diff --git a/usr.sbin/dhcp/common/dlpi.c b/usr.sbin/dhcp/common/dlpi.c
index a493a3c966bb..34f63393a92d 100644
--- a/usr.sbin/dhcp/common/dlpi.c
+++ b/usr.sbin/dhcp/common/dlpi.c
@@ -82,6 +82,11 @@
  * to sleep.
  */
 
+#ifndef lint
+static char copyright[] =
+"$Id: dlpi.c,v 1.1.1.5 1999/04/26 15:43:06 mellon Exp $ Copyright (c) 1998, 1999 The Internet Software Consortium.  All rights reserved.\n";
+#endif /* not lint */
+
 #include "dhcpd.h"
 
 #if defined (USE_DLPI_SEND) || defined (USE_DLPI_RECEIVE)
diff --git a/usr.sbin/dhcp/common/inet.c b/usr.sbin/dhcp/common/inet.c
index 9f43950c3f60..5df00718f12c 100644
--- a/usr.sbin/dhcp/common/inet.c
+++ b/usr.sbin/dhcp/common/inet.c
@@ -40,6 +40,11 @@
  * Enterprises, see ``http://www.vix.com''.
  */
 
+#ifndef lint
+static char copyright[] =
+"$Id: inet.c,v 1.1.1.4 1999/04/26 15:43:07 mellon Exp $ Copyright (c) 1995, 1996, 1998, 1999 The Internet Software Consortium.  All rights reserved.\n";
+#endif /* not lint */
+
 #include "dhcpd.h"
 
 /* Return just the network number of an internet address... */
diff --git a/usr.sbin/dhcp/common/packet.c b/usr.sbin/dhcp/common/packet.c
index 422b2a39ea11..2aa2b5e937af 100644
--- a/usr.sbin/dhcp/common/packet.c
+++ b/usr.sbin/dhcp/common/packet.c
@@ -42,7 +42,7 @@
 
 #ifndef lint
 static char copyright[] =
-"$Id: packet.c,v 1.1.1.5 1999/03/26 17:49:22 mellon Exp $ Copyright (c) 1996 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: packet.c,v 1.1.1.6 1999/04/26 15:43:07 mellon Exp $ Copyright (c) 1996 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -72,6 +72,9 @@ u_int32_t checksum (buf, nbytes, sum)
 		debug ("sum = %x", sum);
 #endif
 		sum += (u_int16_t) ntohs(*((u_int16_t *)(buf + i)));
+		/* Add carry. */
+		if (sum > 0xFFFF)
+			sum -= 0xFFFF;
 	}	
 
 	/* If there's a single byte left over, checksum it, too.   Network
@@ -81,13 +84,15 @@ u_int32_t checksum (buf, nbytes, sum)
 		debug ("sum = %x", sum);
 #endif
 		sum += buf [i] << 8;
+		/* Add carry. */
+		if (sum > 0xFFFF)
+			sum -= 0xFFFF;
 	}
 	
 	return sum;
 }
 
-/* Fold the upper sixteen bits of the checksum down into the lower bits,
-   complement the sum, and then put it into network byte order. */
+/* Finish computing the sum, and then put it into network byte order. */
 
 u_int32_t wrapsum (sum)
 	u_int32_t sum;
@@ -96,17 +101,7 @@ u_int32_t wrapsum (sum)
 	debug ("wrapsum (%x)", sum);
 #endif
 
-	while (sum > 0x10000) {
-		sum = (sum >> 16) + (sum & 0xFFFF);
-#ifdef DEBUG_CHECKSUM_VERBOSE
-		debug ("sum = %x", sum);
-#endif
-		sum += (sum >> 16);
-#ifdef DEBUG_CHECKSUM_VERBOSE
-		debug ("sum = %x", sum);
-#endif
-	}
-	sum = sum ^ 0xFFFF;
+	sum = ~sum & 0xFFFF;
 #ifdef DEBUG_CHECKSUM_VERBOSE
 	debug ("sum = %x", sum);
 #endif
@@ -237,20 +232,25 @@ ssize_t decode_hw_header (interface, buf, bufix, from)
 
 /* UDP header and IP header decoded together for convenience. */
 
-ssize_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
+ssize_t decode_udp_ip_header (interface, buf, bufix, from, data, buflen)
 	struct interface_info *interface;
 	unsigned char *buf;
 	int bufix;
 	struct sockaddr_in *from;
 	unsigned char *data;
-	int len;
+	int buflen;
 {
   struct ip *ip;
   struct udphdr *udp;
   u_int32_t ip_len = (buf [bufix] & 0xf) << 2;
   u_int32_t sum, usum;
-  static int packets_seen;
-  static int packets_bad_checksum;
+  static int ip_packets_seen;
+  static int ip_packets_bad_checksum;
+  static int udp_packets_seen;
+  static int udp_packets_bad_checksum;
+  static int udp_packets_length_checked;
+  static int udp_packets_length_overflow;
+  int len;
 
   ip = (struct ip *)(buf + bufix);
   udp = (struct udphdr *)(buf + bufix + ip_len);
@@ -266,14 +266,23 @@ ssize_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
 #endif /* USERLAND_FILTER */
 
