Experience you can count on.

YourTech has over a decade of experience working with Linux server operating systems and applications. From web servers to databases to mail servers and virtualization, YourTech has consistently provided working solutions. Having done work for both Fortune 500 companies and sole proprietorships, YourTech has a diversified range of skills that would benefit an organization of any size. As most perspective clients prefer to know up front if we can work with their existing software (or planned software), we have attempted to organize a list of the most popular technologies we work with. That being said, we do not consider this list to be all-inclusive. We invite you to review our areas of expertise and to contact us with any questions you have regarding them.

• LAMP

  LAMP originally referred to the combination of the following four open-source programs:

  • Linux, the operating system
  • Apache, the world's most popular web server
  • Mysql, an extremely popular database engine
  • PHP, a popular web programming language

  Though these programs are developed separately by different groups with different goals, they operate well with each other to form a web-application framework. Over time, many variations of this acronym have sprung up: substituting FreeBSD or Solaris for Linux; Lighttpd for Apache; Postgresql for Mysql; Perl, Python, or Ruby on Rails for PHP. The components may change, but the basic framework concept (Operating system, Web Server, Database Engine, and Programming Language) remains the same.

   

  [^]
• Operating Systems

  The operating system (sometimes called simply OS) is the basic software component of a computer. The OS manages and coordinates all the system's activities and also takes care of the computer's resource sharing. The operating system manages the operations of the hardware, relieving application programs of this task, and also provides some services to applications and users.

  Almost all computers (from hand held computers to supercomputers) run an operating system. Some of the best operating systems are Microsoft Windows, Mac OS X, Linux, and Solaris.

  [^]
• Linux

  Linux is the name given to any Unix-like operating system, running the Linux kernel (as originally developed by Linux Torvalds in 1991) . Linux is free software and is also open source. This means that the source code can be used, modified, or redistributed by anyone.

  Linux is widely used as a server operating system due to its stability and performance. This versatile operating system can work an almost everything, from embedded systems to supercomputers.

   

  [^]
• Solaris

  Solaris (also known as Solaris Operating System), is a free Unix-based operating system developed by Sun Microsystems.

  Solaris is perfect for symmetric multiprocessing, supporting a large number of CPUs. The latest Solaris version is Solaris 10. This version features support for x64 (AMD64/EM64T), DTrace (Dynamic Tracing), Solaris Zones, Service Management Facility (SMF) which replaces init.d scripts, and NFSv4. Another great addition in Solaris 10 is ZFS, which includes support for high storage capacities, integration of the concepts of file system and volume management, snapshots and copy-on-write clones, on-line integrity checking and repair, and RAID-Z.

   

  [^]
• FreeBSD

  FreeBSD is a free Unix-like operating system, developed from AT&T Unix. FreeBSD works on Intel x86 family (IA-32) IBM PC compatible computers, DEC Alpha, Sun UltraSPARC, IA-64, AMD64, PowerPC, ARM and NEC PC-9801 architectures along with Microsoft Xbox. FreeBSD comes as a complete operating system and is the first non-Solaris OS to support ZFS.

  Software that runs on Linux will work perfect on FreeBSD without the need of a compatibility layer. Sometimes, programs designed for Linux will run better. Although FreeBSD is Unix-based, it is considered smaller, stable, and more hardened than Linux. However, its features typically lag behind Linux by a large margin.

   

  [^]
• Web Servers

  A web server is a computer program that accepts HTTP requests from web clients (also called web browsers) and sends HTTP responses. The responses contain additional data, usually web pages and linked objects (like images). All web servers use the HTTP protocol to communicate with the browsers. Logging is available on all web servers, allowing the webmaster to collect information about the server's activity.
  
  There are thousands of web servers available on the market. Some are free, while others are quite expensive. Apache is the most popular web server, hosting over 50% of the world's web pages.
  
  

  [^]
• Apache HTTP Server

  The Apache HTTP server (or simply Apache) is a free web server, developed and maintained by an open community of developers led by the Apache Software Foundation. Apache can host both static and dynamic web pages. Virtual hosting allows one single Apache server to serve many different websites simultaneously.

