Glossary (ISPmanager)

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Apache

Apache is a very popular open source HTTP server for modern operating systems, like FreeBSD, Linux, Windows, etc. Apache provides a number of very useful and frequently used features, such as support of HTTP/1.1 and HTTPS, virtual hosts with independent configuration, flexible system of aliases and URL rewriting (mod_rewrite), log files for each virtual host with flexible adjustment of their content, adjustments for each directory by means of .htaccess files, authorization (including authorization using DBM databases) and many other features. For more information about Apache, please visit its official web-site http://apache.org

Auto-responder

An Auto-responder is a computer program that automatically responds to any of the e-mail messages sent to a particular e-mail address or uses an on-line feedback form. Normally, it receives messages from an mail transfer agent (MTA).

Control panel configuration file

Control panel configuration file includes all the settings that are required for the control panel performance and integration with the system. It is located in /usr/local/ispmgr/etc/ispmgr.conf.

Canonical name

Canonical name is a synonym of another domain name. This type of a domain record can be used, for example, if you have several domain names that should be associated with the same IP-address. You need to have one record explicitly resolved on the IP-address, the others will be used as its synonyms. It can be useful when moving to another IP-address. In this case need to make changes only in one record. All synonyms will be resolved on a new IP-address automatically.

CGI

CGI stands for a Common Gateway Interface. CGI is a set of rules for running scripts or programs on a Web server. It is a common way of transaction between clients and web-server. The programs that answer this protocol are CGI programs, or CGI scripts. Though most CGI programs are written in Perl, you can use any programming language, such as С++, or shell language interpreter Bash. Please note, that you need to get an executed file that will be able to read and record information in the format specified in the CGI protocol. CGI functioning is quite simple. The programs are executed on the web server and are normaly located in a special directory, such as cgi-bin. A CGI script is executed on the web server upon receipt of the user's request. The request data are kept in the environment variables or they are received stdin. The script output is transferred by the web server to the client's browser. All CGI programs run with the site administrator privileges. For more information,please visit http://www.w3.org/CGI/.


Database

A database is a collection of information stored on a computer in a systematic way, so that a computer program can use it to answer questions. The software used to manage and query a database is known as a database management system (DBMS), such as MySQL and PostgreSQL. Normally, it is a collection of data organized in two-dimensional tables consisting of named columns (fields) and records (rows) (usually unique).


Disk quota

Disk quota is the size of available hard disk space allocated to a login name (UID) or group (GID). When exceeding the limit, the file system returns an error.


DNS

DNS stands for a Domain Names Server. It is used is to translate alphabetic addresses to IP-addresses and vice versa. One IP-address can be associated with several domain names. And, on the contrary some DNS servers can resolve the same domain name on different IP- addresses depending on the channels' workload. DNS is a distributed name servers' system.In such systems the roups of name servers are responsible for the records associated with sites, domains and subdomains. These groups are called zones. A zone is responsible for the records of a particular domain or group of domains. DNSs are shared databases for domain names and corresponding IP addresses. These bases are kept on name servers (or DNS servers, as they are usually called). Normally, these servers are Unix machines where bind (Berkley Internet Naming Software) is installed. More information can be found RFC1034 here.


Domain name

Domain name is a text name (the Latin alphabet letters, digits, a hyphen and dot) corresponding to a numeric IP-address of a computer on the Internet. A domain name must be unique.

Domain record

Domain record is a record in a domain zone that allows to associate an Internet resource with the IP-address where it is located.

Domain zone

Domain zone is a unit managed by a DNS server and provides information about resolving a particular domain name to an IP-address. It also provides information about name and e-mail servers that server that domain or any of its records. The update information on caching DNS servers is also stored here. The domain zone need to be placed on the servers which are registered as name servers at the domain registrar.

E-mail address

E-mail address is a name identifying an electronic mailbox. Format of electronic addresses may differ depending on the network type. The address, such as username@domain is used on Internet. Normally, a username is the same as a login, but for the cases when the email address is an e-mail alias.

E-mail alias

E-mail alias is an additional e-mail address referring to a particular user mailbox. All messages sent to e-mail alias will be stored in the user's mailbox as well as the messages sent to the address username@site.

E-mail redirect

E-mail redirect is an e-mail address that is used to redirect all incoming messages to another e-mail address on the same or on another e-mail server. An e-mail redirect does not belong to any of the system users.


