.	LVM usually sits on top of RAID blocks or even standard block devices to accomplish the same result as a partitioning, however it is much more flexible than partitions. You can create multiple volumes crossing multiple physical devices, remove physical devices without loosing data, resize the volumes, create snapshots, etc
4.	RAID is either a software or a hardware technique to create data storage redundancy across multiple block devices based on required RAID levels.	LVM is a software tool to manage large pool of storage devices making them appear as a single manageable pool of storage resource. LVM can be used to manage a large pool of what we call Just-a-bunch-of-Disk (JBOD) presenting them as a single logical volume and thereby create various partitions for software RAID.
5.	RAID is NOT any kind of Data backup solution. Its a solution to prevent one of the SPOFs (Single Point of Failure) i.e. DISK failure. By configuring RAID you are just providing an emergency substitute for the Primary disk. It NEVER means that you have configured DATA backup.	LVM is a disk management approach that allows us to create, extend, reduce, delete or resize the volume groups or logical volumes.

Managing Disk Space with LVM -04

Adding A Hard Drive And Removing Another One

We haven't used /dev/sdf until now. We will now create the partition /dev/sdf1 (25GB) and add that to our fileserver volume group.

kilo:~#fdisk /dev/sdf

kilo:~# pvcreate /dev/sdf1
  Physical volume "/dev/sdf1" successfully created

Add /dev/sdf1 to our fileserver volume group:

kilo:~#:vgextend fileserver /dev/sdf1

kilo:~#:vgdisplay

That's it. /dev/sdf1 has been added to the fileserver volume group. Now let's remove /dev/sdb1. Before we do this, we must copy all data on it to /dev/sdf1

kilo:~# pvmove /dev/sdb1 /dev/sdf1
  /dev/sdb1: Moved: 1.9%
  . . .
  /dev/sdb1: Moved: 100.0%

Next we remove /dev/sdb1 from the fileserver volume group:

kilo:~# vgreduce fileserver /dev/sdb1
  Removed "/dev/sdb1" from volume group "fileserver"

kilo:~# vgdisplay
kilo:~#  pvremove /dev/sdb1 

kilo:~#  pvdisplay

You could now remove /dev/sdb from the system (if this was a real system and not a virtual machine).

Managing Disk Space with LVM -03

In this chapter we will learn how to resize our logical volume share which has an ext3 filesystem. (I will show how to resize logical volumes with xfs and reiserfs filesystems further down this tutorial.)
First we must unmount it:

kilo:~# umount /var/share

kilo:~# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              19G  665M   17G   4% /
tmpfs                  78M     0   78M   0% /lib/init/rw
udev                   10M   88K   10M   1% /dev
tmpfs                  78M     0   78M   0% /dev/shm
/dev/sda1             137M   17M  114M  13% /boot
/dev/mapper/fileserver-backup
                      5.0G  144K  5.0G   1% /var/backup
/dev/mapper/fileserver-media
                      1.0G   33M  992M   4% /var/media

Now let's enlarge share from 40GB to 50GB:

kilo:~# lvextend -L+50G /dev/fileserver/share
  Extending logical volume share to 50.00 GB
  Logical volume share successfully resized

Until now we have enlarged only share, but not the ext3 filesystem on share. This is what we do now:

kilo:~# e2fsck -f /dev/fileserver/share
e2fsck 1.40-WIP (14-Nov-2006)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/fileserver/share: 11/5242880 files (9.1% non-contiguous), 209588/10485760 blocks

Make a note of the total amount of blocks (10485760) because we need it when we shrink share later on.

kilo:~# resize2fs /dev/fileserver/share
resize2fs 1.40-WIP (14-Nov-2006)
Resizing the filesystem on /dev/fileserver/share to 13107200 (4k) blocks.
The filesystem on /dev/fileserver/share is now 13107200 blocks long.

Let's mount share:

kilo:~# mount /dev/fileserver/share /var/share

kilo:~# ~# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              19G  665M   17G   4% /
tmpfs                  78M     0   78M   0% /lib/init/rw
udev                   10M   88K   10M   1% /dev
tmpfs                  78M     0   78M   0% /dev/shm
/dev/sda1             137M   17M  114M  13% /boot
/dev/mapper/fileserver-backup
                      5.0G  144K  5.0G   1% /var/backup
/dev/mapper/fileserver-media
                      1.0G   33M  992M   4% /var/media
/dev/mapper/fileserver-share
                       50G  180M   47G   1% /var/share

Managing Disk Space with LVM -02

Basically LVM looks like this:



You have one or more physical volumes (/dev/sdb1 - /dev/sde1 in our example), and on these physical volumes you create one or more volume groups (e.g. fileserver), and in each volume group you can create one or more logical volumes. If you use multiple physical volumes, each logical volume can be bigger than one of the underlying physical volumes (but of course the sum of the logical volumes cannot exceed the total space offered by the physical volumes).
It is a good practice to not allocate the full space to logical volumes, but leave some space unused. That way you can enlarge one or more logical volumes later on if you feel the need for it.
In this example we will create a volume group called fileserver, and we will also create the logical volumes /dev/fileserver/share, /dev/fileserver/backup, and /dev/fileserver/media (which will use only half of the space offered by our physical volumes for now - that way we can switch to RAID1 later on (also described in this tutorial)).

