Monday Apr 08, 2013

Getting Started with OpenLDAP

I decided to try out the OpenLDAP server that is bundled with Oracle Solaris 11.1 after reading Paul Johnson's blog entry Configuring a Basic LDAP Server + Client in Solaris 11. Paul's instructions were helpful, but he didn't explain how to configure OpenLDAP so that it could be used with the Solaris commands which accept the option:

-S files | ldap.

That option is interpreted by the following commands:

In addition, the passwd(1) command accepts -r files | ldap and the User Manager GUI has a Filter Users dialog which has radio buttons for files and ldap. All of these commands depend on LDAP schema extensions that are not configured in OpenLDAP by default. The various schema are documented in Working with Naming and Directory Services and Trusted Extensions Configuration and Administration:

I combined these into a single file called solaris.schema, and copied it into the /etc/openldap/schema directory. I also created and installed another file called automap.schema which contains just the attributes and object classes for the automount service. These are missing from the existing nis.schema file, which is apparently a subset of RFC 2307bis Network Information Service Schema.

Then I modified the configuration file /etc/openldap/slapd.conf to include the required schema, and changed the domain name to gfaden.com

a6,11
> include         /etc/openldap/schema/cosine.schema
> include         /etc/openldap/schema/inetorgperson.schema
> include         /etc/openldap/schema/nis.schema
> include         /etc/openldap/schema/solaris.schema
> include         /etc/openldap/schema/automap.schema
54,55c60,61
< suffix                "dc=my-domain,dc=com"
< rootdn                "cn=Manager,dc=my-domain,dc=com"
---
> suffix                "dc=gfaden,dc=com"
> rootdn                "cn=admin,dc=gfaden,dc=com"

Following Paul's advice, I did the following:

root# chown -R openldap:openldap /var/openldap/
root# svcadm enable ldap/server

Then I wrote two scripts and ran them to create the various containers in the directory. The following script creates empty containers corresponding to the top-level directory object and the organizational units for the object classes.

  1 #!/bin/ksh
  2 
  3 ME=gfaden
  4 LDAP_BASEDN="dc=${ME},dc=com"
  5 LDAP_ROOTDN="cn=admin,${LDAP_BASEDN}"
  6 
  7 TMP_LDIF=$(mktemp /tmp/toplevels.XXXX)
  8 
  9 ( cat << EOF
 10 dn: ${LDAP_BASEDN}
 11 objectClass: dcObject
 12 objectClass: organization
 13 o: ${ME}.com
 14 dc: ${ME}
 15 
 16 EOF
 17 )>  ${TMP_LDIF}
 18 
 19 for ou in users groups rpc protocols networks netgroup \
 20     aliases hosts services ethers projects \
 21     SolarisAuthAttr SolarisProfAttr ipTnet; do
 22 
 23     ( cat << EOF
 24 dn: ou=${ou},${LDAP_BASEDN}
 25 ou: ${ou}
 26 objectClass: top
 27 objectClass: organizationalUnit
 28 
 29 EOF
 30 )>>  ${TMP_LDIF}
 31 done
 32 
 33 ldapadd -cD ${LDAP_ROOTDN} -f ${TMP_LDIF}
 34 rm ${TMP_LDIF}
 

I'm not sure I got all the spelling right in lines 19-21, but it seems to work. There are some subtle differences between what OpenLDAP uses compared to ODSEE. I wrote a similar script to create the automap containers:


  1 #!/bin/ksh
  2 
  3 LDAP_BASEDN="dc=gfaden,dc=com"
  4 LDAP_ROOTDN="cn=admin,${LDAP_BASEDN}"
  5 
  6 TMP_LDIF=$(mktemp /tmp/automap.XXXX)
  7 
  8 for automap in auto_home auto_direct auto_master;do
  9 
 10     ( cat << EOF
 11 dn: automountMapName=${automap},${LDAP_BASEDN}
 12 automountMapName: ${automap}
 13 objectClass: top
 14 objectClass: automountMap
 15 
 16 EOF
 17 )>>  ${TMP_LDIF}
 18 done
 19 
 20 ldapadd -cD ${LDAP_ROOTDN} -f ${TMP_LDIF}
 21 rm ${TMP_LDIF}

The next step was to switch the nameservice configuration so that the host is a client of this ldap server. Since I needed to specify explicit (not anonymous) credentials, I could not use the Automatic Network Configuration Profile (NCP) that is enabled by default for Solaris GUI installations. Instead,  the DefaultFixed NCP must be enabled, and the IP networking must be configured.

root# netadm enable -p ncp DefaultFixed
root# ipadm create-ip net0
root# ipadm create-addr -T dhcp net0/v4

Then I used a modified version of Paul's ldapaddclient(1M) command to make my system an LDAP client of itself:

  1 #!/bin/ksh
  2 ldapclient manual \
  3 -a credentialLevel=proxy \
  4 -a authenticationMethod=simple \
  5 -a defaultSearchBase=dc=gfaden,dc=com \
  6 -a domainName=gfaden.com \
  7 -a defaultServerList=127.0.0.1 \
  8 -a proxyDN=cn=admin,dc=gfaden,dc=com \
  9 -a adminDN=cn=admin,dc=gfaden,dc=com \
 10 -a proxyPassword=secret \
 11 -a enableShadowUpdate=true \
 12 -a objectClassMap=shadow:shadowAccount=posixaccount \
 13 -a serviceSearchDescriptor=passwd:ou=users,dc=gfaden,dc=com \
 14 -a serviceSearchDescriptor=shadow:ou=users,dc=gfaden,dc=com \
 15 -a serviceSearchDescriptor=group:ou=groups,dc=gfaden,dc=c

Since I was doing this on my laptop, I just used localhost for the IP address (line 7). However, I needed to add the admin distinguished name (line 9), and enable shadow update (line 11). Together, these two settings allow the client to make updates without re-authenticating if it is running as root or with all privileges.

Again, following Paul's blog, I enabled DNS, and restarted the name service:

root# svccfg -s name-service/switch setprop config/host = astring: "files dns ldap"
root# svccfg  -s name-service/switch:default refresh
root# svcadm restart name-service/cache

Now I can specify the ldap option for any of the commands listed above. For example:

root# groupadd -S ldap -g 1001 world
root# ldapaddent -d group
world:*:1001:

About

This blog explores some of the security features of Oracle Solaris. In particular, topics such as Role-Based Access Control and Labeled Security are my special interests.

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