+rm -f /srv/fai/nfsroot/root/.ssh/known_hosts
+if [[ $HOSTNAME == kd ]]; then
+ keyscan_arg="-p 8989"
+fi
+key=$(ssh-keyscan $keyscan_arg localhost |& grep -o "ecdsa-sha2-nistp256.*")
+for ip in faiserver $(ip addr show up| grep -w '^ *inet' | awk '{print $2}'| cut -d / -f 1 | grep -vF 127.0.0.1); do
+ echo "$ip $key" >>/srv/fai/nfsroot/root/.ssh/known_hosts
+done
+
+# make it the root because pxe-kexec only looks there.
+# It wouldn't be too hard to change if we needed.
+# We could also just dump things in /srv/tftp, but fai
+# has some defaults, which I don't even use, which expect
+# the other directory, so it's kind of a tossup, whatever.
+# This means fai's example isc-dhcp-server filename directory should remove the fai/ prefix.
+sed -ri 's,^ *(TFTP_DIRECTORY=).*,\1"/srv/tftp/fai",' /etc/default/tftpd-hpa
+systemctl restart tftpd-hpa
+
+
+# serial console
+# mainly from
+# https://wiki.archlinux.org/index.php/working_with_the_serial_console
+# at runtime, running this from ssh worked:
+# https://unix.stackexchange.com/questions/242778/what-is-the-easiest-way-to-configure-serial-port-on-linux
+# stty -F /dev/ttyS0 115200 cs8 -cstopb -parenb
+# /sbin/agetty 115200 ttyS0 linux
+# dated info, but validation that this might work on debian:
+# https://help.ubuntu.com/community/SerialConsoleHowto
+# note in the nfsroot, systemd is not running.
+echo "c0:2345:respawn:/sbin/agetty 115200 ttyS0 linux" >>/srv/fai/nfsroot/etc/inittab