Unit-2-HPBOSE-12th-CS-HP-NOS Administration (Configuration & Maintenance) PDF

## CHAPTER 2 ### NETWORK OPERATING SYSTEM ADMINISTRATION (CONFIGURATION AND MAINTENANCE) ### 2.1 Network Operating System (NOS) A network operating system (NOS) is a computer operating system that is designed primarily to support workstation, personal computer, and, in some instances, older termin...

## CHAPTER 2 ### NETWORK OPERATING SYSTEM ADMINISTRATION (CONFIGURATION AND MAINTENANCE) ### 2.1 Network Operating System (NOS) A network operating system (NOS) is a computer operating system that is designed primarily to support workstation, personal computer, and, in some instances, older terminal that are connected on a local area network (LAN). Artisoft's LANtastic, Banyan VINES, Novell's NetWare, and Microsoft's LAN Manager are examples of network operating systems. In addition, some multi-purpose operating systems, such as Windows Server, RedHat Linux, Debian, Ubuntu Server etc., are some examples of Network Operating system. Installation and maintenance is the important when you have your own network. ### 2.1.1 Network Maintenance Network maintenance basically means you have to do what it takes in order to keep a network up and running and it includes a number of tasks: - Troubleshooting network problems. - Hardware and software installation/configuration. - Monitoring and improving network performance. - Planning for future network growth. - Creating network documentation and keeping it up-to-date. - Ensuring compliance with company policies. - Ensuring compliance with legal regulations. - Securing the network against all kinds of threats. Of course, this list could be different for each network you work on and you may only be responsible for a number of these tasks. All these tasks can be performed in the following way: 1. Structured tasks. 2. Interrupt-driven tasks. Structured means you have a pre-defined plan for network maintenance that will make sure that problems are solved before they occur. This will make your life as a network engineer a whole lot easier. Interrupt-driven means you just wait for trouble to occur and then fix it as fast as you can. Interrupt-driven is more like the "fireman" approach...you wait for trouble to happen and then you try to fix the problem as fast as you can. A structured approach where you have a network maintenance strategy and plan reduces downtime and it's more cost effective. Of course you can never completely get rid of interrupt-driven tasks because sometimes things "just go wrong" but with a good plan we can reduce the number of interrupt-driven tasks for sure. There are five major elements to the maintenance and management of a network. They include: - **Fault management**: Network devices (routers, switches, firewalls, servers, etc.) should be configured to capture logging messages and send them to an external server. Whenever an interface goes down or the CPU goes above 80%, you should receive an email so you can see what is going on.. - **Configuration management**: Any changes made to the network have to be logged. Use a change management system so relevant personnel will be notified of planned network changes. Changes to network devices have to be reported and acknowledged before they are implemented. - **Accounting management**: Charge (guest) users for usage of the wireless network so they'll pay for each 100MB of data or something. This is also commonly used to charge people for long distance VoIP calls. - **Performance management**: Network performance will be monitored on all LAN and WAN links so you know when things go wrong. QoS (Quality of Service) will be configured on the appropriate interfaces. - **Security management**: Create a security policy and implement it by using firewalls, VPNs, intrusion prevention systems and use AAA (Authorization, Authentication and Accounting) servers to validate user credentials. Network breaches have to be logged and a appropriate response has to be made. Whatever network maintenance model you decide to use, there are always a number of routine maintenance tasks that should have listed procedures, here are a couple of examples: - **Configuration changes**: Business are never static but they change all the time. Sometimes you need to make changes to the network to allow access for guest users, normal users might move from one office to another so you'll have to make changes to the network to facilitate this. - **Replacement of hardware**: Older hardware has to be replaced with more modern equipment and it's also possible that production hardware fails so we'll have to replace it immediately. - **Backups**: If we want to recover from network problems such as failing switches or routers then we need to make sure we have recent backups of configurations. Normally you will use scheduled backups so you will save the running-configuration each day, week, month or whatever you like. - **Software updates**: Network devices and operating systems need to be kept up-to-date. Bugs are fixed but also to make sure we don't have devices that are running older software that has security vulnerabilities. - **Monitoring**: Collect and understand traffic statistics and bandwidth utilization so you can spot (future) network problems but also so we can plan for future network growth. ### 2.2 Network Security