MySQL Database Support

MySQL Database Support

It is a open source relational database management System. Our user friendly support professionals are available 24*7 online to ensure that your MySQL installation is running optimally.

Our support professional will help you to

  • Increase your uptime
  • Be more productive
  • Implement resolutions to perform faster

Our support team is available 24×7 to provide support for MySQL and Version of MySQL

MySQL Consultancy

Our MySQL expert consultant can help you in critical MySQL deployments like

  • Architecture and design
  • Performance tuning
  • Back-up and recovery
  • Migration
  • High availability
  • Clustering

MySQL Performance Tuning

Our MySQL experts can do Performance Tuning with MySQL and MariaDB to

  • Diagnose existing performance problems
  • Improved database performance and resource management
  • Identify unknown performance problems
  • Configure, optimize and analyze storage engines
  • Review your operating environment and application infrastructure

MySQL Architecture & Design

Our MySQL experts can help you designing:

  • Online applications
  • Data warehousing, analytical reporting solutions
  • Data collection and auditing methods
  • Data search approaches
  • Large data stores
  • Data modelling and design
  • High availability architectures
  • Load balancing architectures

MySQL High Availability

  • MySQL high availability (HA) ensures that your MySQL database can survive a disaster and recover quickly without losing data. It also means that your MySQL-based application will meet your minimum performance requirements in normal operation.
  • Our expert team can help you analyze your business and application requirements and deploy a highly available MySQL solution for you in less than three days, be it onsite or remote.
  • Our consultants also work with MariaDB Server.
  • We use these technologies for MySQL High Availability:
    • MySQL Replication
    • Semi-sync Replication
    • MariaDB Galera Cluster
    • Galera Cluster
    • Master HA Tool with Multi-Tier Replication
    • MySQL Cluster
    • Linux Shared Storage
    • Linux Shared Storage + Replication

MySQL Cluster Consulting

Our MySQL Cluster experts will enable you to get the highest levels of scalability, availability, and performance from your MySQL Cluster installations.

Services includes:

  • Determining the most appropriate implementation, installation, and configuration of MySQL Cluster for your project and application
  • MySQL Cluster architecture and design
  • MySQL Cluster installation, configuration, and performance tuning
  • MySQL Cluster-specific data modelling and design
  • MySQL Cluster-specific routines and query optimization

MySQL Database Migration

Our Migration experts help you achieve the cost savings associated with replacing your commercial databases with MySQL or MariaDB

  • Migration analysis, cost evaluation and planning
  • Risk analysis and risk mitigation planning
  • Schema remodelling and migration
  • Data migration
  • Query analysis, migration and optimization
  • Analysis, migration, and optimization of stored routines and other database objects
  • Analysis and migration of client connectors

Open Source Consultancy

Having worked with open source technologies since we were founded, Linux Firm understands the great benefits to clients who implement such technologies: saving money on licensing, working with established standards, and gaining advantage from the vast community knowledge-base of open-source development experts.

By working with our highly skilled Linux Consultants, we can provide consultancy in choosing the right applications for your business.

Some of the benefits of open source products are:

  • Low cost installation and maintenance
  • There are no extortionate licensing fees for terminals
  • Linux systems operate much faster and rarely have problems of crashing
  • Linux systems by being open source are constantly developed and therefore any bugs are fixed rapidly
Linux Solutions

Linux Solutions

Linux Solutions in Delhi

Linux Firm provides support to meet your needs for designing, implementing and maintaining Linux systems, and with strong ties to the Linux open Source development community, Linux Firm has clearly recognized as the Linux server maintenance leader.

We are a One Stop Source for all Open Source Needs for any Organization. We provide cost-effective business ready solutions on services and subscription model using Linux and Open Source. Whether your servers are hosted with third parties or are located in your office, whether you require contracted unlimited support services or hourly support services, you’ll receive exceptional server support at all times.

