main: use /dev/urandom by default

Reading /dev/random blocks when the system doesn't have enough
entropy. Reading /dev/urandom doesn't block and is presumed to be
good enough for our purposes

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
pud: set local loopback for multicast tx

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>