It might be a stretch to call the recent "Melissa" virus a positive event because it disrupted
thousands o government and commercial computer systems. But it did put the focus on content
filtering, a network security technology that observers say has been undervalued. In the long run,
many believe this new focus will prove beneficial to users.
As a macro virus attached to an e-mailed Microsoft Corp. Word document, Melissa would
not have been picked up by traditional security solutions such as firewalls or intrusion-detection
systems, which are designed to detect items that break certain global access rules. The only way
to detect a virus such as Melissa is to examine what is inside the e-mail, which can only be done
through content filtering, supporters of the technology said.
Filtering products have been around for years, but manufacturers have been struggling to
meet the needs of organizations that employ varying security policies among different users.
Recently, however, vendors have released filtering products that can be tailored to the needs of
user groups, and industry has begun working on standards that allow these products to work with
Content filtering encompasses several areas of protection. As well as guarding against
viruses, it includes:
E-mail filtering, which controls incoming e-mail that contains spam, file attachments that
are too large or hoax e-mails. It also can be used internally to make sure confidential information
is not accidentally or intentionally sent outside of the organization.
Uniform Resource Locator filtering, which blocks access to inappropriate sites not connected
to a user's work needs.
Malicious-code protection, which prevents hostile code embedded in Java and ActiveX
scripts in otherwise innocuous World Wide Web pages from reaching the user's browser and
The most obvious benefit of filtering products is the ability to boost network security, but
many organizations also use them for internal network control. For example, URL filters can be
used to block access to certain sites and to maintain productivity. Message Inspector, an e-mail
filter produced by Elron Software Inc. uses context-sensitive filtering to weed out offensive or
sensitive communications in e-mail, newsgroups or FTP sites. Message Inspector is an example
of the newer generation of filter products that examine messages for words and phrases used in
conjunction with each other to narrow the range of filter targets. This strategy differs from the
one employed by traditional products that block communications based on factors such as
keywordsa process that can generate a lot of "false positive" alarms.
Melissa presented a clear idea of why people need a gateway-based virus-detection product,
"Viruses need to be kept out of the enterprise altogether because you just can't update all
virus-detection software on desktops in time to catch them."
The International Computer Security Association is working on what it calls the Common
Content Inspection program to define a general application program interface (API) that would
enable filter vendors to fit their products to a range of firewalls.
1, disrupt [dis'rʌpt]
2, hoax [həuks]
Continue reading it-e-56 Content Filtering Sifts out Viruses
Backdoor programs are typically more dangerous than computer viruses, as they can be
used by an intruder to take control of a PC and potentially gain access to an entire network.
Backdoor programs, also referred to as Trojan horses, are typically sent as attachments to
e-mails with innocent-looking file names, tricking users into installing them. They often enable
remote users to listen in on conversations using the host computer's microphone, or even see
through its video camera if it has one. Back Orifice (BO) 2000 is a backdoor program designed
for malicious use. Its main purpose is to maintain unauthorized control over another machine for
reconfiguration and data collection. It takes the form of a client/server application that can
remotely control a machine without the user's knowledge to gather information, perform system
commands, reconfigure machines and redirect network traffic.
With BO an intruder has to know the user's IP address to connect, or could scan an entire
network looking for the victim. Once connected, the intruder can send requests to the BO 2000
server program, which performs the actions the intruder specifies on the victim's computer,
sending back the results.
BO is installed on the server machine simply through the execution of the server application.
This executable file is originally named bo2k.exe, but it can be renamed. The configuration wizard
will step through the various configuration settings, including the server file (the executable), the
network protocol, port number, encryption, and password. Once this process is complete, running
bo2kgui.exe executes the user interface for BO.
It is very difficult to detect BO, because it is so highly configurable. In addition, backdoor
programs are multi-dimensional, so several detection methods are recommended to achieve maximum
protection and awareness of the installation of BO 2000 on a machine or series of machines on a
We recommend coupling the use of an updated version of anti-virus software to detect
which machines on the network have BO installedand intrusion detection software to identify
attacks over the network.
Users are urged to follow three important precautions:
Do not accept files from Internet chat systems.