and IT Career Opportunities Network security is the process of taking preventative measures to protect the underlying networking infrastructure from unauthorized access, misuse, malfunction, modification, destruction or improper disclosure. Network security involves the authorization of access to data in a network, which is controlled by the network security administrator/specialist. Security Specialist are responsible for preventing unauthorized access to our data and responding to privacy breaches. Users choose or are assigned an ID and password or other authenticating information that allows them access to information and programs within their authority. The responsibilities for network Security Specialist are as follows: - Analyze IT specifications to assess security risks - Design and implement safety measures and data recovery plans - Install, configure and upgrade security software (e.g., antivirus programs) - Secure networks through firewalls, password protection and other systems - Inspect hardware for vulnerable points of access - Monitor network activity to identify issues early and communicate them to IT teams - Act on privacy breaches and malware threats - Serve as a security expert and conduct trainings when needed - Draft policies and guidelines The various career opportunities for network specialist are as follows: - Network Technician - System Engineer - System Architect - Network engineer - Network Architect - Field Engineer - Network security Manager - Network Analyst ### 2.3 Windows NT Windows NT is a 32 bit network computer operating system designed for users and businesses needing advanced capability. The first version was released in 1993 as Windows NT 3.1, which was produced for servers and workstations. Windows NT's technology is the base for the Microsoft successor operating system, Windows 2000. Windows NT (“New Technology”) is actually two products: Microsoft NT Workstation and Microsoft NT Server. The Workstation is designed for users, especially business users, who need faster performance and a system a little more fail-safe than Windows 95 and Windows 98. The Server is designed for business machines that need to provide services for network-attached computers. The Server is required, together with an Internet server such as Microsoft's Internet Information Server (IIS), for a Windows system that plans to serve Web pages. ### FEATURES OF WINDOWS NT - Windows NT family introduced default file system NTFS which is capable of recovering from disk errors automatically, support large sized hard disk, provide security like permission and encryption. - Windows NT supports preemptive multitasking feature so that all computer programs share operating system and hardware resources. - Windows NT 4.0 Terminal Server Edition was designed to provide the feature to log on the system remotely. - Window NT supports numerous network features. ### Windows NT Workstation 4.0 system requirements - Pentium based system - 12MB memory (RAM); 16MB recommended - 110MB available hard disk space - CD-ROM drive or access to a CD-ROM over a network - VGA or higher resolution display adapter - Microsoft mouse or compatible pointing device ### Advantages of Windows NT The advantages of Windows NT are as follows: - More pleasing to the eye - Low system requirements - Runs well on old machines if all patches are installed - Faster to operate - Easier to Install - Security implemented on ### Disadvantages of Windows NT The disadvantages of Windows NT are as follows: - More easy to catch viruses and malware - Way unstable and crashes so often if you do not have patches installed ### Difference between Linux and Windows: The difference between Linux and Windows are as follows: | Sr.No. | Linux | Windows | |---|---|---| |1| Linux is free and open source operating system | Windows is a commercial operating system whose source code is inaccessible. | |2| Linux is customizable and a user can modify the code and can change its look and feel. | Windows is not customizable. | |3| No licensing is required to use Linux software | Windows operating system is a proprietary/copyrighted software i.e., the user should have license to use this software. | |4| Linux is reliable software and can often run for months and years without needing to be rebooted. | Windows has improved reliability over the last version of Windows, it still cannot match the reliability of Linux. | |5 | Linux provides high security | Windows continues to be the most vulnerable to viruses, malware, and other attacks and is less secure. | |6| Users can install application without using internet support | An internet connection is needed to install an application in Windows. | |7| In Linux, file names are case sensitive | Windows file name are case-insensitive | |8| Linux, variants have improveddramatically in ease of use | Windows is user friendly and easy to use operating system. | ### 2.4 Linux Firewall Firewall is a network security system that filters and controls the traffic on a predetermined set of rules. This is an intermediary system between the device and the internet. A properly configure firewall can increase the security of computer. All network traffic among the affected networks is routed through the firewall. There are two types of firewalls: software and hardware. Software firewalls tend to be cheap (or free) and easily available while hardware firewalls are more expensive. A software firewall is an application that is installed on a server which controls and restricts network access to the machine. It's generally setup on a specific server where other applications are located. Both Linux and Windows generally come with their own software firewall, while several other third-party options exist as well. The five types of firewall are: 1. Packet filtering firewall 2. Circuit-level gateway 3. Stateful inspection firewall 4. Application-level gateway 5. Next-generation firewall (NGFW) **1. Packet filtering firewall** Packet filtering firewalls operate inline at junction points where devices such as routers and switches do their work. However, these firewalls don't route packets, but rather they compare each packet received to a set of established criteria — such as the allowed IP addresses, packet type, port number, and other aspects of the packet protocol headers. **2. Circuit-level gateway** Circuit-level gateways monitor TCP handshakes and other network protocol session initiation messages across the network as they are established between the local and remote hosts to determine whether the session being initiated is legitimate — whether the remote system is considered trusted. **3. Stateful inspection firewall** State-aware devices, on the other hand, not only examine each packet, but also keep track of whether or not that packet is part of an established TCP or other network session. This offers more security than either packet filtering or circuit monitoring alone, but exacts a greater toll on network performance.. **4. Application-level gateway** This kind of device - technically a proxy and sometimes referred to as a proxy firewall — combines some of the attributes of packet filtering firewalls with those of circuit-level gateways. They filter packets not only according to the service for which they are intended — as specified by the destination port — but also by certain other characteristics, such as the HTTP request string. **5. Next-generation firewall (NGFW)** A typical NGFW combines packet inspection with stateful inspection and also includes some variety of deep packet inspection, as well as other network security systems, such as intrusion detection/prevention, malware filtering and antivirus. A deep packet inspection firewall tracks the progress of a web browsing session. **How the Firewall of Linux works:** Most of the Linux distro's ship with default firewall tools that can be used to configure them. We will be using "IPTables" the default tool provided in Linux to establish a firewall. Iptables is used to set up, maintain and inspect the tables of the IPv4 and IPv6 packet filter rules in the Linux Kernel. [Image of Firewall] A firewall can filter requests based on protocol or target-based rules. ### 2.5 Understanding Basic Disk Concept All the data and information is stored in storage media, such as - Hard disk (HDD) - USB Disk (pen drive) - CD - DVD etc. Big Storage media can be divided and each division is known as partition. We usually partition our Hard Disk. Partitioning is also required to be done during installation. You could have selected other options as well. Other options are used to manage the disk manually. **Disk partitioning or disk slicing** is the creation of one or more regions on a hard disk or other secondary storage, so that an operating system can manage information in each region separately. Partitioning is typically the first step of preparing a newly manufactured disk, before any files or directories have been created. The disk stores the information about the partitions' locations and sizes in an area known as the partition table that the operating system reads before any other part of the disk. Each partition then appears in the operating system as a distinct 'logical' disk that uses part of the actual disk. System administrators use a program called a partition editor to create, resize, delete, and manipulate the partitions. [Image of Disk Layers] ### 2.6 Logical Volume Manager (LVM) LVM stands for Logical Volume Management. LVM, is a storage management solution that allows administrators to divide hard drive space into physical volumes (PV), which can then be combined into volume groups (VG), which are then divided into logical volumes (LV) on which the filesystem and mount point are created. There are 3 concepts that LVM manages: - Volume Groups - Physical Volumes - Logical Volumes **A Volume Group** is a named collection of physical and logical volumes. Typical systems only need one Volume Group to contain all of the physical and logical volumes on the system. Physical Volumes correspond to disks; they are block devices that provide the space to store logical volumes. Logical volumes correspond to partitions: they hold a file system. Unlike partitions though, logical volumes get names rather than numbers, they can span across multiple disks, and do not have to be physically contiguous. [Image of Volume Group] ### 2.7 File Systems The files on Linux are arranged in a tree-based hierarchy, with / (forward slash) denoting the root directory of The filesystem. Everything in Linux is a file - it can be a text-based regular file as well as a special device file (for example, /dev/dsp). Hard disk drives (indicated as