Advanced Shellcoding Techniques

This paper assumes a working knowledge of basic shellcoding techniques, and x86 assembly, I will not rehash these in this paper.  I hope to teach you some of the lesser known shellcoding techniques that I have picked up, which will allow you to write smaller and better shellcodes.
 I do not claim to have invented any of these techniques, except for the one that uses the div instruction.
The multiplicity of mul

This technique was originally developed by Sorbo of darkircop.net.  The mul instruction may, on the surface, seem mundane, and it's purpose obvious.  However, when faced with the difficult challenge of shrinking your shellcode, it proves to be quite useful.  First some background information on the mul instruction itself.

mul performs an unsigned multiply of two integers.  It takes only one operand, the other is implicitly specified by the %eax register.  So, a  common mul instruction might look something like this:

movl $0x0a,%eax
mul $0x0a

This would multiply the value stored in %eax by the operand of mul, which in this case would be 10*10.  The result is then implicitly stored in EDX:EAX.  The result is stored over a span of two registers because it has the potential to be considerably larger than the previous value, possibly exceeding the capacity of a single register(this is also how floating points are stored in some cases, as an interesting sidenote).

So, now comes the ever-important question.  How can we use these attributes to our advantage when writing shellcode?  Well, let's think for a second, the instruction takes only one operand, therefore, since it is a very common instruction, it will generate only two bytes in our final shellcode.  It multiplies whatever is passed to it by the value stored in %eax, and stores the value in both %edx and %eax, completely overwriting the contents of both registers, regardless of whether it is necessary to do so, in order to store the result of the multiplication.  Let's put on our mathematician hats for a second, and consider this, what is the only possible result of a multiplication by 0?  The answer, as you may have guessed, is 0.  I think it's about time for some example code, so here it is:

xorl %ecx,%ecx
mul %ecx

What is this shellcode doing?  Well, it 0's out the %ecx register using the xor instruction, so we now know that %ecx is 0.  Then it does a mul %ecx, which as we just learned, multiplies it's operand by the value in %eax, and then proceeds to store the result of this multiplication in EDX:EAX.  So, regardless of %eax's previous contents, %eax must now be 0.  However that's not all, %edx is 0'd now too, because, even though no overflow occurs, it still overwrites the %edx register with the sign bit(left-most bit) of %eax.  Using this technique we can zero out three registers in only three bytes, whereas by any other method(that I know of) it would have taken at least six.


The div instruction

Div is very similar to mul, in that it takes only one operand and implicitly divides the operand by the value in %eax.  Also like, mul it stores the result of the divide in %eax.  Again, we will require the mathematical side of our brains to figure out how we can take advantage of this instruction.  But first, let's think about what is normally stored in the %eax register.  The %eax register holds the return value of functions and/or syscalls.  Most syscalls that are used in shellcoding will return -1(on failure) or a positive value of some kind, only rarely will they return 0(though it does occur).  So, if we know that after a syscall is performed, %eax will have a non-zero value, and that  the instruction divl %eax will divide %eax by itself, and then store the result in %eax, we can say that executing the divl %eax instruction after a syscall will put the value 1 into %eax.  So...how is this applicable to shellcoding? Well, their is another important thing that %eax is used for, and that is to pass the specific syscall that you would like to call to int $0x80.  It just so happens that the syscall that corresponds to the value 1 is exit().  Now for an example:

     
xorl %ebx,%ebx
mul %ebx
push %edx
pushl   $0x3268732f
pushl   $0x6e69622f
mov %esp, %ebx
push %edx
push %ebx
mov %esp,%ecx
movb $0xb, %al  #execve() syscall, doesn't return at all unless it fails, in which case it returns -1
int $0x80

divl %eax  # -1 / -1 = 1
int $0x80

Now, we have a 3 byte exit function, where as before it was 5 bytes.  However, there is a catch, what if a syscall does return 0?  Well in the odd situation in which that could happen, you could do many different things, like inc %eax, dec %eax, not %eax anything that will make %eax non-zero.  Some people say that exit's are not important in shellcode, because your code gets executed regardless of whether or not it exits cleanly.  They are right too, if you really need to save 3 bytes to fit your shellcode in somewhere, the exit() isn't worth keeping.  However, when your code does finish, it will try to execute whatever was after your last instruction, which will most likely produce a SIG ILL(illegal instruction) which is a rather odd error, and will be logged by the system.  So, an exit() simply adds an extra layer of stealth to your exploit, so that even if it fails or you can't wipe all the logs, at least this part of your presence will be clear.

Unlocking the power of leal

The leal instruction is an often neglected instruction in shellcode, even though it is quite useful.  Consider this short piece of shellcode.

xorl %ecx,%ecx
leal 0x10(%ecx),%eax

This will load the value 17 into eax, and clear all of the extraneous bits of eax.  This occurs because the leal instruction loads a variable of the type long into it's desitination operand.  In it's normal usage, this would load the address of a variable into a register, thus creating a pointer of sorts.  However, since ecx is 0'd and 0+17=17, we load the value 17 into eax instead of any kind of actual address.  In a normal shellcode we would do something like this, to accomplish the same thing:

xorl %eax,%eax
movb $0x10,%eax

I can hear you saying, but that shellcode is a byte shorter than the leal one, and you're quite right.  However, in a real shellcode you may already have to 0 out a register like ecx(or any other register), so the xorl instruction in the leal shellcode isn't counted.  Here's an example:

xorl    %eax,%eax
xorl    %ebx,%ebx
movb    $0x17,%al
int    $0x80
     
xorl %ebx,%ebx
leal 0x17(%ebx),%al
int $0x80

Both of these shellcodes call setuid(0), but one does it in 7 bytes while the other does it in 8.  Again, I hear you saying but that's only one byte it doesn't make that much of a difference, and you're right, here it doesn't make much of a difference(except for in shellcode-size pissing contests =p), but when applied to much larger shellcodes, which have many function calls and need to do things like this frequently, it can save quite a bit of space.



Conclusion

I hope you all learned something, and will go out and apply your knowledge to create smaller and better shellcodes.  If you know who invented  the leal technique, please tell me and I will credit him/her.  

All about ftp must read

Well, since many of us have always wondered this, here it is. Long and drawn out. Also, before attempting this, realize one thing; You will have to give up your time, effort, bandwidth, and security to have a quality ftp server.That being said, here it goes. First of all, find out if your IP (Internet Protocol) is static (not changing)

or dynamic (changes everytime you log on). To do this, first consider the fact if you have a dial up modem. If you do, chances are about 999 999 out of 1 000 000 that your IP is dynamic. To make it static, just go to a place like h*tp://www.myftp.org/ to register for a static ip address.

You'll then need to get your IP. This can be done by doing this:
Going to Start -> Run -> winipcfg or www.ask.com and asking 'What is my IP?'

After doing so, you'll need to download an FTP server client. Personally, I'd recommend G6 FTP Server, Serv-U FTPor Bullitproof v2.15 all three of which are extremely reliable, and the norm of the ftp world.
You can download them on this site: h*tp://www.liaokai.com/softw_en/d_index.htm

First, you'll have to set up your ftp. For this guide, I will use step-by-step instructions for G6. First, you'll have to go into 'Setup -> General'. From here, type in your port # (default is 21). I recommend something unique, or something a bit larger (ex: 3069). If you want to, check the number of max users (this sets the amount of simultaneous maximum users on your server at once performing actions - The more on at once, the slower the connection and vice versa).

The below options are then chooseable:
-Launch with windows
-Activate FTP Server on Start-up
-Put into tray on startup
-Allow multiple instances
-Show "Loading..." status at startup
-Scan drive(s) at startup
-Confirm exit

You can do what you want with these, as they are pretty self explanatory. The scan drive feature is nice, as is the 2nd and the last option. From here, click the 'options' text on the left column.

