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Windows 7

Q and A on Windows 7

Windows 7 news

Windows 7 Virtual Machine How To

OR download the VM Appliance on Torrent Windows 7 Virtual Machine Appliance

Windows XP - Slipstream SP3 and Post SP3 updates

Slipstreaming an install CD has the following steps

Slipstream SP3 using freely available software

Posrt SP3 updates (Zero update CD) Using Ryan's Integrator and the Post sp3 pack - Read the forums for How Tos

Nlite - A tool for preinstallation component removal and update - Also Unattended installs

Another unattended deployment guide

Understanding the System Design/Development Life Cycle process. SDLC

Acronym for system development life cycle. SDLC is the process of developing information systems through investigation, analysis, design, implementation and maintenance. SDLC is also known as information systems development or application development. SDLC is a systems approach to problem solving and is made up of five phases, each comprised of multiple steps and extending over several years of the systems life: (note there are many variations though all consist of these basic five steps) 


1) Analysis        - Conceiving the idea, surveys, expertise, studies, a general feeling of change.
2) Design          - Contractors, company experts, motivated personnel, professional attitude.
3) Implementation  - Overtime, reliability, working with contractors, plenty of training, pilot systems.
4) Testing         - Maintaining two systems, wide range of faults, experience, demanding, training and development.
5) Maintenance     - Routine, customer service, practical experience, providing training.

Consider that these processes extend over many years and that depending where in the SDLC a company is currently operating at there are different opportunities for the engineer's career.

To be actively involved in the early stages of a SDLC the person should have the following skills.

Understanding the Cost versus Benefit of an IT project.

What are Tangible Costs and Benefits?

Tangible costs and benefits are those which are guaranteed.

Examples of cost would be contracts, quotes and tenders. Examples of benefits might be improved productivity, better information.

What are Intangible Costs and Benefits?

Intangible costs and benefits are those which cannot be easily measured.

Examples of cost might be hourly price contracts e.g. hourly maintenance, ongoing training, staffing. Examples of benefits might be staff morale and customer satisfaction.

These must be estimated using models, surveys and case studies.

Being aware of the Cost versus Benefit process enables the employee to be realistic when pressing for change or at least understanding of the effect on such a study on their working conditions.

 

Cables and media.

Level 2 Networking Concepts revisited

LAN - Local Area Network

WAN - Wide Area Network

RFC - Request For Comments - White papers on the standards that make networking work. Every aspect of networking, and computer electronics for that matter, is documented in an RFC somewhere. E.g. RFC 802.3 is the standard for Ethernet wired networking

An excellent resource from Michael Harris of Delmar College. Networking primer

Open Systems Interconnect Model - A layered approach

    7    Application layer        A ll                      The end application that either started or receives the data.
   6    Presentation layer      P EOPLE            Encryption, Data Types
   5    Session layer              S EEM                 Ports & Sockets, Communication sessions
   4    Transport layer          T O                      TCP, Control, Error Checking, Sequencing of Packets
   3    Network layer            N EED                 Packets, IP Addressing, Network Addressing.
   2    Data link layer           D ATA                 Frames, MAC addressing, Network hops.
   1    Physical layer            P ROCESSING   Cables or any media, connectors, hubs

Or as Jon from a previous year => All People Should Thoroughly Network Digital Parsnips  !!!!

Consider how data is ENCAPSULATED (data is framed with header and trailer information at each layer in the process) into IP PACKETS (layer 3) and then ETHERNET FRAMES (Layer 2) in preparation for sending bits on the physical layer.

IP Address and MAC Address

An IP Address is a 32 Bit ( 4 Byte ) number usually represented in what is known as Dotted Decimal Notation, or 192.168.100.100, each section representing 1 Byte (range 0-255).

IP Addresses are standardised in layers 3 and 4 of the OSI model and are embedded in the IP Packet with the data. They represent the final destination NETWORK for the data.

Media Access Control (MAC) is a 48 Bit (12 digit Hexadecimal or 6 Byte) number allocated to every device that is attached to the physical layer of a network, in the world!

Typically the first 6 digits of the MAC address is allocated to a manufacturer, so with knowledge of these numbers you can identify the manufacturer of the device. The last 6 digits represents the serial number of the network card.

