SYNOPSIS

ipa-client-install [OPTION]...

DESCRIPTION

Configures a client machine to use IPA for authentication and identity services.

By default this configures SSSD to connect to an IPA server for authentication and authorization. Optionally one can instead configure PAM and NSS (Name Switching Service) to work with an IPA server over Kerberos and LDAP.

An authorized user is required to join a client machine to IPA. This can take the form of a kerberos principal or a one-time password associated with the machine.

This same tool is used to unconfigure IPA and attempts to return the machine to its previous state. Part of this process is to unenroll the host from the IPA server. Unenrollment consists of disabling the principal key on the IPA server so that it may be re-enrolled. The machine principal in /etc/krb5.keytab (host/<fqdn>@REALM) is used to authenticate to the IPA server to unenroll itself. If this principal does not exist then unenrollment will fail and an administrator will need to disable the host principal (ipa host-disable <fqdn>).

Assumptions

The ipa-client-install script assumes that the machine has already generated SSH keys. It will not generate SSH keys of its own accord. If SSH keys are not present (e.g when running the ipa-client-install in a kickstart, before ever running sshd), they will not be uploaded to the client host entry on the server.

Hostname Requirements

Client must use a static hostname. If the machine hostname changes for example due to a dynamic hostname assignment by a DHCP server, client enrollment to IPA server breaks and user then would not be able to perform Kerberos authentication.

--hostname option may be used to specify a static hostname that persists over reboot.

DNS Autodiscovery

Client installer by default tries to search for _ldap._tcp.DOMAIN DNS SRV records for all domains that are parent to its hostname. For example, if a client machine has a hostname 'client1.lab.example.com', the installer will try to retrieve an IPA server hostname from _ldap._tcp.lab.example.com, _ldap._tcp.example.com and _ldap._tcp.com DNS SRV records, respectively. The discovered domain is then used to configure client components (e.g. SSSD and Kerberos 5 configuration) on the machine.

When the client machine hostname is not in a subdomain of an IPA server, its domain can be passed with --domain option. In that case, both SSSD and Kerberos components have the domain set in the configuration files and will use it to autodiscover IPA servers.

Client machine can also be configured without a DNS autodiscovery at all. When both --server and --domain options are used, client installer will use the specified server and domain directly. --server option accepts multiple server hostnames which can be used for failover mechanism. Without DNS autodiscovery, Kerberos is configured with a fixed list of KDC and Admin servers. SSSD is still configured to either try to read domain's SRV records or the specified fixed list of servers. When --fixed-primary option is specified, SSSD will not try to read DNS SRV record at all (see sssd-ipa(5) for details).

The Failover Mechanism

When some of the IPA servers is not available, client components are able to fallback to other IPA replica and thus preserving a continued service. When client machine is configured to use DNS SRV record autodiscovery (no fixed server was passed to the installer), client components do the fallback automatically, based on the IPA server hostnames and priorities discovered from the DNS SRV records.

If DNS autodiscovery is not available, clients should be configured at least with a fixed list of IPA servers that can be used in case of a failure. When only one IPA server is configured, IPA client services will not be available in case of a failure of the IPA server. Please note, that in case of a fixed list of IPA servers, the fixed server lists in client components need to be updated when a new IPA server is enrolled or a current IPA server is decommissioned.

Coexistence With Other Directory Servers

Other directory servers deployed in the network (e.g. Microsoft Active Directory) may use the same DNS SRV records to denote hosts with a directory service (_ldap._tcp.DOMAIN). Such DNS SRV records may break the installation if the installer discovers these DNS records before it finds DNS SRV records pointing to IPA servers. The installer would then fail to discover the IPA server and exit with error.

In order to avoid the aforementioned DNS autodiscovery issues, the client machine hostname should be in a domain with properly defined DNS SRV records pointing to IPA servers, either manually with a custom DNS server or with IPA DNS integrated solution. A second approach would be to avoid autodiscovery and configure the installer to use a fixed list of IPA server hostnames using the --server option and with a --fixed-primary option disabling DNS SRV record autodiscovery in SSSD.

Re-enrollment of the host

Requirements:

1. Host has not been un-enrolled (the ipa-client-install --uninstall command has not been run).
2. The host entry has not been disabled via the ipa host-disable command.

If this has been the case, host can be re-enrolled using the usual methods.

There are two method of authenticating a re-enrollment:

1. You can use --force-join option with ipa-client-install command. This authenticates the re-enrollment using the admin's credentials provided via the -w/--password option.
2. If providing the admin's password via the command line is not an option (e.g you want to create a script to re-enroll a host and keep the admin's password secure), you can use backed up keytab from the previous enrollment of this host to authenticate. See --keytab option.