To protect your server, you should check 'login check' and 'password check', 'Show relative path (a must!)', and any other options you feel you'll need. After doing so, click the 'advanced' text in the left column. You should then leave the buffer size on the default (unless of course you know what you're doing ), and then allow the type of ftp you want.

Uploading and downloading is usually good, but it's up to you if you want to allow uploads and/or downloads. For the server priority, that will determine how much conventional memory will be used and how much 'effort' will go into making your server run smoothly.

Anti-hammering is also good, as it prevents people from slowing down your speed. From here, click 'Log Options' from the left column. If you would like to see and record every single command and clutter up your screen, leave the defaults.

But, if you would like to see what is going on with the lowest possible space taken, click 'Screen' in the top column. You should then check off 'Log successful logins', and all of the options in the client directry, except 'Log directory changes'. After doing so, click 'Ok' in the bottom left corner.

You will then have to go into 'Setup -> User Accounts' (or ctrl & u). From here, you should click on the right most column, and right click. Choose 'Add', and choose the username(s) you would like people to have access to.

After giving a name (ex: themoonlanding), you will have to give them a set password in the bottom column (ex: wasfaked). For the 'Home IP' directory, (if you registered with a static server, check 'All IP Homes'. If your IP is static by default, choose your IP from the list. You will then have to right click in the very center column, and choose 'Add'.

From here, you will have to set the directory you want the people to have access to. After choosing the directory, I suggest you choose the options 'Read', 'List', and 'Subdirs', unless of course you know what you're doing . After doing so, make an 'upload' folder in the directory, and choose to 'add' this folder seperately to the center column. Choose 'write', 'append', 'make', 'list', and 'subdirs'. This will allow them to upload only to specific folders (your upload folder).

Now click on 'Miscellaneous' from the left column. Choose 'enable account', your time-out (how long it takes for people to remain idle before you automatically kick them off), the maximum number of users for this name, the maximum number of connections allowed simultaneously for one ip address, show relative path (a must!), and any other things at the bottom you'd like to have. Now click 'Ok'.
**Requested**


From this main menu, click the little boxing glove icon in the top corner, and right click and unchoose the hit-o-meter for both uploads and downloads (with this you can monitor IP activity). Now click the lightning bolt, and your server is now up and running.

Post your ftp info, like this:

213.10.93.141 (or something else, such as: 'f*p://example.getmyip.com')

User: *** (The username of the client)

Pass: *** (The password)

Port: *** (The port number you chose)

So make a FTP and join the FTP section


Listing The Contents Of A Ftp:

Listing the content of a FTP is very simple.
You will need FTP Content Maker, which can be downloaded from here:
ht*p://www.etplanet.com/download/application/FTP%20Content%20Maker%201.02.zip

1. Put in the IP of the server. Do not put "ftp://" or a "/" because it will not work if you do so.
2. Put in the port. If the port is the default number, 21, you do not have to enter it.
3. Put in the username and password in the appropriate fields. If the login is anonymous, you do not have to enter it.
4. If you want to list a specific directory of the FTP, place it in the directory field. Otherwise, do not enter anything in the directory field.
5. Click "Take the List!"
6. After the list has been taken, click the UBB output tab, and copy and paste to wherever you want it.


If FTP Content Maker is not working, it is probably because the server does not utilize Serv-U Software.

If you get this error message:
StatusCode = 550
LastResponse was : 'Unable to open local file test-ftp'
Error = 550 (Unable to open local file test-ftp)
Error = Unable to open local file test-ftp = 550
Close and restart FTP Content Maker, then try again.




error messages:

110 Restart marker reply. In this case, the text is exact and not left to the particular implementation; it must read: MARK yyyy = mmmm Where yyyy is User-process data stream marker, and mmmm server's equivalent marker (note the spaces between markers and "=").
120 Service ready in nnn minutes.
125 Data connection already open; transfer starting.
150 File status okay; about to open data connection.
200 Command okay.
202 Command not implemented, superfluous at this site.
211 System status, or system help reply.
212 Directory status.
213 File status.
214 Help message. On how to use the server or the meaning of a particular non-standard command. This reply is useful only to the human user.
215 NAME system type. Where NAME is an official system name from the list in the Assigned Numbers document.
220 Service ready for new user.
221 Service closing control connection. Logged out if appropriate.
225 Data connection open; no transfer in progress.
226 Closing data connection. Requested file action successful (for example, file transfer or file abort).
227 Entering Passive Mode (h1,h2,h3,h4,p1,p2).
230 User logged in, proceed.
250 Requested file action okay, completed.
257 "PATHNAME" created.
331 User name okay, need password.
332 Need account for login.
350 Requested file action pending further information.
421 Too many users logged to the same account
425 Can't open data connection.
426 Connection closed; transfer aborted.
450 Requested file action not taken. File unavailable (e.g., file busy).
451 Requested action aborted: local error in processing.
452 Requested action not taken. Insufficient storage space in system.
500 Syntax error, command unrecognized. This may include errors such as command line too long.
501 Syntax error in parameters or arguments.
502 Command not implemented.
503 Bad sequence of commands.
504 Command not implemented for that parameter.
530 Not logged in.
532 Need account for storing files.
550 Requested action not taken. File unavailable (e.g., file not found, no access).
551 Requested action aborted: page type unknown.
552 Requested file action aborted. Exceeded storage allocation (for current directory or dataset).
553 Requested action not taken. File name not allowed.


 Active FTP vs. Passive FTP, a Definitive Explanation

Introduction
One of the most commonly seen questions when dealing with firewalls and other Internet connectivity issues is the difference between active and passive FTP and how best to support either or both of them. Hopefully the following text will help to clear up some of the confusion over how to support FTP in a firewalled environment.

This may not be the definitive explanation, as the title claims, however, I've heard enough good feedback and seen this document linked in enough places to know that quite a few people have found it to be useful. I am always looking for ways to improve things though, and if you find something that is not quite clear or needs more explanation, please let me know! Recent additions to this document include the examples of both active and passive command line FTP sessions. These session examples should help make things a bit clearer. They also provide a nice picture into what goes on behind the scenes during an FTP session. Now, on to the information...



The Basics
FTP is a TCP based service exclusively. There is no UDP component to FTP. FTP is an unusual service in that it utilizes two ports, a 'data' port and a 'command' port (also known as the control port). Traditionally these are port 21 for the command port and port 20 for the data port. The confusion begins however, when we find that depending on the mode, the data port is not always on port 20.



Active FTP
In active mode FTP the client connects from a random unprivileged port (N > 1024) to the FTP server's command port, port 21. Then, the client starts listening to port N+1 and sends the FTP command PORT N+1 to the FTP server. The server will then connect back to the client's specified data port from its local data port, which is port 20.

From the server-side firewall's standpoint, to support active mode FTP the following communication channels need to be opened:

FTP server's port 21 from anywhere (Client initiates connection)
FTP server's port 21 to ports > 1024 (Server responds to client's control port)
FTP server's port 20 to ports > 1024 (Server initiates data connection to client's data port)
FTP server's port 20 from ports > 1024 (Client sends ACKs to server's data port)


In step 1, the client's command port contacts the server's command port and sends the command PORT 1027. The server then sends an ACK back to the client's command port in step 2. In step 3 the server initiates a connection on its local data port to the data port the client specified earlier. Finally, the client sends an ACK back as shown in step 4.

The main problem with active mode FTP actually falls on the client side. The FTP client doesn't make the actual connection to the data port of the server--it simply tells the server what port it is listening on and the server connects back to the specified port on the client. From the client side firewall this appears to be an outside system initiating a connection to an internal client--something that is usually blocked.



Active FTP Example
Below is an actual example of an active FTP session. The only things that have been changed are the server names, IP addresses, and user names. In this example an FTP session is initiated from testbox1.slacksite.com (192.168.150.80), a linux box running the standard FTP command line client, to testbox2.slacksite.com (192.168.150.90), a linux box running ProFTPd 1.2.2RC2. The debugging (-d) flag is used with the FTP client to show what is going on behind the scenes. Everything in red is the debugging output which shows the actual FTP commands being sent to the server and the responses generated from those commands. Normal server output is shown in black, and user input is in bold.

