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Security Bulletin 9120              DISA Defense Communications System
21 October 1991         Published by: DDN Security Coordination Center
                                  (SCC@NIC.DDN.MIL)   1-(800) 365-3642

                        DEFENSE  DATA  NETWORK
                          SECURITY  BULLETIN

The DDN SECURITY BULLETIN is distributed by the DDN SCC (Security
Coordination Center) under DISA contract as a means of communicating
information on network and host security exposures, fixes, &  concerns
to security & management personnel at DDN facilities.  Back issues may
be  obtained  via  FTP  (or  Kermit)  from  NIC.DDN.MIL  [192.112.36.5]
using login="anonymous" and password="guest".  The bulletin pathname is
SCC:DDN-SECURITY-yynn (where "yy" is the year the bulletin is issued
and "nn" is a bulletin number, e.g. SCC:DDN-SECURITY-9120).
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			RE-REGISTRATION OF TAC USERS

	THIS BULLETIN IS MEANT TO NOTIFY ALL CONCERNED THAT THERE
	IS CURRENTLY A PROBLEM WITH THE TIMELINESS OF TAC USERS
	BEING RE-REGISTERED WITH THE NETWORK INFORMATION CENTER (NIC)
	ONCE THEIR HOSTS ARE MOVED BEHIND CONCENTRATORS/GATEWAYS.
	SPECIFICALLY, WHEN A MILNET DIRECT-CONNECTED HOST IS
	DISCONNECTED AMD MOVED BEHIND A CONCENTRATOR/GATEWAY HOST,
	USERS BEHIND THE ORIGINAL "AUTHORIZING" HOST NEED TO BE RE-
	REGISTERED WITH THE CONCENTRATOR/GATEWAY AS THE AUTHORIZING
	"HOST."  THIS IS NOT HAPPENING IN ALL CASES, OFTEN DUE TO
	HOST ADMINISTRATORS ASSUMING THEY WILL CONTINUE TO BE ABLE TO
	AUTHORIZE TAC CARDS AFTER THEIR HOST IS RE-CONNECTED, AND TO
	CONCENTRATOR/GATEWAY ADMINISTRATORS ASSUMING THAT THEY DO NOT
	PLAY A ROLE IN THE TAC CARD AUTHORIZATION PROCESS.
 
	BEGINNING 15 DECEMBER 1991, THE NIC HAS BEEN DIRECTED TO
	TERMINATE NETWORK ACCESS TO ALL TAC USERS UTILIZING TAC CARDS
	REGISTERED TO "OLD" DIRECT CONNECTED HOSTS.  THE USE OF THESE
	CARDS IS NO LONGER AUTHORIZED UNLESS RE-REGISTRATION HAS BEEN
	ACCOMPLISHED AS DESCRIBED ABOVE.  IN THE FUTURE, TAC ACCESS
	WILL BE TERMINATED WITHIN 15 DAYS AFTER ANY HOST HAS BEEN
	DECONFIGURED.  IT IS, THEREFORE, INCUMBENT UPON HOST
	ADMINISTRATORS TO COORDINATE WITH THE ADMINISTRATOR OF THE
	CONCENTRATOR/GATEWAY AND WITH THE NIC REGISTRAR TO ARRANGE THE
	TIMELY RE-REGISTRATION OF TAC USERS PRIOR TO THE DISCONNECTION
	OF THE HOST TO WHICH THOSE TAC USERS WERE ORIGINALLY REGISTERED.
 
	FOR FURTHER INFORMATION REGARDING THIS GENERAL POLICY OR TO
	COORDINATE SPECIFIC CASES, PLEASE SEND A MESSAGE TO
	REGISTRAR@NIC.DDN.MIL OR CALL 1-800-365-3642/703-802-4535.