Modify configuration from user = nobody to i.e. root then add -rfbauth /root/.vnc/passwd and restart xinetd
Server:/etc/xinetd.d # more vnc
# default: off
# description: This serves out a VNC connection which starts at a KDM login
# prompt. This VNC connection has a resolution of 1024×768, 16bit depth.
service vnc1
{
socket_type = stream
protocol = tcp
wait = no
user = root
server = /usr/X11R6/bin/Xvnc
server_args = :42 -inetd -once -query localhost -geometry 1024×768 -depth 16 -rfbauth /root/.vnc/passwd
type = UNLISTED
port = 5901
}