There are a few interesting things to consider about this dialog. Notice that when the PORT command is issued, it specifies a port on the client (192.168.150.80) system, rather than the server. We will see the opposite behavior when we use passive FTP. While we are on the subject, a quick note about the format of the PORT command. As you can see in the example below it is formatted as a series of six numbers separated by commas. The first four octets are the IP address while the second two octets comprise the port that will be used for the data connection. To find the actual port multiply the fifth octet by 256 and then add the sixth octet to the total. Thus in the example below the port number is ( (14*256) + 178), or 3762. A quick check with netstat should confirm this information.

testbox1: {/home/p-t/slacker/public_html} % ftp -d testbox2
Connected to testbox2.slacksite.com.
220 testbox2.slacksite.com FTP server ready.
Name (testbox2:slacker): slacker
---> USER slacker
331 Password required for slacker.
Password: TmpPass
---> PASS XXXX
230 User slacker logged in.
---> SYST
215 UNIX Type: L8
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls
ftp: setsockopt (ignored): Permission denied
---> PORT 192,168,150,80,14,178
200 PORT command successful.
---> LIST
150 Opening ASCII mode data connection for file list.
drwx------ 3 slacker users 104 Jul 27 01:45 public_html
226 Transfer complete.
ftp> quit
---> QUIT
221 Goodbye.


Passive FTP
In order to resolve the issue of the server initiating the connection to the client a different method for FTP connections was developed. This was known as passive mode, or PASV, after the command used by the client to tell the server it is in passive mode.

In passive mode FTP the client initiates both connections to the server, solving the problem of firewalls filtering the incoming data port connection to the client from the server. When opening an FTP connection, the client opens two random unprivileged ports locally (N > 1024 and N+1). The first port contacts the server on port 21, but instead of then issuing a PORT command and allowing the server to connect back to its data port, the client will issue the PASV command. The result of this is that the server then opens a random unprivileged port (P > 1024) and sends the PORT P command back to the client. The client then initiates the connection from port N+1 to port P on the server to transfer data.

From the server-side firewall's standpoint, to support passive mode FTP the following communication channels need to be opened:

FTP server's port 21 from anywhere (Client initiates connection)
FTP server's port 21 to ports > 1024 (Server responds to client's control port)
FTP server's ports > 1024 from anywhere (Client initiates data connection to random port specified by server)
FTP server's ports > 1024 to remote ports > 1024 (Server sends ACKs (and data) to client's data port)



In step 1, the client contacts the server on the command port and issues the PASV command. The server then replies in step 2 with PORT 2024, telling the client which port it is listening to for the data connection. In step 3 the client then initiates the data connection from its data port to the specified server data port. Finally, the server sends back an ACK in step 4 to the client's data port.

While passive mode FTP solves many of the problems from the client side, it opens up a whole range of problems on the server side. The biggest issue is the need to allow any remote connection to high numbered ports on the server. Fortunately, many FTP daemons, including the popular WU-FTPD allow the administrator to specify a range of ports which the FTP server will use. See Appendix 1 for more information.

The second issue involves supporting and troubleshooting clients which do (or do not) support passive mode. As an example, the command line FTP utility provided with Solaris does not support passive mode, necessitating a third-party FTP client, such as ncftp.

With the massive popularity of the World Wide Web, many people prefer to use their web browser as an FTP client. Most browsers only support passive mode when accessing ftp:// URLs. This can either be good or bad depending on what the servers and firewalls are configured to support.



Passive FTP Example
Below is an actual example of a passive FTP session. The only things that have been changed are the server names, IP addresses, and user names. In this example an FTP session is initiated from testbox1.slacksite.com (192.168.150.80), a linux box running the standard FTP command line client, to testbox2.slacksite.com (192.168.150.90), a linux box running ProFTPd 1.2.2RC2. The debugging (-d) flag is used with the FTP client to show what is going on behind the scenes. Everything in red is the debugging output which shows the actual FTP commands being sent to the server and the responses generated from those commands. Normal server output is shown in black, and user input is in bold.

Notice the difference in the PORT command in this example as opposed to the active FTP example. Here, we see a port being opened on the server (192.168.150.90) system, rather than the client. See the discussion about the format of the PORT command above, in the Active FTP Example section.

testbox1: {/home/p-t/slacker/public_html} % ftp -d testbox2
Connected to testbox2.slacksite.com.
220 testbox2.slacksite.com FTP server ready.
Name (testbox2:slacker): slacker
---> USER slacker
331 Password required for slacker.
Password: TmpPass
---> PASS XXXX
230 User slacker logged in.
---> SYST
215 UNIX Type: L8
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> passive
Passive mode on.
ftp> ls
ftp: setsockopt (ignored): Permission denied
---> PASV
227 Entering Passive Mode (192,168,150,90,195,149).
---> LIST
150 Opening ASCII mode data connection for file list
drwx------ 3 slacker users 104 Jul 27 01:45 public_html
226 Transfer complete.
ftp> quit
---> QUIT
221 Goodbye.


Summary
The following chart should help admins remember how each FTP mode works:

Active FTP :
command : client >1024 -> server 21
data : client >1024 <- server 20

Passive FTP :
command : client >1024 -> server 21
data : client >1024 -> server >1024

A quick summary of the pros and cons of active vs. passive FTP is also in order:

Active FTP is beneficial to the FTP server admin, but detrimental to the client side admin. The FTP server attempts to make connections to random high ports on the client, which would almost certainly be blocked by a firewall on the client side. Passive FTP is beneficial to the client, but detrimental to the FTP server admin. The client will make both connections to the server, but one of them will be to a random high port, which would almost certainly be blocked by a firewall on the server side.

Luckily, there is somewhat of a compromise. Since admins running FTP servers will need to make their servers accessible to the greatest number of clients, they will almost certainly need to support passive FTP. The exposure of high level ports on the server can be minimized by specifying a limited port range for the FTP server to use. Thus, everything except for this range of ports can be firewalled on the server side. While this doesn't eliminate all risk to the server, it decreases it tremendously.

10 reasons why PCs crash U must Know

Fatal error: the system has become unstable or is busy," it says. "Enter to return to Windows or press Control-Alt-Delete to restart your computer. If you do this you will lose any unsaved information in all open applications."

You have just been struck by the Blue Screen of Death. Anyone who uses Mcft Windows will be familiar with this. What can you do? More importantly, how can you prevent it happening?

1 Hardware conflict

The number one reason why Windows crashes is hardware conflict. Each hardware device communicates to other devices through an interrupt request channel (IRQ). These are supposed to be unique for each device.

For example, a printer usually connects internally on IRQ 7. The keyboard usually uses IRQ 1 and the floppy disk drive IRQ 6. Each device will try to hog a single IRQ for itself.

If there are a lot of devices, or if they are not installed properly, two of them may end up sharing the same IRQ number. When the user tries to use both devices at the same time, a crash can happen. The way to check if your computer has a hardware conflict is through the following route:

* Start-Settings-Control Panel-System-Device Manager.

Often if a device has a problem a yellow '!' appears next to its description in the Device Manager. Highlight Computer (in the Device Manager) and press Properties to see the IRQ numbers used by your computer. If the IRQ number appears twice, two devices may be using it.

Sometimes a device might share an IRQ with something described as 'IRQ holder for PCI steering'. This can be ignored. The best way to fix this problem is to remove the problem device and reinstall it.

Sometimes you may have to find more recent drivers on the internet to make the device function properly. A good resource is www.driverguide.com. If the device is a soundcard, or a modem, it can often be fixed by moving it to a different slot on the motherboard (be careful about opening your computer, as you may void the warranty).

