Autentisering via LDAP och Kerberos i FreeBSD 10

Denna guide visar hur man sätter upp autentisering via LDAP/Kerberos i FreeBSD 10. Vi kommer använda SSSD och i guiden heter Kerberos realm EXAMPLE.COM och servern med Kerberos och LDAP heter ns.example.com. Klienten vi sätter upp heter client.example.com.

Installera SSSD

Installera följande:

root # portmaster security/cyrus-sasl2-gssapi

Välj Heimdal från systemetet, dvs BASE.

root # portmaster net/openldap24-sasl-client

Välj GSSAPI. Slutligen installera SSSD:

root # portmaster security/sssd

Kerberos

Editera /etc/krb5.conf:

[libdefaults]
    default_realm = EXAMPLE.COM

[realms]
    EXAMPLE.COM = {
        kdc = ns.example.com
        admin_server = ns.example.com
        default_domain = example.com
    }

[domain_realm]
    .example.com = EXAMPLE.COM
    example.com = EXAMPLE.COM

Skapa en keytab fil för klienten. Logga in mot din KDC med admin-konto som har rättighet att skapa Kerberos principals:

root # /usr/local/bin/kadmin -p kadmin/admin

Kör kadmin kommandot:

kadmin: addprinc -randkey host/client.example.com@EXAMPLE.COM

Spara sen nycklarna i filen /etc/krb5.keytab:

kadmin: ktadd -k /etc/krb5.keytab host/client.example.com@EXAMPLE.COM

Logga ut från kadmin.

PAM

Editera /etc/pam.d/system:

# auth
auth            sufficient      pam_opie.so		no_warn no_fake_prompts
auth            requisite       pam_opieaccess.so	no_warn allow_local
auth            sufficient      /usr/local/lib/pam_sss.so forward_pass
#auth           sufficient      pam_krb5.so		no_warn try_first_pass
#auth           sufficient      pam_ssh.so		no_warn try_first_pass
auth            required        pam_unix.so		no_warn try_first_pass nullok

# account
account         required        /usr/local/lib/pam_sss.so ignore_unknown_user ignore_authinfo_unavail
#account        required        pam_krb5.so
account         required        pam_login_access.so
account         required        pam_unix.so

# session
#session        optional        pam_ssh.so		want_agent
session         required        pam_lastlog.so		no_fail

# password
password        sufficient      /usr/local/lib/pam_sss.so use_authtok
#password       sufficient      pam_krb5.so		no_warn try_first_pass
password        required        pam_unix.so		no_warn try_first_pass

Editera /etc/pam.d/sshd:

# auth
auth            sufficient	pam_opie.so		no_warn no_fake_prompts
auth            requisite	pam_opieaccess.so	no_warn allow_local
auth            sufficient      /usr/local/lib/pam_sss.so forward_pass
#auth           sufficient	pam_krb5.so		no_warn try_first_pass
auth            sufficient	pam_ssh.so		no_warn try_first_pass
auth            required	pam_unix.so		no_warn try_first_pass

# account
account         required	pam_nologin.so
account         required        /usr/local/lib/pam_sss.so ignore_unknown_user ignore_authinfo_unavail
#account        required	pam_krb5.so
account         required	pam_login_access.so
account         required	pam_unix.so

# session
#session        optional	pam_ssh.so		want_agent
session         required	pam_permit.so

# password
password        sufficient      /usr/local/lib/pam_sss.so use_authtok
#password       sufficient	pam_krb5.so		no_warn try_first_pass
password        required	pam_unix.so		no_warn try_first_pass

NSS

Editera /etc/nsswitch.conf:

group: files sss
passwd: files sss

Radera länken /etc/ssl/cert.pem och ersätt med ditt egna CA certifikat.

SSSD

Editera /usr/local/etc/sssd/sssd.conf:

[sssd]
config_file_version = 2
services = nss, pam
domains = LOCAL, EXAMPLE.COM

[nss]
filter_groups = root
filter_users = root
reconnection_retries = 3
entry_cache_timeout = 300
entry_cache_nowait_percentage = 75
#override_shell = /usr/local/bin/bash
#override_homedir = /usr/home/%u

[pam]
reconnection_retries = 3

[domain/LOCAL]
id_provider = local
auth_provider = local
access_provider = permit

[domain/EXAMPLE.COM]
debug_level = 0
min_id = 5000
cache_credentials = true

id_provider = ldap
auth_provider = krb5
chpass_provider = krb5
access_provider = simple
sudo_provider = none

ldap_uri = ldap://ns.example.com
ldap_search_base = dc=example,dc=com
ldap_id_use_start_tls = true
ldap_tls_cacert = /etc/ssl/cert.pem

krb5_realm = EXAMPLE.COM
krb5_server = ns.example.com
krb5_kpasswd = ns.example.com

Skydda filen:

root # chmod 600 /usr/local/etc/sssd/sssd.conf

Editera /etc/rc.conf:

sssd_enable="YES"

Starta sssd:

root # service sssd start

Verifiera med kommandona:

root # getent passwd <username>
root # getent group <groupname>

SSH

För att kunna logga in med Kerberos ticket, editera filen /etc/ssh/sshd_config och ändra följande rad till:

GSSAPIAuthentication yes

Starta om sshd med kommandot:

root # service sshd restart