Error page

Error page is a (URL) page displayed to a user in case of error on web server, such as document not found, authorization required, etc. The URL can either locate on the same site or external one, that allows to use the same error pages for different sites.


File access privileges

In the Unix operating system all files have a set of mandatory attributes that allow to manage access to them by users of a computer where such files are located. Such attributes are the owner of a file, file group and access permissions. The owner of a file is a user UID. Each user is assigned to one or several groups. The file group is the GID of one of these groups. Thus, all the file users can be divided into three categories: owner of a file, group of a file and all others. Each category can do three actions with a file: read (r), write (w) and execute (x). When setting full access permissions to a file, you specify three categories from left to right: for the file owner, file group and all others. For example, "rwx r-x --x" means, that the owner is allowed to perfrom any operation on a file, all members of the file group are allowed to read and execute it, but cannot change, and all others can only execute it. The same scheme is used for directories. Please note! when working with directories "r" means, that a directory can be read, that is to get a list of included files and their attributes, "w" means, that the directory can be changed (you can create, delete and rename any of the files in this directory), "x" means, that permissions specified for that files can be applied to the directory's files. For example, "rwx r-x --x" means that the owner can perform any operations, members of the group can view the list of files and use them, but cannot create, delete and rename the files, and all others can address the files, if they know their names, however they cannot learn the list of files in the directory.

FTP

FTP is File Transfer Protocol that determines the rules for file transfer between computers. You must have access to a remote computer you want to work with and know a login and password. In this case FTP allows you to work with the remote machine as if it was a local one, such as move from one directory to another, view and change its content. More information about FTP can be found RFC959 here.

GID

All system users are divided into groups. Using groups allows you to restrict access to various server resources, such as disk space, privileges for directories and files, depending on the group a user is assigned to. Each user group has a unique nonnegative number that is used as a numerical identifier of group GID (group ID). Once logged in to the system each user receives two numerical identifiers - UID and GID which determine his access permissions to the system resources.

Group of file

The group of a file is one of the categories that determines access permissions to a particular file. It is the GID of one of the users groups. The group of a file can be set by a server administrator or by a file owner with chgrp command.

Home directory

Unlike one-user systems, such as DOS, in multi-user operating systems a user cannot create files anywhere on the disk. Each system user has his home directory. By default only this user and the server administrator can create files there. The user gets into this directory once logged in shell or via FTP.

HTTP and HTTPS

HTTP is a Hypertext Transfer Protocol that is used for information exchange on the Internet. The HTTP protocol used to transfer HTML-documents, but now it is possible to transfer any information, such as pictures, sounds, video and abstract files. HTTP is a protocol of requests and answers. A requesting program (the client) interacts with a responding program (a server) and sends a request including a request method, URL, protocol's version, etc. The server sends a status, protocol's version, a result code or error code, and the answer. HTTPS is the enhanced version of the HTTP protocol for web pages secure transferring via SSL (Secure Socket Layer). This protocol enables to identify the web server and prevent interception of the transmitted information, such as logins and passwords. More information about HTTP and HTTPS can be found at RFC2616 and RFC2818 accordingly.

Inetd

Inetd is an Internet super server that can be used for managing Internet services, such as (POP3, FTP or SSH. Inetd launches the required server to handle connections. Since it may take a long time to start a service, we would recommend that you use inetd for the highly requested services.

IP-address

IP address is a unique 4-byte identifier determining a network node, such as server, a workstation or router, that usese the Internet Protocol for communication between its nodes. A package is transmitted through the network and routed when necessary according to its destination IP-address. The IP-address determines location of a host in the network. In practice, it is not very convenient to use IP-addresses, it is easier to work with domain names.

License

License is a unique set ща information that allows to use the control panel for a certain period on a certain IP-address.

Logs rotation

Logs rotation is the periodic archiving of the web-server's log files in order to save disk space used by a web site.

Mailbox

Mailbox is a partition of disk space that is used to receive and store user's mail that was sent to his e-mail address. POP3 and IMAP protocols are used to receive e-mail. Disk space occupied by the mailbox is included into the quota disk quota of the user.

Mailing list

Mailing list is a collection of e-mail addresses that are used for exchanging e-mail messages. Unlike Internet forums, you do not need to be on-line and read messages via your browser. All messages are sent to your email address that was specified while subscribing. One of the most popular mailing list programs is Majordomo.

Mailing list sender

Mailing list sender is an email address which can be used to send messages to a mailing list. If this address is missing in the senders' list, a mailing administrator will be notified that a non-authorized persons attempted to send a message.