When working inside a computer you should switch it off, unplug the mains lead and touch an unpainted metal surface to discharge any static electricity.

To be fair to Mcft, the problem with IRQ numbers is not of its making. It is a legacy problem going back to the first PC designs using the IBM 8086 chip. Initially there were only eight IRQs. Today there are 16 IRQs in a PC. It is easy to run out of them. There are plans to increase the number of IRQs in future designs.

2 Bad Ram

Ram (random-access memory) problems might bring on the blue screen of death with a message saying Fatal Exception Error. A fatal error indicates a serious hardware problem. Sometimes it may mean a part is damaged and will need replacing.

But a fatal error caused by Ram might be caused by a mismatch of chips. For example, mixing 70-nanosecond (70ns) Ram with 60ns Ram will usually force the computer to run all the Ram at the slower speed. This will often crash the machine if the Ram is overworked.

One way around this problem is to enter the BIOS settings and increase the wait state of the Ram. This can make it more stable. Another way to troubleshoot a suspected Ram problem is to rearrange the Ram chips on the motherboard, or take some of them out. Then try to repeat the circumstances that caused the crash. When handling Ram try not to touch the gold connections, as they can be easily damaged.

Parity error messages also refer to Ram. Modern Ram chips are either parity (ECC) or non parity (non-ECC). It is best not to mix the two types, as this can be a cause of trouble.

EMM386 error messages refer to memory problems but may not be connected to bad Ram. This may be due to free memory problems often linked to old Dos-based programmes.

3 BIOS settings

Every motherboard is supplied with a range of chipset settings that are decided in the factory. A common way to access these settings is to press the F2 or delete button during the first few seconds of a boot-up.

Once inside the BIOS, great care should be taken. It is a good idea to write down on a piece of paper all the settings that appear on the screen. That way, if you change something and the computer becomes more unstable, you will know what settings to revert to.

A common BIOS error concerns the CAS latency. This refers to the Ram. Older EDO (extended data out) Ram has a CAS latency of 3. Newer SDRam has a CAS latency of 2. Setting the wrong figure can cause the Ram to lock up and freeze the computer's display.

Mcft Windows is better at allocating IRQ numbers than any BIOS. If possible set the IRQ numbers to Auto in the BIOS. This will allow Windows to allocate the IRQ numbers (make sure the BIOS setting for Plug and Play OS is switched to 'yes' to allow Windows to do this.).

4 Hard disk drives

After a few weeks, the information on a hard disk drive starts to become piecemeal or fragmented. It is a good idea to defragment the hard disk every week or so, to prevent the disk from causing a screen freeze. Go to

* Start-Programs-Accessories-System Tools-Disk Defragmenter

This will start the procedure. You will be unable to write data to the hard drive (to save it) while the disk is defragmenting, so it is a good idea to schedule the procedure for a period of inactivity using the Task Scheduler.

The Task Scheduler should be one of the small icons on the bottom right of the Windows opening page (the desktop).

Some lockups and screen freezes caused by hard disk problems can be solved by reducing the read-ahead optimisation. This can be adjusted by going to

* Start-Settings-Control Panel-System Icon-Performance-File System-Hard Disk.

Hard disks will slow down and crash if they are too full. Do some housekeeping on your hard drive every few months and free some space on it. Open the Windows folder on the C drive and find the Temporary Internet Files folder. Deleting the contents (not the folder) can free a lot of space.

Empty the Recycle Bin every week to free more space. Hard disk drives should be scanned every week for errors or bad sectors. Go to

* Start-Programs-Accessories-System Tools-ScanDisk

Otherwise assign the Task Scheduler to perform this operation at night when the computer is not in use.

5 Fatal OE exceptions and VXD errors

Fatal OE exception errors and VXD errors are often caused by video card problems.

These can often be resolved easily by reducing the resolution of the video display. Go to

* Start-Settings-Control Panel-Display-Settings

Here you should slide the screen area bar to the left. Take a look at the colour settings on the left of that window. For most desktops, high colour 16-bit depth is adequate.

If the screen freezes or you experience system lockups it might be due to the video card. Make sure it does not have a hardware conflict. Go to

* Start-Settings-Control Panel-System-Device Manager

Here, select the + beside Display Adapter. A line of text describing your video card should appear. Select it (make it blue) and press properties. Then select Resources and select each line in the window. Look for a message that says No Conflicts.

If you have video card hardware conflict, you will see it here. Be careful at this point and make a note of everything you do in case you make things worse.

The way to resolve a hardware conflict is to uncheck the Use Automatic Settings box and hit the Change Settings button. You are searching for a setting that will display a No Conflicts message.

Another useful way to resolve video problems is to go to

* Start-Settings-Control Panel-System-Performance-Graphics

Here you should move the Hardware Acceleration slider to the left. As ever, the most common cause of problems relating to graphics cards is old or faulty drivers (a driver is a small piece of software used by a computer to communicate with a device).

Look up your video card's manufacturer on the internet and search for the most recent drivers for it.

6 Viruses

Often the first sign of a virus infection is instability. Some viruses erase the boot sector of a hard drive, making it impossible to start. This is why it is a good idea to create a Windows start-up disk. Go to

* Start-Settings-Control Panel-Add/Remove Programs

Here, look for the Start Up Disk tab. Virus protection requires constant vigilance.

A virus scanner requires a list of virus signatures in order to be able to identify viruses. These signatures are stored in a DAT file. DAT files should be updated weekly from the website of your antivirus software manufacturer.

An excellent antivirus programme is McAfee VirusScan by Network Associates ( www.nai.com). Another is Norton AntiVirus 2000, made by Symantec ( www.symantec.com).

7 Printers

The action of sending a document to print creates a bigger file, often called a postscript file.

Printers have only a small amount of memory, called a buffer. This can be easily overloaded. Printing a document also uses a considerable amount of CPU power. This will also slow down the computer's performance.

If the printer is trying to print unusual characters, these might not be recognised, and can crash the computer. Sometimes printers will not recover from a crash because of confusion in the buffer. A good way to clear the buffer is to unplug the printer for ten seconds. Booting up from a powerless state, also called a cold boot, will restore the printer's default settings and you may be able to carry on.

8 Software

A common cause of computer crash is faulty or badly-installed software. Often the problem can be cured by uninstalling the software and then reinstalling it. Use Norton Uninstall or Uninstall Shield to remove an application from your system properly. This will also remove references to the programme in the System Registry and leaves the way clear for a completely fresh copy.

The System Registry can be corrupted by old references to obsolete software that you thought was uninstalled. Use Reg Cleaner by Jouni Vuorio to clean up the System Registry and remove obsolete entries. It works on Windows 95, Windows 98, Windows 98 SE (Second Edition), Windows Millennium Edition (ME), NT4 and Windows 2000.

Read the instructions and use it carefully so you don't do permanent damage to the Registry. If the Registry is damaged you will have to reinstall your operating system. Reg Cleaner can be obtained from www.jv16.org

Often a Windows problem can be resolved by entering Safe Mode. This can be done during start-up. When you see the message "Starting Windows" press F4. This should take you into Safe Mode.

Safe Mode loads a minimum of drivers. It allows you to find and fix problems that prevent Windows from loading properly.

Sometimes installing Windows is difficult because of unsuitable BIOS settings. If you keep getting SUWIN error messages (Windows setup) during the Windows installation, then try entering the BIOS and disabling the CPU internal cache. Try to disable the Level 2 (L2) cache if that doesn't work.

Remember to restore all the BIOS settings back to their former settings following installation.

9 Overheating

Central processing units (CPUs) are usually equipped with fans to keep them cool. If the fan fails or if the CPU gets old it may start to overheat and generate a particular kind of error called a kernel error. This is a common problem in chips that have been overclocked to operate at higher speeds than they are supposed to.