When it comes to Linux servers, the situation is no different: simply put, the only certain way of maintaining uptime, preserving system security and ensuring service availability is to utilize a server management solution.  Our technical services are provided over a range of nix-based platforms, including most common variants of Linux (such as Redhat, CentOS, Fedora, Ubuntu and others), as well as FreeBSD.

We invite you to explore the specifics on the services we offer; for your convenience, they are summarized below. Nonetheless, should you have any question about any aspect of our products, support, services or maintenance, please feel free to contact us, and we will be more than happy to promptly answer your inquiry.

Viruses, spyware,Trojan, Root kits,
Remote exploits…..?

“Linux is the preferred operating system for those who demand secure networks.”

Linux is born with security

Linux Security

Clam antivirus / Spam Assassin/Snort / Tripwire/ Wireshark/Nessus /Nagious/ Ntop/Nmap/Chkrootkit/Ethereal /Kismet/Iptables/Shorewall/ IPCOP/SE Linux/PAM/TCP wrapper and hundreds more…

Mailing Solution

Global Address Book
My Sql/Active Directory/Ldap Integration
Mail Achieving / MailDir format
IMAP/POP3/WEBMAIL
Antispam/Antivirus/Attachment Rules
Mail Analyser / Control Panel
Auto Responder / Disclaimer /
Forwarders/Catchall / Grouping
Unlimited User / Unlimited Mail Rules
Mail Backup …. Lot more

Squid Proxy Server

Content filtering/URL Restriction /
Privillege Level of Internet Distribution /
Surfing Monitoring / Reporting/
User/Passwd , Mac , Active Directory,
MySql, LDAP Integration/
MIME Protection / Antivirus /
AntiSpy/Control Panel/
Log Analysis/
Speedy Internet Connection

File Server

Centralised Data Management
Windows AD like Features
Group Policies / Ldap /MySQL/Windows AD integration
Logon Scripts/MIME protection
Unlimited Users / Easy Control Panel
Compatible with windows desktops
Roaming Profile & lot more >>

NAS/Storage

Web User Interface
Command Line Interface
10GigE Drivers
Thin Provisioning
Zettabyte File System
Snapshots
Backup and Restore
File Sharing

Virtualisation

OpenVZ
Virtualbox
VMWare
Xen
Citrix XenServer
Sun xVM
Oracle VM

IM/chat server

Open-Source Java XMPP (Jabber) server.
Open Source Real-Time Communication
Chat Server / IM Messanger
Awesome Client (Cross-platform real-time collaboration client optimized for business and organizations )
MySql / Windows AD connectivity
Online File Transfer
Content filtering / History
Web based real-time collaboration client optimized for business and organizations

Firewall

Build a complete, secure and stable firewall exclusively from Open Source software”
Open Source,
Free,
Community-Supported Security Solution
Unified Threat Management (UTM) functionality
Very easy to install
Use and manage, without losing its flexibility
Application-level proxies for various protocols (HTTP, FTP, POP3, SMTP)
Antivirus support
Virus and spam-filtering for email traffic (POP and SMTP),
Content filtering of Web traffic
A “hassle free” VPN solution (based on OpenVPN).

VoIP

VoIP stands for Voice over Internet Protocol

VoIP is a telephone connection that uses internet instead of the regular telephone network.
VoIP saves your money
Portability – Take It Where You Go
Portability – Take It Where You Go
Compatible with legacy telephony network
VoIP includes all those features that the normal telephone company provides .

CRM

“Customer relationship management (CRM) is a widely-implemented strategy for managing a company’s interactions with customers, clients and sales prospects”

Sales force automation
Customer support & service
Marketing automation
Inventory management
Activity management
Security management
Calendaring
E-mail integration

SVN

Apache™ Subversion®
“Enterprise-class centralized version control for the masses”
Subversion is an open source version control system
Directories are versioned
Copying, deleting, and renaming are versioned.
File locking.
Interactive conflict resolution.
Write-through proxy over WebDAV.
Repository read-only mirroring.
Standalone server option (svnserve).
Executable flag is preserved.
Symbolic links can be versioned.

