Computer Network is a collection of computers, printers, and other equipment are connected in one unit and form a certain system. Information travels through a wired or wireless computer network that allows users to exchange information (data), print on the same printer and can simultaneously use the same application program.
LAN (Local Area Network) is a privately owned network within a single organisasitertentu, building or campus-sized to several kilometers. LANs are often used for connecting personal computers and workstations in the office or a company for sharing and exchanging information.
With a system of this LAN so multiple PCs that had been working on their own, can eventually work together within certain limits, even with a larger computer system. Cooperation can be done also growing from just a mutual exchange of data to use the equipment connected to one computer system.
LAN become so popular is because in general can be used as office automation paralatan. In Figure 1 appears a LAN network that consists of several PCs that are placed at various places. PC is known as a workstation. Each workstation can be used as a stand-allone (stand-alone computer), but also can be used to access storage or output devices, which in this case referred to as peripherals, which are located far from each other but still within a single network.
LAN network will typically consist of: File servers, serves to control the hard drive and plugging into the network. Utility server, with the existence of this equipment allows for each user on the network could use some equipment, such as modems, and other ploter. Printer servers, serves to divide the lawyer-access of the printer into the network so that it can be used for all users. Gateway, is a useful equipment in the network to communicate with other networks.
Figure 1. LAN Network Model
As the name implies, the LAN can only reach the area is restricted area (local), such as for example in one building, one department or one campus (currently limited understanding means no more than 20 km). And because of its short distance, then the data transmission speed becomes very high.
Demands kebututuhan activity in data communications using a LAN today, required a network that has high performance, high-speed access, wide range, and high reliability.
At this time has been developed efforts to improve the performance of LAN becomes higher. The things that have been developed for high performance LAN is as follows:

FDDI is the Fiber Distributid Data Interface (FDDI), which is a speed networking technology, 100-Mbps jakauannya distance can reach 200 km, using models of token ring.
Is CDDI Copper Data Distributid Iterface FDDI protocol which is the development of more than two pairs of wires.
3. Fast Ethernet
Fast Ethernet is a LAN device to support a capacity of 10 Mbps requires a lot of supporting devices such as repeaters, bridges, routers to obtain a higher transfer rate.
4. Gigabit Ethernet
Gigabit Ethernet is an extension of IEEE 802.3 Ethernet standard. Based on Ethernet protocol to increase speed access to ten times as much achieve the 1000 Mbps or 1 Gbps.
100VG-ANYLAN is an IEEE specification for 100-Mbps Token Ring and Ethernet to the implementation of more than 4-pair UTP cable. MAC layer is not compatible with the IEEE 802.3 MAC Layer.
HPPI (High Performance Parallel Interface) was originally designed as a data channel point to point with a master - slave who uses a dedicated cable without switching. Capacity provided 800 Mbps and 1600 Mbps. In the capacity of 800 Mbps twisted pair cables used 50 to channel 50 bits (32 bit data 18 bit control). Every 40 nanoseconds a word was transferred to a simplex channel with a length of no more than 25 m.
7. Fibre CHANEL
It is a system using a fiber optic network capable of providing very large capacity because it has a very wide bandwidth that can be used for data communication with very high speed.
Given the number of models in high-performance LAN authors in the writing of this paper limit the issues discussed only FDDI, which includes:
1. Understanding FDDI
2. FDDI Transmission Media
3. FDDI Specifications
4. Type FDDI
5. Failure Tolerance FDDI
6. Advantages FDDI


1. Understanding Fiber Distributed Data Interface (FDDI)
Fiber Distributed Data Interface (FDDI) is a speed networking technologies by applying a 100-Mbps token-passing method. FDDI Token Ring technology is different from the old, by applying the dual-ring that uses glass fiber cable.
FDDI mostly used as high-speed backbone technology because of its support for the provision of greater bandwidth than ordinary copper wires.
FDDI uses dual-ring architecture with traffic on each of rings in opposite directions (called counter-rotating). Dual-ring architecture consisting of primary and secondary ring. With this architecture, when there is failure of the primary ring FDDI network can still function by automatically using the secondary ring. Primary ring is the default ring that will be used for data transmission and secondary ring will always be idle, unless needed.
The basic form arstektur FDDI ring:
Figure 2. The basic form of architecture FDDI
FDDI Standards developed by the American National Standards Institute (ANSI) X3T9.5 in the mid-1980s, and adopted by the International Organization for Standardization (ISO).

2. FDDI Transmission Media
FDDI uses fiber glass as the main transmission media, but also can use a copper wire transmission media using specifications Copper Distributed Data Interface (CDDI).
FDDI defines two types of fiber cable that can be used, namely Single-Cable-mode single-mode fiber allows only one mode for delivery of light through the fiber. (A mode is a light entering the fiber at a particular point of reflection.), And Multimode - Multimode fiber allows multiple modes of light through fiber cables dirambatkan. The figure below shows the single-mode fiber using a laser light source and multimode fiber using LED cahya sources:
Figure 3. Fiber cable to single mode and multimode
Comparison between Single Mode and Multimode Fiber: Fiber Single-mode ribbon Lepar provide transmission capacity that is larger and long-range fiber cable further than multimode fiber. This is caused by the presence of multiple modes of light propagation in fiber cable that can deliver at different distances. (Depending on the angles in reflection). Given these conditions cause any light coming in the destination at different times. (This is called the dispersion of capital.) Cable single-mode fiber is often used to connect between buildings, while kbel multimode fiber is often used to connect the room or floor in one building. Multimode fiber cable using Light-Emitting Diodes (LEDs) as a tool to produce light, whereas single-mode generally uses a laser beam.

3. FDDI Specifications
FDDI standard specification defined in 4 specifications, namely:
a. Media Access Control (MAC) - MAC specification defines how a transmission medium is accessible, including the definition of the frame format, token handling, addressing, algorithms calculate cyclic redundancy check (CRC), and error recovery mechanisms.
b. Physical Layer Protocol (PHY) - the specification defines the procedures PHY encoding / decoding data, the need for clock, framing and other functions.
c. Physical Medium Dependent (PMD) - tarnsmisi PMD defines the characteristics of media, including glass fiber connections, power level, bit error rates, optical components, and connectors are required.
d. Station Management (SMT) - SMT specification defines FDDI station configuration, ring configurations, and control of the ring, including the addition and reduction of new stations, initialization, kegagaan protection and recovery, scheduling, and collection of statistical data on the FDDI network.
The figure below shows the specification 4 FDDI, and relationships with each other and their relationship with the sublayer is Logical Link Control (LLC):
Figure 4. FDDI Specifications
There are specification and FDDI OSI model, namely the physical specifications and the media-access model of Open Systems Interconnection (OSI) and similar to the IEEE 802.3 Ethernet and IEEE 802.5 Token Ring in relation to the OSI model.
The following figure shows the specification of FDDI and its relationship with the OSI model:
Figure 5. Specification FDDI OSI model

