• Data corruption: If the incident causes data corruption, the organization may be forced to take systems offline until you can recover or rebuild the data. In large databases, this process can take several days, even on the fastest available computers.
• Denial of Service (DoS): A concentrated attack, especially when it originates from large numbers of systems, can render a server or an entire network of servers unreachable to customers and partners. Such attacks can last for hours, days, or even weeks.
• Forensics: Your organization (or law enforcement) may need to carry out forensic operations on affected systems to gather evidence for a possible prosecution. Trained personnel usually conduct forensics on quiescent systems (systems in which activity is halted) to provide stability, ensuring the best possible evidence gathering.

To reduce the effects of a security incident, consider these measures:

• Alternate servers and storage systems: Place alternate systems and storage systems into service while trained personnel perform forensics on affected systems. Before you place affected systems into service, however, the organization needs to be certain that they won't be compromised, too.
• Distributed Denial of Service (DDoS) defense: Some Internet service providers offer a DDoS defense service that may help to restore connectivity to customers and partners. These solutions can cost you, but so can being offline.
• Alternate network locations: If an organization is experiencing a Denial of Service or Distributed Denial of Service, you may be able to avoid disruption by relocating affected servers or networks to another logical place on the Internet. Whether this move works has a lot to do with the determination of the attackers and their ability to change their intended target.
• Backup data: Replication and mirroring are great technologies that can compensate for hardware failures. However, in the case of a deliberate attack, replication or mirroring may propagate the corruption to other storage systems. If this widespread corruption occurs, you may need to recover data from a recent backup - but only if analysts can determine that the attack hasn't affected a recent data backup.
• Heterogeneous (similar) systems: If attackers attack through known vulnerabilities in software, using heterogeneous systems may prevent an attack from reaching some systems. For instance, if an application uses both a Sun system with Oracle databases and a Windows system with SQL Server databases, an attack through the Windows system can't succeed on the Sun server.
• Forensics training and tools: This measure is an up-front investment of dollars and training. With better forensics preparedness, your business can respond more quickly when you need forensic activities, as well as develop alternate strategies that can minimize impact on business operations.

Cable Rules

Here are a few basic rules to follow whenever you are running cable:

• Slack - Always use more cable than you need. Leave plenty of slack
• Test - Always test every segment (the complete, unbroken length of cable running between two distinct points/nodes) of a network as you install it. Even if it is brand new, it may have problems that will be difficult to isolate later.
• Stretching - Avoid stretching UTP cables. The tension exerted when pulling cables should not exceed 10 Kilograms. Over-stretching of UTP will result in effectively untwisting the pairs within the cable sheath. As I will explain later the period of the twist of great importance in reducing cross-talk or noise.
• EMI Sources - Stay at least 3 feet away from EMI sources such as fluorescent lights and other electrical and electronic equipment in particular including copy machines, electric heaters, speakers, printers, TVs, copiers, welding machines, microwave ovens, telephones, fans, elevators, motors, electric ovens, dryers, washing machines, and shop equipment. Once again this is to reduce Electro-magnetic interference (noise).

The less interference/noise the better the signal will be at the receiving end. This helps to reduce corruption of data in transit and so reduces the amount of retransmissions that may be required for maintenance of data integrity throughout the transfer process. This in turn translates to greater effective data throughput which means your network is faster.

• Sensitive Electronics - Whenever you are planning your cable runs it is vital to consider the electrical and electronic environment into which the run will be performed. Just as other EMI sources can result in degradation of the signal in your transmission medium so your transmission medium can cause interference with other devices. Do not run trunk cabling next to life-support systems etc. as this can have consequences that I will not go into here.
• Mobile Phones - Mobile phones can also be an issue that needs to be carefully considered. If you are going to be running your cable through an area that is likely to be heavily populated with mobile phone users then it would be advisable to add additional protection for your cable. Using Shielded Twisted Pair (STP) or another medium that is not susceptible to EMI such as fiber optic cable while more expensive do not have the same susceptibility to EMI as Unshielded Twisted Pair (UTP).
• Open Spaces - If it is necessary to run cable across the floor always cover the cable with cable protectors and fix it firmly to the floor (duct tape does a good job here). For aesthetic reasons you might consider using a rug.

The reasons that you must cover and fix the entire cable firmly to the floor are so that the cable isn't damaged by traffic and that the traffic (people) is not damaged by tripping over a loose cable. Try to avoid open floor cables runs at all times even if it means using more cable by running the cable along a wall.

• Label Cable - Always clearly label your cable at both ends as you run it. This becomes particularly important when it comes time to attach the ends to other devices. It also makes future troubleshooting easier.
• Cable Ties - Apart from the use of duct tape to cover cross-floor cable runs always use cable ties and not tape to keep cables in the same location together.
• Staples - Never use a stapler to secure UTP or STP or any other cable transmission media; rather use telephone wire/RG-6 coaxial wire hangers instead. They are readily available at most hardware stores.
• Outside Use - Never run UTP cable outside of a building as it presents a very real danger in the form of a lightning hazard! It is also very prone to environmental degradation resulting from water damage. Remember electricity and water do not mix.
• Existing Infrastructure - Always inspect your existing infrastructure to make sure that those segments that are already in existence will be compatible with those which you plan to install. This is vital when it comes to such network infrastructure as switches and Network Interface Cards (NIC). You may well be installing higher performance transmission media but will not realise any benefit in data throughput if some elements of your network are incapable of the higher transfer rates.

For Example: installing new CAT 6 cable; which is capable of transmission rates of 1 Gigabit/sec, will have no measurable benefits if the older NICs of your PCs are rated at 10 Megabit/sec. The network will only operate at the speed at which the slowest member of the conversation can operate. So you may have to upgrade your NICs as well. Fortunately they are cheap.

• Regulatory Requirements - Most government and statutory authorities generally require that any cabling that is to be installed into walls or conduit or other fixed structures must be installed by certified and registered personal. So as always please check to confirm the specifics of your situation with your local authorities.
• Instructions - Always obtain and refer to the documentation that the manufacturer of your equipment will have supplied with the equipment or makes available on their website.
• Documentation - Always refer to any existing documentation as it should help you identify much information about the current state of your network. Update this documentation as your work progresses it will be an important resource when it comes time to do some network troubleshooting. If no documentation exists then you will have to create it. Make sure that you include both physical diagrams and logical diagrams of the network. This can be done fairly easily with the aid of software tools such as Microsoft™ Visio, LanFlow® or SmartDraw®.
• Planning and Preparation -Always plan your work in advance. In this way you can ensure that; when it is time to lay cable, you will have enough cable and accessories at hand to complete the job as one complete contiguous sequence of tasks. Going to the hardware or electronics store may be a nice distraction but it will not get the job done on time.
• Implementation Plan - Prepare an implementation plan prior to commencement of the job. This should detail the sequence in which you will be performing the various tasks required.
• Checklists - Prepare and use job-sheet checklists. This is the best way to make sure that you don't overlook any aspect of the installation. If it is good enough for astronauts to use checklists in everything they do we are advised to do likewise. It's all about being prepared.
• Occupational Health and Safety -Site preparation is an often overlooked element when it comes to the task of rolling-out network infrastructure such as cabling. You will need a work area that is well lit and free from clutter.

It is also advisable to make sure that your work area is of restricted access during the period in which the work is being conducted. Children are not welcome by-standers. You will be using tools for cutting cable. Remember sharp objects and implements always present the risk for personal and material injury that you or your organisation is legally responsible for.

Part Two of this guide will introduce you to some of the cable technologies that have been used in the past and some that are still in use today. We will then move on to discussing the most common cabling technologies in current use today.