makedhcp - Creates and updates DHCP configuration files.
makedhcp -n [-l|--localonly]
makedhcp -a [-l|--localonly]
makedhcp -a -d [-l|--localonly]
makedhcp -d noderange [-l|--localonly]
makedhcp noderange [-s statements] [-l|--localonly]
makedhcp -q noderange
makedhcp [-h|--help]
The makedhcp command creates and updates the DHCP configuration on the management node and service nodes. The makedhcp command is supported for both Linux and AIX clusters. Note that it will intentionally not generate UEFI configuration if the OS indicated in nodetype.os is not UEFI supported, even if the OS being booted is shell. On Linux, the DHCP implementation is selected by the site.dhcpbackend attribute. The auto setting keeps ISC DHCP on platforms where it is still available and uses Kea DHCP on platforms such as EL10 and Ubuntu 24.04. For legacy ISC DHCP deployments that need a non-default OMAPI/TSIG key, use site.dhcpomapialgorithm and site.dhcpomapikeyname. If the system uses an alternate ISC DHCP build, site.dhcpomshellpath can point xCAT at that build's omshell binary. In FIPS mode, xCAT defaults to hmac-sha256 and rejects an explicit hmac-md5 value. Before using SHA-based OMAPI, xCAT checks that the configured omshell supports the key-algorithm command. If this check fails, upgrade ISC DHCP or set site.dhcpomshellpath to a compatible binary.
Start by filling out the networks(5) table properly.
Then use the makedhcp -n option to create a new dhcp configuration file. You can set the site table, dhcplease attribute to the lease time for the dhcp client. The default value is 43200.
Next, get the node IP addresses and MACs defined in the xCAT database. Also, get the hostnames and IP addresses pushed to /etc/hosts (using makehosts(8)) and to DNS (using makedns(8)).
Then run makedhcp with a noderange or the -a option. This will inject DHCP configuration data pertinent to the specified nodes. With ISC DHCP, Linux node entries are updated through OMAPI. With Kea DHCP, node reservations are rendered into the Kea JSON configuration, validated, and the Kea service is restarted.
If you need to delete node entries from the DHCP configuration, use the -d flag.
For a node with an IPv6 address, makedhcp reserves the address for one DHCPv6 client identifier (DUID). The duid attribute of the node selects it. Without the attribute, the DUID is the DUID-UUID that UEFI firmware built on EDK2 sends, made from vpd.uuid. vpd.uuid holds the UUID as the operating system reports it in /sys/class/dmi/id/product_uuid. Earlier xCAT releases stored vpd.uuid with the first three fields swapped for nodes from Genesis discovery and for KVM guests from mkvm, clonevm or rscan. Set vpd.uuid of such a node to the UUID that it reports. makedhcp warns about a node whose vpd.uuid looks byte-swapped, and never changes the value. The warning is a report, not a diagnosis. A swap moves the version field, but it leaves a valid version in the first field about half the time. makedhcp cannot report those rows, and it cannot read the UUID that the node itself holds. A node whose vpd.uuid is the nil UUID gets no DUID from it, because nodeimport writes that one value to every PowerKVM node. With Kea DHCP such a node keeps the reservation of its MAC address, like a node with no vpd.uuid. With ISC DHCP it gets no DHCPv6 host, again like a node with no vpd.uuid. Set duid=canonical for a client that sends vpd.uuid in RFC 4122 byte order, or set duid=ll for one that sends the DUID-LL of its MAC, or set the DUID itself. On ppc64le the DUID is that DUID-LL with no attribute set, because SLOF sends it and reports no UUID at all. Nothing above applies to such a node: vpd.uuid is not read for it, and no warning is reported about it. When the firmware and the operating system of a node send different identifiers, only the client that duid selects gets the reserved address.
Create a new dhcp configuration file with a network statement for each network the dhcp daemon should listen on. (Which networks dhcpd should listen on can be controlled by the dhcpinterfaces attribute in the site(5) table.) The makedhcp command will automatically restart the dhcp daemon after this operation. This option will replace any existing configuration file (making a backup of it first). For Linux systems using ISC DHCP, the file will include network entries as well as certain general parameters such as a dynamic range and omapi configuration. For Linux systems using Kea DHCP, the generated files are /etc/kea/kea-dhcp4.conf, /etc/kea/kea-dhcp6.conf when IPv6 networks are configured, and /etc/kea/kea-dhcp-ddns.conf when DDNS is enabled. For AIX systems the file will include network entries. On AIX systems, if there are any non-xCAT entries in the existing configuration file they will be preserved and added to the end of the new configuration file.
Define all nodes to the DHCP server. (Will only add nodes that can be reached, network-wise, by this DHCP server.) The dhcp daemon does not have to be restarted after this. On AIX systems makedhcp will not add entries for cluster nodes that will be installed using NIM. The entries for these nodes will be managed by NIM.
Add the specified nodes to the DHCP server configuration.
For the input noderange, the argument will be interpreted like dhcp configuration file text. This option is only supported by the ISC DHCP backend.
Delete node entries from the DHCP server configuration. On AIX, any entries created by NIM will not be removed.
Delete all node entries, that were added by xCAT, from the DHCP server configuration.
Configure dhcpd on the local machine only. Without this option, makedhcp will also send this operation to any service nodes that service the nodes in the noderange.
Query the node entries from the DHCP server configuration. On AIX, any entries created by NIM will not be listed.
Display usage message.
makedhcp -n makedhcp -aNote: This does not add nodes that will be installed with AIX/NIM.
makedhcp node5 -s 'option root-path \"172.16.0.1:/install/freebsd6.2/x86_64\";' # makedhcp -q node01
node01: ip-address = 91.214.34.156, hardware-address = 00:00:c9:c6:6c:42DHCP configuration files:
[AIX] /etc/dhcpsd.cnf
[SLES] /etc/dhcpd.conf
[RH] /etc/dhcp/dhcpd.conf
[Kea] /etc/kea/kea-dhcp4.conf
[Kea IPv6] /etc/kea/kea-dhcp6.conf
[Kea DDNS] /etc/kea/kea-dhcp-ddns.conf