If you are connected to the Internet, do not enable network sharing without proper security
Do not open e-mail attachments: never run any executable files sent to you (.exe files or .zip
files with a.exe in them). It is safer if these are run through a virus checker first, but they could be
new backdoor programs or viruses that a virus scanner will not detect. It is safe to open Word
documents and Excel spreadsheets if the Microsoft Auto-Run feature is turned off. Allowing
macros to run automatically can spread e-mail viruses such as Melissa. Many people send each
other animations in e-mail: it is easy to put a backdoor program into one of these and users
cannot tell when they infect their computers with Back Orifice 2000.
1, potentially [pə'tenʃəli]
Continue reading it-e-55 Backdoor
Continue reading FTP连接后出现无法显示列表或列表错误问题的解决方法
Just as human viruses invade a living cell and then turn it into a factory for manufacturing
viruses, computer viruses are small program that replicate by attaching a copy of themselves to
another program. Once attached to the host program, the virus then lock for other programs to
"infect". In this way, the virus can spread quickly throughout a hard disk or an entire organization if
it infects a LAN (Local Area Network) or a multi-users system.
 Skillfully written virus can infect and multiply for weeks or months without being detected.
During that time, system backups duplicate the viruses, or copies of data or programs made and
passed to other systems to infect. At some pointdetermined by how the virus was programmed
the virus attacks. The timing of the attack can be linked to a number of situations, including: a
certain time or date; the presence of a particular user ID; the use or presence of a particular file; the
security privilege level of the user; and the number of times of a file is used.
Likewise, the mode of attack varies, so-called "being" viruses might simply display a
message, like the one that infected IBM's main computer system last Christmas with a season's
Malignant viruses, on the other hand, are designed to damage your system. One common
attack is to wipe out data, to delete files, or to perform a format of disk.
There are four main types of viruses: shell, intrusive, operating system, and source code.
Shell viruses wrap themselves around a host and do not modify the original program.
Shell program are easy to write, which is why about half of all viruses are of this type. In
addition, shell viruses are easy for programs like Data Physician to remove.
Intrusive viruses invade an existing program and actually insert a portion of themselves
into the host program. Intrusive viruses are hard to write and difficult to remove without
damaging the host file.
Shell and intrusive viruses most commonly attack executable program filethose with.
COM or. EXE extensionalthough data are also at some risk.
Operating system viruses work by replacing parts of operating system with their own
logic. Very difficult to write, these viruses have the ability, once booted up, to take
total control of your system. According to Digital Dispatch, known versions of operating
system viruses have hidden large amounts of attack logic in falsely marked bad disk
sectors. Others install RAM-resident programs or device drivers to perform infection or
attack functions invisibly from memory.
Source code viruses are intrusive programs that are inserted into a source program
as those written in Pascal prior to the program being compiled. These are the least
common viruses because they are not only hard to write, but also have a limited number
of hosts compared to the other types.
New computer viruses are written all the time, and it's important to understand how your
system can be exposed to them and what can do to protect your computer. Follow the suggestions
listed below to substantially decrease the danger of infecting your computer system with a
potentially dangerous computer virus.
Be very cautious about inserting disks from unknown sources into your computer.
Always scan the disk's files before operating any of them.
Only download Internet files from reputable sites.
Do not open e-mail attachments (especially executable files) from strangers.
Purchase, install, and use an anti-virus software program. The program you choose must
provide three functions:
As new viruses are created everyday, upgrade your anti-virus software regularly.
1, invade [in'veid]
2, replicate ['replikit, 'replikeit]
3, wipe [waip]
Continue reading it-e-54 Computer Viruses
不过目前最新safari只能在mac os系统下面才能提供webgl 见http://www.khronos.org/webgl/wiki_1_15/index.php/Getting_a_WebGL_Implementation#Safari。
OpenGL Shading Language Specification
OpenGL Shading Language Tutorials
OrangeBook's Web Site
Continue reading webGL入门
In the traditional, manual working environment, information (in the form of texts, numbers,
etc.) and medium (such as paper) were closely intertwined. Long experiences in their usage and
the application of anti-counterfeit technology have made traditional forms of information very
difficult to alter. Similarly, it was also difficult to send bogus information by an impersonator.
Even those who succeeded in doing so usually were discovered very easily. In today's world of
information and technology, the Internet is rapidly changing many ways people do things.
Similarly, it has also introduced many management problems. For man and information to
interact, there is a need to establish a reliable information system working environment in which
we grasp, distribute, store and manage information. Such an environment must be able to provide
ample protection against tampering, stealing, delaying, transmission by fictitious parties, denial
of having faxed a document, illegal intrusion and the like. Only so can we build a strong
foundation for an information society.