   /* Check the IP header checksum - it should be zero. */
+  ++ip_packets_seen;
   if (wrapsum (checksum (buf + bufix, ip_len, 0))) {
-	  if (packets_seen &&
-	      (++packets_seen / ++packets_bad_checksum) < 2)
-		  note ("Bad IP checksum: %x",
-			wrapsum (checksum (buf + bufix, sizeof *ip, 0)));
+	  ++ip_packets_bad_checksum;
+	  if (ip_packets_seen > 4 &&
+	      (ip_packets_seen / ip_packets_bad_checksum) < 2) {
+		  note ("%d bad IP checksums seen in %d packets",
+			ip_packets_bad_checksum, ip_packets_seen);
+		  ip_packets_seen = ip_packets_bad_checksum = 0;
+	  }
 	  return -1;
   }
 
+  /* Check the IP packet length. */
+  if (ntohs (ip -> ip_len) != buflen)
+	  debug ("ip length %d disagrees with bytes received %d.",
+		 ntohs (ip -> ip_len), buflen);
+
   /* Copy out the IP source address... */
   memcpy (&from -> sin_addr, &ip -> ip_src, 4);
 
@@ -283,7 +292,23 @@ ssize_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
 
   if (!data) {
 	  data = buf + bufix + ip_len + sizeof *udp;
-	  len -= ip_len + sizeof *udp;
+	  len = ntohs (udp -> uh_ulen) - sizeof *udp;
+	  ++udp_packets_length_checked;
+	  if (len + data > buf + bufix + buflen) {
+		  ++udp_packets_length_overflow;
+		  if (udp_packets_length_checked > 4 &&
+		      (udp_packets_length_checked /
+		       udp_packets_length_overflow) < 2) {
+			  note ("%d udp packets in %d too long - dropped",
+				udp_packets_length_overflow,
+				udp_packets_length_checked);
+			  udp_packets_length_overflow =
+				  udp_packets_length_checked = 0;
+		  }
+		  return -1;
+	  }
+	  if (len + data != buf + bufix + buflen)
+		  debug ("accepting packet with data after udp payload.");
   }
 
   usum = udp -> uh_sum;
@@ -298,12 +323,15 @@ ssize_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
 					       (u_int32_t)
 					       ntohs (udp -> uh_ulen)))));
 
+  udp_packets_seen++;
   if (usum && usum != sum) {
-	  static int packets_seen;
-	  static int packets_bad_checksum;
-	  if (packets_seen &&
-	      (++packets_seen / ++packets_bad_checksum) < 2)
-		  note ("Bad udp checksum: %x %x", usum, sum);
+	  udp_packets_bad_checksum++;
+	  if (udp_packets_seen > 4 &&
+	      (udp_packets_seen / udp_packets_bad_checksum) < 2) {
+		  note ("%d bad udp checksums in %d packets",
+			udp_packets_bad_checksum, udp_packets_seen);
+		  udp_packets_seen = udp_packets_bad_checksum = 0;
+	  }
 	  return -1;
   }
 
diff --git a/usr.sbin/dhcp/common/tables.c b/usr.sbin/dhcp/common/tables.c
index 51a8a4ec4007..4a3d6ae4ef0d 100644
--- a/usr.sbin/dhcp/common/tables.c
+++ b/usr.sbin/dhcp/common/tables.c
@@ -42,7 +42,7 @@
 