hda, sda) can have multiple partitions with different types of filesystem formats, such as ext, ext2, ext3, ext4, and so on.. The filesystem controls how users and programs can access and manage the files. You need to use the mount command to attach each partition/device to the filesystem before accessing the partition/device. The organization of your file system begins when you install Linux. Part of the installation process is to divide your hard disk (or disks) into partitions. Those partitions can then be assigned to: - A part of the Linux file system - Swap space for Linux - Other file system types (perhaps containing other bootable operating systems) [Image of Filesystem Hierarchy] ### Basic File Permissions #### Permission Groups Each file and directory has three user based permission groups: - **owner**: The Owner permissions apply only to the owner of the file or directory, they will not impact the actions of other users. - **group**: The Group permissions apply only to the group that has been assigned to the file or directory, they will not effect the actions of other users. - **all users**: The All Users permissions apply to all other users on the system, this is the permission group that you want to watch the most. #### Permission Types Each file or directory has three basic permission types: - **read**: The Read permission refers to a user's capability to read the contents of the file. - **write**: The Write permissions refer to a user's capability to write or modify a file or directory. - **execute**: The Execute permission affects a user's capability to execute a file or view the contents of a directory. #### Viewing the Permissions You can view the permissions by checking the file or directory permissions in your favorite GUI File Manager (which I will not cover here) or by reviewing the output of the "ls -1" command while in the terminal and while working in the directory which contains the file or folder. The permission in the command line is displayed as: _rwxrwxrwx 1 owner:group 1. **User rights/Permissions** 1. The first character that I marked with an underscore is the special permission flag that can vary. 2. The following set of three characters (rwx) is for the owner permissions. 3. The second set of three characters (rwx) is for the Group permissions. 4. The third set of three characters (rwx) is for the All Users permissions. 2. Following that grouping since the integer/number displays the number of hardlinks to the file. 3. The last piece is the Owner and Group assignment formatted as Owner:Group. #### Modifying the Permissions When in the command line, the permissions are edited by using the command chmod. You can assign the permissions explicitly or by using a binary reference as described below: **Explicitly Defining Permissions** To explicitly define permissions you will need to reference the Permission Group and Permission Types. The Permission Groups used are: - u - Owner - g - Group - o or a - All Users The potential Assignment Operators are + (plus) and - (minus); these are used to tell the system whether to add or remove the specific permissions. The Permission Types that are used are: - r - Read - w - Write - x - Execute So for an example, lets say I have a file named file1 that currently has the permissions set to _rw_rw_rw, which means that the owner, group and all users have read and write permission. Now we want to remove the read and write permissions from the all users group. To make this modification you would invoke the command: chmod a-rw file1 To add the permissions above you would invoke the command: chmoda+rw file1 As you can see, if you want to grant those permissions you would change the minus character to a plus to add those permissions. #### Creating a Filesystem in Linux You would want to create a filesystem in Linux for various reasons - keep your audio and video files, project file separately. - hold your backup files separately. To create a filesystem, you need to create a partition and format it.. ### 2.8 Swap Space Swap space in Linux is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space. While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM. Swap space is located on hard drives, which have a slower access time than physical memory. Swap space can be a dedicated swap partition (recommended), a swap file, or a combination of swap partitions and swap files. [Image of Process without swap space]. Suppose there are two processes running. Both processes are assigned memory pages. CPU is processing process one. The following figure illustrates this scenario.. [Image of Process with swap space]. As we can see in above figure, no memory pages available for another process. System will not start new process until any existing process is finished. Swap space can improve this situation a little bit. If swap space is configured and RAM is filled, idle pages will be moved to swap space. The process of moving idle memory pages from RAM to swap is known as page out. The process of moving required memory pages back from swap to RAM in known as page in. Following figure illustrates this process. ### 2.9 Mount Point Mount is to access a filesystem in Linux. You can mount a filesystem on any directory and access content by entering to that directory. In Linux terms, these directories are called mount points. The