Security in the process of transmission, data resemble all the cash in a bank armored van. It
can be lost or robbed anytime. With the purpose of maintaining data transmission security on the
Internet, most people use encryption technology. Data to be transmitted is first encrypted as a
way to prevent snooping or theft. The "Public-Key Cryptographic System" has the functions of a
"digital signature" and requires no prior exchange of keys while offering the advantages of
"secret communication." To make this system work smoothly, it is first necessary to agree and
certify beforehand as to who or which institution holds a certain key. This goes to say that a
certification management system must first be established to handle issuance or revocation of
electronic certification. In addition to this system, all matters related to its usage and application
services must form part of the basic operations framework of the whole system.
The first important thing in maintaining data security is the periodic making of back-ups.
Personal computer users must periodically make back-ups of data using different back-up tools
(such as diskettes, magnetic tape, removable hard drives, etc.) and store them in a safe location. If
and when data from a personal computer is damaged and cannot be recovered, the back-up copies
will serve their purpose. Thus, the first step in data security is to develop the habit of making
periodic back-ups. It is the most effective way to assure data security under extreme circumstances.
There are many factors that pose a threat to data security. They include viruses, deliberate acts of
sabotage and theft. Users can guard against them using the following methods: Use a protection
password for access to personal computers and the Internet. This prevents the unauthorized from
stealing or damaging data inside personal computers. Handle files with encryption protection and
decipher only when necessary. In this way, even if files are stolen, encryption would still be
necessary to use the files. Files transmitted through the Internet must first be encrypted. The
Internet is an open environment where anybody can intercept data during transmission. Encryption
of such data is an effective way to prevent unwanted disclosure. Respect intellectual property rights
by refraining from using software programs of dubious sources. This way, viral attack can be
avoided or the use of Trojan Horse by the unscrupulous to steal data can be thwarted.
Passwords and names of users of databases and application programs must be kept
confidential. Avoid using birth dates, telephone numbers and other readily accessible figures as
passwords. They must be handled carefully and recorded in secret locations. Periodic changing of
passwords is also recommended. Print-outs of application software programs no longer used must
be shredded to prevent disclosure of data. Build up a no-diskette system environment to avoid
computer virus contamination.
To guarantee data security, the Information Department must, in addition to setting up
comprehensive regulations, ensure cooperation by users. Their usage of computer equipment
according to regulated procedures contributes to the effective maintenance of data security.
It is necessary to build up a data security audit system that includes periodic and random
spot checks and testing of information security and protection operations, as well as conduct
tracking and improvement of deficiencies.
1, intertwined [,intə:'waind]
2, bogus ['bəuɡəs]
3, impersonator [im'pə:səneitə(r)]
4, grasp [ɡrɑ:sp, ɡræsp]
5, tampering ['tæmpəriŋ]
6, fictitious [fik'tiʃəs]
7, van [væn]
9, revocation [,revə'keiʃən]
10, decipher [di'saifə]
12, thwart [θwɔ:t]
13, unscrupulous [ʌn'skru:pjuləs]
14, conduct ['kɔndʌkt, kən'dʌkt]
Continue reading it-e-53 The Development of Data Transmission
例如：使用脚本向一个iframe里面写日志doc.body.innerHTML += ‘<div>…</div>’;
Continue reading IE SaveAs命令问题
The information security system is an integral part of the national security system. The main
functions of the information security system are:
assessing the state of information security in the country, identifying and forecasting
internal and external threats to information security, drafting an information security
developing a comprehensive system of legal, administrative, economic, technical and
other measures and methods aimed at ensuring information security;
coordinating and monitoring the work of information security entities;
protecting information security entities against incomplete, inaccurate and distorted
information and against exposure to information damaging to their life and health;
protecting protected information;
counteracting technical intelligence services;
developing and perfecting an information infrastructure, an information technology
industry, systems, means and services;
organizing scientific research, developing and implementation of scientific,
scientific-technical programmes in the field of information security;
licensing the activities of corporations and individual entrepreneurs in the field of
certifying information systems and means, assessing and rating the compliance of
information facilities with information protection requirements;
state inspection in the field of information security;
creating conditions for preserving and developing intellectual potential in the
preventing, identifying and suppressing offences which are aimed at hurting the rights
and freedoms of corporations and individuals in the information sphere, prosecuting and
trying in court perpetrators of crimes in the information sphere;
carrying out international cooperation in the sphere of information security.
