Client Machine: Authenticate to the Directory Server Through GSSAPI

The final step is to authenticate to the Directory Server by using GSSAPI. The ldapsearch utility provided with the Directory Server provides support for SASL authentication, including GSSAPI, DIGEST-MD5, and EXTERNAL mechanisms. However, to bind by using GSSAPI you must provide the client with the path to the SASL library. Provide the path by setting the SASL_PATH environment variable to the lib/sasl directory:

$ SASL_PATH=SASL-library
$ export SASL_PATH
$

To actually perform a Kerberos-based authentication to the Directory Server using ldapsearch, you must include the -o mech=GSSAPI and -o authzid=principal arguments.

You must also specify the fully qualified host name, shown here as -h directory.example.com, which must match the value of the nsslapd-localhost attribute on cn=config for the server. This use of the -h option is needed because the GSSAPI authentication process requires the host name provided by the client to match the host name provided by the server.

The following example retrieves the dc=example,dc=com entry while authenticated as the Kerberos test user account created previously:

$ ldapsearch -h directory.example.com -p 389 -o mech=GSSAPI \
 -o authzid="kerberos-test@EXAMPLE.COM" -b "dc=example,dc=com" -s base "(objectClass=*)"
version: 1
dn: dc=example,dc=com
dc: example
objectClass: top
objectClass: domain
$

Check the Directory Server access log to confirm that the authentication was processed as expected:

$ tail -12 /local/ds/logs/access

[24/Jul/2004:00:30:47 -0500] conn=0 op=-1 msgId=-1 - fd=23 slot=23 LDAP 
		connection from 1.1.1.8 to 1.1.1.8
[24/Jul/2004:00:30:47 -0500] conn=0 op=0 msgId=1 - BIND dn="" method=sasl 
     version=3 mech=GSSAPI
[24/Jul/2004:00:30:47 -0500] conn=0 op=0 msgId=1 - RESULT err=14 tag=97 
     nentries=0 etime=0, SASL bind in progress
[24/Jul/2004:00:30:47 -0500] conn=0 op=1 msgId=2 - BIND dn="" method=sasl 
     version=3 mech=GSSAPI
[24/Jul/2004:00:30:47 -0500] conn=0 op=1 msgId=2 - RESULT err=14 tag=97 
     nentries=0 etime=0, SASL bind in progress
[24/Jul/2004:00:30:47 -0500] conn=0 op=2 msgId=3 - BIND dn="" method=sasl 
     version=3 mech=GSSAPI
[24/Jul/2004:00:30:47 -0500] conn=0 op=2 msgId=3 - RESULT err=0 tag=97 
     nentries=0 etime=0 dn="uid=kerberos-test,ou=people,dc=example,dc=com"
[24/Jul/2004:00:30:47 -0500] conn=0 op=3 msgId=4 - SRCH base="dc=example,dc=com"
     scope=0 filter="(objectClass=*)" attrs=ALL
[24/Jul/2004:00:30:47 -0500] conn=0 op=3 msgId=4 - RESULT err=0 tag=101 nentries=1 
     etime=0
[24/Jul/2004:00:30:47 -0500] conn=0 op=4 msgId=5 - UNBIND
[24/Jul/2004:00:30:47 -0500] conn=0 op=4 msgId=-1 - closing - U1
[24/Jul/2004:00:30:48 -0500] conn=0 op=-1 msgId=-1 - closed.
$

This example shows that the bind is a three-step process. The first two steps return LDAP result 14 (SASL bind in progress), and the third step shows that the bind was successful. The method=sasl and mech=GSSAPI tags show that the bind used the GSSAPI SASL mechanism. The dn="uid=kerberos-test,ou=people,dc=example,dc=com" at the end of the successful bind response shows that the bind was performed as the appropriate user.