SOLVED:  find automount maps in non-local AD domain.

All,

We solved this a couple of months ago; just took a while to get time to write it up.   We have automounts in our AD domains and autofs finds them. 

By default, autofs always looks in the local domain for its automount maps. 

We have an AD forest with 3 trusted regional subdomains.  Parent COMPANY.COM, with children: AMER.COMPANY.COM, APAC.COMPANY.COM and EMEA.COMPANY.COM. 

For boring historical reasons, we have all our automount maps in AMER child domain.  That works great for Linux servers in AMER.  But what about servers in APAC and EMEA?    You could replicate your automounts in all 3 child domains, but this is tedious and error-prone.  Instead,  you have to modify their sssd.conf file to coerce them to look in AMER for the automount maps.

So for servers in AMER, the sssd.conf file is pretty straightforward:

…

[sssd]

….

domains = amer.company.com

domain_resolution_order = amer.company.com, emea.company.com, apac.company.com, company.com

…

services = nss,pam,ifp,autofs

….

[autofs]

[domain/amer.company.com]

id_provider = ad

autofs_provider = ad

ldap_autofs_search_base = ou=automount,ou=UNIX,dc=AMER,dc=COMPANY,dc=COM

access_provider = simple

auth_provider = ad

ldap_sasl_authid = <fqdn>@AMER.COMPANY.COM

…

simple_allow_groups = …

# look at https://docs.pagure.org/SSSD.sssd/design_pages/subdomain_configuration.html

[domain/amer.company.com/company.com]

ldap_search_base = dc=COMPANY,dc=COM

[domain/amer.company.com/apac.company.com]

ldap_search_base = dc=APAC,dc=COMPANY,dc=COM

[domain/amer.company.com/emea.company.com]

ldap_search_base = dc=EMEA,dc=COMPANY,dc=COM

(Technically we don’t even need ldap_search_base for each child domain.  Sssd will look it up from each AD domain’s rootDSE.  But explaining to the average Linux SE what is an AD rootDSE and how to perform a rootDSE search to verify the search base?  That’s complicated.  It’s easier just to put ldap_search_base in for each child domain.)

Ok, so then for an EMEA sssd.conf, we have to invent a new sssd domain purely for autofs.  That new sssd domain is associated with the AMER child AD domain and the only provider it provides is the autofs_provider.

[sssd]

domains = emea.company.com, amer.autofs

…

domain_resolution_order = emea.company.com, amer.company.com, apac.company.com, company.com

services = nss,pam,ifp,autofs

…

[autofs]

[domain/emea.company.com]

…

id_provider = ad

auth_provider = ad

autofs_provider = none

…

ldap_sasl_authid = <fqdn>@EMEA.COMPANY.COM

ldap_search_base = dc=EMEA,dc=COMPANY,dc=COM

…

simple_allow_groups = …

# look at https://docs.pagure.org/SSSD.sssd/design_pages/subdomain_configuration.html

[domain/emea.company.com/company.com]

ldap_search_base = dc=COMPANY,dc=COM

[domain/emea.company.com/apac.company.com]

ldap_search_base = dc=APAC,dc=COMPANY,dc=COM

[domain/emea.company.com/amer.company.com]

ldap_search_base = dc=AMER,dc=COMPANY,dc=COM

[domain/amer.autofs]

id_provider = none

dns_discovery_domain = amer.company.com

autofs_provider = ldap

ldap_sasl_mech = GSSAPI

ldap_sasl_authid = <fqdn>@EMEA.COMPANY.COM

krb5_server = ORKDC16EMEA02.emea.company.com, ATHDC16EMEA02.emea.company.com, ORKDC16EMEA01.emea.company.com

The “secret sauce”  is in this krb5_servers line for this autofs sssd domain.  All the other lines in this autofs AD domain make sense;  it’s not clear why this krb5_server line is required (but it is).

Spike