How to Manually Configure a Kerberos Client
In this procedure, the following configuration parameters are used:
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Realm name = EXAMPLE.COM
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DNS domain name = example.com
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Master KDC = kdc1.example.com
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Slave KDC = kdc2.example.com
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NFS server = denver.example.com
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Client = client.example.com
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admin principal = kws/admin
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User principal = mre
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Online help URL = http://denver:8888/ab2/coll.384.1/SEAM/@AB2PageView/6956
Note –Adjust the URL to point to the “Graphical Kerberos Administration Tool” section, as described in the Online Help URL in the Graphical Kerberos Administration Tool.
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Become superuser.
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Edit the Kerberos configuration file (krb5.conf).
To change the file from the Kerberos default version, you need to change the realm names and the server names. You also need to identify the path to the help files for gkadmin.
kdc1 # cat /etc/krb5/krb5.conf [libdefaults] default_realm = EXAMPLE.COM [realms] EXAMPLE.COM = { kdc = kdc1.example.com kdc = kdc2.example.com admin_server = kdc1.example.com } [domain_realm] .example.com = EXAMPLE.COM # # if the domain name and realm name are equivalent, # this entry is not needed # [logging] default = FILE:/var/krb5/kdc.log kdc = FILE:/var/krb5/kdc.log [appdefaults] gkadmin = { help_url = http://denver:8888/ab2/coll.384.1/SEAM/@AB2PageView/6956
Note –If you want to restrict the encryption types, you can set the default_tkt_enctypes or default_tgs_enctypes lines. Refer to Using Kerberos Encryption Types for a description of the issues involved with restricting the encryption types.
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(Optional) Change the process used to locate the KDCs.
Starting with the Solaris 10 5/08 and Solaris Express Developer Edition 1/08 releases, by default the Kerberos realm to KDC mapping is determined in the following order:
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The definition in the realms section in krb5.conf.
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By looking up SRV records in DNS.
You can change this behavior by adding dns_lookup_kdc or dns_fallback to the libdefaults section of the krb5.conf file. See the krb5.conf(4) man page for more information. Note that referrals are always tried first.
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(Optional) Change the process used to determine the realm for a host.
Starting with the Solaris 10 5/08 and Solaris Express Developer Edition 1/08 releases, by default the host to realm mapping is determined in the following order:
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If the KDC supports referrals, then the KDC may inform the client which realm the host belongs to.
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By the definition of domain_realm in the krb5.conf file.
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The DNS domainname of the host.
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The default realm.
You can change this behavior by adding dns_lookup_kdc or dns_fallback to the libdefaults section of the krb5.conffile. See the krb5.conf(4) man page for more information. Note that referrals will always be tried first.
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(Optional) Synchronize the client's clock with the master KDC's clock by using NTP or another clock synchronization mechanism.
Installing and using the Network Time Protocol (NTP) is not required. However, every clock must be synchronized with the time on the KDC server within a maximum difference defined in the clockskew relation in the krb5.conf file for authentication to succeed. See Synchronizing Clocks Between KDCs and Kerberos Clients for information about NTP.
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Start kadmin.
You can use the Graphical Kerberos Administration Tool to add a principal, as explained in How to Create a New Kerberos Principal. To do so, you must log in with one of the admin principal names that you created when you configured the master KDC. However, the following example shows how to add the required principals by using the command line.
denver # /usr/sbin/kadmin -p kws/admin Enter password: <Type kws/admin password> kadmin:
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(Optional) Create a user principal if a user principal does not already exist.
You need to create a user principal only if the user associated with this host does not already have a principal assigned to him or her.
kadmin: addprinc mre Enter password for principal mre@EXAMPLE.COM: <Type the password> Re-enter password for principal mre@EXAMPLE.COM: <Type it again> kadmin:
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(Optional) Create a root principal and add the principal to the server's keytab file.
This step is required so that the client can have root access to file systems mounted using the NFS service. This step is also required if non-interactive root access is needed, such as running cron jobs as root.
If the client does not require root access to a remote file system which is mounted using the NFS service, then you can skip this step. The root principal should be a two component principal with the second component the host name of the Kerberos client system to avoid the creation of a realm wide root principal. Note that when the principal instance is a host name, the FQDN must be specified in lowercase letters, regardless of the case of the domain name in the /etc/resolv.conf file.
kadmin: addprinc -randkey root/client.example.com Principal "root/client.example.com" created. kadmin: ktadd root/client.example.com Entry for principal root/client.example.com with kvno 3, encryption type AES-256 CTS mode with 96-bit SHA-1 HMAC added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal root/client.example.com with kvno 3, encryption type AES-128 CTS mode with 96-bit SHA-1 HMAC added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal root/client.example.com with kvno 3, encryption type Triple DES cbc mode with HMAC/sha1 added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal root/client.example.com with kvno 3, encryption type ArcFour with HMAC/md5 added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal root/client.example.com with kvno 3, encryption type DES cbc mode with RSA-MD5 added to keytab WRFILE:/etc/krb5/krb5.keytab. kadmin: -
Create a host principal and add the principal to the server's keytab file.