  Apache HTTP server runs on most operating systems, including Microsoft Windows, Mac OS X, Linux, Unix, FreeBSD, Solaris, Novell NetWare, OS/2, TPF, and eComStation. More than 50% of the web pages available in the Internet are hosted on Apache servers.

   

  [^]
• Lighttpd

  Lighttpd is a free/open source web server designed to be very fast, secure, and flexible. The server is configured for environments where speed is critical. Lighttpd features a low memory footprint and a small CPU load, making it the ideal for servers that suffer from load problems. It works on Unix-like operating systems, like Linux, as well as on Microsoft Windows.

  Because Lighttpd is optimized to serve large files, Youtube, Meebo, and Wikipedia use it as their web server. This server is also used by torrent web sites, like The Pirate Bay, Mininova and isoHunt. Lighttpd is best suited for a high connection count and solves what is known as the 10,000 simultaneous connections issue.

  [^]
• Virtual Hosts

  Virtual hosts are web site domains that are served by the same web server, often on the same IP address. A virtual host is often used by companies or individuals that do not want to purchase and maintain their own Web servers and Internet connections. However, the customer shares the Web services with all the other customers of the virtual hosts. If the virtual host is running multiple web sites from the same server, these web sites will compete for Web server resources.

   

  [^]
• SSL Certificates

  The SSL (Secure Sockets Layer) Certificate is designed to protect web sites and increase the customer's trust. SSL certificates encrypt data between the client and the server, while identifying the server to the client. The identity of certificate owners is verified by a Certificate Authority, when the SSL Certificate is released.

  SSL Certificates are primarily dedicated to positively identifying the owner of a web site, and helps prevent a criminal from imitating a legitimate business.

  [^]
• Authentication

  All web servers support HTTP authentication. For additional security, some servers also support Digest HTTP authentication and Microsoft NTLM authentication. The basic HTTP authentication sends the username and password in a base64-encoded string. Note that if SSL is not used, the username and password are unprotected.

  Here is how it works:

   

  • When the user requests a page from a secured directory on the server, a log in page appears

  • The user fills in the log in page and sends it to the server

  • The web server checks the username and password. The username and password can be checked against many different sources, including flat files, system passwords, databases, or an LDAP directory.

  • If the log in is successful, the browser caches the authentication information and sends it in an HTTP Authorization header with every subsequent page request from the user

  • The server processes the requested page and all future pages containing the HTTP authentication header. It constantly checks if the information is valid for every requested page.

   

  [^]
• Security

  The World Wide Web is definitely not a safe place. There are a lot of security risks when running Web servers. A poorly configured Web server offers attackers the means to:

   

  • Steal confidential documents

  • Execute commands on the server host machine, modifying the system and causing damage

  • Find information about the host machine, allowing them to break the system

  • Launch denial-of-service attacks, blocking the Domain Name Service from serving the web server's users

   

  It is known that large and complex programs contain security holes. Unfortunately, Web servers fit in this category. These servers also have an open architecture that allows arbitrary CGI scripts to be executed on the server side of the connection, responding to remote requests. An attacker can gain control of a poorly configured server and cause damage to the server and to innocent users of Web browsers

   

  [^]
• Web Programming Languages

  Just like programming languages used for other programming tasks, the web programming languages come in a wide diversity. There are no reasons to believe that one web programming language can monopolize the Web development area. Of course, due to their availability and performance, some web programming languages are favored. Ultimately, developers choose the language they work in. One of the most important things to look at when choosing a web programming language is the language's ability to deal with a variety of protocols, formats (for example, graphics), and programming tasks. Web programming languages need to deliver very good performance (both speed and size), safety, and platform independence. Some of the best are PHP, Perl, Python, and Ruby on Rails.

   

  [^]
• PHP

  PHP is a widely-used general-purpose scripting language that was originally created to help produce dynamic web pages. PHP is mainly intended for server-side scripting and is very suited for web development.

  It often runs on a web server, and its main task is to take PHP code as input and create web pages as output. PHP can be installed on almost any web server and works on almost any operating system and platform. PHP serves more than 20 million websites and is used on more than 1 million web servers. The latest official version of PHP is version 5.2.6, released on May 1, 2008.