Linux mount command is used to mount USBs, DVDs, SD cards, and other types of storage devices on a computer running the Linux operating system. Linux uses a directory tree structure. Unless the storage device is mounted to the tree structure, the user can't open any of the files on the computer. #### How to Use the Mount and Umount Commands in Linux External storage media devices are usually mounted in subdirectories of the "/mnt" directory, but they can be mounted by default in any other directory created by the user. In this example, a CD has been inserted into the computer's CD drive. To see the files on the CD, open a terminal window in Linux and enter: Mount/dec/cdrom/mnt/cdrom This command connects the device /dev/cdrom (the CD ROM drive) to the directory /mnt/cdrom so you can access the files and directories on the CD ROM disk under the /mnt/cdrom directory, which is called the mount point. It must already exist when the command is executed. The mount point becomes the root directory of the device's file system. To unmount the same CD ROM drive, enter this command: umount/mnt/cdrom After the unmount command is executed, the files and directories on the CD ROM are longer accessible from the directory tree of the Linux system. This command has the same effect: umount/mnt/cdrom It unmounts the CD ROM. ### 2.10 Shell Scripting If you are using any major operating system you are indirectly interacting to shell. If you are running Ubuntu, Linux Mint or any other Linux distribution, you are interacting to shell every time you use terminal. So before understanding shell scripting we have to get familiar with following terminologies: - Kernel - Shell **Kernel** The kernel is a computer program that is the core of a computer's operating system, with complete control over everything in the system. It manages following resources of the Linux system - - File management - Process management - I/O management - Memory management - Device management etc. **Shell** A shell is special user program which provide an interface to user to use operating system services. Shell accept human readable commands from user and convert them into something which kernel can understand. It is a command language interpreter that execute commands read from input devices such as keyboards or from files. The shell gets started when the user logs in or start the terminal. #### Shell Scripting Usually shells are interactive that mean, they accept command as input from users and execute them. However some time we want to execute a bunch of commands routinely, so we have type in all commands each time in terminal. As shell can also take commands as input from file we can write these commands in a file and can execute them in shell to avoid this repetitive work. These files are called Shell Scripts or Shell Programs. Shell scripts are similar to the batch file in MS-DOS. Each shell script is saved with.sh file extension eg. myscript.sh A shell script have syntax just like any other programming language. If you have any prior experience with any programming language like Python, C/C++ etc. it would be very easy to get started with it. A shell script comprises following elements - - Shell Keywords - if, else, break etc. - Shell commands - cd, Is, echo, pwd, touch etc. - Functions - Control flow - if..then..else, case and shell loops etc. #### Why do we need shell scripts There are many reasons to write shell scripts - - To avoid repetitive work and automation. - System admins use shell scripting for routine backups. - System monitoring. - Adding new functionality to the shell etc. [Image of Shell interaction with Kernel] #### Advantages of shell scripts - The command and syntax are exactly the same as those directly entered in command line, so programmer do not need to switch to entirely different syntax - Writing shell scripts are much quicker - Quick start - Interactive debugging etc. #### Disadvantages of shell scripts - Prone to costly errors, a single mistake can change the command which might be harmful - Slow execution speed - Design flaws within the language syntax or implementation - Not well suited for large and complex task ### 2.11 Creating Groups Using The Command Line in Linux As Linux is a multi-user operating system, there is a high need of an administrator, who can manage user accounts, their rights, and the overall system security. In Linux, every user is assigned an individual account which contains all the files, information, and data of the user. You can create multiple users in a Linux operating system. Managing users is done for the purpose of security by limiting access in certain specific ways. The superuser (root) has complete access to the operating system and its configuration; it is intended for administrative use only. #### The steps to creating a user are: For example, to create a new custom group called "Accounting" from the command line in Ubuntu, run the commands below. sudogroupadd Accounting #### Command To View All Groups To view all groups currently created on your machine, run the commands below. A list of groups will show starting with the group name on the first column. cat /etc/group #### Adding Users To Groups To add a user to a group called 'Accounting' run the commands below. It can also be used to add users to the sudo and admin groups and make them root or