WAN Protocols and Design

Point-to-Point Leased Lines:

WAN protocols used on point-to-point serial links provide the basic function of delivery of data across that one link. As a CCNA, you will be required to understand and configure a variety of protocols used on point-to-point links, including Link Access Procedure Balanced (LAPB),High-Level Data Link Control (HDLC), and Point-to-Point Protocol (PPP). Each of these WAN protocols has the following functions in common:

1)LAPB, HDLC, and PPP provide for delivery of data across a single point-to-point serial link.

2)LAPB, HDLC, and PPP deliver data on synchronous serial links. (PPP supports asynchronous functions as well.)

FRAMING:
Framing is one core feature of any synchronous serial data link protocol. Each of these protocols defines framing so that receiving stations know where the beginning of the frame is, what address is in the header, and the point at which the packet begins. By doing so, the router receiving data can distinguish between idle frames and data frames. Synchronous links, rather than asynchronous links, are typically used between routers.

Synchronous simply means that there is an imposed time ordering at the sending and receiving ends of the link. Essentially, the sides agree to a certain speed, but because it is very expensive to build devices that can truly operate at exactly the same speed,the devices adjust their rates to match a clock source. The process works almost like the scenes in spy novels, when the spies synchronize their watches; in this case, the watches or clocks are synchronized automatically multiple times per minute. Unlike asynchronous links, in which no bits are sent during idle times, synchronous data links define idle frames. These frames do nothing more than provide plenty of signal transitions so that clocks can be adjusted on the receiving end, consequently maintaining synchronization.

4-wire circuit A line from the telco with four wires, comprised of two twisted-pair wires. Each pair is used to send in one direction, so a 4-wire circuit allows full-duplex communication.

2-wire circuit A line from the telco with two wires, comprised of one twisted-pair wire. The pair is used to send in only one direction at a time, so a 2-wire circuit allows only half-duplex communication.

Boot Block Recovery For Free

You don't need to pay a measly sum of dollars just to recover from a boot block mode. Here it is folks:

AWARD Bootblock recovery:

That shorting trick should work if the boot block code is not corrupted, and it should not be if /sb switch is used when flashing the bios (instead of /wb switch).

The 2 pins to short to force a checksum error varies from chip to chip. But these are usually the highest-numbered address pins (A10 and above).

These are the pins used by the system to read the System BIOS (original.bin for award v6), calculate the ROM checksum and see if it's valid before decompressing it into memory, and subsequently allow Bootblock POST to pass control over to the System BIOS.

You just have to fool the system into believing that the System BIOS is corrupt. This you do by giving your system a hard time reading the System BIOS by shorting the 2 high address pins. And when it could not read the System BIOS properly, ROM Checksum Error is detected "so to speak" and Bootblock recovery is activated.

Sometimes, any combination of the high address pins won't work to force a checksum error in some chips, like my Winbond W49F002U. But shorting the #WE pin with the highest-numbered address pin (A17) worked for this chip. You just have to be experimentative if you're not comfortable with "hot flashing" or "replacement BIOS".

But to avoid further damage to your chip if you're not sure which are the correct pins to short, measure the potential between the 2 pins by a voltmeter while the system is on. If the voltage reading is zero (or no potential at all), it is safe to short these pins.

But do not short the pins while the system is on. Instead, power down then do the short, then power up while still shorting. And as soon as you hear 3 beeps (1 long, 2 short), remove the short at once so that automatic reflashing from Drive A can proceed without errors (assuming you had autoexec.bat in it).

About how to do the shorting, the tip of a screwdriver would do. But with such minute pins on the PLCC chip, I'm pretty comfortable doing it with the tip of my multi-tester or voltmeter probe. Short the pins at the point where they come out of the chip.



AMIBIOS Recovery bootblock:
1. Copy a known working BIOS image for your board to a floppy and rename it to AMIBOOT.ROM.
2. Insert the floppy in your system's floppydrive.
3. Power on the system while holding CTRL+Home keys. Release the keys when you hear a beep and/or see the floppy light coming on.
4 . Just wait until you hear 4 beeps. When 4 beeps are heard the reprogramming of the System Block BIOS went succesfull, so then you may restart your system.