   

  [^]
• Perl

  Perl is a dynamic programming language widely used due to its powerful text processing facilities, without arbitrary data length limits. Perl is free software and is available for all Unix-like, POSIX-compliant or otherwise Unix-compatible platforms, Mac OS, and Windows.

  Perl is a general-purpose programming language and was initially created for text manipulation. However, it can be used for a wide range of programming tasks like web development, system administration, network programming, GUI development, and many more. Perl is more practical (efficient, easy to use) than beautiful (elegant, tiny). It includes support for multiple programming paradigms (procedural, object-oriented, and functional styles), reference counting memory management, built-in support for text processing, and a large collection of third-party modules.

   

   

  [^]
• Python

  Python is a general-purpose, very high-level programming language. Python has minimalist core syntax and semantics, and a comprehensive standard library. Python supports multiple programming paradigms (primarily object oriented, imperative, and functional) and is based on a fully dynamic type system and automatic memory management.

  Python is a standard component for many operating systems. It comes with most Linux distributions, NetBSD, OpenBSD, Mac OS X. Slackware, Red Hat Linux, and Fedora use the Anaconda, a pythonic language. Also, Microsoft Windows supports Python.

   

  [^]
• Ruby on Rails

  Ruby on Rails is a free web application framework aiming to make web development faster, simpler and more efficient. It is intended for database-backed web applications. Ruby on Rails uses the Model View Controller (MVC) architecture for organizing the application programming. RoR comes with some very good development tools, like the WEBrick web server and the Rake build system. In Rails, we can see the extensive use of the JavaScript libraries Prototype and Script.aculo.us for Ajax and its graphical interface.

  For the web server, it is recommended to use Apache, lighttpd, or nginx proxying to Mongrel (or using FastCGI). For database, RoR performs well with MySQL, PostgreSQL, SQLite, Oracle, SQL Server, and DB2.

   

  [^]
• Database Engines

  Database engines are underlying components used by a Database Management System (DBMS) to create, delete, read, or update data in a database. The database engines can receive commands via the DBMS's user interface or even via a network port. Examples of database engines are BDE, Jet, ODBC, ADO.

   

  [^]
• Mysql

  MySQL is a relational database management system (RDBMS). MySQL is written in C and C++, and works on most system platforms, including AIX, BSDi, FreeBSD, HP-UX, i5/OS, Linux, Mac OS X, NetBSD, Novell NetWare, OpenBSD, eComStation , OS/2 Warp, QNX, IRIX, Solaris, SunOS, SCO OpenServer, SCO UnixWare, Tru64, Windows 95, Windows 98, Windows ME, Windows NT, Windows 2000, Windows XP, and the 32-bit version of Windows Vista. However, the 64-bit version of Vista is currently not supported. MySQL 5.0 comes in 2 variants: the MySQL Community Server and Enterprise Server.

  All major programming languages with specific APIs have libraries for accessing MySQL databases. ASP or ColdFusion can communicate with the MySQL database through the ODBC interface.

   

  [^]
• PostgreSQL

  PostgreSQL is an open-source object-relational database management system (ORDBMS). In PostgreSQl, functions can be written in several languages:

  • A built-in language called PL/pgSQL resembles Oracle's procedural language PL/SQL

  • Scripting languages are supported through PL/Lua, PL/LOLCODE, PL/Perl, plPHP, PL/Python, PL/Ruby, PL/sh, PL/Tcl and PL/Scheme

  • Compiled languages C, C++, or Java (via PL/Java)

  • The statistical language R through PL/R

   

  Also, PostgreSQL allows user-defined index methods to be created. PostgreSQL supports Triggers, Multi-Version Concurrency Control, Rules, User-defined objects, Inheritance, and Encrypted connections via SSL, among other useful features. PostgreSQL has support for a wide variety of native data types:

  • Arbitrary precision numerics

  • Unlimited length text

  • Geometric primitives

  • IPv4 and IPv6 addresses

  • CIDR blocks, and MAC address data types

  • Arrays

  • XML (as of 8.3)

   

  [^]
• sqlite

  SQLite is an ACID-compliant relational database management system (RDBMS) created as a relatively small C programming library. The SQLite engine is not a standalone process with which the program communicates, unlike the client-server DBMSs. The SQLite library becomes an integral part of the program by being linked in it.

