SYSTEMD-HOMED.SERVICE(8)

NAME
systemd-homed.service, systemd-homed - Home Area/User Account Manager

SYNOPSIS

systemd-homed.service

/usr/lib/systemd/systemd-homed

DESCRIPTION

systemd-homed is a system service that may be used to create, remove, change or inspect home areas (directories and network mounts and real or loopback block devices with a filesystem, optionally encrypted).

Most of systemd-homed's functionality is accessible through the homectl(1) command.

See the Home Directories[1] documentation for details about the format and design of home areas managed by systemd-homed.service.

Each home directory managed by systemd-homed.service synthesizes a local user and group. These are made available to the system using the User/Group Record Lookup API via Varlink[2], and thus may be browsed with userdbctl(1).

systemd-homed.service also manages blob directories for each home directory it manages. See User Record Blob Directories[3] for more details.

KEY MANAGEMENT

User records are cryptographically signed with a public/private key pair (the signature is part of the JSON record itself). For a user to be permitted to log in locally the public key matching the signature of their user record must be installed. For a user record to be modified locally the private key matching the signature must be installed locally, too. The keys are stored in the /var/lib/systemd/home/ directory:

/var/lib/systemd/home/local.private
    The private key of the public/private key pair used for local records. Currently, only a single such key may be installed.

    Added in version 246.

/var/lib/systemd/home/local.public
    The public key of the public/private key pair used for local records. Currently, only a single such key may be installed.

    Added in version 246.

/var/lib/systemd/home/*.public
    Additional public keys. Any users whose user records are signed with any of these keys are permitted to log in locally. An arbitrary number of keys may be installed this way.

    Added in version 246.

All key files listed above are in PEM format.

In order to migrate a home directory from a host "foobar" to another host "quux" it is hence sufficient to copy /var/lib/systemd/home/local.public from the host "foobar" to "quux", maybe calling the file on the destination /var/lib/systemd/home/foobar.public, reflecting the origin of the key. If the user record should be modifiable on "quux" the pair /var/lib/systemd/home/local.public and /var/lib/systemd/home/local.private need to be copied from "foobar" to "quux", and placed under the identical paths there, as currently only a single private key is supported per host. Note of course that the latter means that user records generated/signed before the key pair is copied in, lose their validity.

SEE ALSO

systemd(1), homed.conf(5), homectl(1), pam_systemd_home(8), userdbctl(1), org.freedesktop.home1(5)

NOTES

1.  Home Directories
    https://systemd.io/HOME_DIRECTORY

2.  User/Group Record Lookup API via Varlink
    https://systemd.io/USER_GROUP_API

3.  User Record Blob Directories
    https://systemd.io/USER_RECORD_BLOB_DIRS