diff -uNr dhcp-4.0.0.ORIG/client/clparse.c dhcp-4.0.0/client/clparse.c
--- dhcp-4.0.0.ORIG/client/clparse.c	2008-09-01 13:50:55.000000000 +0100
+++ dhcp-4.0.0/client/clparse.c	2008-09-01 13:51:31.000000000 +0100
@@ -149,6 +149,11 @@
 	status = read_client_conf_file (path_dhclient_conf,
 					(struct interface_info *)0,
 					&top_level_config);
+
+	/* Read any extra configuration from stdin */
+	read_client_conf_stdin ((struct interface_info *)0,
+					&top_level_config);
+	
 	if (status != ISC_R_SUCCESS) {
 		;
 #ifdef LATER
@@ -201,20 +206,17 @@
 	return status;
 }
 
-int read_client_conf_file (const char *name, struct interface_info *ip,
-			   struct client_config *client)
+int read_client_conf_actual (int file, const char *name, 
+			     struct interface_info *ip,
+			     struct client_config *client)
 {
-	int file;
 	struct parse *cfile;
 	const char *val;
 	int token;
 	isc_result_t status;
 	
-	if ((file = open (name, O_RDONLY)) < 0)
-		return uerr2isc (errno);
-
 	cfile = (struct parse *)0;
-	new_parse (&cfile, file, (char *)0, 0, path_dhclient_conf, 0);
+	new_parse (&cfile, file, (char *)0, 0, name , 0);
 
 	do {
 		token = peek_token (&val, (unsigned *)0, cfile);
@@ -230,6 +232,32 @@
 	return status;
 }
 
+int read_client_conf_file (const char *name, struct interface_info *ip,
+			   struct client_config *client)
+{
+	int file;
+	isc_result_t status;
+	
+	if ((file = open (name, O_RDONLY)) < 0)
+		return uerr2isc (errno);
+
+	status = read_client_conf_actual(file, name, ip, client);
+
+	return status;
+}
+
+
+int read_client_conf_stdin (struct interface_info *ip,
+			    struct client_config *client)
+{
+	int file = fileno(stdin);
+	isc_result_t status;
+
+	if (isatty(file)) return ISC_R_NOTFOUND;
+	status = read_client_conf_actual(file, "stdin", ip, client);
+
+	return status;
+}
 
 /* lease-file :== client-lease-statements END_OF_FILE
    client-lease-statements :== <nil>
diff -uNr dhcp-4.0.0.ORIG/common/conflex.c dhcp-4.0.0/common/conflex.c
--- dhcp-4.0.0.ORIG/common/conflex.c	2008-09-01 13:50:55.000000000 +0100
+++ dhcp-4.0.0/common/conflex.c	2008-09-01 13:52:55.000000000 +0100
@@ -103,7 +103,7 @@
 	struct parse **cfile;
 {
 	/* "Memory" config files have no file. */
-	if ((*cfile)->file != -1) {
+	if ((*cfile)->file != -1 && (*cfile)->file != fileno(stdin)) {
 		munmap((*cfile)->inbuf, (*cfile)->bufsiz);
 		close((*cfile)->file);
 	}