Some alternative keys that can be used to force BIOS update (only the System Block will be updated so it's quite safe):
CTRL+Home= restore missing code into system block and clear CMOS when programming went ok.
CTRL+Page Up= restore missing code into system block and clear CMOS or DMI when programming went ok.
CTRL+Page Down= restore missing code into system block and do not clear CMOS and DMI area when programming went ok
Btw: the alternative keys work only with AMIBIOS 7 or higher (so for example an AMI 6.26 BIOS can be only recovered by using CTRL+Home keys).
Boot Block Recovery for FREE

************************************************
BLACKOUT Flashing
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Recovering a Corrupt AMI BIOS chip
With motherboards that use BOOT BLOCK BIOS it is possible to recover a corrupted BIOS because the BOOT BLOCK section of the BIOS, which is responsible for booting the computer remains unmodified. When an AMI BIOS becomes corrupt the system will appear to start, but nothing will appear on the screen, the floppy drive light will come on and the system will access the floppy drive repeatedly. If your motherboard has an ISA slot and you have an old ISA video card lying around, put the ISA video card in your system and connect the monitor. The BOOT BLOCK section of the BIOS only supports ISA video cards, so if you do not have an ISA video card or your motherboard does not have ISA slots, you will have to restore your BIOS blind, with no monitor to show you what’s going on.

AMI has integrated a recovery routine into the BOOT BLOCK of the BIOS, which in the event the BIOS becomes corrupt can be used to restore the BIOS to a working state. The routine is called when the SYSTEM BLOCK of the BIOS is empty. The restore routine will access the floppy drive looking for a BIOS file names AMIBOOT.ROM, this is why the floppy drive light comes on and the drive spins. If the file is found it is loaded into the SYSTEM BLOCK of the BIOS to replace the missing information. To restore your BIOS simply copy a working BIOS file to a floppy diskette and rename it AMIBOOT.ROM, then insert it into the computer while the power is on. The diskette does not need to be bootable or contain a flash utility. After about four minutes the system will beep four times. Remove the floppy diskette from the drive and reboot the computer. The BIOS should now be restored.

Recovering a Corrupt AWARD BIOS
With AWARD BIOS the process is similar but still a bit different. To recover an AWARD BIOS you will need to create a floppy diskette with a working BIOS file in .BIN format, an AWARD flash utility and an AUTOEXEC.BAT file. AWARD BIOS will not automatically restore the BIOS information to the SYSTEM BLOCK for this reason you will need to add the commands necessary to flash the BIOS in the AUTOEXEC.BAT file. The system will run the AUTOEXE.BAT file, which will in turn flash the BIOS. This is fairly easy. Here are the steps you need to take.

· Create a bootable floppy diskette
· Copy the BIOS file and flash utility to the diskette
· Create an text file with any standard text editor and add the following lines

@ECHO OFF
FLASH763 BIOSFILE.BIN /py

In the above example I am assuming that you are using the FLASH763.EXE flash utility. You will need to replace the FLASH763 with the name of whatever flash utility you are using, and replace the BIOSFILE.BIN with the name of the BIOS file you are using. You will also need to change the ‘/py’ to whatever the command is for your flash utility to automatically program the BIOS without user intervention. If you do not know the command to automatically flash your BIOS type the name of the flash utility with a space and then /? to display the utility’s help screen. The help screen should pecify the command switch to automatically flash your BIOS. If you are using the FLASH763.EXE utility then the switch to automatically flash your BIOS is ‘/py’.

BulletProof FTP Server Tutorial

Configuring your Bulletproof FTP Server Tutorial

I am not sure where I found this tutorial, It’s been a while…It might even have been here... ..So if it is one of yours, my hat goes off to you once again....

