IT Essentials II Network Operating Systems

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IT Essentials IINetwork Operating Systems

• Chapter 5Overview of Network Services

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Network Services

• Called
• Services
• Windows 2000
• Daemons
• Linux
• NetWare Loadable Modules (NLMs)
• Novell
• Less are set on by default as they are
  susceptible to attacks

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Remote Access Services

• Popular uses
• Connecting branch offices to one another
• Access to the network after business hours
• Access for telecommuters
• Access to the corporate network for mobile users
• Access to network resources for clients and
  partners

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Telnet Services

• Main Internet protocol for remote connection
• Provides error-free connection
• Beware of
• Hacking
• Password guessing
• Denial of Service attack
• Packet sniffing
• Secure SHell (SSH) is more secure

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Configuring remote access for a client

• Point-to-Point Protocol (PPP)
• PPP daemon (pppd) must be installed
• Can be configured in two ways
• Text-based PPP configuration
• GUI Dialer PPP Configuration
• Connecting using ISDN
• Connecting via DSL and Cable modem Service

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Controlling remote access rights

• Firewalls configured by
• Manually
• GUI tools
• Website configuration
• TCP wrappers
• two files that are used to configure the TCP
  Wrappers,
• /etc/hosts.allow
• /etc/hosts.deny
• Passwords
• Should be sent using SSH
• File Permissions
• Can be used to specify general permissions

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Remote administration to Linux

• Text-Mode Logins
• Logging into a system via Telnet or SSH
• ssh hostname -l jsmith
• Remote Administration Protocols SNMP
• Samba Web Administration Tool (SWAT)
• Web-based tool that is used to administer a Samba
  server
• Webmin
• Another Web-based remote administration tool.

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Directory Services

• A database that organizes files in a hierarchical
  structure
• A directory service identifies all resources on a
  network and makes them accessible to users and
  applications
• Provides system administrators with centralized
  control of all users and resources across the
  entire network
• Benefits
• Data can be easily organized
• Data can be easily secured
• Data can be easily located and accessed

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Directory Services Standards

• Allows compatibility with other platforms and
  directory services
• X.500 Electronic Directory Service (EDS)
  standards
• Structure defined as an upside down tree
• Database is hierarchical
• Three main components
• Directory System Agent (DSA)
• Manages the data
• Directory User Agent (DUA)
• Gives user access
• Directory Information Base (DIB)
• Acts as the central database for storage

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Directory Services Standards

• Directory Access Protocol (DAP) used by X.500
  compliant directory service
• Enables DUA to communicate with the DSA
• Defines how users search, read, add, delete and
  modify entries
• Lightweight Directory Access Protocol (LDAP)
• Subset of DAP that simplifies access to X.500
  directories
• Uses less resources
• Easier to maintain

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Windows 2000s Active Directory

• Information stored in
• Active Directory Database
• Actual directory
• Active Directory Log Files
• Records changes
• Shared System Volume
• Contains scripts and group policy objects
• Domain
• Hierarchical domain tree
• Represents a security and administrative boundary
• Organizational Units (OUs)
• Organises resources within a domain
• Authority can be delegated

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Windows 2000s Active Directory

• Domain Controller (DC)
• Must be one server configured in each domain
• Replication
• Synchronizing data between DCs
• Security
• All objects have an ACL
• Permissions
• Assigned
• Inherited
• Must be a DNS server on every Windows 2000
  network
• Runs only on Windows 2000
• Information can be exchanged with other LDAP
  directory services

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Novells Network Directory Service (NDS)

• NDS introduced in V4
• Hierarchical
• Inverted tree
• Two basic objects
• Container
• Leaf
• Permissions assigned to containers
• Can also run on
• NetWare 4 and 5
• Windows NT and 2000
• IBM AIX and O/S390
• Caldera OpenLinux
• SCO UNIX
• Sun Solaris

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Network Information Service (NIS)

• Daemon must be loaded
• Often works with NFS
• Structure consists of
• NIS Server
• Changes made here
• Copies database to slaves
• NIS Slaves
• Provide information to clients
• Provide load balancing
• NIS Clients
• If configured during install
• Provide NIS domain name
• Provide IP address
• If configured after install
• Use linuxconf utility on client

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Other NOS Services

• Intranets
• Accessible only from inside of the company
• Extranets
• Accessible from outside of the company
• Automating tasks with scripts services
• Visual Basic script (VBScript), JavaScript, Linux
  shell scripting, Pearl, PHP, TCL, REXX, and
  Python
• Domain Name Service (DNS)
• Translate names into IP addresses
• Dynamic Host Configuration Protocol (DHCP)
• Gives automatic network configuration
• Domains
• Represents a security and administrative boundary

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Other NOS Services

• Printing
• Use print servers to manage printing
• Use first in, first out (FIFO) priority
• File sharing
• Windows File Sharing
• Network File Sharing (NFS)
• Web services
• Microsoft's Internet Information Services (IIS)
• Apache Web Server
• HyperText Transfer Protocol (HTTP)
• HyperText Markup Language (HTML)
• HyperText Transfer Protocol Secure (HTTPS)

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Mail Servers

• Comprised of
• Mail transfer agent (MTA)
• Receive mail and forward
• Mail user agent (MAU)
• Microsoft Outlook
• Eudora
• Pine
• Mail delivery agent (MDA)
• Delivers mail to correct box
• Other features
• Web interface programs
• Web based e-mail
• LDAP
• Provides address book sharing

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FTP (File Transfer Protocol)

• Allows users to download or upload files
• Session orientated
• Accessed through GUI programs or CLI

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Virtual Private Networking

• Gives secure access to the company Intranet over
  the Internet
• Relies on
• Encryption software
• Usernames
• passwords

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Questions?