And lot more features >>

CMS

Content management system
Create a Dynamic Website within a day with all functions like
Payment gateway,
Add cart ,
e-commerce,
Picture gallery
Maintaining Security
Managing Objects
Managing Servers
Managing Auditing
Maintaining Report
and a lot more >>

LAMP

Linux-Apache-MySql-PHP
(software bundle)

Easy to code
Easy to deploy
Develop locally
Cheap and ubiquitous hosting
Free Open Source
Strong Community
Great Market Share
web scripting software

Linux Desktop

Open Office / Libra Office
Evolution /thunderbird Mail Client
Mozilla
Compatible with windows based software. / awesome looks and feel
Virus Free / Easy / User friendly
Fast / Stable / Relaible / Error free
Bundled with All Drivers / Softwares/tools/Manual guides

Linux Firm is the best Linux Solutions Company in India with Best Linux Administrators provides Linux and Open Source Consulting, Linux Mail Server, Linux Networking, Linux Website Hosting, Linux Dedicated Server, Linux Hosting, Linux Open Source Web & HTTP Load Balancer, Linux Hosting Services, Best Linux Web Hosting, Linux managed hosting, complete range of Linux services and support solutions, Business Process Outsourcing & Solutions Provider Company in India, USA, Australia, Canada, UK at affordable rates

Linux Server Delhi

Linux Server Delhi

IT Monteur provides support to meet your needs for designing, implementing and maintaining Linux systems, and with strong ties to the Linux open Source development community, IT Monteur has clearly recognized as the Linux server maintenance leader.

We are a One Stop Source for all Open Source Needs for any Organization. We provide cost-effective business ready solutions on services and subscription model using Linux and Open Source. Whether your servers are hosted with third parties or are located in your office, whether you require contracted unlimited support services or hourly support services, you’ll receive exceptional server support at all times.

When it comes to Linux servers, the situation is no different: simply put, the only certain way of maintaining uptime, preserving system security and ensuring service availability is to utilize a server management solution.  Our technical services are provided over a range of nix-based platforms, including most common variants of Linux (such as Redhat, CentOS, Fedora, Ubuntu and others), as well as FreeBSD.

We invite you to explore the specifics on the services we offer; for your convenience, they are summarized below. Nonetheless, should you have any question about any aspect of our products, support, services or maintenance, please feel free to contact us, and we will be more than happy to promptly answer your inquiry.

Viruses, spyware,Trojan, Root kits,
Remote exploits…..?

“Linux is the preferred operating system for those who demand secure networks.”

Linux is born with security

Linux Security

Clam antivirus / Spam Assassin/Snort / Tripwire/ Wireshark/Nessus /Nagious/ Ntop/Nmap/Chkrootkit/Ethereal /Kismet/Iptables/Shorewall/ IPCOP/SE Linux/PAM/TCP wrapper and hundreds more…

Mailing Solution

Global Address Book
My Sql/Active Directory/Ldap Integration
Mail Achieving / MailDir format
IMAP/POP3/WEBMAIL
Antispam/Antivirus/Attachment Rules
Mail Analyser / Control Panel
Auto Responder / Disclaimer /
Forwarders/Catchall / Grouping
Unlimited User / Unlimited Mail Rules
Mail Backup …. Lot more

Squid Proxy Server

Content filtering/URL Restriction /
Privillege Level of Internet Distribution /
Surfing Monitoring / Reporting/
User/Passwd , Mac , Active Directory,
MySql, LDAP Integration/
MIME Protection / Antivirus /
AntiSpy/Control Panel/
Log Analysis/
Speedy Internet Connection

File Server

Centralised Data Management
Windows AD like Features
Group Policies / Ldap /MySQL/Windows AD integration
Logon Scripts/MIME protection
Unlimited Users / Easy Control Panel
Compatible with windows desktops
Roaming Profile & lot more >>