4. Equipment Type FDDI
There are three types of tools / equipment FDDI, namely:
a. Single-Attachment Station (SAS),
Single-Attachment Station (SAS) is a SAS paired only to a FDDI ring through a concentrator, which can be described as follows.
Figure 6. Type SAS FDDI
b. Dual-Attachment Station (DAS)
Dual-Attachment Station (DAS) - Each FDDI DAS has two ports, determined by A and B. The ports that connect the DAS to the dual FDDI ring. Therefore, each port provides a connection to the second ring, both primary and secondary. Watershed can be described as follows.
Figure 7. Type DAS FDDI
c. Concentrator (Dual-Attachment Concentrator [DAC])
FDDI concentrator (also called a dual-attachment concentrator
[DAC]) is a "building" is important from an FDDI network. Concentrator directly attached bath with primary and secondary ring, and convinced that the failure or power failure at any SAS does not make the ring die. This will be very useful when the equipment is installed equipment that is often turned off or turned on, for example, is a PC. The following figure shows the installation of SAS, DAS, and concentrator on the FDDI ring:
Figure 8. FDDI Concentrator Type
5. Failure Tolerance FDDI
FDDI provides several mechanisms to support fault tolerance of FDDI networks, namely:
a. Dual Ring
Dual Ring is the main configuration for fault tolerance for all FDDI network. Dual ring is the main ability of FDDI to handle a failure on its network. If a station on the dual ring fails or dead, or damaged cable, dual-ring configuration is automatically "wrapped" (back to itself) into one ring. When the ring in "wrapped", dual-ring topology becomes a single-ring topology.
Figure 9. Dual Ring

- Ring Station Recovery after a Failure
When a station fails, devices located on both sides will be in "wrap" form a single ring. Network operations will resume back to the station which is still connected to the ring.

- Recovery after a Ring Cable Failure
When a cable failure, the equipment was in second ujungya will do the "wrap". And then the network operational.

- "Recovery" after Multiple faults
When two or more failures occur, FDDI ring is divided into two or more independent rings which of course does not allow a single ring with other rings are interconnected with each other.

- Optical Bypass Switch
An optical bypass switch provides dual-ring operating in a sustainable manner if a device on a dual ring die or fail.

c. Dual Homing
Dual homing provides a redundant configuration for the device is critical to the FDDI network. Essential equipment such as routers or mainframe can use the technique that provides two-homing tambaan similar equipment to support critical operations. In dual-homing situations, critical equipment is connected to two concentrator. One pair of the connection concentrator is expressed as an active connection, and others expressed as a passive partner.
Figure 10. Model Dual-Homing
Passive connections will continue to exist on the backup status of the connection, until the primary sambunan otherwise fail. When this occurs, the passive connection is automatically activated.
The frame format of FDDI can diambarkan like the image below:

Figure 10. FDDI Frame Format

- Preamble - A unique sequence EACH That station prepares for an upcoming frame.
- Start Delimiter - Indicates the beginning of a frame by employing a signaling pattern That
- Differentiates it from the rest of the frame.
- Frame Control - Indicates the size of the address fields, whether the frame contains
- Asynchronous or synchronous data, and other control information.


Proxy server (proxy server) is a computer server or a computer program that can act as another computer to make requests for content from the Internet or an intranet.
Proxy Server acts as a gateway to the world of the Internet to every client computer. Proxy server is invisible to the client computer: a user who interacts with the Internet via a proxy server will not know that a proxy server is handling requests are done. Web server that receives requests from the proxy server will interpret the request-the request as if the request came directly from the client computer, instead of the proxy server.
Proxy servers can also be used to secure private network that is connected to a public network (like internet). Proxy servers have more functionality than a router that features packet filtering because it is a proxy server to operate at a higher level and have a more comprehensive control of network access. Proxy server that functions as a "security agent" for a private network, commonly known as a firewall.

Web server is a server software that functions accept HTTP or HTTPS requests from clients, known as a web browser and sends the results back in the form of web pages are typically in the form of an HTML document. Popular web servers such as Apache and Microsoft Internet Information Services (IIS). Apache is a cross-platform web server, while IIS can only operate in Windows operating systems.

FTP (short for File Transfer Protocol) is an Internet protocol that is running in application layer which is a standard for transferring files (files) the computer between the machines in an internetwork.
FTP is one of the earliest Internet protocol was developed, and is still used today to perform the download (download) and penggugahan (upload) files between your computer and FTP server FTP client. An FTP Client is an application that can issue commands FTP to an FTP server, while the FTP server is a Windows service or daemon that runs on a computer that responds to commands from an FTP client. FTP Commands can be used to change directories, change the transfer mode between binary and ASCII, evocative computer file to the FTP server and download files from FTP servers.
DNS (Domain Name System, the Indonesian language: Domain Name System) is a system that stores information about host name or domain name in the form of scattered databases (Distributed databases) in a computer network, such as the Internet. DNS provides the IP address for each host name and record each letter transmitting server (the mail exchange server) receive electronic mail (email) for each domain.
DNS provides an important service to the Internet, where computer and network hardware work with IP addresses to perform tasks such as addressing and routing (routing), humans in general prefer to use the host name and domain name, for example, is the appointment of a universal source (URL ) and e-mail address. Control link to this need.

A Need for New Number

A problem always arises

Same operation as adding natural numbers; and if we call the elements in our model ‘fractional numbers’, we must be equally clear that these may or may not have the same properties as natural numbers. We use the same words as for natural numbers because we are hoping to generalize the corresponding ideas, in the manner described in Chapter 4, page 61.
In particular, we would like a notation for fractional numbers which (i) is based on same numerals as are used for natural numbers; (ii) allows us to use the same method for adding as those which we have learnt for natural numbers; either as they stand, or extending them by learning a few extra procedures, as we did when we developed our short-multiplication schema into long multiplication.

The model we are going to develop will be the same, except for the nature of the units, for all the physical qualities for which we are using it. So when we refer to ‘cutting up’, we are using it in the generalized sense of any way of breaking up into parts. (we want to keep ‘division’ for the mathematical operation: compare ‘uniting’ sets and ‘adding’ numbers.)
This represents any standard object,

And this represents it cup up into five.

Clearly this way of cutting up is of no use for measurement, however, since we do not know how big* the bits are; and whether or not we get a match with our given object will depend on which bit we choose.
If we cut up our standard object into bits which match each other, according to whatever quality we are trying to measure, this gets over the second problem, of which one we choose. How big the bits are will then depend on how many of them there are. A cutting-up of this kind we will call sharing; bits which are equivalent (i.e. which match in the way described) we will call parts; and we will describe that size of the parts by saying into how many of these parts we have shared our standard object. So this represents a standard object** shared into fifth parts.

This, eighth parts.

This, third parts.

This represents the result of sharing into eighth parts, and then combining*** three of these parts.

We call this fractional parts of an object, or for short ‘three eighths’ of it. A fractional parts is thus a part which is obtained by a double action of sharing and combining. Abstracting what is common to all these double actions, we get in realm 3 a mathematical double operation which is called a fraction.

The mathematical notation for this double operation is (read this as ‘three over eight’). Since the numeral below the line tells us the name of the parts represented, - whether they are fifth…………..
* In the generalized sense; i.e. how heavy, how long, how great an e.m.f.,etc
** Thought it has been emphasized that this is a generalized object on which generalized action of sharing and combining are to be done, it is nevertheless a help to one’s thinking to imagine it as something more concrete; such as a cake which we are literally cutting up into fair shares – i.e. equal volumes of cake.
*** In whatever way is appropriate to the physical quality concerned. If weight, by putting in same scale pan. If volume of cake, the same person eats it.

