Home > Articles > Security > Network Security

  • Print
  • + Share This
This chapter is from the book

The 'ilities

Is security a feature that can be added on to an existing system? Is it a static property of software that remains the same no matter what environment the code is placed in? The answer to these questions is an emphatic no.

Bolting security onto an existing system is simply a bad idea. Security is not a feature you can add to a system at any time. Security is like safety, dependability, reliability, or any other software 'ility. Each 'ility is a systemwide emergent property that requires advance planning and careful design. Security is a behavioral property of a complete system in a particular environment.

It is always better to design for security from scratch than to try to add security to an existing design. Reuse is an admirable goal, but the environment in which a system will be used is so integral to security that any change of environment is likely to cause all sorts of trouble—so much trouble that well-tested and well-understood software can simply fall to pieces.

We have come across many real-world systems (designed for use over protected, proprietary networks) that were being reworked for use over the Internet. In every one of these cases, Internet-specific risks caused the systems to lose all their security properties. Some people refer to this problem as an environment problem: when a system that is secure enough in one environment is completely insecure when placed in another. As the world becomes more interconnected via the Internet, the environment most machines find themselves in is at times less than friendly.

What Is Security?

So far, we have dodged the question we often hear asked: What is security? Security means different things to different people. It may even mean different things to the same person, depending on the context. For us, security boils down to enforcing a policy that describes rules for accessing resources. If we don't want unauthorized users logging in to our system, and they do, then we have a security violation on our hands. Similarly, if someone performs a denial-of-service attack against us, then they're probably violating our policy on acceptable availability of our server or product. In many cases, we don't really require an explicit security policy because our implicit policy is fairly obvious and widely shared.

Without a well-defined policy, however, arguing whether some event is really a security breach can become difficult. Is a port scan considered a security breach? Do you need to take steps to counter such "attacks?" There's no universal answer to this question. Despite the wide evidence of such gray areas, most people tend to have an implicit policy that gets them pretty far. Instead of disagreeing on whether a particular action someone takes is a security problem, we worry about things like whether the consequences are significant or whether there is anything we can do about the potential problem at all.

Isn't That Just Reliability?

Comparing reliability with security is a natural thing to do. At the very least, reliability and security have a lot in common. Reliability is roughly a measurement of how robust your software is with respect to some definition of a bug. The definition of a bug is analogous to a security policy. Security can be seen as a measurement of how robust your software is with respect to a particular security policy. Some people argue that security is a subset of reliability, and some argue the reverse. We're of the opinion that security is a subset of reliability. If you manage to violate a security policy, then there's a bug. The security policy always seems to be part of the particular definition of "robust" that is applied to a particular product.

Reliability problems aren't always security problems, although we should note that reliability problems are security problems a lot more often than one may think. For example, sometimes bugs that can crash a program provide a potential attacker with unauthorized access to a resource. However, reliability problems can usually be considered denial-of-service problems. If an attacker knows a good, remotely exploitable "crasher" in the Web server you're using, this can be leveraged into a denial-of-service attack by tickling the problem as often as possible.

If you apply solid software reliability techniques to your software, you will probably improve its security, especially against some kinds of an attack. Therefore, we recommend that anyone wishing to improve the security of their products work on improving the overall robustness of their products as well. We won't cover that kind of material in any depth in this book. There are several good books on software reliability and testing, including the two classics Software Testing Techniques by Boris Beizer [Beizer, 1990] and Testing Computer Software by Cem Kaner et al. [Kaner, 1999]. We also recommend picking up a good text on software engineering, such as The Engineering of Software [Hamlet, 2001].

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020