diff -NurpP ppp-2.4.2.orig/pppd/options.c ppp-2.4.2/pppd/options.c
--- ppp-2.4.2.orig/pppd/options.c	2005-08-04 21:37:28 +0500
+++ ppp-2.4.2/pppd/options.c	2005-08-04 21:39:38 +0500
@@ -109,6 +109,8 @@ char	linkname[MAXPATHLEN];	/* logical na
 bool	tune_kernel;		/* may alter kernel settings */
 int	connect_delay = 1000;	/* wait this many ms after connect script */
 int	req_unit = -1;		/* requested interface unit */
+int	req_unit_min = -1;	/* requested interface unit min number */
+int	req_unit_max = -1;	/* requested interface unit max number */
 bool	multilink = 0;		/* Enable multilink operation */
 char	*bundle_name = NULL;	/* bundle name for multilink */
 bool	dump_options;		/* print out option values */
@@ -271,6 +273,14 @@ option_t general_options[] = {
       "PPP interface unit number to use if possible",
       OPT_PRIO | OPT_LLIMIT, 0, 0 },
 
+    { "unit_min", o_int, &req_unit_min,
+      "PPP interface minimum unit number to use if possible",
+      OPT_PRIO | OPT_LLIMIT, 0, 0 },
+
+    { "unit_max", o_int, &req_unit_max,
+      "PPP interface maximum unit number to use if possible",
+      OPT_PRIO | OPT_LLIMIT, 0, 0 },
+
     { "dump", o_bool, &dump_options,
       "Print out option values after parsing all options", 1 },
     { "dryrun", o_bool, &dryrun,
diff -NurpP ppp-2.4.2.orig/pppd/pppd.h ppp-2.4.2/pppd/pppd.h
--- ppp-2.4.2.orig/pppd/pppd.h	2005-08-04 21:37:28 +0500
+++ ppp-2.4.2/pppd/pppd.h	2005-08-04 21:40:19 +0500
@@ -307,6 +307,8 @@ extern bool	tune_kernel;	/* May alter ke
 extern int	connect_delay;	/* Time to delay after connect script */
 extern int	max_data_rate;	/* max bytes/sec through charshunt */
 extern int	req_unit;	/* interface unit number to use */
+extern int	req_unit_min;	/* interface unit minimum number to use */
+extern int	req_unit_max;	/* interface unit maximum number to use */
 extern bool	multilink;	/* enable multilink operation */
 extern bool	noendpoint;	/* don't send or accept endpt. discrim. */
 extern char	*bundle_name;	/* bundle name for multilink */
diff -NurpP ppp-2.4.2.orig/pppd/sys-linux.c ppp-2.4.2/pppd/sys-linux.c
--- ppp-2.4.2.orig/pppd/sys-linux.c	2005-08-04 21:37:28 +0500
+++ ppp-2.4.2/pppd/sys-linux.c	2005-08-04 21:48:29 +0500
@@ -638,13 +638,45 @@ static int make_ppp_unit()
 	    || fcntl(ppp_dev_fd, F_SETFL, flags | O_NONBLOCK) == -1)
 		warn("Couldn't set /dev/ppp to nonblock: %m");
 
-	ifunit = req_unit;
-	x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
-	if (x < 0 && req_unit >= 0 && errno == EEXIST) {
-		warn("Couldn't allocate PPP unit %d as it is already in use", req_unit);
-		ifunit = -1;
+	if (req_unit >= 0 && req_unit_min < 0 && req_unit_max < 0) {
+		ifunit = req_unit;
+
 		x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
+		if (x < 0 && req_unit >= 0 && errno == EEXIST) {
+			warn("Couldn't allocate PPP unit %d as it is already in use", req_unit);
+			ifunit = -1;
+			x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
+		}
+	}
+	else if (req_unit_min >= 0 ) {
+		if (req_unit_min >= req_unit_max) {
+			int tmp;
+			/* Swap it */
+			tmp = req_unit_max;
+			req_unit_max = req_unit_min;
+			req_unit_min = tmp;
+		}
+		/* Try 16 interfaces by default */
+		if (req_unit_max < 0)
+			req_unit_max = req_unit_min + 0xF;
+
+		for (ifunit = req_unit_min; ifunit <= req_unit_max; ifunit++) {
+			x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
+			if (x < 0 && errno == EEXIST) {
+				warn("Couldn't allocate PPP unit %d as it is already in use", ifunit);
+			}
+			if ( x >= 0 )
+				break;
+		}
+		if (x < 0)
+		{
+			warn("Couldn't allocate PPP unit from %d to %d as all range is already in use", req_unit_min, req_unit_max);
+			ifunit = -1;
+			x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
+		}
 	}
+
+
 	if (x < 0)
 		error("Couldn't create new ppp unit: %m");
 	return x;