After reading the excellent tutorial on "Creating an FTP" that Norway posted…

(I would suggest reading and following his tutorial first, then following up with this one)

I thought that perhaps this tutorial might be pretty helpful for those interested in knowing how to configure their Bulletproof FTP Server that don't already know how... Here's how to get started…

This is for the BulletProof FTP Server 2.10. However, It should work fine on most following versions as well.

I'm assuming you have it installed and cracked.

Basics
1. Start the program.
2. Click on Setup > Main > General from the pull-down menu.
3. Enter your server name into the 'Server Name' box. Under Connection set the “Max number of users" to any number. This is the limit as to how many users can be on your sever at any time.
4. Click on the 'options' tab of that same panel (on the side)
5. Look at the bottom, under IP Options. Put a check in the box “Refuse Multiple Connections from the same IP”. This will prevent one person from blocking your FTP to others.
6. Also put a check in the 'Blocked Banned IP (instead of notifying client). VERY IMPORTANT! If somebody decides to 'Hammer' (attempt to login numerous times VERY quickly) your server/computer may CRASH if you don't enable this.
7. Click on the 'advanced' tab
8. At the bottom again look at the 'hammering area'
9. Enable 'anti-hammer' and 'do not reply to people hammering' Set it for the following: Block IP 120 min if 5 connections in 60 sec. You can set this at whatever you want to but that is pretty much a standard Click 'OK'

Adding Users
11. Setup > User accounts form pull-down.
12. Right click in the empty 'User Accounts' area on the right: choose 'Add'
13. Enter account name. (ie: logon name)
14. In the 'Access rights' box right click: choose ‘Add’.
15. Browse until you find the directory (folder) you want to share. In the right column you will see a bunch of checkboxes. Put a check in the following ones: Read, Write, Append, Make, List, and +Subdirs. Press 'select'.
16. Enter a password for your new FTP account.
17. Click on 'Miscellaneous' in the left column. Make sure 'Enable Account' is selected. Enable 'Max Number of Users' set it at a number other than zero. 1 for a personal account and more that one for a group account. Enable 'Max. no. of connects per IP' set it at 1

18. Under 'Files' enable 'show relative path' this is a security issue. A FTP client will now not be able to see the ENTIRE path of the FTP. It will only see the path from the main directory. Hide hidden flies as well.
Put a tick in both of these.

Advanced:
You don't need to do any of this stuff, but It will help tweak your server and help you maintain order on it. All of the following will be broken down into small little areas that will tell you how to do one thing at a time.

Changing the Port
The default port is always 21, but you can change this. Many ISPs will routinely do a scan of its own users to find a ftp server, also when people scan for pubs they may scan your IP, thus finding your ftp server. If you do decide to change it many suggest that you make the port over 10,000.
1. Setup > Main > General
2. In the 'Connection' Area is a setting labeled 'Listen on Port Number:'
3. Make it any number you want. That will be your port number.
4. Click 'OK'

Making an 'Upload Only' or 'Download Only' ftp server.
This is for the entire SERVER, not just a user.
1. Setup > Main > Advanced
2. In the advanced window you will have the following options: uploads and downloads, downloads only, and uploads only. By default upload and download will be checked. Change it to whatever you want.
3. Click 'OK’


While you are running your server, usually you will end up spending more time at your computer than you normally do. Don't be afraid to ban IP's. Remember, on your FTP you do as you want.

When you are online you must also select the open server button next to the on-line button which is the on-line Button

You also have to use the actual Numbered ip Address ie: 66.250.216.67

Or even Better yet, get a no-ip.com address

Boot Winxp Fast

Follow the following steps

1. Open notepad.exe, type "del c:\windows\prefetch\ntosboot-*.* /q" (without the quotes) & save as "ntosboot.bat" in c:\
2. From the Start menu, select "Run..." & type "gpedit.msc".
3. Double click "Windows Settings" under "Computer Configuration" and double click again on "Shutdown" in the right window.
4. In the new window, click "add", "Browse", locate your "ntosboot.bat" file & click "Open".
5. Click "OK", "Apply" & "OK" once again to exit.
6. From the Start menu, select "Run..." & type "devmgmt.msc".
7. Double click on "IDE ATA/ATAPI controllers"
8. Right click on "Primary IDE Channel" and select "Properties".
9. Select the "Advanced Settings" tab then on the device or 1 that doesn't have 'device type' greyed out select 'none' instead of 'autodetect' & click "OK".
10. Right click on "Secondary IDE channel", select "Properties" and repeat step 9.
11. Reboot your computer.

