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Chapter 18. Using the KDC Proxy in IdM
Some administrators might choose to make the default Kerberos ports inaccessible in their deployment. To allow users, hosts, and services to obtain Kerberos credentials, you can use the HTTPS service as a proxy that communicates with Kerberos via the HTTPS port 443.
In Identity Management (IdM), the Kerberos Key Distribution Center Proxy (KKDCP) provides this functionality.
On an IdM server, KKDCP is enabled by default and available at https://<server.idm.example.com>/KdcProxy. On an IdM client, you must change its Kerberos configuration to access the KKDCP.
18.1. Configuring an IdM client to use KKDCP Copiar o linkLink copiado para a área de transferência!
As an Identity Management (IdM) system administrator, you can configure an IdM client to use the Kerberos Key Distribution Center Proxy (KKDCP) on an IdM server. This is useful if the default Kerberos ports are not accessible on the IdM server and the HTTPS port 443 is the only way of accessing the Kerberos service.
Prerequisites
-
You have
rootaccess to the IdM client.
Procedure
-
Open the
/etc/krb5.conffile for editing. In the
[realms]section, enter the URL of the KKDCP for thekdc,admin_server, andkpasswd_serveroptions:Copy to Clipboard Copied! Toggle word wrap Toggle overflow For redundancy, you can add the parameters
kdc,admin_server, andkpasswd_servermultiple times to indicate different KKDCP servers.Restart the
sssdservice to make the changes take effect:systemctl restart sssd
# systemctl restart sssdCopy to Clipboard Copied! Toggle word wrap Toggle overflow
18.2. Verifying that KKDCP is enabled on an IdM server Copiar o linkLink copiado para a área de transferência!
On an Identity Management (IdM) server, the Kerberos Key Distribution Center Proxy (KKDCP) is automatically enabled each time the Apache web server starts if the attribute and value pair ipaConfigString=kdcProxyEnabled exists in the directory. In this situation, the symbolic link /etc/httpd/conf.d/ipa-kdc-proxy.conf is created.
You can verify if the KKDCP is enabled on the IdM server, even as an unprivileged user.
Procedure
Check that the symbolic link exists:
ls -l /etc/httpd/conf.d/ipa-kdc-proxy.conf
$ ls -l /etc/httpd/conf.d/ipa-kdc-proxy.conf lrwxrwxrwx. 1 root root 36 Jun 21 2020 /etc/httpd/conf.d/ipa-kdc-proxy.conf -> /etc/ipa/kdcproxy/ipa-kdc-proxy.confCopy to Clipboard Copied! Toggle word wrap Toggle overflow The output confirms that KKDCP is enabled.
18.3. Disabling KKDCP on an IdM server Copiar o linkLink copiado para a área de transferência!
As an Identity Management (IdM) system administrator, you can disable the Kerberos Key Distribution Center Proxy (KKDCP) on an IdM server.
Prerequisites
-
You have
rootaccess to the IdM server.
Procedure
Remove the
ipaConfigString=kdcProxyEnabledattribute and value pair from the directory:ipa-ldap-updater /usr/share/ipa/kdcproxy-disable.uldif
# ipa-ldap-updater /usr/share/ipa/kdcproxy-disable.uldif Update complete The ipa-ldap-updater command was successfulCopy to Clipboard Copied! Toggle word wrap Toggle overflow Restart the
httpdservice:systemctl restart httpd.service
# systemctl restart httpd.serviceCopy to Clipboard Copied! Toggle word wrap Toggle overflow KKDCP is now disabled on the current IdM server.
Verification
Verify that the symbolic link does not exist:
ls -l /etc/httpd/conf.d/ipa-kdc-proxy.conf
$ ls -l /etc/httpd/conf.d/ipa-kdc-proxy.conf ls: cannot access '/etc/httpd/conf.d/ipa-kdc-proxy.conf': No such file or directoryCopy to Clipboard Copied! Toggle word wrap Toggle overflow
18.4. Re-enabling KKDCP on an IdM server Copiar o linkLink copiado para a área de transferência!
On an IdM server, the Kerberos Key Distribution Center Proxy (KKDCP) is enabled by default and available at https://<server.idm.example.com>/KdcProxy.