The host principal is used by remote access services to provide authentication. The principal allows root to acquire a credential, if there is not one already in the keytab file.
kadmin: addprinc -randkey host/denver.example.com Principal "host/denver.example.com@EXAMPLE.COM" created. kadmin: ktadd host/denver.example.com Entry for principal host/denver.example.com with kvno 3, encryption type AES-256 CTS mode with 96-bit SHA-1 HMAC added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal host/denver.example.com with kvno 3, encryption type AES-128 CTS mode with 96-bit SHA-1 HMAC added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal host/denver.example.com with kvno 3, encryption type Triple DES cbc mode with HMAC/sha1 added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal host/denver.example.com with kvno 3, encryption type ArcFour with HMAC/md5 added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal host/denver.example.com with kvno 3, encryption type DES cbc mode with RSA-MD5 added to keytab WRFILE:/etc/krb5/krb5.keytab. kadmin: -
(Optional) Add the server's NFS service principal to the server's keytab file.
This step is only required if the client needs to access NFS file systems using Kerberos authentication.
kadmin: ktadd nfs/denver.example.com Entry for principal nfs/denver.example.com with kvno 3, encryption type AES-256 CTS mode with 96-bit SHA-1 HMAC added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal nfs/denver.example.com with kvno 3, encryption type AES-128 CTS mode with 96-bit SHA-1 HMAC added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal nfs/denver.example.com with kvno 3, encryption type Triple DES cbc mode with HMAC/sha1 added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal nfs/denver.example.com with kvno 3, encryption type ArcFour with HMAC/md5 added to keytab WRFILE:/etc/krb5/krb5.keytab. Entry for principal nfs/denver.example.com with kvno 3, encryption type DES cbc mode with RSA-MD5 added to keytab WRFILE:/etc/krb5/krb5.keytab. kadmin: -
Quit kadmin.
kadmin: quit
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(Optional) Enable Kerberos with NFS.
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Enable Kerberos security modes in the /etc/nfssec.conf file.
Edit the /etc/nfssec.conf file and remove the “#” that is placed in front of the Kerberos security modes.
# cat /etc/nfssec.conf . . # # Uncomment the following lines to use Kerberos V5 with NFS # krb5 390003 kerberos_v5 default - # RPCSEC_GSS krb5i 390004 kerberos_v5 default integrity # RPCSEC_GSS krb5p 390005 kerberos_v5 default privacy # RPCSEC_GSS
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Enable DNS.
If the /etc/resolv.conf file has not already been created, then create this file as the service principal canonicalization is dependent upon DNS to do this. See the resolv.conf(4) man page for more information.
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Restart the gssd service.
After the /etc/resolv.conf file has been created or modified you must then restart the gssd daemon to reread any changes.
# svcadm restart network/rpc/gss
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If you want the client to automatically renew the TGT or to warn users about Kerberos ticket expiration, create an entry in the /etc/krb5/warn.conf file.
See the warn.conf(4) man page for more information.
Example 23–12 Setting Up a Kerberos Client Using a Non-Solaris KDC
A Kerberos client can be set up to work with a non-Solaris KDC. In this case, a line must be included in the /etc/krb5/krb5.conf file in the realms section. This line changes the protocol that is used when the client is communicating with the Kerberos password-changing server. The format of this line follows.
[realms]
EXAMPLE.COM = {
kdc = kdc1.example.com
kdc = kdc2.example.com
admin_server = kdc1.example.com
kpasswd_protocol = SET_CHANGE
}
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Example 23–13 DNS TXT Records for the Mapping of Host and Domain Name to Kerberos Realm
@ IN SOA kdc1.example.com root.kdc1.example.com (
1989020501 ;serial
10800 ;refresh
3600 ;retry
3600000 ;expire
86400 ) ;minimum
IN NS kdc1.example.com.
kdc1 IN A 192.146.86.20
kdc2 IN A 192.146.86.21
_kerberos.example.com. IN TXT "EXAMPLE.COM"
_kerberos.kdc1.example.com. IN TXT "EXAMPLE.COM"
_kerberos.kdc2.example.com. IN TXT "EXAMPLE.COM"
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Example 23–14 DNS SRV Records for Kerberos Server Locations
This example defines the records for the location of the KDCs, the admin server, and the kpasswd server, respectively.
@ IN SOA kdc1.example.com root.kdc1.example.com (
1989020501 ;serial
10800 ;refresh
3600 ;retry
3600000 ;expire
86400 ) ;minimum
IN NS kdc1.example.com.
kdc1 IN A 192.146.86.20
kdc2 IN A 192.146.86.21
_kerberos._udp.EXAMPLE.COM IN SRV 0 0 88 kdc2.example.com
_kerberos._tcp.EXAMPLE.COM IN SRV 0 0 88 kdc2.example.com
_kerberos._udp.EXAMPLE.COM IN SRV 1 0 88 kdc1.example.com
_kerberos._tcp.EXAMPLE.COM IN SRV 1 0 88 kdc1.example.com
_kerberos-adm._tcp.EXAMPLE.COM IN SRV 0 0 749 kdc1.example.com
_kpasswd._udp.EXAMPLE.COM IN SRV 0 0 749 kdc1.example.com
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