Burn a BIN without a CUE using NERO

You've downloaded a *.BIN file, but there was no *.CUE file associated and you still want to burn the *.BIN file using Nero

Your options are:

1) Create yourself a *.CUE

2) Convert the *.BIN to an *.ISO

3) OR use Nero to burn without the *.CUE file!!!

Yes, that's possible... just follow these steps and you will be sorted. No need for *.CUE files anymore

Ok, here we go...

1) Start Nero

2) File -> Burn Image

3) Browse to the *.BIN file that you want to burn and open it

4) A window saying "Foreign Image Settings" will open

5) Check the settings. They should be as followed:

* Type of image: leave it to Data Mode 1
* Select the Raw Data check box
Note ->> The block size will change automatically from 2048 to 2352
* Leave Image Header and Image Trailer unchanged and set to 0
* Leave "Scrambled" and "Swapped" check boxes unchecked

6) Click on burn!

7) Enjoy

This tut was for Nero 5.x.x.x, I was told that "Burn Image" is under "recorder" in Nero 6. The rest of the steps should be the same...
xkalibur

cannot use my password to get back into Windows XP

Because of the security features built into Windows XP, it is virtually impossible to get back into the system without the password.
You have several options to try and get around this problem.


If you have access to another user account with administrator rights, you can use that account to change the password
of the account that is locked out. You can also use the default Administrator account that is built into Windows XP.

First you need to boot the system into Safe Mode.
1.Restart your system.
2.When you see the blue Dell globe or screen, press the ( F8 ) key about 3 times a second.
3.You should get the Windows startup menu. Use the (Up or Down) arrow keys to highlight (SafeMode)
4.Press (Enter) on (Safe Mode), then press (Enter) on (Windows XP).
5.The system should boot to Safe Mode.

Once you are at the Account Log on Screen, click on the icon
for the user account with administrator rights, or click on the icon
for the administrators account.
Note: For Home the Administrator account isn't normally shown & in Safe Mode you have to press Ctrl+Alt+Delete keys twice to show.
For PRO you can do this in normal mode

When the system has booted to the desktop, use the following steps to change the accounts password.
1.Click Start, Control Panel, Administrative Tools.
2.Click Computer Management.
3.Double click Local Users and Groups, double click the folder Users.
4.Right click on the account name that is locked out, and click on Set Password.
5.You may get a warning message about changing the password, simply click proceed.
6.Leave the New Password box blank, also leave the Confirm Password box blank.
7.Click OK, and OK again.
8.Then close all Windows, reboot the system and try to log in.


There are also applications that can recover the password for you.
The following companies provide these applications at a cost.
iOpus® Password Recovery XP here.
LostPassword.com, here.
Asterisk Password Recovery XP v1.89 here.
Windows XP / 2000 / NT Key here.


If the above information does not help in recovering the password, the only option left is to
format the hard drive then reinstall Windows and the system software.

Calculating Offsets

Introduction

This tutorial is more of a tip than a tutorial. It just explains how to calculate offsets for jumps and calls within the program you are patching.

Types of Jumps/Calls

Here I will just describe the different types of jumps and calls which you will come across:

Short Jumps
Short jumps be they conditional or unconditional jumps are 2 bytes long (or 1 nibble if your Californian ;-). These are relative jumps taken from the first byte after the two bytes of the jump. Using short jumps you can jump a maximum of 127 bytes forward and 128 bytes backwards.

