Debugging with gdb

Question

Can anybody provide tutorial on gdb for debugging executable.
Note: I m asking for debugging executable using the assembly code not from code( code file is not with me).
this is much used in
cracking passwords
fetching strings

Answer 1

That's just the same as debugging a binary with source code, except that you won't be able to break at specific line numbers, and if it's compiled without debugging symbols you're out of luck.