1, integral ['intigrəl]
n. [数学] 积分, 完整, 部分
2, assess [ə'ses]
3, doctrine ['dɔktrin]
4, distorted [dis'tɔ: tid]
a. 扭歪的, 受到曲解的
5, counteract [,kauntə'rækt]
6, sphere [sfiə]
7, perpetrator [,pə:pi'treitə]
Continue reading it-e-52 Information Security System
The issue of information security and data privacy is assuming tremendous importance among
global organizations, particularly in an environment marked by computer virus and terrorist attacks,
hackings and destruction of vital data owing to natural disasters.  When it comes to information
security, most companies fall somewhere between two extreme boundaries: complete access and
complete security. A completely secure computer is one that is not connected to any network and
physically unreachable by anyone. A computer like this is unusable and does not serve much of a
practical purpose. On the other hand, a computer with complete access is very easy to use, requiring
no passwords or authorization to provide any information.  Unfortunately, having a computer with
complete access is also not practical because it would expose every bit of information publicly,
from customer records to financial documents. Obviously, there is a middle ground this is the art
of information security.
The concept of information security is centered on the following components:
Integrity: gathering and maintaining accurate information and avoiding malicious modification
Availability: providing access to the information when and where desired
Confidentiality: avoiding disclosure to unauthorized or unwanted persons
For an information system to be secure, it must have a number of properties:
 service integrity. This is a property of an information system whereby its availability,
reliability, completeness and promptness are assured;
data integrity. This is a property whereby records are authentic, reliable, complete, unaltered
and useable, and the processes that operate on them are reliable, compliant with regulatory
requirements, comprehensive, systematic, and prevent unauthorized access, destruction, alteration
or removal of records. These requirements apply to machine-readable databases, files and archives,
and to manual records;
data secrecy . This is a property of an information system whereby information is available
only to those people authorized to receive it. Many sources discuss secrecy as though it was only
an issue during the transmission of data; but it is just as vital in the context of data storage and
authentication. Authentication is a property of an information system whereby assertions
are checked. Forms of assertion that are subjected to authentication include:
"data authentication", whereby captured data's authenticity, accuracy, timeliness,
completeness and other quality aspects are checked;
"identity authentication", whereby an entity's claim as to its identity is checked.
This applies to all of the following:
the identity of a person;
the identity of an organizational entity;
the identity of a software agent; and
the identity of a device.
"attribute authentication", whereby an entity's claim to have a particular attribute is
checked, typically by inspecting a "credential". Of especial relevance in advanced
electronic communications is claim of being an authorized agent, i.e. an assertion by a
person, a software agent or a device to represent an organization or a person.
Non-repudiation. This is a property of an information system whereby an entity is unable
to convincingly deny an action it has taken.
There is a strong tendency in the information systems security literature to focus on the
security of data communications. But security is important throughout the information life-cycle,
i.e. during the collection, storage, processing, use and disclosure phases, as well as transmission.
Each of the properties of a secure system identified above needs to be applied to all of the
information life-cycle phases.
1, tremendous [tri'mendəs]
2, malicious [mə'liʃəs]
3, disclosure [dis'kləuʒə]
4, promptness [prɔmptnis]
5, whereby [(h)wєə'bai]
7, literature ['litəritʃə]
Continue reading it-e-51 Concept of Information Security
What's actually involved in programming the actual process of writing programs? Here's a
quick overview of the process:
Write a program.
Compile the program.
Run the program.
Debug the program.
Repeat the whole process until the program is finished.
Let's discuss those steps one by one.
I have a small amount of bad news for you: you can't write programs in English. It would be
nice indeed to be able to type "count the number of words in a sentence" into your computer and
have it actually understand, but that's not going to happen for a while (unless someone writes a
program to make a computer do that, of course). Instead, you have to learn a programming
Much of a programming language is indeed in English. Programming languages commonly
use words like "if", "repeat", "end" and such. Also, they use the familiar mathematical operators
like "+" and "=". It's just a matter of learning the "grammar" of the language; how to say things
So, we said "Write a program". This means: write the steps needed to perform the task,
using the programming language you know. You'll do the typing in a programming environment
(an application program which lets you write programs, which is an interesting thought in itself).
