To run dhcrelay in DHCPv6 mode add the -6 argument and specify the “lower interface” (on which queries will be received from clients or from other relay agents) and the “upper interface” (to which queries from clients and other relay agents should be forwarded). Copy dhcrelay.service to dhcrelay6.service and edit it as the root user:

~]# cp /lib/systemd/system/dhcrelay.service /etc/systemd/system/dhcrelay6.service
~]# vi /etc/systemd/system/dhcrelay6.service

Edit the ExecStart option under section [Service] add -6 argument and add the “lower interface” and “upper interface” interface, for example:

ExecStart=/usr/sbin/dhcrelay -d --no-pid -6 -l em1 -u em2

For other options see the dhcrelay(8) man page.

To activate the changes made, as the root user, restart the service:

~]# systemctl --system daemon-reload
~]# systemctl restart dhcrelay6