Avira Antivir Rescue over PXE

What you need:

• A working PXE system with PXELinux
  
• A linux environment (a live cd will do)
  
• 7zip
  

Now, here's what you need to do! Don't worry, those are easy steps. I've included too many rather that not enough, along with comments so you understand each one of them. If all goes well, you'll be done in 15 minutes.

1. Download rescue_system-common-en.exe from Avira website (unless you can download the ISO, in this case download it and go to step 4)
   
   
2. Use 7zip to extract the content of rescue_system-common-en.exe to a temporary folder.
   
   
3. There should be a large file in ".rsrc\RCDATA". This is an ISO file.
   
   
4. Use 7zip to extract the content of the large file to another temporary folder (rename the file with the ".iso" extention if needed)
   
   Avira Rescue scans for its scanner files on local devices (such as CD) and copies them to its local filesystem. But with PXE, the only thing available is vmlinuz and initrd.gz. We'll be tweaking the latter to include those files as Avira Rescue does not support NFS (although it does support wget but that's another story and needs a web server).
   
   Now, start your Linux environment and get access to the extracted iso files, where initrd.gz is located. We need to unzip it, resize it so there's space left for updates, mount it, include the needed files in it, unmount it, and zip it back.
   
   
5. Everything should be done as root
   su
   
   
6. Unzip initrd
   gzip -d initrd.gz
   
   
7. Add 50MB of free space to initrd
   dd if=/dev/zero bs=1M count=50 >> initrd
   
   
8. Check the file to make sure everything's fine and fix anything wrong
   e2fsck -fp initrd
   
   
9. Make the filesystem included in initrd use the extra space
   resize2fs initrd
   
   
10. Make a temporary mount location
    mkdir iso
    
    
11. Mounts the initrd filesystem to iso
    mount -o loop initrd iso
    
    
12. Go into the iso folder and there, make this directory tree (Case sensitive):
    media/Devices/pxe
    
    
13. In the extracted ISO files, there should be a folder named "Antivir". Always as root, copy the entire content of this folder to the pxe folder you just made.
    
    
14. In the pxe folder, do the following to make sure the antivir file locaded in the pxe folder is executable!
    chmod a+x antivir
    
    
15. Now leave the iso folder
    
    
16. Unmount the filesystem
    umount iso
    
    
17. This will tell you the size of initrd. Take note of it.
    ls -lk initrd
    
    
18. Zip the initrd file using maximum compression.
    gzip -9 initrd
    
    
19. Now, copy the newly tweaked initrd.gz file, AND the original vmlinuz file form the extracted iso files to your PXE server.
    
    
20. edit your pxelinux.cfg/default (or whatever) file and add an entry based on this one:
    

    label 1
    MENU LABEL ^Antivir Rescue System
    KERNEL antivir/vmlinuz
    APPEND vga=769 initrd=antivir/initrd.gz ramdisk_size=185000 root=/dev/ram0 rw console=/dev/vc/4

    
    
21. Change the value of "ramdisk_size" to the value noted at step 17 plus a few. I had 184747 so I put 185000.
    Note: At this stage, you could also look at the isolinux.cfg file located in the extracted iso for some more boot options.
    

And voilà, you should have a working Antivir Rescue working over PXE!

Thanks go to:
NiteHawk for helping me out in this thread
Avira for choosing Linux as a base system for your tool! FREEDOM!!!