NAS/Storage

Web User Interface
Command Line Interface
10GigE Drivers
Thin Provisioning
Zettabyte File System
Snapshots
Backup and Restore
File Sharing

Virtualisation

OpenVZ
Virtualbox
VMWare
Xen
Citrix XenServer
Sun xVM
Oracle VM

IM/chat server

Open-Source Java XMPP (Jabber) server.
Open Source Real-Time Communication
Chat Server / IM Messanger
Awesome Client (Cross-platform real-time collaboration client optimized for business and organizations )
MySql / Windows AD connectivity
Online File Transfer
Content filtering / History
Web based real-time collaboration client optimized for business and organizations

Firewall

Build a complete, secure and stable firewall exclusively from Open Source software”
Open Source,
Free,
Community-Supported Security Solution
Unified Threat Management (UTM) functionality
Very easy to install
Use and manage, without losing its flexibility
Application-level proxies for various protocols (HTTP, FTP, POP3, SMTP)
Antivirus support
Virus and spam-filtering for email traffic (POP and SMTP),
Content filtering of Web traffic
A “hassle free” VPN solution (based on OpenVPN).

VoIP

VoIP stands for Voice over Internet Protocol

VoIP is a telephone connection that uses internet instead of the regular telephone network.
VoIP saves your money
Portability – Take It Where You Go
Portability – Take It Where You Go
Compatible with legacy telephony network
VoIP includes all those features that the normal telephone company provides .

CRM

“Customer relationship management (CRM) is a widely-implemented strategy for managing a company’s interactions with customers, clients and sales prospects”

Sales force automation
Customer support & service
Marketing automation
Inventory management
Activity management
Security management
Calendaring
E-mail integration

SVN

Apache™ Subversion®
“Enterprise-class centralized version control for the masses”
Subversion is an open source version control system
Directories are versioned
Copying, deleting, and renaming are versioned.
File locking.
Interactive conflict resolution.
Write-through proxy over WebDAV.
Repository read-only mirroring.
Standalone server option (svnserve).
Executable flag is preserved.
Symbolic links can be versioned.

And lot more features >>

CMS

Content management system
Create a Dynamic Website within a day with all functions like
Payment gateway,
Add cart ,
e-commerce,
Picture gallery
Maintaining Security
Managing Objects
Managing Servers
Managing Auditing
Maintaining Report
and a lot more >>

LAMP

Linux-Apache-MySql-PHP
(software bundle)

Easy to code
Easy to deploy
Develop locally
Cheap and ubiquitous hosting
Free Open Source
Strong Community
Great Market Share
web scripting software

Linux Desktop

Open Office / Libra Office
Evolution /thunderbird Mail Client
Mozilla
Compatible with windows based software. / awesome looks and feel
Virus Free / Easy / User friendly
Fast / Stable / Relaible / Error free
Bundled with All Drivers / Softwares/tools/Manual guides

IT Monteur provides Dedicated Linux Server Hosting in India

Logical Volume Manager

Logical Volume Manager

Logical volume management provides a higher-level view of the disk storage on a computer system than the traditional view of disks and partitions. This gives the system administrator much more flexibility in allocating storage to applications and users.

Storage volumes created under the control of the logical volume manager can be resized and moved around almost at will, although this may need some upgrading of file system tools.

The logical volume manager also allows management of storage volumes in user-defined groups, allowing the system administrator to deal with sensibly named volume groups such as “development” and “sales” rather than physical disk names such as “sda” and “sdb”.

Logical volume management is traditionally associated with large installations containing many disks but it is equally suited to small systems with a single disk or maybe two.

 One of the difficult decisions facing a new user installing Linux for the first time is how to partition the disk drive. The need to estimate just how much space is likely to be needed for system files and user files makes the installation more complex than is necessary and some users simply opt to put all their data into one large partition in an attempt to avoid the issue.

Once the user has guessed how much space is needed for /home /usr / (or has let the installation program do it) then is quite common for one of these partitions to fill up even if there is plenty of disk space in one of the other partitions.

