NAME

       ssh_filter_btrbk - 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", "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" ssh-rsa AAAAB3NzaC1...hwumXFRQBL btrbk@mydomain.com

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.

       -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

       btrbk(1), btrbk.conf(5), btrfs(8)

AUTHOR

       Axel Burri axel@tty0.ch