FAQ: Real-World Networks

Transcription

1 Question 1: What are client-side and server-side processes? Answer 1: The terms client-side and server-side are sometimes called frontend (client) and back-end (server) processes (Davis & Rajkumar, 2004). Generally speaking, any activity controlled by the user is a front-end process. Querying a database, clicking a mouse, pressing keys on a keyboard, logging on to a system, directing file storage, requesting encryption, directing a document be printed, and calling for are all front-end processes (Dean, 2006). A client creates input. Based on that input, the server will provide output, which is the back-end process. Server processes include encrypting data by providing an algorithm, using TCP/IP protocol to send traffic across a network, searching a database for information, and displaying it to the user. It might also include connecting to Web services for access to the Internet, calling from the storage site (simple mail transfer protocol-smtp), issuing an authentication challenge to a user, and permitting access. Even in a standalone system, the back-end process responds to the user's request. The front-end/back-end processes are always there. At the network level, back-end control of these processes occurs in the management or directory services (Davis & Rajkumar, 2004). If the service is not available for the user locally, the back-end process may redirect service requests to another backend provider outside the system. Question 2: What is TCP/IP protocol? Answer 2:TCP/IP stands for transmission control protocol/internet protocol, and it is a group of rules and applications that establish and maintain networking connectivity. The term protocol refers to the structure and rules that allow electronic network data transfers. TCP/IP was designed to provide data control, format, structure, process management, and accountability for data transferred between network nodes. It is considered a free open source software that is modifiable by the users and developers. It is supported by all network environments (LAN, MAN, and WAN) and is the standard in all networking applications (Dean, 2006). TCP/IP is actually two principle protocols: the TCP and the IP. The TCP TCP protocol is responsible for reliable data transfers; it sizes the data so the receiver has the ability to use it (Dean, 2006). TCP validates receipt of all data sent at each end of the connection (sender/receiver) no matter how far 1

2 away the data is transferred (Davis & Rajkumar, 2004). It also establishes an agreement with the receiver concerning how the information is to be sent regarding size and format; this is initiated by a connection handshake (Dean, 2006). Finally, TCP provides packet sequencing so the receiver can reassemble the data correctly and flow control. All packets are validated by a message sent from the receiver verifying (acknowledging) the packets received to the sender. The IP The other core protocol in this suite is the Internet protocol. IP is associated with addressing and identifying routing from the source (sender) to the receiver (destination) through all the intermediate nodes. It is a connectionless protocol relying on TCP to validate sent data. IP addressing is applied to the IP datagram (encapsulated frame) packet before sending along with routing instruction to the network (Dean, 2006). It can also apply encryption called IPSec. Question 3: What are some basic functionalities of a network operating system (NOS)? Answer 3: Not all network operating systems (NOSs) are equal. However, the incorporation of the following functions can be achieved by installing a base OS and optional server components. These are the most prominent NOSs on the market today: Windows Servers (2000, 2003) UNIX (both proprietary and open source) Macintosh OS X Linux (most distributions) Novell NetWare The OS is centrally managed and controls the system resources, applications, data remote access services, security, and network devices. The NOS will provide secure access to the network using policy, procedure, software, and devices such as firewalls, routers, and switches. The NOS will also provide the following functions to users on the network: Remote access using authentications Connection to other network entities and networks (an organization's 2