Mailing list subscriber

Mailing list subscriber is an email address which receives all the messages sent to a mailing list. Majordomo allows to subscribe automatically according to subscription policy. You may subscribe to a mailing list by sending a message that contains "subscribe list_name" to majordomo@site_name.

majordomo

Majordomo is a program written in Perl that allows to automatically manage mailing lists. When the list is set, all operations can be performed by email. If you you want to subscribe, you need to send an e-mail message with a particular command in the message body to majordomo@site_name. Majordomo is not a mail transfer agent (MTA) and does not deliver mail, but forms messages sent to a mailing list, archive them, if necessary, and perform other operations, such as subscription or unsubscription. For more information, please visit majordomo official site: http://www.greatcircle.com/majordomo/.

MySQL

MySQL is an open source relational database management system that uses Structured Query Language (SQL), the most popular language for adding, accessing and processing data in a database. Because it is open source, anyone can download MySQL and tailor it to one's needs in accordance with the general public license. For more information about MySQL, please visit its official web-site http://www.mysql.com.

Name server

Name server is a DNS server that contains domain information and provides it, if necessary. Normally, a domain is registered on two and more name servers, if one of them cannot be accessed, the other will provide the information. These servers are specified while registering a domain name.

File owner

A file owner is one of the categories used to determine file permissions. It is UID of one of the users who has created this file. Also the owner can be set by a server administrator with the chown command.

Password

A series of characters that enables someone to access a file, computer, program, shell, FTP, email, MySQL, FrontPage, etc. A control panel password is used to prevent unauthorized users from changing your information. The password must contain a combination of characters difficult to guess.

PHP

PHP (Hypertext Preprocessor) was specially designed for web-programming and is a widely used language for creating shared scripts. Unlike other programming languages, such as С or Perl, where output HTML-document is formed by calling functions within the program, when using PHP you write a script similar to a HTML-document and put a PHP code where you need. Unlike JavaScript, PHP-scripts are processed on the server, rather than on a client side. A browser will get a HTML-document, rather than a scrip. Its main advantage is that on the one hand it is user-friendly for a novice web-developer and provides a wide range of features to professionals. PHP-scripts can be processed in two nodes: as CGI and with an Apache module. In the first case, all PHP features are supports and scripts run faster. On the other hand, when scripts are used as CGI, a higher level of security is archived. More information about PHP can be found on its official site http://www.php.net.

POP3

The POP3 protocol is used to transfer e-mail messages from mailboxes of the POP3-compatible mail servers. Using mail clients, such as MS Outlook, TheBat!, Eudora, you can download email from your mailbox to your computer, where it can be easily located, if necessary. Besides, mail programs provides you with many useful functions, for example they can work with several mailboxes, sort out messages by folders, set various filters (anti-virus and anti-spam). Email is sent through the SMTP protocol that can also be customized in the same mail program. More information about POP3 protocol can be found RFC1939 here.

Redirect

Redirect is a transfer of one URL to another on the same or different site. The client browser will be automatically redirected to a new URL.

Scheduler

Scheduler (cron) is a program that is used to execute scheduled commands. More information can be found here.

Sendmail

Sendmail is one of the oldest and widely used mail transfer agents in the world. Mail transfer agents move email from one server to another. Sendmail is not a client program for reading email. It sends messages to another MTA where a mailbox of a addressee is located. Mail servers, as well as the mail client and the outgoing mail server are interacted via the SMTP protocol. Sendmail is a fast, powerful and very flexible server that provides a wide range of additional functions, such as SMTPAUTH authorization, secure connection through TLS/STARTTLS, connection of third-party programs for messages analysis (viruses scanning) and so on. More information about sendmail can be found on its official site http://www.sendmail.org.

Server administrator

Server administrator (root) is a system super user who is granted full access to all his server files and functions. On a Unix server the administrator's UID is "0". Since 'root' has full access to the system, any error made by the root can cause fatal consequence. You can use the command su to obtain temporary root privileges. Please note, that the administrator's password is transferred as a plain text, the protocol (telnet, FTP or POP3) are very insecure. Use SSH to log into shell.

Shell

Shell is a command interpreter, and allows users to use a command line. The user enters commands into the command line, shell interprets and sends them to the operating system. This possibility provides the shell with many useful functions. For example, there is a number of special symbols which enables to choose names of files using presets. Shell can readdress input and output, execute operations in background when the user is performing another task. Shell can read commands from a file (shell script) that allows to create pre-defined sets of commands and execute them by running a corresponding script. Shell starts when an authorized user registers in the system. Shell can be accessed directly from the terminal or remotely via telnet or other special programs, such as ShellGuard, SecureCRT, or TeraTerm.

