/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/ is in ltsp-server 5.5.1-1ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/000-basic-configuration
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/000-daemon-handling
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/001-apt-keys
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/001-set-accept-unsigned-packages
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/001-set-arch
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/001-set-components
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/001-set-dist
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/001-set-mint-dist
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/002-cross-arch
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/005-tmpdir
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-apt-pinning
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-debconf-frontend
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-debconf-seeds
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-debootstrap
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-enable-popcon
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-etc-hostname
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-etc-mtab
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-http-proxy
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-manage-mirror
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-mount-devpts
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-serial-console
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-set-resolver
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-updates-mirrors
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/010-var-lib-nfs
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/015-sources-list
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/019-ltsp-cluster
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/020-apt-get-update
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/020-kernel-img-conf
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/020-kernel-selection
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/025-locales
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/030-artwork
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/030-default-lts-conf
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/030-early-packages
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/030-fat-client
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/030-kiosk
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/030-late-packages
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/030-loopback
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/035-apt-get-upgrade
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/035-copy-timezone
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/035-default-modules
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/035-install-debs
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/040-copy-package-cache
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/040-copy-package-lists
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/040-mount-package-cache
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/040-update-sshkeys
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/090-clean-package-cache
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/095-rootpass
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/095-update-image
/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/099-mount-cdrom