Using Windows to access Ext4 partitions

Pi Jessie has a FAT32 boot partition and this allows Windows to 'see' the basic system configuration files. However the rest of Jessie (including the network setup files) are all on the *nix Ext4 partition, which is 'invisible' to Windows.

In fact the Jessie .img creates 2 primary partitions on the SDHC card (first a FAT32 and then an Ext4). The current version (2016) of the Open Source ex2fsd project can only 'see' the first primary partition - and that's the FAT32 one - so it's of no use. Also useless is the Ext2 Installable File System For Windows (IFS driver) = it would usually show an Ext partition, but since it can't handle 2 primary partitions it shows nothing at all

The only software I have found capable of accessing (read/write) the Ext4 partition is Paragon ExtFS for Windows. This is 'commercial' software but the 'Free trial' version does the job (when the trial 'times out' it limits the read/write speed to 5mbs, but still has all the functionality you need).

Windows 7 (or later) users can install the current version, Paragon ExtFS for Windows (the 5Mbs free trial limitation won't stop you making edits). If you can't get it from Paragon, you can download it from here Windows XP users need the older version. One source that won't try to 'hi-jack' your PC (with some 'Driver Installer' or other Adware Trojan) is this German download site. If that link fails to work, right click, and 'save link as' Paragon_ExtFS_for_Windows_2.1.440.exe here.

On the first screen of the installer, I clicked the 'Registration' link to the Paragon web site and filled in my details - but when I clicked 'Submit' I got a 'page can't be displayed' error. However the Paragon web site did actually eMail me the required keys. Just in case it doesn't work for you, here are some I found on the web :-
PRODUCT KEY: PSG-278-PEE-PL-314774750
SERIAL NUMBER: 03002-CE51C-F17E4-40BCB

After install, WinPatrol will pop-up twice = once for the 'update service' (reject, unless you want Paragon to update you to the non-XP version :-) ) and again for the 'driver' (allow).

Note, you will need to reboot your PC to get the 'service' to launch correctly, after which the SDHC Ext4 partition should appear in Windows Explorer (My Computer) as a new drive letter

The 'ExtFS for Windows XP' Command GUI window will auto-assign drive letters to each Ext2/3/4 partition it finds. If you launch the GUI, it will ONLY show the disk(s) containing Ext partitions. The files and folders can then be accessed and written to by Windows 'as usual'.