The following patch is adopted from ISC DHCP version 4.3.0.
http://ftp.isc.org/isc/dhcp/4.3.0/dhcp-4.3.0.tar.gz

--- dhcp-4.1-ESV-R7/server/stables.c.orig	Thu Aug 23 19:23:54 2012
+++ dhcp-4.1-ESV-R7/server/stables.c	Mon Apr 28 16:37:14 2014
@@ -244,6 +244,7 @@
 	{ "delayed-ack", "S",			&server_universe,  58, 1 },
 	{ "max-ack-delay", "L",			&server_universe,  59, 1 },
 #endif
+	{ "ignore-client-uids", "f",		&server_universe,  60, 1 },
 	{ NULL, NULL, NULL, 0, 0 }
 };
 
--- dhcp-4.1-ESV-R7/server/dhcp.c.orig	Thu Aug 23 19:23:54 2012
+++ dhcp-4.1-ESV-R7/server/dhcp.c	Mon Apr 28 16:36:18 2014
@@ -2304,31 +2304,40 @@
 	/* Update Client Last Transaction Time. */
 	lt->cltt = cur_time;
 
-	/* Record the uid, if given... */
-	oc = lookup_option (&dhcp_universe, packet -> options,
-			    DHO_DHCP_CLIENT_IDENTIFIER);
-	if (oc &&
-	    evaluate_option_cache (&d1, packet, lease,
-				   (struct client_state *)0,
-				   packet -> options, state -> options,
-				   &lease -> scope, oc, MDL)) {
-		if (d1.len <= sizeof lt -> uid_buf) {
-			memcpy (lt -> uid_buf, d1.data, d1.len);
-			lt -> uid = lt -> uid_buf;
-			lt -> uid_max = sizeof lt -> uid_buf;
-			lt -> uid_len = d1.len;
-		} else {
-			unsigned char *tuid;
-			lt -> uid_max = d1.len;
-			lt -> uid_len = d1.len;
-			tuid = (unsigned char *)dmalloc (lt -> uid_max, MDL);
-			/* XXX inelegant */
-			if (!tuid)
-				log_fatal ("no memory for large uid.");
-			memcpy (tuid, d1.data, lt -> uid_len);
-			lt -> uid = tuid;
+	/* See if we want to record the uid for this client */
+	oc = lookup_option(&server_universe, state->options,
+	    SV_IGNORE_CLIENT_UIDS);
+	if ((oc == NULL) ||
+	    !evaluate_boolean_option_cache(&ignorep, packet, lease, NULL,
+		packet->options, state->options,
+		&lease->scope, oc, MDL)) {
+
+		/* Record the uid, if given... */
+		oc = lookup_option (&dhcp_universe, packet -> options,
+		    DHO_DHCP_CLIENT_IDENTIFIER);
+		if (oc &&
+		    evaluate_option_cache (&d1, packet, lease,
+			(struct client_state *)0,
+			packet -> options, state -> options,
+			&lease -> scope, oc, MDL)) {
+			if (d1.len <= sizeof lt -> uid_buf) {
+				memcpy (lt -> uid_buf, d1.data, d1.len);
+				lt -> uid = lt -> uid_buf;
+				lt -> uid_max = sizeof lt -> uid_buf;
+				lt -> uid_len = d1.len;
+			} else {
+				unsigned char *tuid;
+				lt -> uid_max = d1.len;
+				lt -> uid_len = d1.len;
+				tuid = (unsigned char *)dmalloc (lt -> uid_max, MDL);
+				/* XXX inelegant */
+				if (!tuid)
+					log_fatal ("no memory for large uid.");
+				memcpy (tuid, d1.data, lt -> uid_len);
+				lt -> uid = tuid;
+			}
+			data_string_forget (&d1, MDL);
 		}
-		data_string_forget (&d1, MDL);
 	}
 
 	if (host) {
--- dhcp-4.1-ESV-R7/server/dhcpd.conf.5.orig	Wed May  7 18:37:36 2014
+++ dhcp-4.1-ESV-R7/server/dhcpd.conf.5	Wed May  7 18:38:46 2014
@@ -2302,6 +2302,19 @@
 must be a constant value.
 .RE
 .PP
+The
+.I ignore-client-uids
+statement
+.RS 0.25i
+.PP
+.B ignore-client-uids \fIflag\fB;\fR
+.PP
+If the \fIignore-client-uids\fR statement is present and has a value of
+\fItrue\fR or \fIon\fR, the UID for clients will not be recorded.
+If this statement is not present or has a value of \fIfalse\fR or
+\fIoff\fR, then client UIDs will be recorded.
+.RE
+.PP
 The
 .I infinite-is-reserved
 statement
--- dhcp-4.1-ESV-R7/includes/dhcpd.h.orig	Thu Aug 23 19:23:53 2012
+++ dhcp-4.1-ESV-R7/includes/dhcpd.h	Mon Apr 28 16:11:17 2014
@@ -627,6 +627,7 @@
 #define SV_LIMIT_PREFS_PER_IA		57
 #define SV_DELAYED_ACK			58
 #define SV_MAX_ACK_DELAY		59
+#define SV_IGNORE_CLIENT_UIDS		60
 
 #if !defined (DEFAULT_PING_TIMEOUT)
 # define DEFAULT_PING_TIMEOUT 1