The "route flush" command doesn't remove enough routes.  It only removes
gateway routes, leaving behind cloned routes and manually added default
routes.  This is a problem if you change your set of interfaces.

My fix is below.  I also added a flushall command, but it's dangerous and
not recommended.  If you remove everything, you can't add any back in.

*** route.c-	Fri Oct 13 21:13:42 1995
--- route.c	Thu Aug  1 01:21:59 1996
***************
*** 196,202 ****
  			/* NOTREACHED */
  
  		case K_FLUSH:
! 			flushroutes(argc, argv);
  			exit(0);
  			/* NOTREACHED */
  		}
--- 196,206 ----
  			/* NOTREACHED */
  
  		case K_FLUSH:
! 			flushroutes(argc, argv, 0);
! 			exit(0);
! 			/* NOTREACHED */
! 		case K_FLUSHALL:
! 			flushroutes(argc, argv, 1);
  			exit(0);
  			/* NOTREACHED */
  		}
***************
*** 209,217 ****
   * associated with network interfaces.
   */
  void
! flushroutes(argc, argv)
  	int argc;
  	char *argv[];
  {
  	size_t needed;
  	int mib[6], rlen, seqno;
--- 213,222 ----
   * associated with network interfaces.
   */
  void
! flushroutes(argc, argv, doall)
  	int argc;
  	char *argv[];
+ 	int doall;
  {
  	size_t needed;
  	int mib[6], rlen, seqno;
***************
*** 267,273 ****
  		rtm = (struct rt_msghdr *)next;
  		if (verbose)
  			print_rtmsg(rtm, rtm->rtm_msglen);
! 		if ((rtm->rtm_flags & RTF_GATEWAY) == 0)
  			continue;
  		if (af) {
  			struct sockaddr *sa = (struct sockaddr *)(rtm + 1);
--- 272,278 ----
  		rtm = (struct rt_msghdr *)next;
  		if (verbose)
  			print_rtmsg(rtm, rtm->rtm_msglen);
! 		if (!(rtm->rtm_flags & (RTF_GATEWAY | RTF_STATIC | RTF_LLINFO)) && !doall)
  			continue;
  		if (af) {
  			struct sockaddr *sa = (struct sockaddr *)(rtm + 1);