Part, eighth part, thirrd part, etc,- this is called the denominator of the fraction. The numeral above the line tells us how many such parts are combined, and is called the numerator.
The nation might appear to suggest, both from our habit of reading downwards and from its often being written as for convenience in printing or typing, that the combining is done first, whereas in the foregoing description we first share into 8 part and then combine 3 of these. Hewever, we shell see that this actions are commutative- we get the same result whichever we do first. So the notation may be taken as representing simultancously booth of the two possibel orders of the mathematical double operation.
Start with a standart object.

Share into 8 parts.

Coimbine 3 of these eighy parts: result. Three eighth-parts of an object.

Now the other way about. Start with a standard object.

Combine 3 of these standard object.

Share this into 8 parts: result, one eight part of three objects.

Except for their arragement(which does not affect the quantity), the shaded part is the same as before. So the fraction represents(÷, 8 x 3), as embodied in the first set of diagrams above, and (×, 3 : 8), as embodied in the second set of diagrams. This is one reason for reading as ‘three over eight’, rathere than ‘three eighths’, which implies only the first of these alternative orders.

Equivalent fractions
We shall now reverse the process. By using embodiments of these doble operations which we call fractions and equivalence relation between fractions.

Fraction Embediment

And so on; the pattern is clear.
Though the fraction themselves are different, they correspond to same amount of whatever physical quality we are concorned with. If we applied the corresponding actions of sharing and combining to a standard object, the resulting part-objects would match. Whit units attached, the fraction represent equal measures. (Equal amounts of cake, in the concret example). In this respect they are therefore equifalent; and we may collect them together into the equivalent class { .
In the same way we can find other sets of equivalent fractions. For example:

Set of equivalent fractions: { .
Another example, this time without diagrams: {
Not only is the pattern of each equiovalence class clear, but a general method of forming them is beginning to energe.

Start with any fraction,
Double both upper and lower numbers
Treble both upper and lower numbers,

Equivalence class

And, in general, if a, b, kare natural numbers, then the fraction (is equivalent to) .

This works both ways; since also , we can get another fraction equivalent to any given fraction by either multiplying or dividing the numerator by the same natural number. The former we can always do; the latter, which is the well-known ‘cancelling’ rule, sometimes.
Example: .
We also have: .
So these also belong to the last named equivalence class, which we can now write:
{ .

Fractional numbers

The caracteristic property of any set ot equifalent fraction we call a fractional number. Whit a unit attached, each fraction in an equivalence class represent the same measure; and, without the unit, it represent the same number. This means that we can use any fraction from the set as a name for the number of that set; and, although this invites confosion if we do not know what is going on, if we do know, it has considerable advantages for purposes of calculation.
So if we are talking about fractions, which are double operations,

If we are talking about fractional numbers,

For each denotes the same equivalence class. The sign in the middle therefore indicates which of the two is meant.

Adding fractional numbers. We want this matematical operation to correspond to combining part-objects. This is straightforward if the numbers are represented by fractions having the same denominator, for we are then combining part-objects of the same kind; an essential already note on page 187. but we have to remember that adding does not mean quite the same for fractional numbers as for natural numbers. To remind ourselves of this we use for the new kind of addition, and + for the old kind.

If the denominators are not equal, this is where the interchange-ability principle within equivalences sets (page 176) comes to our help. Since all the fractions in a equivalence set stand for the same number, we can choose whichever ones suit us best for some other purpose, in this case a calculation.
Suppose that we want to add (say)
Replace by these equivalent fractions
Which stand for the same numbers
As before. For denominator, we choose
4 9=36.
Now we can add.
It should, of course, make no difference which fractions we us as replacements, provided that they stand for the original numbers and have the same denominators. Let us try the calculation by a different route.
First we will replace
The original fraction by =
Equivalent ones using =
The canceling rule.
Now we can find a =
Smaller common =
Denominator, namely =
2 3=6. =
This answer looks different, but of course represents the same fractional number as , since = = . So we have verified that the interchangeability principle works in this case. A general proof is not difficult, but requires the use algebra. Multiplying fractional numbers. As yet we have no meaning for ‘multiplying’ in the new context of fractional numbers. We could of course decide to do without a meaning – there are plenty of mathematical system which have only one operation. But we shall then not have generalized the natural number system completely, so we ought to try. We can either look for a meaning for ‘multiplication’ which is satisfactory in the realm of pure mathematics, and then see whether it provides a useful working model for realm 1; or we can use the requirement of a satisfactory working models to suggest a meaning, and then check whether it is mathematically acceptable. Both approaches have their merits. The latter, being less abstract, is the one we shall use here.
Start as usual with a standard object.

Then this object represents the fraction

In natural numbers, 3 4 when embodied in physical objects means : start with a 3 set

And combine 4 of these.

So in fractional numbers, might reasonably mean : start with two third-parts of an object,

And take four fifth-parts of this.

In natural numbers ‘calculate 3 4’ means ‘find the number of the resulting set’. In fractional numbers, ’calculate ’ might therefore reasonably mean ‘find what fractional part of the object the resulting part-object is’. The resulting part-object is shown by the cross-hatched area. The original object has now been shared into 15 parts (3 5), and the cross-hatched area combines 8 (2 4) of these.

This suggests that

Would be a reasonable way to multiply these fractions ; reasonable, in the sense that it gives a good working model for part-objects. It also satisfies requirements (i) and (ii) on page 186 very well.
These two methods, for addition and multiplication of fractional numbers, are of course those which have been agreed by mathematicians – we have been pretending we did not know in order to try to see how they were arrived at. Stated generally, if a, b, c, d are natural numbers, then the method for adding is:

And the method for multiplying is

Where and refer to operations on fractional numbers, and + and to those on natural numbers.
There is still much unsaid about fractional numbers. Techniques for manipulating them have not been systematized, and decimal notation – which can greatly simplify some of these manipulations – has not been introduced. Neither of these will be done here, since the present aim is comprehension rather than skill at computation. Also, we have not checked that the fractional numbers have the five properties of a number system which we found in Chapter 9 to be so important. This we must certainly do. Since the treatment is algebraic, is has been put into an appendix to this chapter. The reader who does not think easily in algebraic terms may take it on trust, since he already has the ideas, and only requires to be assured that they also hold good for fractional numbers. There is also a third matter of importance, which is whether and to what extent natural and fractional numbers can be intermixed. This last point will be discussed in Chapter 12, with the help of the ideas of isomorphism and mathematical generalization.

Fractional numbers have the five properties of a number system
Let a, b, c, d, e, f, x, y ,stand for any natural numbers.
Than , etc. will represent fractional numbers.
We can only add if the denominators are equal.

This property follows immediately from the corresponding property for natural numbers, and the same is true for all the other properties.