With logical volume management, the whole disk would be allocated to a single volume group and logical volumes created to hold the / /usr and /home file systems. If, for example the /home logical volume later filled up but there was still space available on /usr then it would be possible to shrink /usr by a few megabytes and reallocate that space to /home.

Another alternative would be to allocate minimal amounts of space for each logical volume and leave some of the disk unallocated. Then, when the partitions start to fill up, they can be expanded as necessary.

As an example: Joe buys a PC with an 8.4 Gigabyte disk on it and installs Linux using the following partitioning system:

/boot    /dev/hda1     10 Megabytes
swap     /dev/hda2    256 Megabytes
/        /dev/hda3      2 Gigabytes
/home    /dev/hda4      6 Gigabytes

This, he thinks, will maximize the amount of space available for all his MP3 files.

Sometime later Joe decides that he want to install the latest office suite and desktop UI available but realizes that the root partition isn’t large enough. But, having archived all his MP3s onto a new writable DVD drive there is plenty of space on /home.

His options are not good:

 

  1. Reformat the disk, change the partitioning scheme and reinstall.
  2. Buy a new disk and figure out some new partitioning scheme that will require the minimum of data movement.
  3. Set up a symlink farm on / pointing to /home and install the new software on /home

With LVM this becomes much easier:

Jane buys a similar PC but uses LVM to divide up the disk in a similar manner:

/boot     /dev/hda1        10 Megabytes
swap      /dev/vg00/swap   256 Megabytes
/         /dev/vg00/root     2 Gigabytes
/home     /dev/vg00/home     6 Gigabytes

 

Note boot is not included on the LV because bootloaders don’t understand LVM volumes yet. It’s possible boot on LVM will work, but you run the risk of having an unbootable system.

 

Warning root on LV should be used by advanced users only
root on LVM requires an initrd image that activates the root LV. If a kernel is upgraded without building the necessary initrd image, that kernel will be unbootable. Newer distributions support lvm in their mkinitrd scripts as well as their packaged initrd images, so this becomes less of an issue over time.

When she hits a similar problem she can reduce the size of /home by a gigabyte and add that space to the root partition.

Suppose that Joe and Jane then manage to fill up the /home partition as well and decide to add a new 20 Gigabyte disk to their systems.

Joe formats the whole disk as one partition (/dev/hdb1) and moves his existing /home data onto it and uses the new disk as /home. But he has 6 gigabytes unused or has to use symlinks to make that disk appear as an extension of /home, say /home/joe/old-mp3s.

Jane simply adds the new disk to her existing volume group and extends her /home logical volume to include the new disk. Or, in fact, she could move the data from /home on the old disk to the new disk and then extend the existing root volume to cover all of the old disk.

 

Disk Management

Disk Management In Linux

Linux OS will consider every thing as files even hardware too, for example if there is one hard disk in a Linux system then it is represented as hda(harddisk “A”)under /dev folder

For example if we have 2 Hard disks then the representation is like below
/dev/hda
/dev/hdb
Where /dev/hda is primary master HDD and /dev/hdb is primary slave HDD

If we want to represent floppy drive then the representation is as below
/dev/fd0

If we want to represent second floppy drive then the representation is
/dev/fd1

If we want to represent cdrom
/dev/cdrom

If we want to represent DVD-writer
/dev/dvdwriter

If we want to represent special devices such as SATA,USB-mass storageetc then the representations are as below
/dev/sda
/dev/sdb
/dev/sdc till up to /dev/sdz

Suppose if we ant to represent partitions on HDD it goes as below
/dev/hda0 for first partition in primary master HDD
/dev/hda1 for second partition in primary slave HDD
/dev/sdd5 for forth partition in special device 4

 

Before creating any partitions we should remember the following things.
a.
 Check for what purpose we want to create the partitions(for example for creating swap)
b. Check weather any free space left by using fdisk -l command