One remedy is to get a bigger better fan and install it on top of the CPU. Specialist cooling fans/heatsinks are available from www.computernerd.com or www.coolit.com

CPU problems can often be fixed by disabling the CPU internal cache in the BIOS. This will make the machine run more slowly, but it should also be more stable.

10 Power supply problems

With all the new construction going on around the country the steady supply of electricity has become disrupted. A power surge or spike can crash a computer as easily as a power cut.

If this has become a nuisance for you then consider buying a uninterrupted power supply (UPS). This will give you a clean power supply when there is electricity, and it will give you a few minutes to perform a controlled shutdown in case of a power cut.

It is a good investment if your data are critical, because a power cut will cause any unsaved data to be lost.

Ripping off pop machinez by od^phreak

Ok. First of all, I have tried every single file I could find on how  to rip off coin changers, candy machines, etc. etc. None of them worked. Believe me, I tried every one. I don't know if these articles
were just to gain a better U/L D/L ratio or what but they didn't work. I have one that does. This trick
only works on COCA COLA machines. Don't ask me why. It has something to do with the validator on the machines. Take a dollar bill (as crisp as possible) and lay it
george-side-up with our dear first prez. facing left as if you were going to
stick it in the machine. now take some scotch tape and make 2 strips a long as
the dollar. now take those pieces of tape and attach them to the white edge of
the dollar facing you (just the one edge). your dollar should look like this
now.

-----
-   -  <---- Dollar
-   -
-   -
-   -
+---+
|   |
|   |  <---Strips of tape
|   |
|   |

Now take scotch tape and make bars across the two pieces of tape
already connected to your dollar(sort of like a ladder) overlapping each one
just a little. get down to the bottom and turn the bill over and do the same
thing on the other side (just the ladder rungs). now take a pair of sissors
and trim the tape to make it all even and square. now take something hard and
run it over the tape a few times to ensure that it won't come off. (remeber
kindergarten? put the glue on and press down hard while you count to 10?)
now you're ready. take your new and improved currency to the nearest coke
machine with a dollar bill vindicator and insert your dollar. you have to let
the bill go in almost until you cant hold the tape anymore (it's important to
let the bill get in far enough for the scanner to read the dollar) and then
whip it back out. You should hear the click of the machine and your change
drop out. make your selection and voila! Now the cool thing is when you find
a machine that only takes 50 cents. cause you get your coke and 50 cents!!




note: this document is for informational purposes ONLY. The author of this
article assumes no responsibility for the use or mis-use of this article.


 thank you and c-ya later

      od^Phreak

BBS Crashing Techniques

In the following file, all references made to the name Unix, may also be substituted to the Xenix operating system.Brief history:  Back in the early sixties, during the development of third
generation computers at MIT, a group of programmers studying the potential of

computers, discovered their ability of performing two or more tasks
simultaneously.  Bell Labs, taking notice of this discovery, provided funds for
their developmental scientists to investigate into this new frontier.  After
about 2 years of developmental research, they produced an operating system they
called "Unix".

  Sixties to Current:  During this time Bell Systems installed the Unix system
to provide their computer operators with the ability to multitask so that they
could become more productive, and efficient.  One of the systems they put on the
Unix system was called "Elmos".  Through Elmos many tasks (i.e.  billing,and
installation records) could be done by many people using the same mainframe.

  Note:  Cosmos is accessed through the Elmos system.

  Current:  Today, with the development of micro computers, such multitasking
can be achieved by a scaled down version of Unix (but just as powerful).
Microsoft,seeing this development, opted to develop their own Unix like system
for the IBM line of PC/XT's.  Their result they called Xenix (pronounced
zee-nicks).  Both Unix and Xenix can be easily installed on IBM PC's and offer
the same functions (just 2 different vendors).

  Note:  Due to the many different versions of Unix (Berkley Unix, Bell System
III, and System V the most popular) many commands following may/may not work.  I
have written them in System V routines.  Unix/Xenix operating systems will be
considered identical systems below.

  How to tell if/if not you are on a Unix system:  Unix systems are quite common
systems across the country.  Their security appears as such:

Login;     (or login;)
password:

  When hacking on a Unix system it is best to use lowercase because the Unix
system commands are all done in lower- case.

  Login; is a 1-8 character field.  It is usually the name (i.e.  joe or fred)
of the user, or initials (i.e.  j.jones or f.wilson).  Hints for login names can
be found trashing the location of the dial-up (use your CN/A to find where the
computer is).

  Password:  is a 1-8 character password assigned by the sysop or chosen by the
user.

      Common default logins
   --------------------------

   login;       Password:

   root         root,system,etc..
   sys          sys,system
   daemon       daemon
   uucp         uucp
   tty          tty
   test         test
   unix         unix
   bin          bin
   adm          adm
   who          who
   learn        learn
   uuhost       uuhost
   nuucp        nuucp

  If you guess a login name and you are not asked for a password, and have
accessed to the system, then you have what is known as a non-gifted account.  If
you guess a correct login and pass- word, then you have a user account.  And,
if you guess the root password, then you have a "super-user" account.  All Unix
systems have the following installed to their system:  root, sys, bin, daemon,
uucp, adm

  Once you are in the system, you will get a prompt.  Common prompts are:


$

%

#


  But can be just about anything the sysop or user wants it to be.

  Things to do when you are in:  Some of the commands that you may want to try
follow below:

  who is on (shows who is currently logged on the system.)
  write name (name is the person you wish to chat with)
  To exit chat mode try ctrl-D.
  EOT=End of Transfer.
  ls -a (list all files in current directory.)
  du -a (checks amount of memory your files use;disk usage)
  cd\name (name is the name of the sub-directory you choose)
  cd\ (brings your home directory to current use)
  cat name (name is a filename either a program or documentation your username
has written)

  Most Unix programs are written in the C language or Pascal since Unix is a
programmers' environment.

  One of the first things done on the system is print up or capture (in a
buffer) the file containing all user names and accounts.  This can be done by
doing the following command:



cat /etc/passwd



  If you are successful you will a list of all accounts on the system.  It
should look like this:

root:hvnsdcf:0:0:root dir:/:
joe:majdnfd:1:1:Joe Cool:/bin:/bin/joe
hal::1:2:Hal Smith:/bin:/bin/hal

  The "root" line tells the following info :

login name=root
hvnsdcf   = encrypted password
0         = user group number
0         = user number
root dir  = name of user
/         = root directory

  In the Joe login, the last part "/bin/joe " tells us which directory is his
home directory (joe) is.

  In the "hal" example the login name is followed by 2 colons, that means that
there is no password needed to get in using his name.

  Conclusion:  I hope that this file will help other novice Unix hackers obtain
access to the Unix/Xenix systems that they may find.  There is still wide growth
in the future of Unix, so I hope users will not abuse any systems (Unix or any
others) that they may happen across on their journey across the electronic
highways of America.  There is much more to be learned about the Unix system
that I have not covered.  They may be found by buying a book on the Unix System
(how I learned) or in the future I may write a part II to this........
**************************************
*       A beginners guide to:        *
*          H A C K I N G             *
*                                    *
*                U N I X             *
*                                    *
*          By Jester Sluggo          *
*         Written 10/08/85           *
**************************************

Where Upload (.js) Files Free-Javascript Files Hosting Sites List

Where to upload the .js files or javascript files so as can be used by us for running it successfully without bandwidth problems.As i post many hacks and tricks with the usage of .js files,i was having many accounts on googlepages and geocities and use to share that bandwidth and storage with my
readers but after the upcoming news that both the google and yahoo have decided to close there services of googlepages and geocities,its been difficult for me to find an good server to with enough bandwidth and share with our readers.

So i am asking my readers now to upload these files to there own server as mine will not be working because of bandwidth problems.But many of them dont know where to upload these .js files,so i have started a list of sites to share where these .js files can be uploaded and used but these sites have limited bandwidth but its sufficient for single blog user.So you can join these below sites and use there hosting services,if it dont full fill your requirement just upload your files to different servers below to distribute the bandwidth.