3 extranet, intranet, and peer network domains) Backup processes to ensure data integrity and availability Simple modification of the client lists such as being able to add, delete, and change permissions for clients Applications that monitor the status of network components' functionality System updates to all nodes Manages efficient server functionality and capability including load balancing, virtual machine implementation, and resource duplication in a distributed network configuration Mitigates internal network problems such as hardware or software failure using fault tolerance techniques The network OS must be able to function as a computer OS and network OS because of the fact that the node it is installed on must manage its internal client/server requirements. Question 4: What are some primary factors to consider when selecting a NOS for an organization? Answer 4: Not all NOSs support all computer systems and applications. Commonly used NOSs provide compatibility or can be configured to support system requirements. Interoperability among these NOSs is available through installation of client/server protocol applications like Samba, NWLink, or shared directory service (SDS) for UNIX. The following are some of the primary considerations when selecting a network OS environment: Compatibility A NOS must be compatible with the systems currently being used. For example, if a peer-to-peer network is the current system and the organization wants to deploy a NOS that uses a different OS platform, the file systems do not work well together; therefore, a Samba client would be required on the Windows computer. The application must be considered part of the network upgrade. Security A NOS must be able to provide system security for the organization. Implementation of some NOSs reduces the security protection of other systems. For example, if a system is using Windows 2000 Professional with a 3

4 new technology file system (NTFS), encrypted files could be saved to the Fat32 file system, but all encryption would be lost. Summary There are other considerations as well. Every organization must keep in mind its users' knowledge of systems, resistance to change, and training users on new OSs. It is also important to consider the cost of a new system, upgrades, and maintenance. Question 5: What are the hardware requirements to install different OSs? Answer 5: Each network operating system has a set of minimum hardware support requirements to function. The following are the minimum requirements for different OSs: Windows Server 2003 Processor > 133 MHz or higher Pentium type (550 MHz recommended; the install supports 4 processors in a single server.) Memory > 128 MB RAM is the absolute minimum (recommended 256 MB), and maximum support is 4 GB RAM Storage > compatible hard drive with 1.5 GB of free space CD/ROM is required unless the install is over a network connection Solaris10 Processor > AMD or Pentium Memory > 512 MB RAM Storage 5 to 7 GB CD/ROM or DVD/ROM drive for input Solaris 10 can support up to 128 processors per server (clustering is possible) MAC OS X Processor > G3, G4, G5, imac, emac (Macintosh computers), or an Intel Pentium 3 (as of Aug 2005) platform Memory > 256 MB RAM Storage > 4 GB of available disk space 4

5 CD/DVD drive required Linux Server Processor > Intel X86 compatible (any AMD/Intel) Memory > 64 MB RAM Storage > Linux compatible hard disk drive with 2 GB free space Linux compatible CD/ROM drive or paired 3.5 inch floppy disk Novell NetWare 6.5 Server Processor > IBM compatible Pentium II, AMD K7 (Up to 32 processors can be supported at one time.) Memory > 512 MB of RAM (recommended 1 GB) Storage > at least 2 GB of free space (recommended 4 GB) CD/ROM required for install Windows Server 2008 Windows Server 2012 All operating systems have a hardware compatibility list (HCL) that identifies what devices can be used with each OS. If the device is not on the HCL, there is no assurance that it will work with that OS. Some of the devices on the HCL may require special configuration to work properly. Plug and Play (PNP) components can be used on most operating system platforms when configured properly. In many cases, software compatibility lists also identify what programs can be used on specific platforms. Question 6: How can different NOSs share files? Answer 6: Most operating systems can share data files despite the difference between platforms (Dean, 2006). The industry has established common standards for data reading and transfer. Common text formats like the ASCII (American Standard Code for Information Interchange) provide a numerical value for the letters, spaces, numbers, and special characters on the keyboard. These universally implemented values are seen as the characters they represent in all OSs. Along with the standard direct conversion, internal applications within the OS provide access to the file system. The file access protocols provide different OSs access to different file formats (Dean, 2006). Within Windows Server 2003 and Windows XP, file access is through CIFS (common Internet file system) (Davis & Rajkumar, 2004). CIFS 5