So if there is any free space then we can directly create partitions

step1Check there is any free space or not
#fdisk -l
Disk /dev/hda: 20.0 GB, 20060651520 bytes255 heads, 63 sectors/track, 2438 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesDevice Boot Start End Blocks Id System/dev/hda1 1 1024 8225248+ b W95 FAT32/dev/hda2 * 1025 2438 11357955 c W95 FAT32 (LBA)Disk /dev/hdb: 80.0 GB, 80060424192 bytes255 heads, 63 sectors/track, 9733 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesDevice Boot Start End Blocks Id System/dev/hdb1 * 1 2432 19535008+ 83 Linux/dev/hdb2 2433 2554 979965 82 Linux swap / Solaris/dev/hdb3 2555 6202 29302560 83 Linux/dev/hdb4 6203 9733 28362757+ 5 Extended/dev/hdb5 6203 9733 28362726 83 Linux

fdisk is a command which will show all the disks present in the system weather it is partition or free space. From the above out put we can clearly know that the system is having 2 harddisks one with 20GB and the other with 80GB(with red mark). This is an interview question how to find Harddisk size in linux.

Step2Use fdisk command on the disk in order to create the partitions
#fdisk /dev/hda

Here it will show full details of /dev/hda Disk /dev/hdb: 80.0 GB, 80060424192 bytes255 heads, 63 sectors/track, 9733 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesDevice Boot Start End Blocks Id System/dev/hdb1 * 1 2432 19535008+ 83 Linux/dev/hdb2 2433 2554 979965 82 Linux swap / Solaris/dev/hdb3 2555 6202 29302560 83 Linux/dev/hdb4 6203 9733 28362757+ 5 Extended/dev/hdb5 6203 9733 28362726 83 Linuxcommand (m for help):

So press m to explore your self .

Step3Creating new partition.

Press n with out quote to create new partition. So specify your size in prbytes/kb/mb with + preseeding to the value suppose if you want to create a new partition of 23mb you have to say +23MB then press enter

One more example create a new partion of 538kb? thinking????????? still thinking?????? yes you are right it is +538KB

Step4 : So what next? Suppose you donot want to create this partition so delete it. At this point the partition table changes are not updated to partition table to do this one just type q.

Step5 : Updating the created partition to partition table just press w with out quotes thats it you are almost done.

Step6 : So you have updated the changes to partition table then you have to say this change to Kernel so for doing that there are two ways

A. Just restart the system(so you are thinking this is easiest way ha? never do this on live servers because you have to give 99.999% uptime to your servers. so always do second way.

B. Just execute partprob command this will update the partition table changes to kernel #partprob /dev/hda

Rsync

rsync is a file synchronization and file transfer program for Unix-like systems that minimizes network data transfer by using a form ofdelta encoding called the rsync algorithm. rsync can compress the data transferred further using zlib compression, and SSH orstunnel can be used to encrypt the transfer.

rsync is typically used to synchronize files and directories between two different systems, one local and one remote. For example, if the command rsync local-file user@remote-host:remote-file is run, rsync will use SSH to connect as user to remote-host.[4] Once connected, it will invoke another copy of rsync on the remote host, and then the two programs will talk to each other over the connection, working together to determine what parts of the file are already on the remote host and don’t need to be transferred over the connection.

rsync can also operate in daemon mode, where it listens by default on TCP port 873, serving files in the native rsync protocol (using the “rsync://” syntax).

It is released under the GNU General Public License version 3 and is widely used.

Uses

rsync originated as a replacement for rcp and scp. As such, it has a similar syntax to its parent programs.[11] Like its predecessors, it requires the specification of a source and of a destination; either of them may be remote, but not both. Because of the flexibility, speed and scriptability of rsync, it has become a standard Linux utility, included in all popular Linux distributions. It has been ported to Windows (via Cygwin, Grsync or SFU) and Mac OS.

