Example Setup of Dynamic DNS

A P P E N D I X A

This appendix describes how to configure the Dynamic Domain Name Service (DDNS) on a typical customer’s infrastructure. The instructions and example configuration provided here do not affect ILOM or the service processor (SP).

The following topics are covered in this appendix:

Dynamic DNS Overview

Example Dynamic DNS Configuration

Dynamic DNS Overview

Once DDNS is configured, new ILOM systems will be automatically assigned a host name and an IP address at install time. Thus, once you have configured DDNS, clients can use either host names or IP addresses to access any ILOM SPs that have been added to the network.

By default, ILOM systems are shipped with Dynamic Host Configuration Protocol (DHCP) enabled so that you can use DHCP to configure the SP’s network interface. With DDNS, you can further leverage DHCP to automatically make the DNS server aware of the host names of ILOM systems that have been added to the network and configured using DHCP.

Note - Domain Name Service (DNS) support, which was added to ILOM in the 3.0 release, allows hosts such as NTP servers, logging servers, and firmware upgrade servers, to be referred to within the ILOM command-line interface (CLI) and other user interfaces by host name or IP address. DDNS support, as described in this appendix, allows SPs to be referred to by their host names without being manually configured.

ILOM systems are assigned well-known host names consisting of a prefix followed by a hyphen and the ILOM SP product serial number. For rackmounted systems and server modules, the host name will consist of the prefix SUNSP and the product serial number. For a server chassis with multiple chassis monitoring modules (CMMs), the host name for each CMM will consist of the prefix SUNCMMn and the product serial number, where n is 0 or 1. For example, given a product serial number of 0641AMA007, the host name for a rackmounted system or a server module would be SUNSP-0641AMA007. For a server chassis with two CMMs, the host names for the CMMs would be SUNCMM0-0641AMA007 and SUNCMM1-0641AMA007.

Once DDNS has been configured, SP/DHCP/DNS transactions are automatically executed to add new host names and associated IP addresses to the DNS database. Each transaction comprises the following steps:

1. ILOM creates the SP host name using the appropriate prefix and the product serial number and the ILOM SP sends the host name to the DHCP server as part of the DHCP request.

2. When the DHCP server receives the request, it assigns an IP address to the ILOM SP from an available pool of addresses.

3. The DHCP server then sends an update to the DNS server to notify it of the newly configured ILOM SP’s host name and IP address.

4. The DNS server updates its database with the new information, thus completing the SP/DHCP/DNS transaction.

Once an SP/DHCP/DNS transaction is completed for a given host name, clients can make a DNS request using that host name and DNS will return the assigned IP address.

To determine the host name of a particular ILOM SP, simply check the product serial number on the outside of the SP itself and combine the product serial number with the appropriate prefix as described above. You can also determine host names by checking the server logs for DNS zone update messages.

Note - You can use the CLI to change the SP host name to something other than the default. However, if you change the host name to a non-default name, clients must use that host name to refer to the SP using DNS.

The DNS information is updated when a DHCP lease renewal causes an IP address change, and the DNS information is deleted when the DHCP lease is released.

Note - For all ILOM SPs that have been assigned host names prior to DDNS support or that may have been configured using DDNS and MAC address-based host names, the previously configured host names will remain in effect.

Example Dynamic DNS Configuration

This section describes how to set up an example DDNS configuration. You can use the procedures and sample files provided here, with site-specific modifications, to set up your own DDNS configuration.

Note - How you set up DDNS depends on the infrastructure in use at your site. Solaris, Linux, and Windows operating systems all support server solutions that offer DDNS functionality. This example configuration uses Debian r4.0 as the server operating system environment.

This following topics are covered in this section:

Assumptions

Configure and Start the DHCP and DNS Servers

References

Assumptions

This example configuration is based on the following assumptions:

There is a single server that handles both DNS and DHCP for the network the SP resides on.

The SP network address is 192.168.1.0.

The DHCP/DNS server address is 192.168.1.2

The IP addresses from 192.168.1.100 to 192.168.1.199 are used as a pool to provide addresses to the SP and other clients.

The domain name is example.com.

There is no existing DNS or DHCP configuration in place. If there is, use the following files as a guideline to update the existing configuration.

Configure and Start the DHCP and DNS Servers

To configure the servers, follow these steps:

1. Install the bind9 and dhcp3-server packages from the Debian distribution.

Installing the dnsutils package provides access to dig, nslookup and other useful tools as well.

2. Using dnssec-keygen, generate a key to be shared between the DHCP and DNS servers to control access to the DNS data.

3. Create a DNS configuration file named /etc/bind/named.conf that contains the following:

options {
  directory "/var/cache/bind";
  auth-nxdomain no;    # conform to RFC1035
  listen-on-v6 { any; };
};
// prime the server with knowledge of the root servers
zone "." {
  type hint;
  file "/etc/bind/db.root";
};
// be authoritative for the localhost forward and reverse zones, // and for broadcast zones as per RFC 1912
zone "localhost" {
  type master;
  file "/etc/bind/db.local";
};
zone "127.in-addr.arpa" {
  type master;
  file "/etc/bind/db.127";
};
zone "0.in-addr.arpa" {
  type master;
  file "/etc/bind/db.0";
};
zone "255.in-addr.arpa" {
  type master;
  file "/etc/bind/db.255";
};
// additions to named.conf to support DDNS updates from dhcp server
key server.example.com {
  algorithm HMAC-MD5;
  secret "your-key-from-step-2-here"
};
zone "example.com" {
  type master;
  file "/etc/bind/db.example.com";
  allow-update { key server.example.com; };
};
zone "1.168.192.in-addr.arpa" {
  type master;
  file "/etc/bind/db.example.rev";
  allow-update { key server.example.com; };
};

4. Add empty zone files for the local network.

Empty zone files should be named /etc/bind/db.example.com and /etc/bind/db.example.rev.

Copying the distribution supplied db.empty files is sufficient; they will be updated automatically by the DNS server.

5. Create a /etc/dhcp3/dhcpd.conf file that contains the following:

ddns-update-style interim;
ddns-updates      on;
server-identifier server;
ddns-domainname   "example.com.";
ignore client-updates;
key server.example.com {
  algorithm hmac-md5;
  secret your-key-from-step-2-here;
}
zone example.com. {
  primary 127.0.0.1;
  key server.example.com;
}
zone 1.168.192.in-addr.arpa. {
  primary 127.0.0.1;
  key server.example.com;
}
default-lease-time 600;
max-lease-time 7200;
authoritative;
log-facility local7;
subnet 192.168.1.0 netmask 255.255.255.0 {
  range 192.168.1.100 192.168.1.199;
  option domain-name-servers 192.168.1.2;
}

6. After completing steps 1 through 5 above, run the /etc/init.d script to start the DNS and DHCP servers.

Once the servers are running, any new ILOM SPs configured for DHCP will be automatically accessible using their host name when they are powered on. Use log files, dig, nslookup, and other utilities for debugging, if necessary.

References

For more information on the Linux DHCP and DNS servers used in this example, see the Internet Systems Consortium web site at: http://www.isc.org/