Long Jumps
Long jumps if they are relative are 6 bytes long for conditional jumps and are 5 bytes long for unconditional jumps. For conditional jumps 2 bytes are used to identify that it is a long jump and what type of jump (je, jg, jns etc) it is. The other 4 bytes are used to show how far away the target location is relative to the first byte after the jump. In an unconditional jump only 1 byte is used to identify it as a long unconditional jump and the other 4 are used to show it's target's relative position, as with the conditional jumps.

Calls
There are two different types of calls which we will use. The normal type of call works the same as the long jumps in that it is relative to it's current position. The other type gives a reference to a memory location, register or stack position which holds the memory location it will call. The position held by the later is direct e.g. the memory location referenced may contain 401036h which would be the exact position that you would call, not relative to the position of the call. The size of these types of calls depends on any calculations involved in the call i.e. you could do: 'call dword ptr [eax * edx + 2]'. Long jumps can also be made using this method, but I didn't say that earlier as to avoid repetition.

Tables
Here is a brief list of all the different types of jumps/calls and their appropriate op-codes. Where different jumps have the same Op-Codes I have grouped them:

Jump Description Short Op-Code Long Op-Code
call procedure call E8xxxxxxxx N/A
jmp u nconditional jump EBxx E9xxxxxxxx
ja/jnbe jump if above 77xx 0F87xxxxxxxx
jae/jnb/jnc jump if above or equal 73xx 0F83xxxxxxxx
jb/jc/jnae jump if below 72xx 0F82xxxxxxxx
jbe/jna jump if below or equal 76xx 0F86xxxxxxxx
jcxz/jecxz jump if cx/ecx equals zero E3xx N/A
je/jz jump if equal/zero 74xx 0F84xxxxxxxx
jne/jnz jump if not equal/zero 75xx 0F85xxxxxxxx
jg/jnle jump if greater 7Fxx 0F8Fxxxxxxxx
jge/jnl jump if greater or equal 7Dxx 0F8Dxxxxxxxx
jl/jnge jump if less 7Cxx 0F8Cxxxxxxxx
jle/jng jump if less or equal 7Exx 0F8Exxxxxxxx
jno jump if not overflow 71xx 0F81xxxxxxxx
jnp/jpo jump if no parity/parity odd 7Bxx 0F8Bxxxxxxxx
jns jump if not signed 79xx 0F89xxxxxxxx
jo jump if overflow 70xx 0F80xxxxxxxx
jp/jpe jump if parity/parity even 7Axx 0F8Axxxxxxxx
js jump if sign 78xx 0F88xxxxxxxx



Calculating Offsets (finding in the xx's in table)

You will need to be able to calculate offsets when you add jumps and make calls within and to the code you have added. If you choose to do this by hand instead of using a tool then here are the basics:

For jumps and calls further on in memory from your current position you take the address where you want to jump/call and subtract from it the memory location of the next instruction after your call/jump i.e.:

(target mem address) - (mem location of next instruction after call/jump)

Example
If we wanted to jump to 4020d0 and the next instruction *after* the jump is at location 401093 then we would use the following calculation:

4020d0 - 401093 = 103d

We then write the jump instruction in hex as e93d100000 where e9 is the hex op-code for a long relative jump and 3d100000 is the result of our calculation expanded to dword size and reversed.

For jumps and calls to locations *before* the current location in memory you take the address you want to call/jump to and subtract it from the memory location of the next instruction after your call/jump, then subtract 1 and finally perform a logical NOT on the result i.e.

NOT(mem address of next instruction - target mem address - 1)

Example
If we wanted to call location 401184 and the address of the next instruction after the call is 402190 then we do the following calculation:

NOT(402190 - 401184 - 1 ) = ffffeff4

We can then write our call instruction in hex as e8f4efffff where e8 is the hex op-code for relative call and f4efffff is the result of the calculation in reverse order.

If you want to practice with different examples then the best way to do this is to use a disassembler like WDASM which shows you the op-codes and try and work out the results yourself. Also as an end note you don't have to perform these calculations if you have enough room to make your jump or call instruction into an absolute jump call by doing the following as represented in assembler:

mov eax, 4020d0
call eax (or jmp eax)

Final Notes

Make life easier and use a program to do this ;-)