Windows – How to Backup WSL Before System Reset or Reinstall

My preferred way of backing up a remote virtual server is to simply copy files - the kernel is on the host anyway. Of course, you will have to exercise some care when restoring, and it may not be possible to do a full restore (unlike a disk image). On the other hand, it's easier to migrate to another server, such as a local one for testing.

Now, downloading lots of little files over a remote connection actually is quite slow, due to a lot of overhead. This is more significant if you are physically far away from the server. Normally, I prefer to bundle everything into a single tar archive, and then compress it for a smaller size.

The command for this is tar cpzf filename.tar.gz / (where / means back up everything from the root recursively). you may wish to exclude existing backup files - if you plan to keep a lot of backups, it would be easier to put them all in one directory and exclude that directory. Then you just need to download that file with any method you like.

Restoring would be with the command tar xpf filename.tar while in the root directory. You can also specify the target directory with -C.

I'm copying the answer given in another similar thread (https://stackoverflow.com/a/50942800/9966057).

It's no use trying to tweak your session setup.

Full answer : https://github.com/Microsoft/WSL/issues/3183

Short version : ssh-agent forwarding is broken by a getsockopt bug in wsl / ubuntu 18.04 (or any other linux I would imagine).