 #ifndef lint
 static char copyright[] =
-"$Id: tables.c,v 1.1.1.3 1999/02/18 21:48:51 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: tables.c,v 1.1.1.4 1999/04/26 15:43:08 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -130,20 +130,20 @@ struct option dhcp_options [256] = {
 	{ "dhcp-client-identifier", "X",		&dhcp_universe, 61 },
 	{ "option-62", "X",				&dhcp_universe, 62 },
 	{ "option-63", "X",				&dhcp_universe, 63 },
-	{ "option-64", "X",				&dhcp_universe, 64 },
-	{ "option-65", "X",				&dhcp_universe, 65 },
-	{ "option-66", "X",				&dhcp_universe, 66 },
-	{ "option-67", "X",				&dhcp_universe, 67 },
-	{ "option-68", "X",				&dhcp_universe, 68 },
-	{ "option-69", "X",				&dhcp_universe, 69 },
-	{ "option-70", "X",				&dhcp_universe, 70 },
-	{ "option-71", "X",				&dhcp_universe, 71 },
-	{ "option-72", "X",				&dhcp_universe, 72 },
-	{ "option-73", "X",				&dhcp_universe, 73 },
-	{ "option-74", "X",				&dhcp_universe, 74 },
-	{ "option-75", "X",				&dhcp_universe, 75 },
-	{ "option-76", "X",				&dhcp_universe, 76 },
-	{ "dhcp-user-class-identifier", "t",		&dhcp_universe, 77 },
+	{ "nisplus-domain", "t",			&dhcp_universe, 64 },
+	{ "nisplus-servers", "IA",			&dhcp_universe, 65 },
+	{ "tftp-server-name", "t",			&dhcp_universe, 66 },
+	{ "bootfile-name", "t",				&dhcp_universe, 67 },
+	{ "mobile-ip-home-agent", "IA",			&dhcp_universe, 68 },
+	{ "smtp-server", "IA",				&dhcp_universe, 69 },
+	{ "pop-server", "IA",				&dhcp_universe, 70 },
+	{ "nntp-server", "IA",				&dhcp_universe, 71 },
+	{ "www-server", "IA",				&dhcp_universe, 72 },
+	{ "finger-server", "IA",			&dhcp_universe, 73 },
+	{ "irc-server", "IA",				&dhcp_universe, 74 },
+	{ "streettalk-server", "IA",			&dhcp_universe, 75 },
+	{ "streettalk-directory-assistance-server", "IA", &dhcp_universe, 76 },
+	{ "user-class", "t",				&dhcp_universe, 77 },
 	{ "option-78", "X",				&dhcp_universe, 78 },
 	{ "option-79", "X",				&dhcp_universe, 79 },
 	{ "option-80", "X",				&dhcp_universe, 80 },
diff --git a/usr.sbin/dhcp/includes/osdep.h b/usr.sbin/dhcp/includes/osdep.h
index 781b04b024a3..5db5d8a5865e 100644
--- a/usr.sbin/dhcp/includes/osdep.h
+++ b/usr.sbin/dhcp/includes/osdep.h
@@ -119,10 +119,10 @@
 #  include "cf/cygwin32.h"
 #endif
 
-#ifdef NeXT
-# ifdef __APPLE__
-#  include "cf/rhapsody.h"
-# else
+#ifdef __APPLE__
+# include "cf/rhapsody.h"
+#else
+# if defined (NeXT)
 #  include "cf/nextstep.h"
 # endif
 #endif
diff --git a/usr.sbin/dhcp/relay/dhcrelay.c b/usr.sbin/dhcp/relay/dhcrelay.c
index 143e4784f604..52eb153ce565 100644
--- a/usr.sbin/dhcp/relay/dhcrelay.c
+++ b/usr.sbin/dhcp/relay/dhcrelay.c
@@ -42,7 +42,7 @@
 
 #ifndef lint
 static char ocopyright [] =
-"$Id: dhcrelay.c,v 1.1.1.13 1999/04/09 17:52:09 mellon Exp $ Copyright (c) 1997, 1998, 1999 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: dhcrelay.c,v 1.1.1.14 1999/04/26 15:43:10 mellon Exp $ Copyright (c) 1997, 1998, 1999 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -76,7 +76,7 @@ struct server_list {
 static char copyright [] =
 "Copyright 1997, 1998, 1999 The Internet Software Consortium.";
 static char arr [] = "All rights reserved.";
-static char message [] = "Internet Software Consortium DHCP Relay Agent V2.0b1pl25";
+static char message [] = "Internet Software Consortium DHCP Relay Agent V2.0b1pl27";
 static char contrib [] = "Please contribute if you find this software useful.";
 static char url [] = "For info, please visit http://www.isc.org/dhcp-contrib.html";
 
diff --git a/usr.sbin/dhcp/server/db.c b/usr.sbin/dhcp/server/db.c
index 1aee7b3df597..6de5a79165d2 100644
--- a/usr.sbin/dhcp/server/db.c
+++ b/usr.sbin/dhcp/server/db.c
@@ -42,7 +42,7 @@
 
 #ifndef lint
 static char copyright[] =
-"$Id: db.c,v 1.1.1.7 1999/02/18 21:48:54 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: db.c,v 1.1.1.8 1999/04/26 15:43:11 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -231,6 +231,15 @@ void new_lease_file ()
 		error ("Can't fdopen new lease file!");
 	}
 
+	/* Write an introduction so people don't complain about time
+	   being off. */
+	fprintf (db_file, "# All times in this file are in UTC (GMT), not %s",
+		 "your local timezone.   This is\n");
+	fprintf (db_file, "# not a bug, so please don't ask about it.   %s",
+		 "The format of this file is\n");
+	fprintf (db_file,
+		 "# documented in the dhcpd.leases(5) manual page.\n\n");
+
 	/* Write out all the leases that we know of... */
 	counting = 0;
 	write_leases ();