Chapter 2 Flashcards
(33 cards)
What Is a Linux Server?
- Linux desktops primarily focus on personal programs
- The server runs programs that provide shared
resources (called services) to multiple
users (clients), normally in a network environment
Launching Services
■ As a background process, running at all times
listening for requests (daemons)
■ As a process spawned by a parent program that
listens for the requests (super-servers)
super-server program
- internet daemon (inetd)
- extended internet daemon (xinetd)
Listening for Clients
- The network protocol for a service defines exactly
how network clients communicate with the service,
using preassigned network ports. - Ports are defined within the TCP and UDP standards
- Common Internet well-known port numbers:
Protocol Port number FTP 20,21 SSH 22 TELNET 23 SMTP 25 DNS 53 DHCP 67 HTTP 80 POP 109,110 SMB 137-139 IMAP 143.220 LDAP 389 HTTPS 443 NFS 2049
Serving the Basics
The three Internet services:
■ Web services
■ Database services
■ Email services
Web Servers
The Apache Server
The nginX Server
The lighthttpd Package
The Apache Server
- most popular web server on the Internet
- modularity
The nginX Server
- web proxy, mail proxy, web page cache, and even
load-balancing server - smaller memory
- handling large traffic
The lighthttpd Package
- low memory usage and low CPU usage
- built-in database
Database Servers
The Structured Query Language (SQL) provides a common method for clients to send requests to the database server and retrieve the data
open-source database servers:
- The PostgreSQL Server
- The MySQL Server
- The MongoDB Server
The PostgreSQL Server
- to rival the popular commercial database servers of
the day. - PostgreSQL is very versatile, with versatility comes
complexity - had a reputation for being somewhat slow
The MySQL Server
- fast database system.
- basic features
- high-profile Internet web applications
- LAMP platform
The MongoDB Server
- object-oriented databases
- NoSQL database doesn’t create tables but instead
stores data as individual documents. - NoSQL document can contain different data elements
- JavaScript Object Notation (JSON) elements
Mail Servers
■ The mail transfer agent (MTA) - on the Linux server
■ The mail delivery agent (MDA) - on the Linux server
■ The mail user agent (MUA) - end users,
The Mail Transfer Agent
- handling both incoming and outgoing email
messages on the server.
■ sendmail: very complex to configure correctly
■ Postfix: its simplicity. Instead of one large complex
configuration file, Postfix uses just two small
configuration files
■ Exim: one large program – avoid queuing messages
– immediate delivery
The Mail Delivery Agent
- concentrate only on delivering messages to local
users
■ Binmail: simplicity
■ Procmail: versatility in creating user-configured
recipes that allow a user to direct how the server
processes received mail
Serving Local Networks
- File Servers
- Network Resource Servers
File Servers
sharing files in a local network environment:
■ Peer-to-peer
■ Client/server
common server software packages
■ NFS : share folders in a network environment
- nfs-utils -
■ Samba : allow Linux systems to interact with
Windows clients and servers.
-System Message Block (SMB)-
Print Servers
■ Common Unix Printing System (CUPS)
Network Resource Servers
■ IP Addresses ■ Logging ■ Name Servers ■ Network Management ■ Time
IP Addresses
- Dynamic Host Confi guration Protocol (DHCP)
- Linux DHCP server package: DHCPd
- For Linux DHCP clients:
■ dhclient
■ dhcpcd
■ pump
Logging
■ rsyslogd
■ journald
Name Servers
- Linux servers use the BIND software package to
provide DNS naming services - main program in BIND is named
Network Management
- Simple Network Management Protocol (SNMP)
- SNMPv1: simple password authentication
- SNMPv2: basic level of security and bulk transmission
- SNMPv3: strong authentication and data encryption
capabilities as well as provides a more
streamlined
management system.