Managing Disk Space with LVM -01

The Linux Logical Volume Manager (LVM) is a mechanism for virtualizing disks. It can create "virtual" disk partitions out of one or more physical hard drives, allowing you to grow, shrink, or move those partitions from drive to drive as your needs change. It also allows you to create larger partitions than you could achieve with a single drive.

Traditional uses of LVM have included databases and company file servers, but even home users may want large partitions for music or video collections, or for storing online backups. LVM and RAID 1 can also be convenient ways to gain redundancy without sacrificing flexibility.

This article looks first at a basic file server, then explains some variations on that theme, including adding redundancy with RAID 1 and some things to consider when using LVM for desktop machines.

Setting up a large (2TB+) hard disk drive on Linux

1. Physically install the hard drive.

After installing the drive, check that the BIOS detected your new drive with the correct size.
When I do this I get an error similar to: "WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted."

2. Identify the device

Also check the device has been detected by linux and identify the device name.

root@turtle:~# ls /dev/sd*
/dev/sda  /dev/sda1  /dev/sda2  /dev/sda5  /dev/sdb

This shows a hard drive 'sda' with existing partitions sda1, sda2 and sda5. It also shows a hard drive 'sdb', but with no partitions detected. The new hard drive will have no partitions, so we can identify it as device 'sdb'

Bypassing Bad fstab Failure When Booting Linux

If /etc/fstab file is created with errors or the hardware configuration changes such as adding hard disks, Linux will boot into failure state. We can bypass the fstab failure by adding booting parameters to Linux. We can do this in two methods:

Method 1: Boot to single user mode 

When booting into single user mode, Linux will not mount anything. Then we can remount the / to some directory in read/write mode and then edit the /etc/fstab.
1. Boot Linux into single user mode
Press ESC in the grub menu and press ‘e’ to edit the grub entry. Add single to the kernel parameter like this:

kernel /vmlinuz-2.6.32.21-166.fc12.i686 ro root=/dev/mapper/VolGroup-LogVol00 vga=792 single

How To Reset Root Password On CentOS 7

The way to reset the root password on centos7 is totally different to Centos 6. Let me show you how to reset root password in CentOS 7.

1 – In the boot grub menu select option to edit.

2 – Select Option to edit (e).

Reset Your Forgotten Root Password On RHEL 7

Sometimes you forget stuff like meetings, seminars,passwords etc. I do. But forgetting a password to a Servers with no easy way to reset it while locked outRedhat servers is one of such systems. If you forget the root password to your RHEL 7 SERVERS, it’s almost virtually impossible to reset it while you’re locked out.

At the boot menu, press e to edit the existing kernel . Then, go to the kernel line (the line starting with linux16) .

How To Setup MariaDB Galera Cluster

MariaDB is a relational database management system (RDBMS) and  MariaDB Galera Cluster is a synchronous multi-master cluster for MariaDB. It is available on Linux only, and only supports the XtraDB/InnoDB storage engines. This article explains how to setup MariaDB Galera Cluster 10.0 with 2 nodes running on CentOS 6.5 x86_64 resulting in a HA (high-availability) database cluster.

How to Deploy and Configure MaxScale for SQL Load Balancing with Read-Write Split

There are two models of load balancing: transport and application layer. HAProxy is a great TCP load balancer, but it’s lack of SQL awareness effectively limits its ability to address certain scaling issues in distributed database environments. In the open source world, there’s been a few SQL-aware load balancers, namely MySQL Proxy, ProxySQL and MaxScale, but they all seemed to be in beta status and unfit for production use. So we were pretty excited when the MariaDB team released a GA version of MaxScale earlier this year. In this blog, we’ll have a look at MaxScale and see how it compares with HAProxy.

Proxmox VE- One Public IP

Proxmox VE - One Public IP

This guide will show you how to set up Proxmox with only one public IP. We will configure an extra interface bridge and make sure VM traffic is NATed. I have a few dedicated servers, some run Proxmox. Most of them however have only a few IP's. Therefore the VM's in proxmox cannot all have a public IP. For most of them that is not a problem. If needed I run a proxy or set up iptables to forward ports to the VM's.

This guide is tested on a proxmox machine running proxmox version 3.2.

Proxmox VE_part 1

Proxmox VE (virtual environment) is a distribution based on Debian Etch (x86_64); it provides an OpenSource virtualization platform for running virtual machines (OpenVZ and KVM) and comes with a powerful, web-based control panel (it includes a web-based graphical console that you can use to connect to the virtual machines). With Proxmox VE, you can even create a cluster of virtualization hosts and create/control virtual machines on remote hosts from the control panel. Proxmox VE also supports live migration of virtual machines from one host to the other. This guide shows how you can use Proxmox VE to control KVM and OpenVZ virtual machines and how to create a small computing cloud with it