info-vax@ucbvax.ARPA (08/19/85)
From: Richard Garland <OC.GARLAND@CU20B.ARPA> I have a question on the DECServer-100 and perhaps on all LAT-11 terminal servers prompted by a Column in the Aug. 1985 issue of Hardcopy magazine. The column "DEC Troubleshooter" by Ken O'Mohundro on page 150 says in regard to data from the server to the Host(s): "The real bummer here is that all hosts that are supporting servers must respond to the data - even though the data is not destined for that particular host. ... This is because instead of selective transmission, the server multicasts the data to the Ethernet so that all the hosts pick it up. ... the messages contained (in a packet) might be for a variety of hosts, not just one." Is this true? Does the LAT protocol mix data for different hosts and use multicast packets? I'm concerned with the security implications of this. We eventually hope to have several segments of Ethernet connected by Link-level bridges which filter packets and keep things belonging on one side from going to the other. An assumption has always been that servers and hosts would cummunicate in a 1-to-1 mode, i.e. not multi- or broadcast. The capability the bridge gives of creating secure sections of ethernet (that is secure from eavesdroping by hosts on another section) would be compromised by this scheme used by the terminal server. Any one out there have any information on this. Thanks in advance Rg -------