I have a box which has no permanent IP addresses except those
which are configured on loopback device. Something like
ppp server with pile of serial lines and no ethernet at all.

On loopback there is usual 127.0.0.1/8 address configured
and also 1.2.3.4/8 address which is a "server address"
to use for ppp clients for DNS etc.

kdc cannot start on it if there is no active ppp interfaces.

If there are active ppp's, it starts, but don't reply from
1.2.3.4 because it has sockets bound to ppp ip address(es)
only, which are dynamic.

I have a patch which remedies this using just one socket bound
to 0.0.0.0 and recvmsg/IP_PKTINFO trick. Would it be revieved
or maybe you have some fundamental reasons against it?
--
vda