  To reduce latency in database access, the program uses simple function calls (function calls are faster than inter-process communication. The entire database, including definitions, tables, indices, and the data itself, is stored as a single cross-platform file on the host machine. By simply locking the entire database file at the beginning of a transaction, a simple yet effective locking design is achieved. While SQLite can handle multiple users, it is best geared towards applications requiring more data being read than written.

  Applications written against a SQLite backend become much more portable, having less dependencies than an application requiring a traditional back-end database server. A great example of this is Firefox 3 which uses a SQLite database file to store configuration settings and profile information.

   

  [^]
• Mail Servers

  Mail servers (also known as mail transfer agents or MTAs, mail transport agents, mail routers or Internet mailers) are applications that receive incoming e-mail from local users (by local users we understand people within the same domain) and remote senders. After receiving, the mail servers forward outgoing e-mail for delivery. Any computer dedicated to running such applications is also called a mail server. Some of the most common mail servers are Microsoft Exchange, qmail, Exim and sendmail.

  [^]
• IMAP

  IMAP (abbreviation from Internet Message Access Protocol, previously called Internet Mail Access Protocol, Interactive Mail Access Protocol (RFC 1064), and Interim Mail Access Protocol) is an application layer Internet protocol that allows local clients to access e-mail on remote servers. The IMAP operates on port 143. Virtually any e-mail client or server supports IMAP.

  The current version is IMAP version 4 revision 1, since 1996. IMAP4 supports encrypted login mechanisms and plain-text transmission of passwords, unlike most Internet protocols. IMAP protocol also allows multiple clients to simultaneously access the mailbox. Clients can detect changes made to the mailbox by other concurrently connected clients.

  [^]
• Courier IMAP

      Courier IMAP is a fast, scalable, enterprise Internet Message Access Protocol server that uses Maildirs. Courier IMAP used by many Email service providers because it's made to handle hundreds of thousands of mail accounts. Courier IMAP has an IMAP and POP3 aggregation proxy and has practically infinite horizontal scalability.

  For example, in a proxy configuration, a pool of Courier servers services the initial IMAP and POP3 connections from clients. They wait to receive the client's log in request, look up the server that actually holds this mail account's mailbox, and establish a proxy connection to the server. All this is done in a single, seamless process. Also, to achieve optimum resource usage, mail accounts can be moved between different servers.

   

  [^]
• Dovecot

  Dovecot is an open source IMAP and POP3 server for Linux and UNIX-like systems. The server was created with security in mind and primarily aims to be a lightweight, fast, and easy to set up open source mailserver. Dovecot can work with standard mbox, Maildir, and with its own experimental native high-performance dbox formats. Also, Dovecot is compatible with UW IMAP as well as with mail clients accessing the mailboxes directly.

  Dovecot also includes a Mail delivery agent (called Local delivery agent in Dovecot's documentation), featuring optional Sieve filtering support.

   

  [^]
• Courier IMAP

  maildirs. Courier IMAP used by many Email service providers because it's made to handle hundreds of thousands of mail accounts. Courier IMAP has an IMAP and POP3 aggregation proxy and has practically infinite horizontal scalability.

  For example, in a proxy configuration, a pool of Courier servers services the initial IMAP and POP3 connections from clients. They wait to receive the client's log in request, look up the server that actually holds this mail account's mailbox, and establish a proxy connection to the server. All this is done in a single, seamless process. Also, to achieve optimum resource usage, mail accounts can be moved between different servers.

   

  [^]
• Cyrus IMAP

  The Cyrus IMAP server, unlike other IMAP server implementations, is generally intended to be run on sealed servers (where normal users are not permitted to log in). Cyrus IMAP's mail spool file system has a very similar layout to the Maildir format used by many popular email servers like qmail, Courier, and Dovecot. Cyrus IMAP's spool format is said to have improved performance and scalability to Maildir. Also, the spool format is stored in parts of the file system that are private to the Cyrus IMAP system. Users can access their mail through IMAP/IMAP-S, POP3/POP3-S or KPOP protocols.

