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Why is he making a packer?
by drudru11 6y ago
Why is he making a packer?
- royjacobs 6y agoThe better question is, why not?
- scintill76 6y ago> amos loves to tinker
- killercup 6y agoStart at part 1. No, he doesn't give you an answer, but you might just find it interesting enough to no longer have the qusstion.
- chrisseaton 6y agoI don’t understand what a ‘packer’ is - is it a linker?
- rustybolt 6y agoFrom what I understand, it's something that 'packs' an application, either to preserve space or to obfuscate it (making it a little bit harder to reverse engineer it since you have to peek at the extracted contents in the memory instead of at the file contents). So when you would run a packed application, there application would essentially start to unpack an encrypted/compressed blob of memory, and then jump to it once it's unpacked.
- haecceity 6y agoIt compresses executables.
- killercup 6y ago> I don’t understand what a ‘packer’ is You've found the right series of articles then!
- chrisseaton 6y agoI read it - I did't find an explanation of what it was that he was building, just how he was building it.
- saagarjha 6y agoThink of it of decompression software bundled along with a compressed version of the program you actually want to run. So execution starts in the uncompression part, it unzips all the code into memory, and then starts running the program you actually cared about.
- abiogenesis 6y agoSee https://en.wikipedia.org/wiki/Executable_compression https://en.wikipedia.org/wiki/Executable_compression . They have been around since forever.
- icedchai 6y agoPackers were common in the 80's and 90's to save disk space. I mostly remember them from Amiga warez and demos.
- chadcmulligan 6y agoThe first few paragraphs on the first part explains it? Executables have been fascinating to me ever since I discovered, as a kid, that they were just files. If you renamed a .exe to something else, you could open it in notepad! And if you renamed something else to a .exe, you'd get a neat error dialog. Clearly, something was different about these files. Seen from notepad, they were mostly gibberish, but there had to be order in that chaos. 12-year-old me knew that, although he didn't quite know how or where to dig to make sense of it all. So, this series is dedicated to my past self. In it we'll attempt to understand how Linux executables are organized, how they are executed, and how to make a program that takes an executable fresh off the linker and compresses it - just because we can.