ssh_filter_btrbk(1)
===================
:date: 2026-07-19
:release-version: 0.32.7
:man manual: Btrbk Manual
:man source: Btrbk {release-version}


NAME
----

ssh_filter_btrbk - ssh command filter script for btrbk


SYNOPSIS
--------

[verse]
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
--------

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


AUTHOR
------

Axel Burri <axel@tty0.ch>