   

  [^]
• UW-IMAP

  The UW IMAP server is the reference server implementation of the Internet Message Access Protocol (IMAP). UW IMAP is designed to be aggressively compatible with existing legacy mail stores and systems, unlike many other server implementations. UW IMAP is also "plug-and-play" installable and does not require any site-specific configuration.

  UW IMAP is based on the c-client mail engine (used by Pine e-mail client). c-client currently supports many mail store formats, like mbox, mix, mbx, MMDF, tenex, mtx, mh, mx, and Usenet news spools. UW IMAP comes with POP2 and POP3 servers, the mailutil utility program, and the dmail and tmail MTAs.

   

  [^]
• SMTP

  Simple Mail Transfer Protocol (SMTP) is a text-based "push" protocol that does not allow anyone to "pull" messages from a remote server on demand. In SMTP, one or more recipients of a message are specified (and most of the time verified to exist) along with the message text and possibly other encoded objects. After this first step, the message is sent to the remote server. Any end-user's Mail User Agent (MUA) or relaying server's Mail Transport Agents (MTA) can act as an SMTP client. The email client knows the outgoing mail SMTP server from its configuration.
   
  The SMTP client opens a TCP connection to server's port 25 and one can test any SMTP server by simply using the telnet program.
  

  [^]
• Postfix

  Postfix is a free open source mail transfer agent (MTA). It is used for the routing and delivery of email. Postfix was created as a fast and secure alternative to the Sendmail mail transfer agent.

  Postfix offers many useful features, like:

   

  • Transport Layer Security

  • advanced content filtering.

  • many databases for maps: Berkeley DB, CDB, DBM, LDAP, MySQL and PostgreSQL.

  • mbox-style and Maildir-style mailboxes

  • address rewriting, VERP, SMTP-AUTH via SASL

  • Milter support (compatible with Sendmail milters)

   

  [^]
• qmail/vpopmail

  Qmail is a free mail transfer agent (MTA) running on Unix, and one of the five most popular Unix mail servers. Qmail was the first security-aware mail transport agent. It also had a very good protection against stack and heap overflows, format string attacks, or temporary file race conditions. Qmail was originally designed to provide a fast way for managing large mailing lists and it was obviously faster than Sendmail.

   

  [^]
• Exim Internet Mailer

  Exim is a free general and flexible mail transfer agent (MTA) working on Unix-like operating systems. It features extensive facilities for checking incoming e-mail. Exim is programmed to deliver any email immediately (does not have a central queue manager) and often handled thousands of emails per hour efficiently, in busy environments. Exim Internet Mailer is a very configurable mailer with many features that are lacking in other MTAs.

   

  [^]
• Spam Filtering

  Lately, spam emails are a big concern, growing exponentially from year to year. Spam filtering is the process of distinguishing illegitimate spam email from legitimate email. Spam filtering software block spam email while letting legitimate emails pass. Very useful, spam filtering protects users from viruses, unsolicited advertising, and save them the time it would take to manually delete the spam email.

   

  [^]
• SpamAssassin

  SpamAssassin is a program released under the Apache License 2.0, used for e-mail spam filtering. The filtering is based on content-matching rules, and SpamAssasin also features DNS-based, checksum-based and statistical filtering, supported by both external programs and online databases.

  SpamAssassin has support for:

  • DNS-based blackhole lists

  • URI blacklists such as SURBL or URIBL.com which track spam websites

  • checksum-based filters such as the Distributed Checksum Clearinghouses, Vipul's Razor and the Cloudmark Authority plug-in (commercial)

  • Hashcash

  • Sender Policy Framework

   

  [^]
• DNS Blacklists

  A DNS Blacklist (abbreviated DNSBL) is a means by which Internet websites can publish a list of IP addresses that people might want to avoid. The lists are delivered in a format which can be easily accessed and queried by computer programs working on the Internet. DNS black lists are mostly used to publish lists of addresses that are linked to spamming. Most mail transport agent (MTA) software can be set to reject or flag messages sent from an IP listed on one or more such lists.