6 is widely supported in commercial software products. Additionally, connecting network platforms requires unique applications to support the data transfer. Novell Client for Windows provides the Window Server control of Novell client nodes. NWLink supports Windows client management by Novell servers. Samba allows file sharing in client and server configurations by a UNIX or Linux platform supporting Windows and Mac OS X (Davis & Rajkumar, 2004). In some cases, "a universal software application called middleware is necessary to translate requests and responses between the client and server" (Dean, 2006). With middleware, other applications such as Samba are unnecessary. Question 7: What are some differences between network operating systems? Answer 7: NOSs are more alike than they are different in their functionalities; however, there are some components that make each NOS unique. Some NOSs even have different editions of the same NOS to meet diverse customer needs. For example, Windows Server 2003 has four different editions. Management applications, files types, and system 6

7 management are just some areas where NOSs vary in functionality. Management Applications In Windows Server 2003, management applications are predefined using Microsoft Management Console (MMC). The routines or snap-ins provide tools for common tasks such as creating accounts, changing passwords, monitoring event logs, and permitting the administrators to script their own snap-in and service calls. Service snap-ins minimize the need for command line interfaces (Dean, 2006). Although Linux has some of these common administrative functions, it does not have to use a graphical user interface (GUI). Commands can be implemented using a command line interface. Nearly all the administration processes in Windows Server 2003 are executed by snap-in. File types In Windows Server 2003 (WinSrv2003), file management supports the following file types: FAT16 FAT32 UDF (Universal Disk Format used on CD-ROMs) CDFS (CD-ROM file system allowing CD file sharing and application installation) NTFS (new technology file system) However, the common FAT16 and FAT32 are also supported by other OSs. The UDF support is available on Linux and Novell platforms, but not on UNIX or MAC OS X. UNIX/Linux NFS cannot directly be supported by Window Server 2003 (WinSrv2003) but can be managed with Samba. NTFS is the file system of choice with Windows Server 2003 and XP because of its security support (Davis & Rajkumar, 2004). Files managed in NTFS can be stored as encrypted files and transfer from one NTFS system to another; the encryption remains enforced. When files are transferred to a different file system, the encryptions are in a plain text format. NTFS is supported by the security suite Kerberos that establishes security mechanisms and authentication controls for the network. Kerberos is available with other OSs 7

8 as an option instead of a standard. WinSrv bit processor format can support the NT file system (NTFS). It can establish file partition as large as 16 exabytes (EB 2 64 bytes). No other NOS can do this. WinSrv2003 and MAC OS X communicate using NTFS (Dean, 2006). Built into WinSrn2004 is a compression algorithm that can automatically compress files up to 40%. This saves a lot of disk space considering that 10 GB HD fully converted to NTFS uses only 6 GB. None of the other NOSs have that ratio of compression. Interface Design WinSvr2003 was designed to provide GUI interface for all activities providing easy use and a short learning curve. It uses a familiar interface mouse base execution and pointer pen and stored system applications. UNIX and some Linux distributions rely on the command line interface; however, GUI interface are available for both. The applications to support the OS are still mostly command line scripts. Mac OS X and NetWare provide primary GUI interfaces. The built-in applications are limited and third party support is needed (Dean, 2006). System management WinSrv2003 maintains its files and management systems using an application called Active Directory (AD) (Davis & Rajkumar, 2004). Active Directory works as the system manager and primary backup domain controllers. The purpose of AD is to provide the system copies of the user account data and a file system image so in the event a server fails, the system will automatically have access to user accounts on other servers. Any server that AD is installed on will have the user data (Dean, 2006). In most other operating systems, the management function must be specifically delegated to the server. No automatic assignment is available. The exception to this rule is with Novell Netware 6.5 NDS; Netware Directory Service and e-directory assumes the role as domain control. Question 8: How can Windows Server 2003 interact with other network operating systems (NOSs)? Answer 8: It is not uncommon for a network to contain multiple platform 8