administrator. sudousermod -a -G Accounting username #### Removing Users From Groups To remove a user from the Accounting group, run the commands below. sudodeluser username Accounting #### List Groups Users Belong To To view the groups a user belongs to, run the commands below. sudo groups username #### Deleting Groups In Ubuntu For example, to delete the Accounting Group, run the commands below: sudodelgroup Accounting ### 2.12 Administering Groups and users using GUI Tools #### Step 1) Go to the system settings look for an icon which says 'User Accounts'. [Image of "User Accounts" Icon] #### Step 2) Click on the unlock icon and enter a password when prompted, then click the plus sign. [Image of "Unlock" Icon] #### Step 3) A new window would pop up, asking you for adding information to the new user account. The account type offers two choices - standard and administration(Ubuntu Limitation). If you want the new user to have administrative access to the computer, select Administrator as the account type. Administrators can do things like add and delete users, install software and drivers, and change the date and time. Otherwise, choose standard. Fill in the full name, username and click on create. [Image of "Create New Account"] #### Step 4) The new account would show, but would be disabled by default. To activate it, click the password option and add a new password. Click change to enable the account. [Image of "Account Disabled" and "Enable Account"] #### Step 1) Highlight the user account and click the minus sign to delete. [Image of "Account" Icon and "Delete" Icon] #### Step 2) For disabling click on the area where the password is stored, and you would get the following prompt. Select disable this account and click on change. [Image of "Disable Account" Prompt] #### Adding Users To the User Groups If you do not want to run the commands in terminal to manage users and groups, then you can install a GUI add-on. sudo apt-get install gnome-system-tools Once done, type users-admin Check user settings, and a tab Manage Groups will appear. [Image of "Users" Window] ### Linux/Unix user management commands | Command | Description | |---|---| | sudoadduser username | Adds a user | | sudopasswd -1 'username' | Disable a user | | sudouserdel -r 'username' | Delete a user | | sudousermod -a -G GROUPNAME USERNAME | Add user a to a usergroup | | sudodeluser USER GROUPNAME | Remove user from a user group | | finger | Gives information on all logged in user | | finger username | Gives information of a particular user | ### SUMMARY **Network Operating System (NOS)** A network operating system (NOS) is a computer operating system that is designed primarily to support workstation, personal computer, and, in some instances, older terminal that are connected on a local area network (LAN). **Network Maintenance** Network maintenance basically means you have to do what it takes in order to keep a network up and running and it includes a number of tasks: **Windows NT** Windows NT is a 32 bit network computer operating system designed for users and businesses needing advanced capability. Windows NT ("New Technology") is actually two products: Microsoft NT Workstation and Microsoft NT Server. **Linux Firewall** Firewall is a network security system that filters and controls the traffic on a predetermined set of rules. This is an intermediary system between the device and the internet. A properly configure firewall can increase the security of computer. **Disk partitioning or disk slicing** is the creation of one or more regions on a hard disk or other secondary storage, so that an operating system can manage information in each region separately. **Logical Volume Manager (LVM)** LVM stands for Logical Volume Management. LVM, is a storage management solution that allows administrators to divide hard drive space into physical volumes (PV), which can then be combined into volume groups (VG), which are then divided into logical volumes (LV) on which the filesystem and mount point are created. **File Systems** The files on Linux are arranged in a tree-based hierarchy, with / (forward slash) denoting the root directory of the filesystem. Everything in Linux is a file - it can be a text-based regular file as well as a special device file (for example, /dev/dsp). **Swap Space** Swap space in Linux is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space. **Mount Point :** Mount is to access a filesystem in Linux. You can mount a filesystem on any directory and access content by entering to that directory. **Shell Scripting** Some time we want to execute a bunch of commands routinely, so we have type in all commands each time in terminal. As shell can also take commands as input from file we can write these commands in a file and can execute them in shell to avoid this repetitive work. ### EXERCISE 1. What do you understand by Network Maintenance? 2. What is Windows NT? What are its advantages and disadvantages? 3. What are responsibilities of network security specialist? 4. What do you mean by Linux firewall? Explain its types. 5. What is the difference between Linux and Windows? Explain. 6. What do you mean by LVM? Explain. 7. What is a swap space? Explain. 8. What is mount point in Linux? 9. What do you mean by shell scripting? Explain. 10. What do you understand by disk partition? -End-