   

  [^]
• SMTP Auth

  A DNS Blacklist (abbreviated DNSBL) is a means by which Internet websites can publish a list of IP addresses that people might want to avoid. The lists are delivered in a format which can be easily accessed and queried by computer programs working on the Internet. DNS black lists are mostly used to publish lists of addresses that are linked to spamming. Most mail transport agent (MTA) software can be set to reject or flag messages sent from an IP listed on one or more such lists.

   

  [^]
• pop-before-smtp

  POP before SMTP (also known as SMTP after POP) is a method of authorization used by e-mail server software which allows users to send e-mail from anywhere, as long as they can also fetch their mail from the very same place.

  In other words, any user is allowed to use SMTP from any IP address as long as he has previously made a successful login into the POP service at the same mail hosting provider, from the same IP address, within a predefined timeout period.

   

  [^]
• Zimbra Platform

  Zimbra is an open source server and client software used for messaging and collaboration. It supports email, group calendaring, contacts, and web document management and authoring. Zimbra server is supported by Mac OS X, Linux, appliances, and virtualization platforms. The Zimbra Web 2.0 Ajax client runs on Internet Explorer, Firefox, and Safari. It features easy integration of web portals, business applications, and VoIP using web services.

   

  [^]
• DNS

  Domain Name Server (DNS) helps assign Internet names to organizations, without concerning about the physical routing hierarchy represented by the numeric IP address. Hyperlinks and/or Internet contact information can remain exactly the same, regardless of what the current IP routing arrangements may be, and can take a readable form (like "example.com"). Internet names are much easier to remember than IP addresses (like "206.23.119.66"). People can give friendly names to URLs or e-mail addresses without concerning about how the machine will actually locate them.

   

  [^]
• BIND DNS

  Berkeley Internet Name Domain (BIND) is an implementation of the DNS protocols. It provides a freely redistributable reference implementation of the major components of the DNS, and includes:

  • Domain Name System server

  • Domain Name System resolver library

  • Tools for managing and verifying the proper operation of the DNS server

  Today, the BIND DNS Server is used by most of the name serving machines on the Internet and provides a very flexible and stable architecture able to support an organization's naming architecture.

   

  [^]
• djbdns

  The djbdns software package is a simple and security-aware DNS implementation built to cover BIND's security holes. Djbdns contains the following components:

   

  Servers:

  • dnscache - the DNS resolver and cache

  • tinydns - a database-driven DNS server

  • walldns - a "reverse DNS wall", providing IP to domain name lookup only

  • rbldns - a server designed for DNS blacklisting service

  • pickdns - a database-driven server that chooses from matching records depending on the requester's location

  • axfrdns - a zone-transfer server

   

  Client tools:

  • axfr-get - a zone-transfer client

  • dnsip - simple address from name lookup

  • dnsipq - address from name lookup with rewriting rules

  • dnsname - simple name from address lookup

  • dnstxt - simple text record from name lookup

  • dnsmx - mail exchanger lookup

  • dnsfilter - looks up names for addresses read from stdin, in parallel

  • dnsqr - recursive general record lookup

  • dnsq - non-recursive general record lookup, useful for debugging

  • dnstrace (and dnstracesort) - compr[^]

  • vegadns

    VegaDNS is a small administration tool that allows easy administration of DNS records through a web browser. VegaDNS is written in PHP and includes a list of useful features:

    • Tiered access with Senior Admin, Group Admin, and User levels

    • Import multiple domains at once via AXFR

    • Uses PHP Sessions, no cookies required

    • Uses the Smarty template engine for clear separation of PHP from HTML

    • Web configurable Default Records you can use to auto-populate new domains

    • Free (GPL)

     

    [^]
  • NicTool

    NicTool is free DNS management software that helps users manage their DNS fast and secure. It features a nice and simple web interface for users, administrators, and clients to help them access and update their DNS zone data. NicTools also has a rich API for provisioning systems to interact with.