If KKDCP has been disabled on a server, you can re-enable it.
Prerequisites
-
You have
rootaccess to the IdM server.
Procedure
Add the
ipaConfigString=kdcProxyEnabledattribute and value pair to the directory:ipa-ldap-updater /usr/share/ipa/kdcproxy-enable.uldif
# ipa-ldap-updater /usr/share/ipa/kdcproxy-enable.uldif Update complete The ipa-ldap-updater command was successfulCopy to Clipboard Copied! Toggle word wrap Toggle overflow Restart the
httpdservice:systemctl restart httpd.service
# systemctl restart httpd.serviceCopy to Clipboard Copied! Toggle word wrap Toggle overflow KKDCP is now enabled on the current IdM server.
Verification
Verify that the symbolic link exists:
ls -l /etc/httpd/conf.d/ipa-kdc-proxy.conf
$ ls -l /etc/httpd/conf.d/ipa-kdc-proxy.conf lrwxrwxrwx. 1 root root 36 Jun 21 2020 /etc/httpd/conf.d/ipa-kdc-proxy.conf -> /etc/ipa/kdcproxy/ipa-kdc-proxy.confCopy to Clipboard Copied! Toggle word wrap Toggle overflow
18.5. Configuring the KKDCP server I Copiar o linkLink copiado para a área de transferência!
With the following configuration, you can enable TCP to be used as the transport protocol between the IdM KKDCP and the Active Directory (AD) realm, where multiple Kerberos servers are used.
Prerequisites
-
You have
rootaccess.
Procedure
Set the
use_dnsparameter in the[global]section of the/etc/ipa/kdcproxy/kdcproxy.conffile to false.[global] use_dns = false
[global] use_dns = falseCopy to Clipboard Copied! Toggle word wrap Toggle overflow Put the proxied realm information into the
/etc/ipa/kdcproxy/kdcproxy.conffile. For example, for the [AD.EXAMPLE.COM] realm with proxy list the realm configuration parameters as follows:[AD.EXAMPLE.COM] kerberos = kerberos+tcp://1.2.3.4:88 kerberos+tcp://5.6.7.8:88 kpasswd = kpasswd+tcp://1.2.3.4:464 kpasswd+tcp://5.6.7.8:464
[AD.EXAMPLE.COM] kerberos = kerberos+tcp://1.2.3.4:88 kerberos+tcp://5.6.7.8:88 kpasswd = kpasswd+tcp://1.2.3.4:464 kpasswd+tcp://5.6.7.8:464Copy to Clipboard Copied! Toggle word wrap Toggle overflow ImportantThe realm configuration parameters must list multiple servers separated by a space, as opposed to
/etc/krb5.confandkdc.conf, in which certain options may be specified multiple times.Restart Identity Management (IdM) services:
ipactl restart
# ipactl restartCopy to Clipboard Copied! Toggle word wrap Toggle overflow
18.6. Configuring the KKDCP server II Copiar o linkLink copiado para a área de transferência!
The following server configuration relies on the DNS service records to find Active Directory (AD) servers to communicate with.
Prerequisites
-
You have
rootaccess.
Procedure
In the
/etc/ipa/kdcproxy/kdcproxy.conffile, the[global]section, set theuse_dnsparameter to true.[global] configs = mit use_dns = true
[global] configs = mit use_dns = trueCopy to Clipboard Copied! Toggle word wrap Toggle overflow The
configsparameter allows you to load other configuration modules. In this case, the configuration is read from the MITlibkrb5library.Optional: In case you do not want to use DNS service records, add explicit AD servers to the
[realms]section of the/etc/krb5.conffile. If the realm with proxy is, for example, AD.EXAMPLE.COM, you add:[realms] AD.EXAMPLE.COM = { kdc = ad-server.ad.example.com kpasswd_server = ad-server.ad.example.com }[realms] AD.EXAMPLE.COM = { kdc = ad-server.ad.example.com kpasswd_server = ad-server.ad.example.com }Copy to Clipboard Copied! Toggle word wrap Toggle overflow Restart Identity Management (IdM) services:
ipactl restart
# ipactl restartCopy to Clipboard Copied! Toggle word wrap Toggle overflow