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samba

The Samba module allows to install one or more AD domains in a NS8 cluster. An AD domain (or realm, in Kerberos terms), can have one or more domain controllers (DCs). Provisioning a new domain and joining an additional domain controller to an existing domain are both implemented by the same action: configure-module.

A Samba DC requires a dedicated IP address. Two DCs cannot share the same IP.

Do not assign the IP address of a untrusted network! The IP address assigned to Samba DC exposes internal services that are not designed to be exposed publicly. The IP address can be added to the cluster VPN routes, so DCs can see each other and perform replication.

The LDAP service of Samba DCs does not allow clear-text LDAP binds: enable TLS or use Kerberos/GSSAPI authentication in external applications. Applications that run as cluster modules must connect to the LDAP service of Samba DCs through the Ldapproxy instance running on the local node; read the core documentation for more information about Ldapproxy.

Installation

A Samba module instance is also an account provider. It must be installed with the specific add-internal-provider action:

api-cli run add-internal-provider --data '{"image":"samba","node":1}'

Provision

For example, to provision a new domain:

api-cli run module/samba1/configure-module --data - <<EOF
{
    "provision":"new-domain",
    "adminuser":"administrator",
    "adminpass":"Nethesis,1234",
    "realm":"ad.$(hostname -d)",
    "nbdomain":"DP",
    "hostname":"dc1",
    "ipaddress":"10.133.0.2"
}
EOF

Further Samba instances for the same realm can be joined to the existing domain. The command is similar.

api-cli run module/samba2/configure-module --data - <<EOF
{
    "provision":"join-domain",
    "adminuser":"administrator",
    "adminpass":"Nethesis,1234",
    "realm":"ad.$(hostname -d)",
    "hostname":"dc2",
    "ipaddress":"10.124.0.2"
}
EOF

IP routing for the AD domain

In multiple DCs domains, DCs must connect each other to join the domain and for data replication. If a DC cannot contact other DCs the provision procedure fails.

For this reason, if the IP of some domain controller is not in the routable networks of other nodes, then it is automatically configured to be routed through the cluster VPN. This typically happens if domain controllers reside in different networks.

Check the IP addresses of domain controllers are routed through the VPN with the following commands:

wg
ip route

The following command applies the necessary changes to the system routing table and to the Wireguard runtime configuration. It is automatically executed at system startup and when the VPN configuration changes, so manual execution should not be needed:

apply-vpn-routes

See also the Core VPN documentation.

Create a new user account

Create a new user and assign it to the developers group

api-cli run module/samba1/add-user --data - <<EOF
{
  "user": "alice",
  "display_name": "Alice Jordan",
  "password": "secret",
  "locked": false,
  "groups": [
      "developers"
  ]
}
EOF

User management web portal

The samba module provides a public web portal where AD users can authenticate and change their passwords.

The module registers a Traefik path route, with the domain name as suffix. For instance:

https://<node FQDN>/users-admin/domain.test/

The backend endpoint is advertised as users-admin service and can be discovered in the usual ways, as documented in Service discovery. For instance:

api-cli run module/mymodule1/list-service-providers  --data '{"service":"users-admin", "filter":{"domain":"dp.nethserver.net","node":"1"}}'

The event service-users-admin-changed is raised when the serivice becomes available or is changed.

The backend of the module runs under the api-moduled.service Systemd unit supervision. Refer also to api-moduled documentation, provided by ns8-core repository.

API implementation code is under imageroot/api-moduled/handlers/, which is mapped to an URL like

https://<node FQDN>/users-admin/domain.test/api/

The .json files define the API input/output syntax validation, using the JSON schema language. As such they can give an idea of request/response payload structure.

File server

If Samba binds to the internal VPN interface (see ipaddress attribute in the Provision section) it is not reachable by clients in other networks.

On the contrary, a Samba instance can be used as a file server from Windows-compatible clients and they can access shared folders and home directories with domain credentials (guest access does not work at all).

  • Whenever a user session is established the user's home directory is created in the homes volume.

  • To create and manage shared folders, use the file server API. Shared folders are stored in the shares volume. If a shared folder has the same name of a domain user, the home directory of that user is no longer accessible.

    • list-shares
    • add-share, alter-share, remove-share
    • reset-share-acls

Restore from backup

The module backup contains shared folders, home dirs and DC state.

For a single DC domain, run the restore on a system with the original DC IP address. If this is not the case, the restore procedure configures the restored DC with the node VPN IP address. Then use set-ipaddress action to change the DC IP address. Network clients must be reconfigured to find the AD DNS server! For instance:

api-cli run module/samba1/set-ipaddress --data '{"ipaddress": "10.15.21.100"}'

In a domain with multiple domain controllers, DC state is replicated. In case of a node failure it is not necessary to restore from backup unless the failing node is also a file server. In this case the restore procedure only extracts the contents of home directories and shared folders from the backup set. When the procedure completes, go to the Domain and users page and resume the configuration of the DC: it must be joined to the domain as a new DC.

Migration notes

Migration is implemented in the import-module action.

  • The NS7 DC role is transferred to NS8 by copying /var/lib/samba dir contents. The NS7 file-server role can be transferred to NS8 too.
  • If file-server role is migrated, the host name is retained as a NetBIOS alias and a DNS CNAME record, pointing to the DC host name.
  • The migration procedure synchronizes the existing Posix ACLs of shared folders. A special backward-compatible configuration is applied to shares created by the migration procedure. The samba-reset-acls command clears that special configuration, too.
  • Home directories are migrated like shared folders. Shared folders have higher priority over home dirs: if a shared folder has the same name of a domain user, the home directory cannot be accessed.
  • Guest access does not work in NS8, because it is not implemented by the Samba DC role
  • user.SAMBA_PAI attribute is not copied to NS8 shares. It contains the ACL protected/don't inherit flag. See map acl inherit.