Client Authentication:Fedora via sssd/ldap
Introduction
This how-to shows how to configure a SME-server (>=8b6) and a client Fedora (tested with F22 for this how-to) for a LDAP based SSSD authentication of the client machine on the configured user accounts of the SME. This way is more simple that the way via winbind Client Authentication:Fedora. Further more, the winbind method doesn't seem to work on a Fedora 22.
The SSSD authentication via LDAP allows to login with the SME-user accounts, even if the client machine is offline. Nevertheless, I recommend to create a local user with the admin rights for the emergency case.
These lines are a translation and an application of the method given by Daniel: https://wikit.firewall-services.com/doku.php/tuto/ipasserelle/authentification/fedora_sssd_on_sme. Many thanks to him for it.
In this how-to: we assume that:
the host name of the SME is "sme-server" and the domain is "domain.tld".
Configuration of the SME-server
There is quite no necessary configuration of the SME.
- The only thing to do is to create a user (named "auth" in this how-to) via the server-manager and to give him a valid password ("something_very_secret" in the how-to).
It is not required to make "auth" member of any group.
- In addition, it is recommended to install and configure PHPki in order to make the managing of the certificates easier and to allow Fedora to accept a non-official certificate of the authentication.
Configuration of the client Fedora
Installation
Install the OS as usual, without any particularity.
Add the necessary packages
dnf install oddjob-mkhomedir sssd policycoreutils-python
Preparare the /home folder
The “/home” folders of the users will be placed at the same place as on the SME (/home/e-smith/fies/users). This must be configured to avoid blocks from SELinux:
mkdir -p /home/e-smith/files/users/ semanage fcontext -a -e /home /home/e-smith/files/users restorecon -R /home/e-smith/files/users restorecon -R /var/lib/sss
Acive and enable the oddjobd daemon
This deamon will create the personal /home folders at the first login of the users.
systemctl start oddjobd.service systemctl enable oddjobd.service
Manage the CA of the SME
after having installed phpki, go to https://www.domain.tld/phpki and download on the client machine the certificate of authority (ca.crt).
Place a copy of it into /etc/phpki/tls/certs/ and give the 644 permissions:
cp ~/download/ca.crt /etc/phpki/tls/certs/ chmod 644 /etc/phpki/tls/certs/ca.crt
Place another copy of the ca into /etc/pki/ca-trust/source/anchors/ and install the certificate system wide:
cp ~/download/ca.crt /etc/pki/ca-trust/source/anchors/ update-ca-trust
(Note: to remove the ca systemwide: remove ca.crt from /etc/pki/ca-trust/source/anchors/ and run update-ca-trust again. See https://fedoraproject.org/wiki/Features/SharedSystemCertificates:Testing#How_to_add_a_systemwide_CA)
Configure SSSD
The configuration is made by the file /ets/sssd/sssd.conf. This file doesn't exist by default. Therefore it has to be created and it needs to get the permissions 600 to allow the daemon to start:
cat <<'_EOF' > /etc/sssd/sssd.conf [sssd] config_file_version = 2 services = nss, pam domains = LDAP [nss] [pam] [domain/LDAP] id_provider = ldap auth_provider = ldap ldap_schema = rfc2307 ldap_uri = ldap://sme-server.domain.tld ldap_default_bind_dn = uid=auth,ou=Users,dc=domain,dc=tld ldap_default_authtok = something_very_secret ldap_default_authtok_type = password ldap_search_base = dc=domain,dc=tld ldap_user_search_base = ou=Users,dc=domain,dc=tld ldap_group_search_base = ou=Groups,dc=domain,dc=tld ldap_user_object_class = inetOrgPerson ldap_user_gecos = cn ldap_tls_reqcert = hard ldap_tls_cacert = /etc/pki/tls/certs/ca.crt ldap_id_use_start_tls = true # uncomment below if the SME is a “iPasserelle” #ldap_user_shell = desktopLoginShell # comment below if the SME is a “iPasserelle” override_shell = /bin/bash cache_credentials = true enumerate = true # It is possible to filter the logins via a LDAP-filer # by commenting the both lines below. # In this exemple, only the users member of the group netusers # will be valid on this host. # posixMemberOF is a parameter only for a iPasserelle #access_provider = ldap #ldap_access_filter = (|(posixMemberOf=admins)(uid=backup)) _EOF chmod 600 /etc/sssd/sssd.conf
Start and enable the daemon sssd
- This daemon must be automatically started by running the client machine:
systemctl start sssd.service systemctl enable sssd.service
- You should check that sss is set as a source in the /etc/nsswitch.conf. Normally it has been done automatically
[...] passwd: files sss shadow: files sss group: files sss [...]
General configuration
- The system must be configured in order to use sssd.
This is done very easily by using the tool authconfig:
authconfig --enablemkhomedir --enablesssd --enablesssdauth --update
getent passwd
should show you the users of the SME.
If it doen't work:
- check first of all if the password of the user “auth” is present in clear by the parameter “ldap_default_authtok” of /etc/sssd/sssd.conf.
- Further more, for tests and debug, you can set “ldap_tls_reqcert = never” to avoid problems due to a non accepted CA.
Thats all. Enjoy!