Any equation of type ax2 + bx + c = 0 where a, b, and c are constants and a <> 0, is in standard form for a quadratic equation.
Quadratic equations of type ax2 + bx + c = 0 and ax2 + bx = 0 (c is 0) can be factored to solve for x. Examples:
1. Problem: Solve 3x2 + x - 2 = 0 for x.
Solution: Factor.
(3x - 2)(x + 1) = 0
Use the principle of zero products,
which says, if ab = 0, either
a, b, or both must be
equal to zero.
3x - 2 = 0, x + 1 = 0
3x = 2 , x = -1
x = (2/3)
x = -1, (2/3)

2. Problem: Solve 3x2 + 5x = 0 for x.
Solution: Factor.
x(3x + 5) = 0
Use the principle of zero products.
x = 0, 3x + 5 = 0
3x = -5
x = -(5/3)
x = 0, -(5/3)
Quadratic equations of type ax2 + c = 0 can be solved by solving for x. Example:

3. Problem: Solve 3x2 = 6 for x.
Solution: Recognize that the equation is quadratic because it is the same as 3x2 - 6 = 0.
Divide each side by 3.
x2 = 2
Take the square root of each side.
x = SQRT(2), -(SQRT(2))
Many times you will come across quadratic equations that are not easy to factor or solve. In those cases, there is a special formula called the quadratic formula that you can use to solve any quadratic equation.
The solutions of any quadratic equation, ax2 + bx + c = 0 is given by the following formula, called the quadratic formula:

-b ± SQRT(b2 - 4ac)
x = -------------------

1. Problem: Solve 3x2 + 5x = -1 for x.

Solution: First find the standard form of
the equation and determine a, b,
and c.

3x2 + 5x + 1 = 0
a = 3
-5 ± SQRT(52 - 4(3)(1))
x = -----------------------
2 * 3

b = 5
c = 1

Plug the values you found for a, b, and c into the quadratic formula. Perform any indicated operations.

-5 ± SQRT(25 - 12)
x = ------------------

-5 ± SQRT(13)
x = -------------
The solutions are as follows:

-5 + SQRT(13) -5 - SQRT(13)
x = -------------, -------------
6 6
Some equations are not quadratic equations, but are in the same form, such as x4 - 9x2 + 8 = 0. To solve equations such as that, you make a substitution, solve for the new variable, and then solve for the original variable. Example:

1. Problem: Solve x4 - 9x2 + 8 = 0 for x.

Solution: Let u = x2. Then substitute u for every x2 in the equation.
u2 - 9u + 8 =0
(u - 8)(u - 1) = 0
Utilize the principle of zero products.
u - 8 = 0, u - 1 = 0
u = 8 , u = 1
Now substitute x2 for u and solve the equations.

x2 = 8, x2 = 1
x = ±SQRT(8), x = ± 1
x = ±2(SQRT(2))

x = ±2(SQRT(2)), ±1

Another way to solve systems of equations is by substitution. In this method, you solve on equation for one variable, then you substitute that solution in the other equation, and solve. Example:
1. Problem: Solve the following system:
x + y = 11
3x - y = 5

Solution: Solve the first equation for y (you could solve for x - it doesn't matter).
y = 11 - x
Now, substitute 11 - x for y in the second equation. This gives the equation one variable, which earlier algebra work has taught you how to do.

3x - (11 - x) = 5
3x - 11 + x = 5
4x = 16
x = 4
Now, substitute 4 for x in either equation and solve for y. (We use the first equation below.)

4 + y = 11
y = 7

The solution is the ordered pair,
(4, 7).
The last method, addition, is probably the most complicated, but is necessary when dealing with more complex systems, such as systems with three or more variables. The idea behind the addition method is to replace an equation with a combination of the equations in the system. To obtain such a combination, you multiply each equation by a constant and add. You choose the constants so that the resulting coefficient of one of the variables will be 0. Example:

2. Problem: Solve the following system:
5x + 3y = 7
3x - 5y = -23
Solution: Multiply the second equation by 5 to make the x-coefficient a multiple of 5. (This works because it does not change the equation (see the multiplication property).)

15x - 25y = -115

Next, multiply the first equation by -3 and add it to the second equation. This gets rid of the x-term.

-15x - 9y = -21
15x - 25y = -115
- 34y = -136

Now, solve the second equation for y. Then substitute the result into the first equation and solve for x.

-34y = -136
y = 4

5x + 3(4) = 7
5x + 12 = 7
5x = -5
x = -1
The solution is the ordered pair, (-1, 4).

Since you would need a three-dimensional coordinate system to solve systems in three variables, solving graphically is not an option. Substitution would work, but is usually unmanageable. Therefore, we will use the addition method, which is basically the same process as it is with systems in two variables.
1. Problem: Solve the following system:
x + y + z = 4
x - 2y - z = 1
2x - y - 2z = -1

Solution: Start out by multiplying the first equation by -1 and add it to the second equation to eliminate x from the second equation.

-x - y - z = -4
x - 2y - z = 1
-3y - 2z = -3

Now eliminate x from the third equation by multiplying the first equation by -2 and add it to the third equation.
-2x - 2y - 2z = -8
2x - y - 2z = -1
-3y - 4z = -9

Next, eliminate y from the third equation by multiplying the second equation by -1 and adding it to the third equation.

3y + 2z = 3
-3y - 4z = -9
-2z = -6

Solve the third equation for z.

-2z = -6
z = 3

Substitute 3 for z in the second equation and solve for y.

-3y - 2z = -3
-3y - 2(3) = -3
-3y - 6 = -3
-3y = 3
y = -1

Lastly, substitute -1 for y and 3 for z in the first equation and solve for x.

x + (-1) + 3 = 4
x + 2 = 4
x = 2

The answer is (2, -1, 3).

The easiest way to solve systems of inequalities is to solve them by graphing. Therefore, it is best if you know how to graph inequalities in two variables (5x - 4y < 13, for example). Example:
1. Problem: Graph y < x.

Solution: First graph the equation y = x. However, the line must be drawn dashed because the less than sign tells us the line is not included in the solution. Next, test a point that is located above the line and one that is below the line. Any point you pick above the line, such as (0, 2), y is greater than x, so points above the line are not in-cluded in the solution. Points below the line, such as (3, -3) have a y value that is less than the x value, so all points below the line are included in the solution.

To solve a system or conjunction of inequalities, it is easiest to graph each of the inequalities and then find their intersection. Example:
1. Problem: Graph the following system:
2x + y >= 2
4x + 3y <= 12
(1/2) <= x <= 2
y >= 0

Solution: See the figure below.


(An approach in the field of educational research)

Analysis of variance is part of the statistics was first introduced by Sir Ronald & Fisher. This analysis has been utilized in all areas of research that uses quantitative data. In the implementation, analysis of variance using ANOVA (Analysis of Variance). In the education sector analysis of variance was used to test whether there are similarities or differences between the learning methods and sebagianya.