Here Goes The List :-

1)Sigmirror:-It provides 5Gb Webspace and 7Gb Bandwidth/month

2)Hotlinkfiles:-It provides 1Gb Webspace and 4Gb Bandwidth/month.

3)Ripway:-It provides only 30Mb Webspace and 150Mb Bandwidth/day or 4.5Gb/month.

4)Boxstr:-It provides 5Gb Webspace and 1Gb Bandwidth/daily.Just upload your file and get the direct link to make it work.

5)Fileave:-It provides 30Mb Webspace and 1Gb Bandwidth.You can prefer to use it only for some of your file with usage of 1Gb bandwidth.

6)Mydatanest:-It provides 2Gb Webspace and 20Gb Bandwidth/month.You can prefer to use it for most of your file as bandwidth is much more than above sites.

7)Getdropbox:-It provides 2Gb Webspace and Bandwidth is unknown To me.

8)Yourjavascript:-New Provider as no need of account just host any script and get its link.

I got only these sites but they are very less i would like to get more sites listed here so if you are using or knowing any other site to host .js files please leave them in comments i will update the list.

NordVPN – Best UK VPN for secure & anonymous surfing

If you are having trouble with restricted sites and want to access the internet with freedom, then all you need is a good VPN client. This article is specifically pointed towards the UK people who face the problem of blocked websites and are not able to access the music or movie streaming sites. So
today we’ll be discussing a VPN UK, which is an all in one solution to unlock the blocked sites and bypass internet censorship.
What is VPN?

A VPN or a Virtual Private Network works as a security tool for sending and receiving data and interpreting your computer as if it is directly connected to a private network. Mostly, the corporate sectors use a VPN to protect sensitive data and the genuine IP of your computer by hiding it with an alias IP. A VPN has the ability to conceal your online activities from a different location which lets you virtually browse the web from a separate location and unlock the block sites.

NordVPN review

NordVPN is the best UK VPN that consists of the most advanced features that you seek in a VPN. This VPN client offers ultimate security to your network and offers complete privacy to your identity and online activities. With NordVPN, you can anonymously browse the web without revealing your details like location and IP address. You can choose any of the supported server locations and browse pretending as if you are browsing from that place. It is the best VPN to bypass internet censorship and avail lightning fast internet service without producing any log of your activities.


Features of NordVPN

• The key features and benefits of using NordVPN UK VPN are:
• Encrypts data twice using the Double VPN technology.
• Fastest VPN servers from 711 global server locations from 54 different countries.
• Strictly no log policy + Tor over VPN.
• Supports anonymous browsing.
• Automatic Kill Switch that instantly shuts any website specified in advance.
• DNS leak resolver.
• Supports up to 6 devices at a time.
• 24 x 7 customer support.
• Unlimited bandwidth.
• Supports IKEv2/IPsec, OpenVPN, PPTP, L2TP, IPSec protocols.
• Supports shared (static/ dynamic) IP.
• Encrypted chat.
• Custom software for Windows, OS X, iOS, and Android.
• Pay using Bitcoin, PayPal, Credit Cards and more.
• Supports P2P VPN.

Server Locations

NordVPN VPN UK supports servers from 711 worldwide locations and from 54 different countries, which are updated on a regular basis. Few of the locations supported by NordVPN are mentioned below.

Canada, Mexico, Costa Rica, United States, Iceland, Norway, Denmark, Finland, Estonia, Belgium, Ireland, United Kingdom, Switzerland, Austria, Albania, Poland, Slovakia, Greece, Israel, Egypt, Turkey, Portugal, India, Thailand, Vietnam, Malaysia, Hong Kong, Taiwan, South Korea, Japan, France.

Supported Devices

NordVPN is one of the best UK VPN providers that lets you connect up to 6 devices at a time. The following mentioned are the supported devices by NordVPN:
Android
iOS (iPhone and iPad)
Windows
Mac OS X
Linux
Blackberry


NordVPN- Best VPN UK
Security & Privacy of NordVPN, best VPN UK

NordVPN, VPN for UK is very much concerned about your privacy issues. This is why they have applied the Double VPN technology that provides double data encryption and DDoS protected. They use a two-node server link that locks down inbound and outbound data using military grade AES-256-CBC encryption which is applied twice. NordVPN offers 100% anonymity with strict no log policy. Therefore, no log, no record stored from their end. They also support Tor over VPN and sends encrypted traffic over the Tor network. NordVPN supports IKEv2/IPsec, OpenVPN, PPTP, L2TP, and IPSec protocols that can be optionally selected while connecting to the VPN.

NordVPN offers complete security while using public WiFi networks. When you are using Open WiFi, NordVPN will protect you from getting your information leaked to hackers and Government agencies. While accessing WiFi from the public places like coffee shops, airports, restaurants, etc., snoopers keep a keen eye on your activities. So accessing the same with NordVPN will keep your identity hidden and fool the one who’s watching you. Moreover, it will prevent your information and browsing activities from getting leaked and all your searches will be kept private.
Pricing and Plans (NordVPN cost)

NordVPN comes in three major plans and pricing. Get NordVPN
The simple plan offers a 1-month plan for $11.95 billed every month.
The standard plan offers a 6-month plan for $42 ($7/month) billed every 6 months.
The best plan is the 1-year plan for $69 ($5.75/month) billed annually.


How to buy and start using VPN?

To purchase NordVPN, you need to go to the https://nordVPN.com/pricing/ page and select a plan. It will redirect you to the checkout page. Sign in with your NordVPN account and choose your preferred plan from the dropdown. If you don’t have an account, you will have to create it. Choose your payment method- credit card, PayPal or Bitcoin and enter the details. Click Buy now and follow the process step by step.

To use NordVPN, please follow the steps below:
Download the purchased file from your NordVPN account and install it.
A shortcut will appear on your desktop after the installation is completed.
Double-click the file to open NordVPN and you will find the login screen.
Log in with your NordVPN credentials.
The main screen will appear where you will find the server location map and a menu on the top left corner.



The connect button will appear at the top, click on it to connect.
It will display your new virtual IP and location.

Connect to NordVPN server using different ways
You can also connect by clicking the country pin on the map. Meanwhile, you can click the List option on the left and select a country from the list.




Connect to NordVPN – Best UK VPN
You can also use the Connection Wizard if you are unsure about the location. The Connection Wizard will give you recommendations based on your requirement. You can also search for servers from the search menu in the top right corner by typing the location name or category.
The Servers tab in the menu will let you find specific servers those are neatly organized into categories and countries. You can also add servers to your favorite list by clicking the heart symbol next to it.




Connected to UK’s best VPN – NordVPN

After getting connected, start your browser and check entering the URL of a blocked site. NordVPN will easily let you access the site without exposing your real IP and location.

Speed, Pros & Cons, and customer support – NordVPN
Speed

NordVPN offers incredibly high speed and accessibility to any site you want. The VPN internet speed also depends on your internet connection and the primary speed obtained from it. NordVPN does not let you lose speed due to security and delivers blazing fast connectivity. With this VPN client, you can seamlessly stream movies and music without facing a long time buffering and load. From large file transfers to video streaming from Netflix, Hulu, BBC, etc., you will get super-fast access and speed with NordVPN.
Pro(s) & Con(s)

Apart from all such incredible features, NordVPN includes a few advantages and disadvantages:

• Pro(s)
• No logging of your activities.
• Unlimited speed and bandwidth.
• Support all VPN protocol.
• The majority of the server locations supported.
• Tor over VPN support.
• Offers a 3-day trial version.
• Cheap and reliable pricing.

