Modifying and Saving in IDA

Is it possible to add code to a current binary in IDA and then save then to recompile 开发者_如何学Pythonthe binary? I've looked over Google, but no suggestions as to whether IDA can do this. If not, whats the best to add some pretty heavy modifications to obsolete firmware?

Would I have to load in additional classes/functions from a file?

You can't recompile your source data file with IDA (the program's 'Create an EXE file' tool found in its main main doesn't do anything - It's basically stubbed with a message box telling the used that the selected output file type is not supported).

Your only option might be to compile your code with the source file's compiler, add a new segment to the source file's image where you dump your custom (compiled)code and patch the appropriate locations in the original code (.text) segment to call into your code. Have no clue if IDA supports the kind of static patching required for steps #2 and #3, but you'll probably find other tools to help you with that (you could start with OllyDbg).

I haven't ever tried to do anything of that sort before, so take my suggestion with a pinch of salt. I have however seen various binaries that have arbitrary segments attached to them.

EDIT: Take a look at this question while you are at it - IDA pro asm instructions change

when i have to do small updates on my binary, i like hexedit, kinda nice & options are easy. (small updates ;) )