The MAC address is standardised at the Data Link layer of the OSI model. Ethernet frames are addressed with the MAC address of the the next networking device the data must travel through on its path to the final destination (Usually a router, gateway, proxy or switch). In fact the very last hop to the destination node is addressed to the MAC address of that device. The IP address is only used to located the network where this node resides.

Network devices (Routers, Switches) unpack the Ethernet Frame to inspect the IP Packet to determine which network to send it to next. Once this is determined (Often it isn't really known so the device just hands it up-one-level to a higher level of authority over networks) the IP Packet is packed into a new Ethernet Frame and re-addressed to the next MAC address on the way. Networked devices always 'know' the MAC address of directly connected nodes as they communicate using broadcasts and build a table known as an ARP table (Address Resolution Protocol)

You may begin to see how the OSI model becomes an illustrative tool for how networking occurs and how different tasks, protocols and instructions are performed in each defined layer.

Ethernet and CSMA/CD

Ethernet is the term used to collectively name the protocols, hardware and services used in modern networks. Often referred to as 802.3 which is the RFC that defines it.

CSMA/CD stands for Carrier Sense Multiple Access / Collision Detection.

This basically means that all nodes can 'hear' each others signals, sense a collision and respond by waiting a random amount of time to retransmit. This enables effective communication in relatively congested networks. The carrier sense is a voltage that all nodes can detect and interpret as a busy signal.

Networking tools, TRY THESE in DOS.

ping

Ping is a DOS command, the parameters are either the IP address or URL of the node you wish to test communication with. This tests confirms the media (Layer 1). If you use an IP Address the TCP/IP protocol (Layers 3&4) on both devices are OK and if you use a URL it also confirms DNS is working.

ping 127.0.0.1

The IP address 127.0.0.1 is known as the loopback address. It is a special address all IP networked devices have that is used for testing the TCP/IP protocol of the local machine and for internal data networking between applications on your PC. This test, if successful, confirms the machine's TCP/IP protocol. It doesn't mean though that the machine is correctly set up! Other settings such as the workgroup, IP Network & Address, Subnet mask could still be incorrectly specified preventing networking. Pinging the loopback address only confirms the protocol & adaptor (NIC) are installed and working. This test also doesn't test the NetBUI protocol responsible for file and printer sharing.

netstat

This report shows the OSI Layer 5 sessions. Ports and sockets

Displays current network sessions. Using the -a switch shows the sockets as PCNAME:PORT. Using the -n switch shows the sockets as IPADDRESS:PORT

Local connections that are well-known-ports indicate your PC is serving a service to another PC. Foreign connections with well-known-ports indicate your PCis a client to a service from a remote PC.


Some well-known ports are:

80       HTTP     (Connection to web servers)
25       SMTP     (Email transfer) 
110     POP3      (Email authorisation)
23       TELNET (Insecure remote administration)
139     NetBIOS (File or printer sharing)

There is 16 Bit of system memory allocated to registering ports for networking sessions. This means there are apprx. 65536 ports on a PC. The first 1025 are reserved and are called well-known ports. These ports are documented and regulated by the IANA to ensure network security for specified processes like email, Telnet and web hosting.

Shields Up is a site that probes your networking ports for breaches in security. Well-known ports should be reported as Stealthy or Closed to external probing.

In networking file paths, two backslashes (or two forward in Linux and the web) means that the following name in the path is a PC acting as a server offering files or services.

To see all workstations on the LAN try

net view

net is a DOS command with a suite of uses Used in conjunction with view it will show all named PCs on your workgroup. Used with share (net share) it will show what shares your PC is making available to the network.

To find what shares a computer on the LAN is offering try

net   view    \\network_pc_name

tracert

The parameter would be either an IP address or a URL

Reports each hop the packet goes through on its way to a destination and shows the time in milliseconds. Good for diagnosing a faulty/congested switch, router or gateway. Some firewalls block these ICMP packets preventing this tool from reporting correctly, though not usually a problem within a LAN.


To 'watch' a packet travel to Australia. Examine the time when it first reaches Sydney.  
Note, the time is a round trip time!  Using a DOS command prompt try ...

tracert   www.yahoo.com.au  >  c:\mytrace.txt


Some organisations for you to lookup on Google or Webopedia.

IEEE = Institute of Electrical & Electronic Engineers

IANA = Internet Assigned Numbers Authority

W3C = World Wide Web Consortium