A common programming environment is CodeWarrior, and another common one is InterDev, but
you don't need to worry about those just yet. Some programming environments are free, and
some you have to buy just like any other application program. Commercial (non-free)
programming environments cost anything from $50 to $500+, and you'll almost always get a
huge discount if you're a student or teacher of some kind.
Incidentally, the stuff you type to create a program is usually called source code, or just code.
Programmers also sometimes call programming coding. We think it sounds slightly cooler.
In order to use a program, you usually have to compile it first. When you write a program
(in a programming language, using a programming environment, as we mentioned a moment
ago), it's not yet in a form that the computer can use. This isn't hard to understand, given that
computers actually only understand lots of 1s and 0s in long streams. You can't very well write
programs using only vast amounts of 1s and 0s, so you write it in a more easily-understood form
(a programming language), then you convert it to a form that the computer can actually use. This
conversion process is called compiling, or compilation. Not surprisingly, a program called a
compiler does the compiling.
It's worth mentioning that if your program has problems which the compiler can't deal with,
it won't be able to compile your program.
You'll be pleased to hear that your programming environment will include a suitable compiler
(or maybe more than one compiler: each different programming language your programming
environment allows you to use requires its own compiler). Compilers are just fancy programs, so
they too are written by programmers. Programmers who write compilers are a bit like gods; they
make it possible for everyone else to program.
Now that you've compiled the program into a form that the computer can use, you want to
see if it works: you want to make the computer perform the steps that you specified. This is
called running the program, or sometimes executing it. Just the same as how a car isn't of much
use if you don't drive it, a program isn't of much use if you don't run it. Your programming
environment will allow you to run your program too.
You've probably heard the term "debug" before (it's pronounced just as you might expect:
"dee-bug"). It refers to fixing errors and problems with your program. As I'm sure you know, the
term came about because the earliest computers were huge building-sized contraptions, and
actual real-life insects sometimes flew into the machinery and caused havoc with the circuits and
valves. Hence, those first computer engineers had to physically "debug" the computers they had
to scrape the toasted remains of various kinds of flying insects out of the inner workings of their
machines. The term became used to describe any kind of problem-solving process in relation to
computers, and we use it today to refer purely to fixing errors in our code.
You may also have heard the phrase "it's not a bug, it's a feature". Programmers sometimes
say this when someone points out a problem with their programs; they're saying that it's not a bug,
but rather a deliberate design choice (which is almost always a lie). This is rather like
accidentally spilling coffee all over yourself whilst simultaneously falling down some stairs, then
getting up and saying "I meant to do that".
Once again, your programming environment will help you to debug your programs (indeed,
you'll often find the picture of an insect shown in your programming environment to indicate
debugging). You usually debug your program by stepping through it. This means just what it
sounds like: you go through your program one step at a time, watching how things are going and
what's happening. Sooner or later (usually later), you'll see what's going wrong, and slap yourself
upside the head at the ridiculously obvious error you've made.
And then you repeat the whole process until you're happy with the program. This is trickier
than it might sound, since programmers are never happy with their programs. You see,
programmers are perfectionists never satisfied until absolutely everything is complete and
elegant and powerful and just gorgeous. Programmers will commonly release a new version of
their program every day for a couple of weeks after the initial release.
As you can imagine, enjoying an intellectual challenge is an important trait to have when
you're going back to correct and enhance your code many times over. You'll actually find that you
can't wait to get back into your program and fix the bugs, make improvements, and refine the
And that's the basic process of programming. Note that most programming environments
will make a lot of it much easier for you, by doing such things as:
Warning you about common errors
Taking you to the specific bit of code which is causing the compiler to puke
Letting you quickly look up documentation on the programming language you're using
Letting you just choose to run the program, and compiling it automatically first
Colouring parts of your code to make it easier to read (for example, making numbers a
different colour from other text)
And many other things
So, don't worry too much about the specifics of compiling then running then debugging or
whatever. The purpose of this section was mostly to make you aware of the cyclical nature of
programming: you write code, test it, fix it, write more, test it, fix, and so on.
1, fancy ['fænsi]
2, contraption [kən'træpʃən]
3, havoc ['hævək]
7, scrape [skreip]
9, spilling ['spiliŋ]
10, whilst [wailst]
11, slap [slæp]
13, gorgeous ['gɔ:dʒəs]
14, trait [treit]
Continue reading it-e-50 What's actually involved in programming