In a study of quantitative data obtained must be processed and analyzed to become an information that we want. The process of acquisition, processing, and data analysis are usually referred to as the statistical method. According to Hadi Sutrisno (1996: 3) statistic is knowledge related to the ways of data collection, processing or penganalisisannya and conclusion based on the collection and analyzing data that are made. While the analysis of the data itself, according to Hasan, Iqbal (2004: 29) can be interpreted as follows: (1) to compare two things or two variable value / more to know the difference / ratio is then drawn a conclusion, (2) regulate the process of sequence data, mengorganisaikannya into a pattern, categories, and the basic outline of the unit, (3) detailing the process of formal efforts to find a theme and to formulate hypotheses as suggested by the data and in an effort to provide assistance on themes and hypotheses. And according Setyowati, Eni (2008: 1) Statistics is the science of collecting, organizing, presenting, analyzing, and interpreting the data into information for effective decision making emmbantu. The excess of data with statistical analysis are: (1) allows an exact description of something. Verbal symbols is more efficient than verbal language, (2) allows a person to work exactly in the process and ways of thinking. Although not absolutely true, but it can be set up to which level of the conclusion is correct, (3) researchers provide summaries of research results in a more meaningful and more compact because it provides certain rules, (4) can draw general conclusions, and (5) possible to conduct forecasts (Hasan, Iqbal, 2004: 30). One of the quantitative data with statistical analysis is the analysis of variance.
Before we perform analysis of variance we need to first understand the concept of experimental design, because the analysis of variance was an experiment or experimental research.

Experimental design
Experiments are generally carried out to find something. Therefore, theoretically, be interpreted as a test or experiment planned inquiry to obtain new facts (Steel and Torrie, in Herawati Nita, 2007: Online). And experimental design can be interpreted as a test or series of tests in which significant changes made to the variables of a process or system so that we can observe and identify the reasons for the change in output response. While according to the Herawati Miliken and Johnson, Nita (2007: Online), the experimental design is very related to the planning of research to obtain the maximum information from materials that are available. And can also be interpreted as a set of rules / way / procedure to apply the treatment to the experimental units.
From the various definitions of the above, it is clear that the purpose of the experiment is similar to that answer one or more questions to get the maximum information by: (1) Determine which variables most affect the response (response), (2) determine how sets of independent variables that influence The dependent variable thus approaching the desired nominal value, (3) Determine how the set of independent variables that influence the dependent variable range of small, (4) Determine how to set up an independent variable so that the uncontrollable variables as small as possible.
In designing a study, researchers often control the specific influences such as treatment, population, or a combination of treatments. Therefore, before the research goes it raises some questions that must be answered: (1) How many treatments that must be applied, (2) How many times each treatment must be observed, (3) What are the units of parole, (4) How to apply to the treatment unit experiment and observing the response, (5) Can the design was analyzed and compared?
To be able to answer these questions directly and do not have can not be answered in general. Here, the experimental design is used so that it can play an important role in the development process and the process of finding and solving problems in order to enhance research.
Three main principles in experimental design are: (1) Deuteronomy. Deuteronomy is applied one treatment to more than one experimental unit. Apling Deuteronomy is of importance in an investigation and has the function to provide experimental error, increase precision by reducing the standard deviation, improve generalization, (2) randomization. Randomization is the underlying statistical methods in experimental design. Randomization is the application of treatments to experimental units so that all / any single experiment has an equal opportunity to emnerima a treatment. The concept of randomization is valid also for decision or determination of a sub sample of observation units. Randomization function to avoid bias, ensure the existence of freedom between observations, and overcome the sources of variability that are known but unpredictable effects; (3) Grouping. Grouping is a technique used to improve the accuracy of the experiment. Grouping done if there is a source of diversity that can be known and its influence can be estimated. Experimental material arranged in groups of experimental units are relatively uniform (Herawati, Nita, 2007: Online)

Variety Analysis
During this time, analysis of variance was used in the biometric field (agriculture, biology, medicine, engineering, etc.). In this paper we will focus on the use of analysis of variance in education. Analysis of variance was first introduced by Sir Ronald & Fisher and is basically an arithmetic process for dividing the total sum of squares into components associated with a known source of variability (Steel and Torrie, 1991: 168). In Hadi, Sutrisno (1988: 367), analysis of variance was also known as variance analysis is a tool to test hypotheses about differences in the mean zero value of more than two samples simultaneously. According Suharyadi (2004: 440), analysis of variance (ANOVA) was used to distinguish three or more with the middle value assumptions underlying ANOVA are (a) sample obtained from a normal population, (b) each population has the same standard deviation, and ( c) all populations are independent of each other. From bebarapa definition above we can conclude that the analysis of variance is a method of describing the total diversity of the data into components that measure various sources of diversity with the aim of testing the similarity some central values in one go.
Analysis of variance is the separation of the total number of kuadarat into components associated with a known source of variability. In the analysis of variance involving real test basic assumptions are: (1) Effect of additive treatment and environment, (2) are random experimental error, to spread freedom and normal dis ekitar middle value range of zero and common (same). These basic assumptions is an absolute thing that must be filled in using analysis of variance. Non-fulfillment of one or more assumptions can affect both the real level (level of significance) and the sensitivity of F or t the deviation from the null hypothesis is true.
In the case of abnormalities, the actual real rate is usually larger than those stated. This resulted in rejection of the null hypothesis opportunity hypothesis is true when larger, in other words too often be said when in fact not significantly different. Researchers may think that he used the real level 5 percent when in fact 7a tau 8 percent. If the assumption is not fulfilled aditifitas heterogeneity will cause an error. Various error components contributed by various observations did not expect the same variety. This resulted in a general range of assumptions automatically become not met as well. While the assumption of freedom of error will didapats ecara done directly if the randomization.
Because of these basic assumptions is absolute, after the data obtained from the research, then the first step is to test the crew if the data meet the assumptions there. Recently many statistical software that can help researchers to test these assumptions more easily. And if these assumptions are not met after testing proved one way around that is to perform data transformation.
Basically the analysis of variance was divided into five categories, namely (1) Analysis of Variety I (Classification of One Way / One Way Anova), (2) Variety Analysis II (Classification Many Directions), (3) Analysis of Variety III (Factorial Experiments), ( 4) Variety Analysis IV (Split plot design), and (5) V Variety Analysis (Number of Child-Class is not the same) (Steel and Torry, 1991: 168). In this paper only be described analysis of variance was I, II, and III.

Variety Analysis I (One-Way ANOVA)
According to Santoso, Singgih (2007: xxvi), Analysis of variance I used to completely randomized design. This design is the simplest and only examine the contents of the data column. Statistical procedures used are one-way anova. Now this with the help of existing software such as SPSS, statistical and sebagainyakita will be easier to do anova test without doing the calculation manually. In this discussion we will try to use the aid of statistical software SPSS 16.0 application.
Guide to do a one-way ANOVA test were as berikuit:
1. Determine and Hi Ho
2. Determine the confidence level or a significant level; in general level of confidence (confidence level) is 95% so that the significant level (significant level) is 100% - 95% = 5%
3. Determine the statistical procedures that will be used:

SSB formula above can be calculated by:

SSW formula above can be calculated by:

Where SST (total sum of square) is a quadratic toatal all values of data, which can be expressed by the formula:

4. Take the conclusion to accept or reject H0
If statistics count If statistics count> statistical tables, then H0 is rejected.
Example application: A school melakukan research to determine whether a variety of teaching methods baru give different results, or not with the academic ability of students to examine the effectiveness of both methods, in this study included standard methods that have been used in the schools as a comparison, while two The new method is the method of X and Y. methods Each method is applied to 5 students with different students. After three months of training, academic ability is measured through a test score. Data from the study are as follows:

Student Name X Y Standard
A 49 71 83
B 60 60 87
C 57 65 89
D 59 59 92
E 55 69 95
(Kurniawan, 2007: Online)
Analysis: In the case of so-called factor (independent variable) is a teaching method while the level / treatment are three methods of teaching and the score was the dependent variable.
Testing procedures are:
1. Create a hypothesis:
Ho: score values using three methods of teaching the same relative to each other.
(Μ1 = μ2 = μ3)
Hi: at least one score value of a different teaching methods with other methods.
2. 95% confidence level and 5% significance level.
3. With SPSS 16.0 statistical procedures
1 1 49
2 1 60
3 1 57
4 1 59
5 1 55
6 2 71
7 2 60
8 2 65
9 2 59
10 2 69
11 3 83
12 3 87
13 3 89
14 3 92
15 3 95

SPSS output is as follows:

F count = 64.877
F table (0:05; 2.12) = 3.88
Therefore, calculated F> F table, so Ho rejected
It was concluded that teaching methods are applied to produce at least one score in three different teaching methods or in other words, these three methods of teaching have a different impact on students' academic abilities.

