[OllyDBG] Setting a break-point

Iamcoolz Jul 31, 2014

  1. Iamcoolz

    Iamcoolz Forum Administrator Staff Member XPG Administrator
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    What is up guys, another tutorial to help those to debug their programs!

    Breakpoints, what they are, how ollyDBG sets it and what it does!
    Breakpoints are specific instructions that monitor a certain address in code, these breakpoints allow developers to find bugs and errors in their code.

    Example:

    Developer A releases a new program, customer a tries to use it and it keeps failing to start, but most programs won't display an error message, the developer goes into the program, sets a breakpoint on the program as a whole, and then the program starts and wherever the crash is coming from, it will then show the developer where it is crashing, and hopefully he/she can fix that.

    OllyDBG has a feature in it that allows the user to set a breakpoint, all OllyDBG does when you set the program is it replaces the first byte (information) with a special instruction that would return an error to the developer i.e. - 0xCC. This little byte of information is known to OllyDBG and acts as a trap, to prevent the program from running any farther and identifying the bug up till that point.

    So to set a breaking point on Olly, it is fairly simple. Load up a program of any type in OllyDBG:

    [​IMG]

    Right click on the address, breakpoint, toggle or just click F2 on the address:

    [​IMG]

    After you click that, the adress will become red and this allows OllyDBG to identify it as a breakpoint and it won't allow the program to run any farther:

    [​IMG]

    This is a simple way of doing a breaking point.

    Enjoy XPG
     

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