Consequences of the re-enrollment on the host entry:

1. A new host certificate is issued
2. The old host certificate is revoked
3. New SSH keys are generated
4. ipaUniqueID is preserved

OPTIONS

BASIC OPTIONS

--domain=DOMAIN

Set the domain name to DOMAIN. When no --server option is specified, the installer will try to discover all available servers via DNS SRV record autodiscovery (see DNS Autodiscovery section for details).

--server=SERVER

Set the IPA server to connect to. May be specified multiple times to add multiple servers to ipa_server value in sssd.conf or krb5.conf. Only the first value is considered when used with --no-sssd. When this option is used, DNS autodiscovery for Kerberos is disabled and a fixed list of KDC and Admin servers is configured.

--realm=REALM_NAME

Set the IPA realm name to REALM_NAME. Under normal circumstances, this option is not needed as the realm name is retrieved from the IPA server.

--fixed-primary

Configure SSSD to use a fixed server as the primary IPA server. The default is to use DNS SRV records to determine the primary server to use and fall back to the server the client is enrolled with. When used in conjunction with --server then no _srv_ value is set in the ipa_server option in sssd.conf.

-p, --principal

Authorized kerberos principal to use to join the IPA realm.

-w PASSWORD, --password=PASSWORD

Password for joining a machine to the IPA realm. Assumes bulk password unless principal is also set.

-W

Prompt for the password for joining a machine to the IPA realm.

-k, --keytab

Path to backed up host keytab from previous enrollment. Joins the host even if it is already enrolled.

--mkhomedir

Configure PAM to create a users home directory if it does not exist.

--hostname

The hostname of this machine (FQDN). If specified, the hostname will be set and the system configuration will be updated to persist over reboot. By default a nodename result from uname(2) is used.

--force-join

Join the host even if it is already enrolled.

--ntp-server=NTP_SERVER

Configure ntpd to use this NTP server.

-N, --no-ntp

Do not configure or enable NTP.

--force-ntpd

Stop and disable any time&date synchronization services besides ntpd.

--nisdomain=NIS_DOMAIN

Set the NIS domain name as specified. By default, this is set to the IPA domain name.

--no-nisdomain

Do not configure NIS domain name.

--ssh-trust-dns

Configure OpenSSH client to trust DNS SSHFP records.

--no-ssh

Do not configure OpenSSH client.

--no-sshd

Do not configure OpenSSH server.

--no-sudo

Do not configure SSSD as a data source for sudo.

--no-dns-sshfp

Do not automatically create DNS SSHFP records.

--noac

Do not use Authconfig to modify the nsswitch.conf and PAM configuration.

-f, --force

Force the settings even if errors occur

-d, --debug

Print debugging information to stdout

-U, --unattended

Unattended installation. The user will not be prompted.

--ca-cert-file=CA_FILE

Do not attempt to acquire the IPA CA certificate via automated means, instead use the CA certificate found locally in in CA_FILE. The CA_FILE must be an absolute path to a PEM formatted certificate file. The CA certificate found in CA_FILE is considered authoritative and will be installed without checking to see if it's valid for the IPA domain.

--automount-location=LOCATION

Configure automount by running ipa-client-automount(1) with LOCATION as automount location.

SSSD OPTIONS

--permit

Configure SSSD to permit all access. Otherwise the machine will be controlled by the Host-based Access Controls (HBAC) on the IPA server.

--enable-dns-updates

This option tells SSSD to automatically update DNS with the IP address of this client.

--no-krb5-offline-passwords

Configure SSSD not to store user password when the server is offline.

-S, --no-sssd

Do not configure the client to use SSSD for authentication, use nss_ldap instead.

--preserve-sssd

Disabled by default. When enabled, preserves old SSSD configuration if it is not possible to merge it with a new one. Effectively, if the merge is not possible due to SSSDConfig reader encountering unsupported options, ipa-client-install will not run further and ask to fix SSSD config first. When this option is not specified, ipa-client-install will back up SSSD config and create new one. The back up version will be restored during uninstall.

UNINSTALL OPTIONS

--uninstall

Remove the IPA client software and restore the configuration to the pre-IPA state.

-U, --unattended

Unattended uninstallation. The user will not be prompted.

FILES

Files that will be replaced if SSSD is configured (default):

/etc/sssd/sssd.conf

Files that will be replaced if they exist and SSSD is not configured (--no-sssd):

/etc/ldap.conf
/etc/nss_ldap.conf
/etc/libnss-ldap.conf
/etc/pam_ldap.conf
/etc/nslcd.conf

Files replaced if NTP is enabled:

/etc/ntp.conf
/etc/sysconfig/ntpd
/etc/ntp/step-tickers

Files always created (replacing existing content):

/etc/krb5.conf
/etc/ipa/ca.crt
/etc/ipa/default.conf
/etc/openldap/ldap.conf

Files updated, existing content is maintained:

/etc/nsswitch.conf
/etc/pki/nssdb
/etc/krb5.keytab
/etc/sysconfig/network