borg serve

borg [common options] serve [options]
optional arguments
  --restrict-to-path PATH restrict repository access to PATH. Can be specified multiple times to allow the client access to several directories. Access to all sub-directories is granted implicitly; PATH doesn’t need to directly point to a repository.
  --restrict-to-repository PATH restrict repository access. Only the repository located at PATH (no sub-directories are considered) is accessible. Can be specified multiple times to allow the client access to several repositories. Unlike --restrict-to-path sub-directories are not accessible; PATH needs to directly point at a repository location. PATH may be an empty directory or the last element of PATH may not exist, in which case the client may initialize a repository there.
  --append-only only allow appending to repository segment files. Note that this only affects the low level structure of the repository, and running delete or prune will still be allowed. See Append-only mode (forbid compaction) in Additional Notes for more details.
  --storage-quota QUOTA Override storage quota of the repository (e.g. 5G, 1.5T). When a new repository is initialized, sets the storage quota on the new repository as well. Default: no quota.

Common options

Description

This command starts a repository server process. This command is usually not used manually.

Examples

borg serve has special support for ssh forced commands (see authorized_keys example below): it will detect that you use such a forced command and extract the value of the --restrict-to-path option(s).

It will then parse the original command that came from the client, makes sure that it is also borg serve and enforce path restriction(s) as given by the forced command. That way, other options given by the client (like --info or --umask) are preserved (and are not fixed by the forced command).

Environment variables (such as BORG_XXX) contained in the original command sent by the client are not interpreted, but ignored. If BORG_XXX environment variables should be set on the borg serve side, then these must be set in system-specific locations like /etc/environment or in the forced command itself (example below).

# Allow an SSH keypair to only run borg, and only have access to /path/to/repo.
# Use key options to disable unneeded and potentially dangerous SSH functionality.
# This will help to secure an automated remote backup system.
$ cat ~/.ssh/authorized_keys
command="borg serve --restrict-to-path /path/to/repo",restrict ssh-rsa AAAAB3[...]

# Set a BORG_XXX environment variable on the "borg serve" side
$ cat ~/.ssh/authorized_keys
command="export BORG_XXX=value; borg serve [...]",restrict ssh-rsa [...]

Note

The examples above use the restrict directive. This does automatically block potential dangerous ssh features, even when they are added in a future update. Thus, this option should be preferred.

If you’re using openssh-server < 7.2, however, you have to explicitly specify the ssh features to restrict and cannot simply use the restrict option as it has been introduced in v7.2. We recommend to use no-port-forwarding,no-X11-forwarding,no-pty,no-agent-forwarding,no-user-rc in this case.