diff -ru nstx-1.1-beta6.tuntap/Makefile nstx-1.1-beta6/Makefile
--- nstx-1.1-beta6.tuntap/Makefile	2009-03-16 23:22:11.000000000 +0000
+++ nstx-1.1-beta6/Makefile	2009-03-16 23:27:09.000000000 +0000
@@ -1,9 +1,9 @@
 CFLAGS += -ggdb -Wall -Werror -Wsign-compare 
 
-NSTXD_SRCS = nstxd.c nstx_encode.c nstx_pstack.c nstx_dns.c nstx_tuntap.c nstx_queue.c
+NSTXD_SRCS = nstxd.c nstx_encode.c nstx_pstack.c nstx_dns.c nstx_tuntap.c nstx_queue.c nstx_util.c
 NSTXD_OBJS = ${NSTXD_SRCS:.c=.o}
 
-NSTXCD_SRCS = nstxcd.c nstx_encode.c nstx_pstack.c nstx_dns.c nstx_tuntap.o nstx_queue.c
+NSTXCD_SRCS = nstxcd.c nstx_encode.c nstx_pstack.c nstx_dns.c nstx_tuntap.o nstx_queue.c nstx_util.c
 NSTXCD_OBJS = ${NSTXCD_SRCS:.c=.o}
 
 PROGS = nstxd nstxcd
diff -ru nstx-1.1-beta6.tuntap/nstx_util.c nstx-1.1-beta6/nstx_util.c
--- nstx-1.1-beta6.tuntap/nstx_util.c	2004-06-27 21:43:34.000000000 +0000
+++ nstx-1.1-beta6/nstx_util.c	2009-03-16 23:28:37.000000000 +0000
@@ -27,6 +27,10 @@
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
+#include <arpa/inet.h>
+#include <errno.h>
 
 #include "nstxfun.h"
 
@@ -48,6 +52,48 @@
    close(fd);
 }
 
+static int iface_addr(const char * name, in_addr_t * result) {
+    int r, s;
+    struct ifreq ifr;
+    struct sockaddr_in * sin;
+    
+    s = socket(AF_INET, SOCK_DGRAM, 0);
+
+    if (s < 0) {
+        perror("socket");
+        return s;
+    }
+
+    strncpy(ifr.ifr_name, name, sizeof(ifr.ifr_name));
+    ifr.ifr_name[sizeof(ifr.ifr_name) - 1] = 0;
+
+    r = ioctl(s, SIOCGIFADDR, &ifr);
+
+    if (r < 0) {
+        perror("ioctl(SIOCGIFADDR)");
+        return r;
+    }
+
+    sin = (struct sockaddr_in *)&ifr.ifr_addr;
+    *result = sin->sin_addr.s_addr;
+
+    if (*result == INADDR_ANY || *result == INADDR_NONE) {
+        fprintf(stderr, "interface %s has no assigned address\n", name);
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
+int addr_convert(const char * s, in_addr_t * result) {
+    *result = inet_addr(s);
+
+    if (*result != INADDR_NONE)
+        return 0;
+
+    return iface_addr(s, result);
+}
+
 #ifdef WITH_PKTDUMP
 void
 pktdump (const char *prefix, unsigned short id, const char *data,
diff -ru nstx-1.1-beta6.tuntap/nstxd.8 nstx-1.1-beta6/nstxd.8
--- nstx-1.1-beta6.tuntap/nstxd.8	2009-03-16 23:23:46.000000000 +0000
+++ nstx-1.1-beta6/nstxd.8	2009-03-16 23:29:59.000000000 +0000
@@ -22,8 +22,8 @@
 Tun mode (default)
 .IP \-T
 Tap mode
-.IP \-i ipaddr
-Bind to this IP address rather than every available address
+.IP \-i ipaddr|interface
+Bind to this IP address or interface rather than every available address
 .IP \-C dir
 Chroot to this directory on startup
 .IP \-D
diff -ru nstx-1.1-beta6.tuntap/nstxd.c nstx-1.1-beta6/nstxd.c
--- nstx-1.1-beta6.tuntap/nstxd.c	2009-03-16 23:23:46.000000000 +0000
+++ nstx-1.1-beta6/nstxd.c	2009-03-16 23:32:45.000000000 +0000
@@ -61,7 +61,7 @@
 	    "\t-t (tun mode, default)\n"
 	    "\t-T (tap mode)\n"
 #endif
-	    "\t-i ip.to.bi.nd (bind to port 53 on this IP only)\n"
+	    "\t-i ip|interface (bind to port 53 on this IP/interface only)\n"
 	    "\t-C dir (chroot() to this directory after initialization)\n"
 	    "\t-D (call daemon(3) to detach from terminal)\n"
 	    "\t-g (enable debug messages)\n"
@@ -80,14 +80,15 @@
    int		 daemonize = 0;
    int		 logmask = LOG_UPTO(LOG_INFO);
    int tun = 1;
+   int r;
    
    while ((ch = getopt(argc, argv, "gDC:u:hd:I:i:tT")) != -1) {
 	switch(ch) {
 	case 'i':
-		bindto = inet_addr(optarg);
-		if (bindto == INADDR_NONE) {
-			fprintf(stderr, "`%s' is not an IP-address\n",
-			    optarg);
+        r = addr_convert(optarg, &bindto);
+        if (r < 0) {
+            fprintf(stderr, "couldn't use interface %s: %s\n", optarg,
+                    strerror(-r));
 			exit(EX_USAGE);
 		}
 		break;
diff -ru nstx-1.1-beta6.tuntap/nstxfun.h nstx-1.1-beta6/nstxfun.h
--- nstx-1.1-beta6.tuntap/nstxfun.h	2009-03-16 23:23:46.000000000 +0000
+++ nstx-1.1-beta6/nstxfun.h	2009-03-16 23:28:37.000000000 +0000
@@ -102,4 +102,6 @@
 void pktdump (const char *, unsigned short, const char *, size_t, int);
 #endif
 
+int addr_convert(const char *, in_addr_t *);
+
 #endif /* _NSTXHDR_H */