Variety Analsisi II (Classification Many Directions)
In the analysis of variance II we not only use a single classification, but many classifications. Entered into this dual classification is not only possibly be done in many investigations but is also very useful to get more information and more accurate. According to Santoso, Singgih (2007: xxviii) II analysis of variance was used for the randomized block design. This design to test the contents of columns and rows of data. Same statistical procedures used with a one-way anova.
Example applications: the same problem but variable analysis of variance was first included in the testing of students to determine whether the student 1 to 5 resulted in a score of academic ability. A school conducted a study to determine whether the various new teaching methods give different results, or not with the academic ability of students to examine the effectiveness of both methods, in this study included standard methods that have been used in schools as a comparison, while the two new methods The method is a method of X and Y. Each method is applied to five students. After three months of training, academic ability is measured through a test score. Data from the study are as follows:
Student Name X Y Standard
A 49 71 83
B 60 60 87
C 57 65 89
D 59 59 92
E 55 69 95
(Kurniawan, 2007: Online)
In this model there is a block variable, namely STUDENT. Now there will be two tests, namely the influence of the method and influence of students, in the language of the test statistics are columns and rows.
To test the column that contains the variable method of teaching procedures performed:
1. Create a hypothesis:
Ho: score values using three methods of teaching the same relative to each other.
(Μ1 = μ2 = μ3)
Hi: at least one score value of a different teaching methods with other methods.
2. 95% confidence level and 5% significance level.
3. With SPSS 16.0 statistical procedures

F count = 64.877
F table (0:05; 2.12) = 3.88
Therefore, calculated F> F table, so Ho rejected
It was concluded that teaching methods are applied to produce at least one score in three different teaching methods or in other words, these three methods of teaching have a different impact on students' academic abilities.
The procedure to test the line that contains the variable students is as follows:
Ho: no significant differences between the academic ability of students in existing schools
Hi: at least one school with different academic scores than other schools
1 1 49
2 1 60
3 1 57
4 1 59
5 1 55
1 2 71
2 2 60
3 2 65
4 2 59
5 2 69
1 3 83
2 3 87
3 3 89
4 3 92
5 3 95

P value (sig) for variable p-value method = 0.000 (sig) for the variable name = 0.796. The value of having a probability value above 5% so thank Ho.
It can be concluded that the average score of academic ability was not significantly different for students who are there, the average score of academic ability relative the same four methods for both students A, B, C, D, and E. While the variables of teaching methods are analyzed with the conclusion remains that there are clear differences in scores of academic abilities seen from the method of teaching provided.

Variety Analysis III (Factorial Experiments)
In the analysis of variance III there are a number of treatment in each of several categories that form a grid treatment. Selection of decomposition of the design of treatment leads to the treatment sum of squares into components of the additive-konponen following hypothesis test (Steel and Torrie, 1993: 403).
Factor is a kind of treatment, and in the factorial experiment, each factor has several treatments. Factorial experiment is an experiment so that treatment consists of all possible combinations of levels of several factors. This experiment gives a huge advantage in explanatory research, which to our knowledge about the optimum level of each factor is still very minimal. This experiment is testing the contents of columns and rows of data, as well as whether there is any interaction between the contents of columns and rows. Satatistik procedure used is TWO-WAY ANOVA.
Example applications:

School Name X Y Standard
A 49 71 83
A 60 60 87
B 57 65 89
B 59 59 92

In this model the interaction between variables was tested columns and rows.
1. Create a hypothesis
Ho: There is no interaction between the methods with these schools
Hi: There is an interaction between the methods with these schools
2. Procedures with SPSS 16.0


Steel and Torrie, Principles and Procedures of Statistics A Biometrics Approach, Jakarta, Gramedia Pustaka Utama, 1993.
Hasan, Iqbal, Research Analysis With Statistics, Jakarta, Earth Literacy, 2006.
Hadi, Sutrisno, Statistics 3, Yogyakarta, Andi Offset, 1993.
Suharyadi, Statistics for Modern Economy and Finance, Jakarta, Salemba Four, 2004.
Setyowati, Eni, Diktat Maetode Statistics, Tulungagung, STAIN, 2008.
Sudjana. Statistical Methods. Bandung, Tarsito, 1996.
Setyowati, Eni, Application Module Statistics with SPSS 16.0. Tulungagung, STAIN, 2008.
Hamang, Abdul, Statistical Methods, Jakarta, Graha Science, 2005.
Santoso, Singgih, Questions answered Statistics with SPSS and EXCEL, Jakarta, Gramedia, 2007.
Herawati, Nita, 2007, Experimental Design (Online) 20pdf/BAHANMETODOL.DOSEN.pdf, accessed on January 28, 2008
Kurniawan, Deni, 2007. Analysis of variance of a Direction (One Way ANOVA) - Similar pages, accessed on 28 January 2008

Installation on Debian Woody Mailserver

This guide is intended as a small tutorial making use email server with packages available in Debian Woody. This document (try to) explain how to install qmail (+ patches), vpopmail, courier-imap, squirrellmail, clamav and some configuration needed.
1. Installing Qmail
Debian Woody provides qmail-src package that contains the source code for qmail that has been equipped with a build-script that allows you to make compiled. Source package qmail is fully equipped with QMAILQUEUE patch that allows you to change the contents of the queue before a mail is sent.
In addition to qmail-src itself, qmail also requires ucspi-tcp are also included in Debian Woody with a package-src-tcp ucspi. This package serves as TCP Server that manage network connections made by qmail.
Installing the two packages above can be done by:
root: ~ # apt-get install qmail-src-tcp-src uscpi
After the above two packages are installed we will compile ucspi-tcp first, then we do a compilation on qmail.
root: ~ # build-ucspi-tcp
You will be prompted to enter the directory to compile (the default / tmp / ucspi-tcp). Follow the instructions on the screen, and once finished you will get a file-tcp_0.88 ucspi-5_i386.deb who can direct you to install.
root: ~ # dpkg-i / tmp/ucspi-tcp/ucspi-tcp_0.88-5_i386.deb
There are some patches required to build a qmail binary, namely:
1. qmail-1:03-maxrcpt.patch: Used to limit the number of recipients per email. RFC2821 states that a MTA should be able to receive at least 100 recipients for each mail, but may also if we do not want to accept it. These restrictions serve to reduce spam.
2. qmail-1:03-mfcheck.3.patch: Used to reject email if the sender domain is invalid.
3. qmail-1:03-quotas-1.1.patch: Used to set the "over quota" as a hard error. Without this patch, "over quota" in the destination address so that only produces a soft error message will be transmitted continuously until the maximum age in the queue is reached.
4. qmail-date-localtime.patch: Useful for qmail to use the local date format in your email header.
5. qmail-smtpd-auth: Forcing users to login before sending email. It is useful to avoid sending emails which carried by a virus / worm.
Some of the patches above have been merged by John M. Simpson ( into a patch ie-1:03 qmail-jms1.4a.patch that can be downloaded from
Note: Make sure that before the compilation process begins mailserver IP addresses and domains you have registered with the Domain Name Server you use. If not please contact your network administrator, or if you are the network administrator immediately add the DNS entry mailserver.
Diasumsukan here that you have downloaded the patch already is in the / tmp directory, and compile done in the directory / tmp / qmail.
root: ~ # build-qmail
This script unpacks the qmail source into a directory, and
compiles it to Produce a qmail binary *. deb files.

