ssh_filter_btrbk - Man Page
ssh command filter script for btrbk
Synopsis
ssh_filter_btrbk.sh [-s|--source] [-t|--target] [-d|--delete] [-i|--info] [--snapshot] [--send] [--receive] [-p|--restrict-path <path>] [-l|--log] [--sudo]
Description
ssh_filter_btrbk.sh restricts SSH commands to commands used by btrbk. It examines the SSH_ORIGINAL_COMMAND environment variable (set by sshd) and executes it only if it contains commands used by btrbk.
The accepted commands are specified by the "--source", "--target", "--delete" and "--info" options.
The following commands are always allowed:
- "btrfs subvolume show" (not affected by "--restrict-path")
- "btrfs subvolume list" (not affected by "--restrict-path")
- "readlink"
- "test -d" (only if "compat busybox" configuration option is set)
- "cat /proc/self/mountinfo"
- pipes through "gzip", "pigz", "bzip2", "pbzip2", "bzip3", "xz", "lzop", "lz4", "zstd" (stream_compress)
- pipes through "mbuffer" (stream_buffer, rate_limit)
Example line in /root/.ssh/authorized_keys on a backup target host:
command="ssh_filter_btrbk.sh --target --delete --restrict-path /mnt/btr_backup",restrict ssh-rsa AAAAB3NzaC1...hwumXFRQBL btrbk@example.org
Options
- -s, --source
Allow commands for backup source: "btrfs subvolume snapshot", "btrfs send". Equivalent to "--snapshot --send".
- -t, --target
Allow commands for backup and archive target: "btrfs receive", "mkdir".
- -d, --delete
Allow commands for subvolume deletion: "btrfs subvolume delete". This is used for backup source if snapshot_preserve_daily is not set to “all”, and for backup targets if target_preserve_daily is not set to “all”.
- -i, --info
Allow informative commands: "btrfs subvolume find-new", "btrfs filesystem usage". This is used by btrbk info and diff commands.
- --snapshot
Allow btrfs snapshot command: "btrfs subvolume snapshot".
- --send
Allow btrfs send command: "btrfs send".
- --receive
Allow btrfs receive command: "btrfs receive".
- -p, --restrict-path <path>
Restrict commands to <path>. Note that "btrfs subvolume show", "btrfs subvolume list" are NOT affected by this option.
It is not possible to restrict commands to exact subvolume names, as btrfs-receive(8) takes a <path> as argument (directory, not including the subvolume file name to be created, this is encoded in the send-stream).
- -l, --log
Log ACCEPT and REJECT messages to the system log.
- --sudo
Allow btrfs commands to be called via sudo. Enable this if you have "backend btrfs-progs-sudo" in your btrbk configuration file.
Availability
Please refer to the btrbk project page https://digint.ch/btrbk/ for further details.
See Also
Author
Axel Burri axel@tty0.ch