Securely copying with escalated privileges with rsync

| tagged with
  • rsync
  • sudo
  • ssh

Securely copying with escalated privileges with rsync

Recently I had to migrate some files from one machine to another. As usual, rsync was the first tool I reached for, but a few considerations complicated matters: 1. both the source and destination locations required escalated privileges to access 2. remote root logins were not allowed on either machine, ruling out sudo rsync $path root@$dest 3. passwordless sudo was not allowed on either machine, ruling out sudo rsync --rsync-path='sudo rsync'.

Consequently, the solution here is to use rsync’s daemon mode. However, it’s obviously undesireable to start a privileged rsync daemon on the open internet. For this reason, we run the rsync daemon over an ssh tunnel. Here is how,

  1. on the destination: ssh -L 9000:127.0.0.1:9000 \$src_host
  2. on the source: create an rsyncd.conf, $ cat >rsyncd.conf <<EOF use chroot = false port = 9000 [src] path = $src_path uid = $user gid = $group EOF
  3. on the source: sudo rsync --daemon --config=rsyncd.conf --no-detach
  4. on the destination: sudo rsync -a --info=progress2 rsync://127.0.0.1:9000:\$src_path \$dest_path