Generic syntax:

rsync [OPTION] … SRC [SRC][USER@]HOST:DEST
rsync [OPTION][USER@]HOST:SRC [DEST]

…where SRC is the file or directory (or a list of multiple files and directories) to copy from, and DEST represents the file or directory to copy to. (Square brackets indicate optional parameters.)

rsync can synchronize Unix clients to a central Unix server using rsync/ssh and standard Unix accounts. It can be used in desktop environments, for example to efficiently synchronize files with a backup copy on an external hard drive. A scheduling utility such as cron can carry out tasks such as automated encrypted rsync-based mirroring between multiple hosts and a central server.

Examples

A command line to mirror FreeBSD might look like:

 % rsync -avz --delete ftp4.de.FreeBSD.org::FreeBSD/ /pub/FreeBSD/

The Apache HTTP Server supports only rsync for updating mirrors.

rsync -avz --delete --safe-links rsync.apache.org::apache-dist /path/to/mirror

The preferred (and simplest) way to mirror the PuTTY website to the current directory is to use rsync.

rsync -auH rsync://rsync.chiark.greenend.org.uk/ftp/users/sgtatham/putty-website-mirror/ .[15]

A way to mimic the capabilities of Time Machine (Mac OS) – see also tym.

#date=`date "+%Y-%m-%dT%H:%M:%S"`
date=`date "+%FT%T"`
rsync -aP --link-dest=$HOME/Backups/current /path/to/important_files $HOME/Backups/back-$date
ln -nfs $HOME/Backups/back-$date $HOME/Backups/current

Shadow Password

Shadow Passwords

In environments with multiple users, it is very important to use shadow passwords provided by the shadow-utils package to enhance the security of system authentication files. For this reason, the installation program enables shadow passwords by default.
The following is a list of the advantages shadow passwords have over the traditional way of storing passwords on UNIX-based systems:
  • Shadow passwords improve system security by moving encrypted password hashes from the world-readable /etc/passwd file to /etc/shadow, which is readable only by the root user.
  • Shadow passwords store information about password aging.
  • Shadow passwords allow the /etc/login.defs file to enforce security policies.
Most utilities provided by the shadow-utils package work properly whether or not shadow passwords are enabled. However, since password aging information is stored exclusively in the /etc/shadow file, any commands which create or modify password aging information do not work. The following is a list of utilities and commands that do not work without first enabling shadow passwords:
  • The chage utility.
  • The gpasswd utility.
  • The usermod command with the -e or -f option.
  • The useradd command with the -e or -f option.

User And Group Management

 Introduction to Users and Groups

While users can be either people (meaning accounts tied to physical users) or accounts which exist for specific applications to use, groups are logical expressions of organization, tying users together for a common purpose. Users within a group can read, write, or execute files owned by that group.
Each user is associated with a unique numerical identification number called a user ID (UID). Likewise, each group is associated with a group ID (GID). A user who creates a file is also the owner and group owner of that file. The file is assigned separate read, write, and execute permissions for the owner, the group, and everyone else. The file owner can be changed only by root, and access permissions can be changed by both the root user and file owner.
Additionally, Red Hat Enterprise Linux supports access control lists (ACLs) for files and directories which allow permissions for specific users outside of the owner to be set. For more information about this feature, refer to the Access Control Lists chapter of the Storage Administration Guide.

User Private Groups

Red Hat Enterprise Linux uses a user private group (UPG) scheme, which makes UNIX groups easier to manage. A user private group is created whenever a new user is added to the system. It has the same name as the user for which it was created and that user is the only member of the user private group.
User private groups make it safe to set default permissions for a newly created file or directory, allowing both the user and the group of that user to make modifications to the file or directory.
The setting which determines what permissions are applied to a newly created file or directory is called a umask and is configured in the /etc/bashrc file. Traditionally on UNIX systems, the umask is set to 022, which allows only the user who created the file or directory to make modifications. Under this scheme, all other users, including members of the creator’s group, are not allowed to make any modifications. However, under the UPG scheme, this group protection is not necessary since every user has their own private group.