--- ntp-4.2.4/ntpd/ntp_peer.c.loopback 2006-12-28 13:03:31.000000000 +0100 +++ ntp-4.2.4/ntpd/ntp_peer.c 2007-01-07 09:24:54.000000000 +0100 @@ -664,9 +664,13 @@ * This might happen in some systems and would preclude proper * operation with public key cryptography. */ - if (ISREFCLOCKADR(srcadr)) + if (ISREFCLOCKADR(srcadr)) { + if (!loopback_interface) { + netsyslog(LOG_ERR, "missing loopback interface!"); + exit(1); + } interface = loopback_interface; - else + } else if (cast_flags & (MDF_BCLNT | MDF_ACAST | MDF_MCAST | MDF_BCAST)) { interface = findbcastinter(srcadr); #ifdef DEBUG