in file /etc/default/grub variable GRUB_CMDLINE_LINUX
ip=<ipaddress>:<server-address unused for luks>:<gateway>:<netmask>:<hostname>:eth1:static
or for dhcp
ip=:::::eth0:dhcp
in file /etc/mkinitcpio.conf add to hooks dropbear encryptssh
mkinitcpio-utils for encryptssh mkinitcpio-dropbear for dropbear