So Multinet do not control the local port number when
in active mode.
Correct. AFAIK this is like most TCP applications (e.g. telnet) that initiate outgoing,
active, connections.
Does that mean it also accepts connections from
anywhere for passive connections?
Yep.
Or how do they authenticate? IP address only?
Authenticate?? We don't need no stinking authentication :-)
Seriously, though, AFAIK Multinet tunnels have no authentication at all. If somebody
out there was smart enough to know what we were doing and spoof the DECnet packets, then
they could probably break in. Or at least they could take over the DECnet tunnel -
whether they could log in and access files depends on how secure you've made your
host. Since a lot of the HECnet hosts, especially ones with TCP/IP tunnels, already have
direct Internet facing ports for telnet, ssh, ftp, etc the question of DECnet security
seems moot.
You can always configure your router, as I have, to only forward port 700 traffic from
specific Internet hosts. That'll solve the problem unless somebody also cares enough
to go to the trouble of spoofing IPs as well.
Getting off topic - don't I remember that there was a way to set a password on
point-to-point DDCMP circuits? How (or rather, at what level in the protocol stack) was
that implemented ?
Bob