Site

Site is a collection of hypertext pages, scripts and graphic elements that are used in pages design. It represents Internet resource on the server connected to the network, and available for users of this network for free or by authorized or limited access.

Site administrator

Site administrator is a system user and a site owner. All the pages, scripts, mailing listsbelong this user. He can access them via FTP. All the site's scripts run under permissions of this user. Site administrator can access such modules, as User management, mailing lists, redirects, subdomains, error pages. Also he can customize web server's log rotation for his site.

Site alias

The name of a site domain name that differs from the official name. Aliases are used to work with subdomains, pointing to subdirectories, rather than a site root directory.

Site template

Site template is a collection of pre-defined parameters, such as quota size of disk space, maximum amount of outgoing traffic and maximum number of users which are automatically set for a new site.

SMTP

SMTP (Simple Mail Transfer Protocol) is a protocol for transferring e-mail messages on the Internet. SMTP is used to send messages from a client server to a receiver. With mail programs, like MS Outlook, TheBat!, Eudora you can create messages using a number of useful features, such as formatting, spell checking and so on. Due to functional peculiarities (this protocol is rather old) SMTP cannot store the messages at the receiver side. Therefore we have to use POP3 to receive e-mail. For more information about SMTP, please visit RFC821.

SSH

SSH (Secure Shell) is a program that is used to log into a remote computer, execute commands on a remote machine, and to transfer files from one machine to another. It provides secure authentication and communication over the insecure channels. It replaces rlogin, rsh, rcp, and rdist, that have a number of drawbacks. First, the infromation (including passwords) is transferred in the open form, so anybody within the network can obtain this information. Second, password (telnet, ftp) and IP-address (rlogin) authorization is very insecure. SSH allows to solve all such problems. Using even a minimal installation will encrypt a password if you are prompted to enter it.

SSI

SSI (Server-Side Includes) is the directives that are inserted directly into an HTML-document and used to transfer the web server's instructions. When the web server meets the directives called SSI-enclosures, it interprets them and performs corresponding actions, such as insert an HTML-fragment from another file, dynamic format of pages depending on some variables (type of the browser) and the other useful features. SSI can be very advantageous when one has to support a heavy site with a certain structure and regular elements of the code on all the pages. Generally speaking, it is convenient to consider that the site consists of separate blocks, each of them responsible for a particular part of the page. Physically these blocks are HTML-files that contain a part of the code necessary to perform their task.

SSL

The Secure Sockets Layer (SSL) is a protocol that allows to safely transfer messages on the Internet.Usually SSL is used to secure the information that is transferred through HTTP. Other protocols, such as SMTP, FTP and POP3 can also be used. SSL supports data encryption, server authentification, messages integrity. For more information, please visit http://wp.netscape.com/eng/ssl3/.

Subscription policy

Subscription policy is a set of rules used for subscription to a mailing list. There are four types for the subscription policy : open, read-only, closed and mandatory.

Traffic

Traffic is the amount of information that goes through the server per a certain period. Traffic can be incoming (the outside information, such as HTTP-requests, uploaded files, incoming e-mail) and outgoing (the information transferred by the server outside, such as web-pages viewed by the site visitors, downloaded files, outgoing email).


UID

Each system user has his own unique identifier - a login. It is the internal number associated with a user ID. When a user is logged into the system, he receives two numerical identifiers - UID and GID, they determine user's access permissions to the server resources.

URL

URL (Uniform Resource Locator) is used to describe the location of files, news, etc. on the Internet. Normally, URL contains a method of access, such as http, https, ftp, the name of a host computer on which it is located, the path to a resource, a domain name or IP-address of the server, a port, a list of parameters and anchors. For example http://domain.name:8080/cgi-bin/process.cgi?id=3&value=12, https://domain.name/articles.html#35.

User

User (account in the operating system) is a set of parameters, such as login name, password, UID, GID (user's group identifier), home directory, shell and other parameters, depending on the operating system type. Administrator can locate usernames in various programs log files and manage user's parameters, such as forbid them to access certain files, limit disk quota, restrict usage of CPU and RAM.

Username

A username (login) is a unique identifier of a user account in the Unix operating system. This name is used to enter shell or use such services, as FTP or e-mail.

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