    All updates are checked for validity before being accepted and all changes are logged. You can also setup permissions for a zone to another user, or even a group of users. NicTools gives users the ability to grant other users permission to publish to their DNS servers, while prohibiting alteratio

     

    [^]
  • Web Control Panel

    Basically, a web control panel is a web-based interface that helps system administration. Simply by using a web browser, administrators can setup user accounts, Apache, DNS, file sharing, and so on. The web control panel removes the need for manual editing of configuration files, while providing the option to manage a system from the console or even remotely.

     

    [^]
  • cPanel

    cPanel (short for control Panel) is a graphical web-based web-hosting control panel. cPanel is specifically designed to simplify the administration of a websites and its interface helps handle all aspects of website administration, like management of PGP keys, crontab tasks, mail and FTP accounts, and mailing lists. The cPanel targets commercial web hosting services so it does not come as a reduced-cost personal use license. Only non-profit organizations can request a free license or a license at reduced cost.

     

    [^]
  • Webmin

    Webmin is a web-based system configuration tool based on Perl. It is supported by OpenSolaris, Linux and some other Unix-like systems. Webmin helps users configure many operating system internals, like users, services, disk quotas, configuration files. Users also have options to control and modify many OpenSource applications, like Apache HTTP Server, PHP, or MySQL.

    Webmin communicates through TCP port 10000 and can also use SSL (if OpenSSL is installed, with some additional Perl Modules). This software allows users to control many machines through a single interface, or seamless login on other Webmin hosts on the same subnet or LAN.

     

    [^]
  • Virtualization

    Virtualization means creating a virtual machine using a combination of hardware and software. Virtualization is performed on a given hardware platform by host software (a control program). The host software creates a simulated computer environment (the actual virtual machine) for any guest software. The guest software (often a complete operating system) runs just like if would if it were installed on a stand-alone hardware platform. In most cases, a single physical machine simulates many virtual machines. The only limit to their number is the host's hardware resources. Also, there is no requirement for the guest's Operating System to be the same as the host's.

    The primary benefits of server virtualization are consolidation, increased utilization, and ability to rapidly provision and start a virtual machine. Another benefit is the increased ability to dynamically respond to faults by re-booting the virtual machine or moving it to different hardware.

     

    [^]
  • Xen

    Xen is a free software virtual machine monitor that allows several guest operating systems to be simultaneously run on the same computer hardware. Xen uses paravirtualization on most CPUs. Paravirtualization means that the guest operating system must be modified to use a special hypercall application binary interface (ABI) instead of certain architectural features. By using paravirtualization, Xen achieves very good performance even on its host architecture (x86) which is very uncooperative with traditional virtualization techniques.

     

    [^]
  • BSD Jails

    FreeBSD jail is an implementation of operating system-level virtualization, allowing server administrators to divide a computer system based on FreeBSD into many independent mini-systems, called jails.

    FreeBSD jails have three very important purposes:

    • Virtualization: Each and every jail is a virtual environment that runs on the host computer with its own files, processes, user and superuser accounts. From within a jailed process, the environment is indistinguishable from the real system.

    • Security: Each and every jail is sealed from the other jails, providing additional security.

    • Ease of delegation: Because of the limited scope of a jail, FreeBSD Jail allows server administrators to easily delegate several tasks which require superuser access without giving out complete control over the system.

     

    [^]
  • VMWare

    VMware Server can create, edit, and play virtual machines. It uses a client-server model, allowing remote access to virtual machines, at the cost of some graphical performance (and 3D support). In addition to the ability to run virtual machines created by other VMware products, it can also run virtual machines created by Microsoft Virtual PC.

     

    [^]
  • Solaris Zones

    Solaris Zones is a very good example of operating system-level virtualization technology. Solaris Zones was first available as an integrated part of Solaris 10. Each and every zone acts as a completely isolated virtual server within a single operating system instance.

    Every zone has its own node name, virtual network interfaces, and storage. There is no minimum amount of dedicated hardware per zone, except the disk storage (necessary for its unique configuration). This means that zones do not require dedicated CPUs, memory, physical network interfaces or HBAs. However, you can allocate these to one zone.

     

    [^]