33.10. Updating DNS Records Systematically When Using External DNS
33.10. Updating DNS Records Systematically When Using External DNS When using external DNS, Identity Management does not update the DNS records automatically after a change in the topology. The following procedures explain how you can update the DNS records managed by an external DNS service systematically, which reduces the need for manual DNS updates. For a basic overview, see Section 33.10.1, "Updating External DNS in Identity Management" . For procedures and examples, see: Section 33.10.2, "GUI: Updating External DNS Records" if you use a GUI to manage the external DNS records Section 33.10.3, "Command Line: Updating External DNS Records Using nsupdate " if you use the nsupdate utility to manage the external DNS records 33.10.1. Updating External DNS in Identity Management Updating DNS records removes old or invalid DNS records and adds new records. You must update DNS records after a change in your topology, for example: After installing or uninstalling a replica After installing a CA, DNS, KRA, or Active Directory trust on an Identity Management server 33.10.2. GUI: Updating External DNS Records Display the records that you must update. Use the ipa dns-update-system-records --dry-run command. Use the external DNS GUI to update the records. 33.10.3. Command Line: Updating External DNS Records Using nsupdate This section describes how to manually update external DNS records using the nsupdate utility. You can also use the commands from this section in a script to automate the process. Generating a File with the DNS Records for nsupdate Use the ipa dns-update-system-records --dry-run command with the --out option. The option specifies the path of the file to generate: The generated file contains the required DNS records in the format accepted by the nsupdate utility. The generated records rely on: Automatic detection of the zone in which the records are to be updated Automatic detection of the zone's authoritative server If you are using an atypical DNS setup or if zone delegations are missing, nsupdate might not be able to find the right zone and server. In this case, add the following options to the beginning of the generated file: server specifies the server name or port of the authoritative DNS server to which nsupdate sends the records zone specifies the zone name of the zone where nsupdate places the records Example: Submitting the Dynamic DNS Update Request to the Name Server When sending a request using nsupdate , make sure you properly secure it. You can secure the request using these mechanisms: Transaction Signature (TSIG) protocol TSIG enables you to use nsupdate with a shared key. See Procedure 33.1, "Sending an nsupdate Request Secured Using TSIG" . GSS algorithm for TSIG (GSS-TSIG) GSS-TSIG uses the GSS-API interface to obtain the secret TSIG key. GSS-TSIG is an extension to the TSIG protocol. See Procedure 33.2, "Sending an nsupdate Request Secured Using GSS-TSIG" Procedure 33.1. Sending an nsupdate Request Secured Using TSIG Make sure you meet these prerequisites: Your DNS server must be configured for TSIG. See these server configuration examples: BIND , PowerDNS Both the DNS server and its client must have the shared key. Run nsupdate , and provide the shared secret using one of these options: -k to provide the TSIG authentication key: -y to generate a signature from the name of the key and from the Base64-encoded shared secret: Procedure 33.2. Sending an nsupdate Request Secured Using GSS-TSIG Make sure you meet these prerequisites: Your DNS server must be configured for GSS-TSIG. See these server configuration examples: BIND , PowerDNS , Windows DNS . Note This procedure assumes that Kerberos V5 protocol is used as the technology for GSS-API. To submit the DNS update request, authenticate with a principal allowed to update the records, and run nsupdate with the -g option to enable the GSS-TSIG mode: Additional Resources the nsupdate (8) man page RFC 2845 describes the TSIG protocol RFC 3645 describes the GSS-TSIG algorithm
ipa dns-update-system-records --dry-run IPA DNS records: _kerberos-master._tcp.example.com. 86400 IN SRV 0 100 88 ipa.example.com. _kerberos-master._udp.example.com. 86400 IN SRV 0 100 88 ipa.example.com. [... output truncated ...] ipa dns-update-system-records --dry-run --out dns_records_file.nsupdate IPA DNS records: _kerberos-master._tcp.example.com. 86400 IN SRV 0 100 88 ipa.example.com. _kerberos-master._udp.example.com. 86400 IN SRV 0 100 88 ipa.example.com. [... output truncated ...] cat dns_records_file.nsupdate zone example.com. server 192.0.2.1 ; IPA DNS records update delete _kerberos-master._tcp.example.com. SRV update add _kerberos-master._tcp.example.com. 86400 IN SRV 0 100 88 ipa.example.com. [... output truncated ...] nsupdate -k tsig_key.file dns_records_file.nsupdate nsupdate -y algorithm:keyname:secret dns_records_file.nsupdate kinit principal_allowed_to_update_records @ REALM nsupdate -g dns_records_file.nsupdate