Linux with Operating System Concepts

Risk assessment
is a necessary undertaking for any organization that has assets to protect. 
In risk assessment, the organization identifies its assets and the vulnerabilities of those 
assets. They also identify their organizational goals. From the vulnerabilities, a 
threat 
analysis
can be performed. Next, the threats are organized by seriousness based on their 
likelihood of occurring, the potential damage that the threat can cause, and the impact on 
the organization based on the prioritized goals. The organization can judge the risk that its 
assets are under from the identified threats and formulate strategies to reduce these risks.
One risk that any organization will face is that of a disaster, whether natural (flood, fire, 
and earthquake) or man made (explosion caused by armed conflict or terrorism, sabotage, 
and theft). Of course, not all threats are disasters but it is important to plan for disasters. 
Thus, we have 
disaster planning
. Disaster planning is the process of ensuring that the orga-
nization can still function amid disaster. Disaster recovery consists of the steps necessary 
to bring the organization back up to full (or even partial) strength after a disaster.
While disaster planning and recovery can encompass assets of the organization that 
include personnel, infrastructure, reputation, and so forth, here, we will solely concen-
trate on information technology (IT). We can divide the IT assets into roughly three 
components:
• Hardware
• Software
• Data
Although hardware and software are the assets that the company will purchase, it is 
data that are the most critical. The hardware and software are replaceable whereas the data 
may not be. So, the most important part of disaster planning is to ensure that the data are 
safeguarded.
In this chapter, we have already explored backups and RAID technologies. However, 
even painstaking backups can be defeated without some common sense applied to the pro-
cess. Let us consider. You as a system administrator backup all of /home and /var weekly 
and then perform incremental backups every night. You retain backups for weeks and you 
perform a full archive once every 6 months, retaining the archives for 10 years. Your sys-
tem uses RAID 1 technology so that information is fully duplicated in case of a problem 
before you have a chance for the increment evening backup. Yet, this plan, as cautious as it 
sounds, may not be enough.

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Maintaining and Troubleshooting Linux
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605
Your RAID file server is located on the ground floor of the building. You back all of the 
file system to magnetic tapes that you leave in your office behind a locked door and you 
place the archival backups in a safe, also in your office. Your office is also on the first floor 
of the building. The river next to your building crests at 10 feet above flood stage that enters 
your building, flooding 3 feet of the first floor. The RAID server is on the floor while the 
magnetic tapes and safe are also low to the ground. This disaster leaves you with no data 
except perhaps any data saved on local workstations in higher floors of the building. Oops! 
Now, imagine instead that your office is located on the fifth floor. This will most likely save 
you from flooding, but a fire could destroy the entire building.
A simple solution to this scenario is to make sure that your backups are never on the 
same site as your original data. Where might you keep the data? If your organization has 
offices in other locations, move the backup media there, whether by physically transport-
ing them or performing the backups over a network. If your organization does not include 
other locations, then take your backup media to a bank and lock it up for a week at a time 
(unless a disaster requires that you retrieve it).
Another strategy is to extend the idea behind RAID 1. Use two file servers, one being a 
mirror. Locate the second file server off-site. If you do not have a second site, rent file server 
space from some organization that offers storage area network support.
Making sure data are backed up and available after a disaster is only part of a solution. 
For most organizations, extended downtime can be extremely costly. If the company has a 
web portal and the webserver is brought down during a disaster, the company is unable to 
do any business in that time. If a company offers credit information on clients, it needs to 
be able to respond to telephone or electronic requests at any time. Downtime will impact 
this. Any form of downtime can not only damage the company’s ability to business but in 
the long run, its reputation.
One solution is to distribute the data and processing to multiple sites. It is unlikely that 
more than one site would be impacted by a disaster. Although this is an expensive solution, 
if the company is large enough, it would be located in several sites in any event. The cost 
then is one of ensuring that the data and processing centers can all function together or sep-
arately. One additional advantage to distributing the processing across centers is that load 
balancing can be implemented so that servers are kept equally busy with incoming requests.
Another threat to data is keeping them secure. If there is sensitive information being 
maintained such as the customer’s credit card numbers, it is essential that this information 
must not be accessible by any unauthorized personnel (whether within the organization 
or hacker). Authentication of course is the common solution to ensure that access is only 
granted to authorized users. Encryption is another common solution. Encryption tech-
nologies are readily available and can be applied to individual files, entire file systems, or 
messages broadcast over the network. Chapter 5 discussed openssl and briefly mentioned 
other encryption tools available in Linux.
Another concern in maintaining the security of data comes from authorized users of the 
data in the form of a