The directory will of Nowhere this is done end up containing the source
and package qmail binary files for the package, along with a
directory containing the unpacked source.

Enter a directory Nowhere you would like to do this [/ tmp / qmail]
dpkg-source: extracting 1:03 qmail qmail-ins

dpkg-source: extracting 1:03 qmail qmail-ins

Qmail binary package compiled some will from now
If you want to apply a custom patch, switch to another console and do it now
Can this take long time, depending on your machine

Press ENTER to continue ...
Do not press ENTER, open the shell again, and do a patch on qmail.
root: ~ # cd / tmp/qmail/qmail-1.03
root: / # patch-p1 tmp/qmail/qmail-1.03 You will get some error, fix the file content by mengkopikan Makefile.rej and qmail-smtpd.c.rej manually (how? Please ask your neighbors, or asked to mbah google). After you fix it press ENTER to start the compilation process.
After the compilation process is completed you will get the file / tmp/qmail/qmail_1.03-24_i386.deb in the directory / tmp / qmail. This file can be directly installed on multiple computers without having to recompile.
root: ~ # dpkg-i / tmp/qmail/qmail_1.03-24_i386.deb
When the installation process failed to detect qmail domain that you use, fill in your domain name for the mailserver on file / var / qmail / control / me by editing the file directly, or by executing the following:
root: ~ # echo "nama.domain.anda"> / var / qmail / control / me
After installation is complete do not forget to enter the domain that are handled in / var / qmail / control / rcpthosts. This is intended to put your mailserver does not become an open relay mail server that can be misused by parties who do not bertanggugjawab.
Do not forget to check the contents of the file / etc / network tcp.smtp to determine which ones could use your mailserver. By default, the contents of this file are: allow, RELAYCLIENT = ""
You can change the contents of that file into: allow, RELAYCLIENT = ""
[Your IP Network]: allow, RELAYCLIENT = ""
: Allow
With such a configuration, all mail originating from localhost and from your network can use this mailserver to send email to anywhere, whereas those from outside the network can only use this mailserver to send mail to addresses on the domain that you specify on / var / qmail / control / rcpthosts. The difference of these two models this behavior is determined by RELAYCLIENT = "". This variable option causes menyandangnya network has the right to use this mailserver to send mail to any address (not mentioned only in the / var / qmail / control / rcpthost).
After you change the contents of / etc / tcp.smtp do not forget to build the database by running the command:
root: ~ # tcprules / etc / tcp.smtp.cdb / etc / tcp.smtp.tmp The last thing you should do now is to change the storage behavior of qmail to use Maildir format. Debian qmail compilation does not require supervision and daemontools script but uses the file / etc / init.d / qmail as well as other servers that are in Debian. For that you can change the file on the alias_empty = "| / usr / sbin / qmail-procmail" to alias_empty = ". / Maildir /". These settings are roughly on the lines 14 and 15.
After that you can run (start) / stop (stop) and restart qmail with the command:
root: ~ # / etc / init.d / qmail [start | stop | restart]
You can try out your new mailserver by using telnet as described in the piece of program below.
root: ~ # telnet localhost 25

Trying ...
Connected to localhost.
Escape character is'^]'. 220 ESMTP
250 ok
250 ok
354 go ahead
type your message here
and after completion end with a dot (.)
250 ok [odd numbers]
When you get answers like the one above it means that your mailserver is running well. Congratulations! Please make a coffee, drink and rest awhile, the qmail installation has been completed.
2. Installing vpopmail
Vpopmail is a program that allows a mailserver to handle many domains and many users without having to create a user entry in / etc / passwd. Each domain can have one postmaster account itself with a different password. Installing vpopmail is not making us have to change the settings in qmail because these settings are handled by vpopmail installation process automatically.
In addition to the above goal, vpopmail pop3 server is also included which allows us to download emails on the server to the mail client on your local computer, ie Outlook Express or Mozilla. This facility helps you to avoid your mailbox on the mailserver completely, so that emails sent to you will not bounce.
To install this package you do not have to install first like the installation of qmail and ucspi-tcp, but can directly install from the. Deb that exist. To be able to install using apt-get, add the following line to / etc / apt / sources.list you. woody deb vpopmail
You can select multiple backend storage username information, including the following:
1. CDB: Storage is done by using the CDB file.
2. MySQL: Storage is done by using the mysql database.
3. lmysql: Same as mysql but with the additional support of Large Sites.
4. pgsql: Storage is done by using a PostgreSQL database.
5. Oracle: database storage using Oracle.
To install vpopmail, type the command below. Later, all sorts of dependency / join dependencies will be installed automatically. Backend authentication is installed by default CDB.
root: ~ # apt-get install-bin vopomail
There are some basic commands provided by vpopmail. These commands are basic commands commonly used in the management of their domain users in it.
· Vadddomain: used to add a virtual domain and that domain postmaster.
· Vadduser: used to add users on virtual domains.
· Vpasswd: used to change user passwords in the virtual domain.
· Vdeluser: used to delete a user's virtual domain.
· Vdeldomain: used to delete a virtual domain.
root: ~ # vadddomain
Please enter the password for Postmaster: *****
Enter password again: *****