Subscribe to NordVPN

Con(s)
Cannot connect to multiple devices to the same server with the same protocol.
No phone call support.
Customer Support

NordVPN UK VPN service offer top notch customer support with the availability of three contact options- live chat, email, and contact form. For any kind of query, complaint, or support, you can get in touch with their team and they will respond within 48 hours. Unfortunately, the service does not offer support over a phone call or else the communication had been faster. According to our experience, the response time is too much delayed and one cannot wait for 48 hours to get a resolution. The live chat feature in unavailable most of the time and hence, one needs to contact the team via email. For less urgent inquiries, you can contact them via the contact form. In our verdict, NordVPN requires more development in their customer service, but probably the reason can be the least number of complaints they receive because of the flawless software.


Conclusion

Overall, NordVPN offers outstanding service with their software and the advanced technologies they’ve used in it. The VPN software contains the most plus points and does not leave any room for the deficiency. With a wide number of server locations, you can easily switch between them while staying connected to the web. With multiple IPs, you can peacefully browse the web and get access to the restricted sites and NordVPN does not constrain you from any time or speed limit.

Talking about the security, NordVPN offers simplicity over security which is a sign of excellence. Without any critical tools or options, it lets you easily access the web with full security and privacy which is sought out by most users. It keeps your identity hidden and offers full privacy over your internet activities without storing any log. So if you are seeking for a secure web access with secrecy, then NordVPN is the ultimate companion for you.

Display Message or Warning during Windows 7 bootup

Well sometimes your PC is used by many users and you want to show message or warning during windows bootup to them. Then Here’s the way,

(1) Go to Run, type Regedit and press enter. Registry Editor will be opened as shown in screenshot.



(2) Now Navigate to HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrent VersionPoliciesSystem.


(3) Now double click on System and on right half of the editor you will see legalnoticecaption and legalnoticetext.

Legalnoticecaption : You can write caption of your message after double clicking on it.
Legalnoticetext : Here you need to write the main text of your message or warning.



And here’s how message will be appeared during bootup,
Usage
This will be useful if your PC have certain restrictions and you want to show to whoever logging in to your pc.

Convert Infix Expression To Postfix Expression & Evaluate It Using C Programming

So here we implemented Stack Operation using C Program.  http://www.inicong.com/2016/11/stack-implementation-using-c.html

Now, We will implement one of its application using C Programming. Using this program we will be able to convert infix string to postfix string & evaluate it.

Simple example
(1) a+b is infix string.
(2) +ab is prefix string.
(3) Ab+ is postfix string.

From here You can Download the program.
http://www.4shared.com/file/KRAjUBI_/2TOP.html


Infix To Postfix Conversion & Evaluation










From here You can Download the program.
http://www.4shared.com/file/KRAjUBI_/2TOP.html

Stack Implementation Using C Programming Language

Stack is a very popular data structure used for storing & retrieving data. It is last in first out data structure where data can be inserted & deleted from one end (from top) only.

Real Time Applications Of Stack
(1) Memory Management
(2) Expression Conversion & Evaluation (Prefix, Infix, Postfix)
(3) Backtracking (Finding minimal path, In Games)

Infix To Postfix Conversion & Evaluation
http://www.inicong.com/2016/11/convert-infix-expression-to-postfix.html

Java, .Net, Php etc. technologies provide apis to push, pop elements into stack but in C,C++ we have to implement that libraries.

Using this C Program, you will be able to push, pop, peep, display data onto stack.

(1) Push :- Insert Element at top of the stack.
(2) Pop :- It deleted top most element from the stack.
(3) Peep :- It returns Top Most Element without deleting it.
(4) Display :- It displays stack contents.


You can download program from here also :
http://www.4shared.com/file/AWMYMWSn/1Stack.html


Here is the program.











You can download program from here also :
http://www.4shared.com/file/AWMYMWSn/1Stack.html

Singly Circular LinkedList Implementation Using C Programming

Please refer this article for Linklist basics :
http://www.inicong.com/2016/11/singly-linkedlist-implementation-using.html
Singly Circular LinkList differs from Singly Linklist in only 1 way. Here last element also point to
1st element where in case of singly linklist , it was not pointing to any element.
You can download the program from here.
http://www.4shared.com/file/U4QzGK0l/5SinglyCircular.html
Implementation



















You can download the program from here.
http://www.4shared.com/file/U4QzGK0l/5SinglyCircular.html

Singly LinkedList Implementation Using C Programming

Link List is a very popular & dynamic data structure as we do not need to allocate the memory before using it. In case of array, stack, queue etc. predefined size needed to be allocated in memory.

• Link List uses the free memory slots.
• No need of allocate memory before using it.
• Elements are linked via their addresses. i.e. first node has address of 2nd node, 2nd node has address of 3rd node ___________, last node has empty address field as it does not point to any one.

Applications

(1) It can be used in Games, Operating System where memory needs to be allocated where needed.
(2) In web browsers, Downloaders.

You can download the program from here.
http://www.4shared.com/file/XhqxZbKG/4SinglyLinkList.html


Singly Linklist Implementation






















You can download the program from here.
http://www.4shared.com/file/XhqxZbKG/4SinglyLinkList.html

6 best VPN router for small businesses to secure all their devices

Hide My Ass VPN routers have been leading the market. For the stronger security of all your devices, these routers are strongly recommended by technical persons. They provide easy VPN configuration
and lets you use the web like a private VPN network with unlimited and unrestricted access to all the sites around the world. So today we will be mentioning the best Hide My Ass VPN routers, which is the best VPN for torrents, those are leading the market and are ultimate for personal as well as business uses.

What is a VPN router?

A VPN wireless router is a device that creates a secure VPN tunnel to expand your network for connecting to multiple devices within a secure environment. A router like TP-Link VPN router enables 24/7 secure access to the web from anywhere in the world and it keeps the data encrypted by shielding your network from hackers and snoopers. A “VPN router” is built to protect online data by safeguarding your real identity and displaying a virtual location of your browsing activities. This way your real IP address remain hidden and hackers won’t be able to track you or steal your sensitive data. The VPN setup is also an easy process and it can be installed by anyone.
Why to use a VPN router?

People mainly install VPN to strengthen their network security and access the home network and resources from a virtual location and network. But for different people, the reason for using a VPN might vary. For instance, for a downloader who wants to download illegal content or torrent files require a VPN firewall router because his ISP has blocked that site particularly. So using a VPN for router will allow him to access that site from a virtual location and he can download the contents from that web page. On the other hand, an office worker wants to access those resources are blocked by his official authority. So he can connect to VPN router to access those sites from a different IP. This way the reasons for using a VPN router might vary so it depends on upon the choice of the individual.
Best VPN router for small business and individual users

Here we will be listing the 6 best VPN enabled router devices for your personal and business uses.
(1) Asus RT-N66U Tomato FlashRouter

The Asus RT-N66U Tomato FlashRouter provides end-to-end VPN solution to make your network anonymous through an HMA server of your choice. The VPN client contains a powerful 600 MHz processor, 4 times the high-end industry norm in flash memory or RAM, dual-band wireless speeds up to 900 Mbps, 2 USB ports, and a lot more features. The router provides high-speed VPN servers to bypass Geo-locations without compromising with your internet speed. It is good for 4 to 6 users who seek for high-quality video streaming.

Security & Privacy

The Asus router VPN provides top notch security to encrypt your network and hide your identity. Whatever you browse remain discreet with you and nothing is being tracked by the network or third-party agents and prying eyes.

Pricing

The Asus RT-N66U Tomato FlashRouter costs $299.99 $249.99 and can be purchased from FlashRoutes.


Asus RT-N66U router


(2) Asus RT-AC88U DD-WRT FlashRouter

The Asus RT-AC88U DD-WRT FlashRouter provides maximum performance with its 8 wired internet ports that improve your connectivity. It strengthens your network using a Broadcom 1.4GHz processor, 4 massive and powerful external antennas, and the flash memory/RAM in it. This dedicated router is perfect for gamers and users who seek to stream 4K videos. You can seamlessly stream high-quality video from Netflix, Hulu, ESPN, BBC, etc. with improved and endpoint security and avail an additional layer of encryption with full privacy.