9 OSs and servers (Dean, 2006). The following are some examples of how Windows Server 2003 can interact with different NOSs. Netware and Windows Server 2003 If a user must update client information in the Windows Server 2003 Active Directory, the application Microsoft Directory Synchronization Service (MSDSS) must be installed. The Windows server must be the domain controller to run this service. The installation provides administrative access between WinSrv2003 Active Directory and NetWare's e-directory database (Dean, 2006). What happens if it was the other way around? Perhaps a Windows client on a Windows server needs access to the NetWare server. A Windows client can access the NetWare server if the Windows server has installed Client Services for NetWare (CSNW) and NWLink. These two services permit a Windows client to logon to a NetWare server to access services like printers, files, and other resources controlled by that server. Windows can operate with NetWare and NetWare can work with Windows simply by installing services. MAC OS X OS X is based on an open source UNIX kernel, but the MAC OS X Server is a proprietary UNIX OS. One of the unique aspects about UNIX-like systems is that they can use similar applications to interact. Samba is a client and server application that allows UNIX systems to communicate with Windows. What allows Windows to communicate with UNIX? UNIX-type systems and Windows have access to a service called LDAP (Lightweight Directory Access Protocols) that sets up a common directory format. Due to its TCP/IP protocol and LDAP compatibility, these two OSs can communicate. What happens if the LDAP is not established between Windows and UNIX? Windows can work with that as well. Microsoft has software that comes with the server OS that will integrate the servers' directory allowing the clients on the UNIX side to access resources to the Windows resources. The application belongs to the Microsoft Service for UNIX Suite. UNIX and Novell 9

10 Connectivity between UNIX and Novell may be a surprise as well. Recently, Novell has decided to implement a SUSE Linux kernel (one of the over four hundred Linux distributions available) to provide interoperability and access resources on the UNIX/Linux platforms. Question 9: How can users help maintain a secure system? Answer 9: The user is the most important entity in the security process. Breaches of security can be caused by user oversight, complacency, or ignorance. The user must understand his or her part in establishing a secure work site. Simple things may have the most impact. The following are some ways that a user can assist in maintaining a secure system: User Security The user has to protect the information that allows him or her to use the system; it consists of a user ID password and digital signature. The user should avoid writing down the password and use the same cautions with this information that he or she would use with bank statements or other personal information. Individual Workstations A system can be compromised if a user opens a bad file, plugs in a personal thumb drive, or downloads an attachment and opens it. The results of these actions can infect an entire network with a virus and shutdown the system. The user should take adequate care of the privilege of using the system. As a user, there are certain responsibilities to ensure an organization's network remains secure. Here are some appropriate uses of an individual workstation: Follow any policy regarding the use of the company's asset. If the use of personal devices or downloading is acceptable, the user should run a virus check before opening or using the device. If there is a breach in security, the user should cooperate with any investigation conducted. Password Compromise 10

11 A user should never write a password down. If anybody other than the user sees the password, it is compromised. A password provides a user with access to the business assets that he or she needs to do a job. A compromised password opens the system up for attacks and security breaches. Question 10: What are some security services in a client/server environment? Answer 10: Security service encompasses a wide array of functions provided by the system, including user/group account management (network administration), password management (password policy), policy enforcement (monitoring compliance), lockout policy management (security log violations), access control lists for users to open applications and files (access granted/denied), and file permission allowing a user to read, write, or modify any files accessed. Security services manage authentication and authorized access from remote sites, creating the interface for the RADIUS or TACACS servers as well and the CHAPS services (Dean, 2006). The services keep track of system keys for encryption, records revoked accesses, requests certificates, and manages digital signatures and hashed password files. The security services provide for implementation of NAT (Network Address Translation) protocol, monitor and enforce boundary security (access in and out of the private network by user) through the firewall configurations, and provide a vehicle to audit access attempts through the intrusion detection systems. All system-controlled security processes are considered security services. References Davis, W. S., & Rajkumar, T. M. (2004). Operating systems: A systematic view (6th ed.). Boston, MA: Prentice Hall. Dean, T. (2006). Network+ guide to networks (4th ed.). Boston, MA: Thomson Technology. 11