root: ~ # vadduser
Please enter the password for ****
Enter password again: ****
In the above example it appears that domain has been successfully made and we also have created a new user for that domain name ie
3. Installation CourierIMAP
IMAP is provided by CourierIMAP IMAP version 2. The service is similar to that provided by the pop3 service, but we do not have to use the IMAP email on the mailserver to move our computer, but we still can read the email through our favorite email client.
CourierIMAP Installation is easy enough, add the following line in / etc / apt / sources.list. woody deb courier
Installation can be done with the command:
root: ~ # apt-get install courier-imap
Courier IMAP supports multiple authentication modules. Settings for the determination of this module is contained in the file / etc / courier / imapd, in part AUTHMODULES. Some examples of supported authentication methods are:
· Authpam: Used to validate the user using PAM library, so the courier does not perform authentication independently, but by using a library that has been provided by the PAM.
· Authpwd: Used to validate the user based on the file / etc / passwd.
· Authshadow: Just like authpwd, but the password for the user is taken from / etc / shadow.
· Authuserdb: Used to validate a user based userdb database.
· Authvchkpw: Used to validate user from vpopmail.
· Authcram: As authuserdb but not directly take the username and password, but through the mechanism of "Challenge / Response Authentication Mechanism (CRAM)."
· Authmysql: Used to validate the user that is stored in MySQL database.
· Authpgsql: Used to validate the user who deposited the PostgreSQL database.
· Authldap: Used to validate users from an LDAP directory.
Because here we store the username by using vpopmail, then we should run the authentication is authvchkpw. Thus confirm that the file / etc / courier / imapd there is a line that contains: AUTHMODULES = "authvchkpw".
Many other configurations you can do. You can read the configuration file from beginning to end. In each configuration there must be a caption that accompanies it, so you can read to find out the meaning.
After configuration is complete you can run (start) / stop (stop) and restart CourierIMAP with the command:
root: ~ # / etc / init.d / courier-imap [the start | stop | restart]
After you successfully install CourierIMAP, you can try to telnet to the IMAP server with port 143. For example, if you telnet from the computer you are installing, you can run a command like below.
root: ~ # telnet localhost 443
Trying ...
Connected to localhost.
Escape character is'^]'.
* OK Courier-IMAP ready. Copyright 1998-2002 Double Precision, Inc..
See COPYING for distribution information.
If you already get an answer as above, means you have an IMAP server works well.
4. Installing Antivirus (ClamAV)
ClamAV antivirus opensource is one whose primary goal is to clean / quarantine files that are exposed to viruses circulating via email. To be able to scan incoming ClamAV does not work alone, but to be able to check ClamAV installation need help qmailscanner which will be discussed in the next chapter.
ClamAV virus database is updated regularly. You can track the activities of this project through the website In addition to downloading the manual way, ClamAV has also called freshclam daemon that periodically download the virus database from the internet, so you do not need to routinely conduct anti-virus maintenance (cool term from the world of BSD: Install and forget it).
Before you install ClamAV, add the following line in / etc / apt / sources.list. woody deb clamav
For installations using the command:
root: ~ # apt-get install clamav
Once installation is finished you can continue to the next section. ClamAV does not require any configuration.
5. Installing qmail-scanner
Qmail-scanner is a program used by ClamAV (anti-virus or whatever) to check the virus from the qmail-queue (particularly attachments). Qmail-scanner checks all SMTP connections to each connection that entering or exiting the server (depending on configuration). When qmail-scanner found a virus then bervirus emails will be quarantined.
Lo qmail-scanner is not a program. Qmail-scanner is a perl script that is run by the tcp-server to check for viruses on qmail-queue. Qmail-scanner requires some additional libraries from perl is perl-SUID, libtime-hires-perl, as well as several other programs such as tnef, razor, and others. You do not need to install all the programs it manually because when qmail-scanner installation, the programs will come installed automatically. To install qmail-scanner you can run the command:
root: ~ # apt-get install qmail-scanner
After installation is complete your can see, and if necessary change the file / var / spool / qmailscan / quarantine-attachments.txt. This file contains definitions of some viruses and you can also prevent the delivery of several types of files, eg. Scr,. PIF, etc., that you suspect is commonly used by viruses to spread themselves. If you change the file you should run the command
root: ~ # / usr / sbin /
to update the results of your changes on the database file. CDB to be used by qmail-scanner. Apart from that file, you can also change the file / usr / sbin / to make some adjustments to your system. Full details about this file can you ask Mbah Google.
Now, we need to do is change the course of an email to "stop" prior to the clinic to check for viruses before deployment to the recipient. By default, before an email is sent to the recipient that will go into a queue list. Virus scanning performed just before the email into the queue. That's when qmail-scanner do its job. For that, we should mention an email from the network which must be examined by qmail-scanner.
For that purpose we do that by providing a global variable on a particular connection, which this task is performed by TCPSERVER. Required variables are QMAILQUEUE. If at first the contents of / etc / tcp.smtp you like: allow, RELAYCLIENT = ""
192.168.10.: Allow, RELAYCLIENT = ""
: Allow
(Assuming 192.168.10.x is your network) and you want to check all incoming email from outside your network, you can change that file into: allow, RELAYCLIENT = ""
192.168.10.: Allow, RELAYCLIENT = ""
: Allow, QMAILQUEUE = "/ usr / sbin /"
If you want to check all email that passes through your mailserver, you can add QMAILQUEUE = "/ usr / sbin /" on all the networks were mentioned. Do not forget that you must re-generate the database qmail-scanner with the command below.
root: ~ # / usr / sbin /
6. Activation SMTP Auth
SMTP Auth is one way to keep your mailserver is not used illegally by the parties are not responsible. Therefore, each connection that will send out an email domain that is mentioned in / var / qmail / control / rcpthosts must provide a username and password. If the username and password mentioned is true, then the email will be forwarded to the recipient, if not then the connection will be closed. Emails that led to a local address does not need to be validated first.
SMTP Auth working mode is to set the variable RELAYCLIENT = "" at each connection of successful authentication. Given the variables, then a connection can send emails to anywhere. Therefore, if you want all connections from the 192.168.10 network. must login first, then you should remove RELAYCLIENT = "" from the file / etc / tcp.smtp so that file now contains: allow, RELAYCLIENT = ""
192.168.10.: Allow
: Allow, QMAILQUEUE = "/ usr / sbin /"
Now you must change the file / etc / init.d / qmail. Find the command that runs qmail-smtpd and change (given the parameters) to be:
/ Usr / sbin / qmail-smtpd `hostname-f` / usr / bin / checkpassword / bin / true 2> & 1 .......( etc),
and restart qmail. Be sure also to run
root: ~ # chmod 4755 / usr / bin / checkpassword
checkpassword can do so with good authentication.
To try it, we need to provide a valid username and password. Suppose we are username and password are confidential. We will try the username and password to send out an email to our network. Previously you had to mengencode second string above with the algorithm "base64" that can be made with such a small perl script below. (Thx for asfik mas).
use MIME:: Base64;
print ('Username:');
encode_base64 print ('');
print ('Password:');
encode_base64 print ('secret');
Suppose the name of the script above is, when executed will be like this:
root: ~ # perl
Username: YWRtaW5AZG9tYWlua3UuYml6
Password: cmFoYXNpYQ ==
Now we just tried to send an email.
root: ~ # telnet localhost 25
Trying ...
Connected to localhost.
Escape character is'^]'. 220 ESMTP
334 VXNlcm5hbWU6
334 UGFzc3dvcmQ6
== cmFoYXNpYQ
235 ok, go ahead (# 2.0.0)
If you get an answer as above, then the authentication has been running well. But when you get the answer 535 authorization failed (# 5.7.0) that means you should check back if there are less than your installation process.
7. Installing a Webmail (Squirrelmail)
Installing Squirrelmail requires Apache webserver, and PHP4 that supports IMAP. You just download it from and then extract the directory / var / www and run scripts that are included to configure your webmail.
In addition to their own download, you can also install Debian squirrelmail from the command:
root: ~ # apt-get install squirrelmail
and run the script / etc / squirrelmail / squirrelmail to adjust the settings with an existing mailserver.
8. Reference
3. and all it's derivatives
4. mailing list
5. mas tulisan2 asfik that many really
6. and masi much more:)
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