Security & Privacy

The Asus RT-AC88U DD-WRT FlashRouter adds a layer of security while you stream media contents and hides your original IP address. It shows that you are streaming content from a different location and keeps your anonymity well maintained.

Pricing


The Asus RT-AC88U DD-WRT FlashRouter is tagged with $549.99 $499.99 and can be availed from FlashRouters.


Asus RT-AC88U DD-WRT router


(3) Linksys E2500 Tomato FlashRouter
The Linksys E2500 Tomato FlashRouter offers the fastest N600 wireless speed capacity with 4 internal antennas. This router can well manage the wireless transmission power, manage access restrictions, utilize an always-on protective firewall, etc. It supports the popular Tomato firmware and is one of the popular mid-level Tomato routers. The Linksys E2500 Tomato FlashRouter is best for 2-4 users who want private internet access to basic email and video streaming with 1-3 connected devices. The Linksys VPN router is ultimate for small and medium sized home and businesses.

Security & Privacy
The Linksys E2500 Tomato FlashRouter is a top level IPsec (Internet Protocol Security) provider that encrypts your network while you have access to the web. It maintains privacy with all the connected devices and displays your virtual location and IP.

Pricing
The router can be purchased from FlashRouters with a price of $199.99 $149.99.


Linksys E2500 Tomato router


(4) Linksys WRT1900ACS Router + Google Chromecast Bundle

The Linksys WRT1900ACS Router is a great router VPN for streaming media from the popular services like Netflix, Hulu, and Amazon Video directly from your HDTV. It keeps your network encrypted while you stream and also offers a Google Chromecast HDMI Streaming Player to perform this task reliably. The Linksys WRT1900ACS is a high-rated router that lets you anonymously stream content without revealing your identity to anyone.

Security & Privacy

Being a top-class home VPN router this device provides full security for your activities and content so that you can seamlessly access the web. It is great for personal and business uses and so whichever network you use, you cannot be tracked.

Pricing

The Linksys WRT1900ACS Router + Google Chromecast Bundle costs $444.98 $414.98and can be availed from FlashRouters.


Linksys WRT1900ACS Router

(5) Netgear AC1450 DD-WRT FlashRouter

The Netgear AC1450 DD-WRT FlashRouter can unblock the popular media streaming sites like Hulu, Amazon Instant, etc. It delivers first class next-Gen Wireless-AC signals for the latest tech gadgets and supports streaming on 4-6 connected devices. The router runs on Broadcom 800 MHz dual-core processor, which is one of the best processors which is offered with DD-WRT support. The Netgear AC1450 DD-WRT FlashRouter prepares your network for the latest devices, meanwhile, it offers support for legacy devices and provides top-level dual band Wireless-N speeds.

Security & Privacy

The Netgear VPN router offers premium security to your activities and keeps your connection safe, strong, and encrypted. The better is the processor, the faster the VPN-encrypted information you can get.

Pricing

The Netgear AC1450 DD-WRT FlashRouter is priced $279.99 $229.99 and you can get VPN from FlashRouters.


Netgear AC1450 DD-WRT router

(6) Netgear R8000 DD-WRT FlashRouter

The Netgear R8000 DD-WRT FlashRouter is an ultimate combination of style and power that safeguards your WiFi network and raises it to the next-Gen Wireless-AC standards. This router revamps your networking options and controls for any device and still offers full support for legacy devices like Wireless-N and Wireless-G. This router is ultimate for 10-12 users who are looking for high-quality video streaming and gaming on 12 to 14 connected devices. The Netgear R8000 DD-WRT FlashRouter is perfect for large sized homes and business. It consists of 6 external antennas that deliver dedicated WiFi bands. The router also includes a Broadcom 1GHz dual-core processor that makes it one of the best dual core routers that offer DD-WRT support.

Security & Privacy

The Netgear R8000 DD-WRT FlashRouter offers ultimate security to your network with its advanced technology, which is much better than the other routers. It is known for its high standard performance and connection delivery.

Pricing
The Netgear R8000 DD-WRT FlashRouter can be purchased from FlashRouters at a price of $499.99 $399.99.


Netgear router

Hope you liked reading about best VPN routers.
How to setup VPN on router?

For HideMyAss VPN router setup, please refer to the following links:

https://support.HideMyAss.com/hc/en-us/sections/200541146-Routers
https://support.HideMyAss.com/hc/en-us/articles/202720956-Router-VPN-configuration-Getting-started

This will let you easily configure your routers and make them accessible.
Pro(s) & Con(s) of HideMyAss routers

Besides having such incredible features and qualifications, the HideMyAss VPN for routeralso contains some demerits. So let’s have a look at its major pro(s) and con(s).

Pro(s)

• Well balances the server loads
• Supports multiple VPN protocol
• Unlimited bandwidth and server switching
• Allows file sharing
• Do not keep any log of your online activity
• Provides a secure IP
• Compatible with almost all devices and OS’ like Windows, Linux, and Mac
• 24/7 premium customer support
• Keeps you safe from hackers
• Allows media streaming from any country
• Maintains your privacy and confidentiality
• 30-day money back guarantee
• Allows Bitcoin payment
• Refer a friend promo
• Cheap and affordable
• Supports the major countries and locations like the United States, United Kingdom, London, Singapore, Australia, India, South Africa, Europe, France, Spain, Germany, Romania, Canada, Bruges, Hong Kong, Frankfurt, Johannesburg, and lots more

Con(s)

• A maximum of 2 devices can be connected simultaneously
• They actually keep log files
• No free trial available
• Live chat is accessible for only 12 hours a day

Customer Support
The HideMyAss routers VPN support program provides 4 basic options to solve your problems. The first option is the Getting Started which is mainly for the first time users who are confused with the basic operations of the router. Here you will find answers to a number of questions related to account and billing, router apps, FAQ, etc. You can also search their database by typing any keyword related to your issue and the support page will find all the relevant answers for you.

The Knowledge Base option provides a vast number of resolutions about the routers like the advanced FAQ, troubleshooting the WiFi router problems, device issues, technology and any issue about the router. You will find the A to Z of the problems in this section which are specifically listed for the advanced or experienced users.

Another option is the Previous Software Versions which are for users who are still using the older versions of their VPN software and still facing issues with them. You can also submit a support ticket relating to any particular issue you are facing. The ticket can be sent by filling up a form through the HideMyAss website and their support team will get back to you as early as possible.

HideMyAss also offers a live chat feature through which you can chat with their support team in real-time and get any issue fixed immediately. Their customer support is available online 24 x 7 to pay attention to your issue and try to resolve them.
HideMyAss VPN router review

HideMyAss has collaborated with Sabai Technology to get you the best rated possible routers that support VPN and for accessing the blocked content and allowing you to remain safe and anonymous from any browser, including Google Chrome, Mozilla Firefox, IE, and Safari. Their routers allow you to connect to multiple devices using a single secure SSL VPN connection. These VPN compatible routers let you access your favorite VPN sites without revealing your identity and IP address with complete privacy and safety. The routers also prevent any hackers and snoopers from stealing your information or anything you are using to access a web page. It keeps your usernames, passwords, credit/debit card information, and phone number safe and averts anyone from recording them. So HideMyAss has pre-configured their routers with Sabai Technology and contains built-in VPN so that you can access all your favorite sites without worrying about your privacy and security.

Conclusion

The HideMyAss routers are much advanced and upgraded compared to its competitors those are struggling hard to beat it in the market. These VPN capable routers give you seamless access to any site those are blocked by your ISP or organization. With their high-end processors, you can access the web at a super-fast speed that even your normal connection cannot provide. And if you are more into content streaming then you can enjoy it at a super speed and access unlimited movies and shows. The HideMyAss routers are not only meant for bypassing internet censorship, but they perform in a buttery smooth way. So if you are opting to use VPN router with VPN server then try out the HideMyAss VPN routers which are the “best VPN router for small business“.