--- ppp-2.4.4/pppd/demand.c

+++ ppp-2.4.4/pppd/demand.c

@@ -45,6 +45,7 @@

 #include <sys/socket.h>

 #ifdef PPP_FILTER

 #include <pcap-bpf.h>

+#include <linux/if_ether.h>

 #endif

 #include "pppd.h"

@@ -341,6 +342,7 @@

 	return 0;

     proto = PPP_PROTOCOL(p);

 #ifdef PPP_FILTER

+    *p = 1; /* set outbound for the filter rule */

     p[0] = 1;		/* outbound packet indicator */

     if ((pass_filter.bf_len != 0

 	 && bpf_filter(pass_filter.bf_insns, p, len, len) == 0)

@@ -350,6 +352,7 @@

 	return 0;

     }

     p[0] = 0xff;

+    *p = 0xff; /* restore original ppp header */

 #endif

     for (i = 0; (protp = protocols[i]) != NULL; ++i) {

 	if (protp->protocol < 0xC000 && (protp->protocol & ~0x8000) == proto) {

--- ppp-2.4.4/pppd/options.c

+++ ppp-2.4.4/pppd/options.c

@@ -1459,6 +1459,10 @@

     int ret = 1;

     pc = pcap_open_dead(DLT_PPP_PPPD, 65535);

+    if (!pc) {

+        option_error("error in pass-filter expression: pcap_open_dead failed\n");

+        return 0;

+    }

     if (pcap_compile(pc, &pass_filter, *argv, 1, netmask) == -1) {

 	option_error("error in pass-filter expression: %s\n",

 		     pcap_geterr(pc));

@@ -1480,6 +1484,11 @@

     int ret = 1;

     pc = pcap_open_dead(DLT_PPP_PPPD, 65535);

+    if (!pc) {

+        option_error("error in active-filter expression: pcap_open_dead failed\n");

+        return 0;

+    }

+

     if (pcap_compile(pc, &active_filter, *argv, 1, netmask) == -1) {

 	option_error("error in active-filter expression: %s\n",

 		     pcap_geterr(pc));