path: root/package/network/services/hostapd/patches/710-Add-network-specific-BSSID-black-and-white-lists.patch

Add network specific BSSID black and white lists

This change adds the configuration options "bssid_whitelist" and
"bssid_blacklist" used to limit the AP selection of a network to a
specified (finite) set or discard certain APs.

This can be useful for environments where multiple networks operate
using the same SSID and roaming between those is not desired. It is also
useful to ignore a faulty or otherwise unwanted AP.

In many applications it is useful not just to enumerate a group of well
known access points, but to use a address/mask notation to match an
entire set of addresses (ca:ff:ee:00:00:00/ff:ff:ff:00:00:00).

This change expands the data structures used by MAC lists to include a
mask indicating the significant (non-masked) portions of an address and
extends the list parser to recognize mask suffixes.

Signed-off-by: Stefan Tomanek <stefan.tomanek@wertarbyte.de>
---
 src/utils/common.c                 |  86 ++++++++++++--
 src/utils/common.h                 |   3 +
 wpa_supplicant/config.c            | 223 ++++++++++++++++++++++++-------------
 wpa_supplicant/config_ssid.h       |  12 ++
 wpa_supplicant/events.c            |  45 ++++++++
 wpa_supplicant/p2p_supplicant.c    |  40 ++++---
 wpa_supplicant/wpa_supplicant.conf |  15 +++
 7 files changed, 323 insertions(+), 101 deletions(-)

diff --git a/src/utils/common.c b/src/utils/common.c
index 9902004..dd6e4aa 100644
--- a/src/utils/common.c
+++ b/src/utils/common.c
@@ -36,6 +36,25 @@ int hex2byte(const char *hex)
 }
 
 
+static const char * hwaddr_parse(const char *txt, u8 *addr)
+{
+	size_t i;
+
+	for (i = 0; i < ETH_ALEN; i++) {
+		int a;
+
+		a = hex2byte(txt);
+		if (a < 0)
+			return NULL;
+		txt += 2;
+		addr[i] = a;
+		if (i < ETH_ALEN - 1 && *txt++ != ':')
+			return NULL;
+	}
+	return txt;
+}
+
+
 /**
  * hwaddr_aton - Convert ASCII string to MAC address (colon-delimited format)
  * @txt: MAC address as a string (e.g., "00:11:22:33:44:55")
@@ -44,25 +63,46 @@ int hex2byte(const char *hex)
  */
 int hwaddr_aton(const char *txt, u8 *addr)
 {
-	int i;
+	return hwaddr_parse(txt, addr) ? 0 : -1;
+}
 
-	for (i = 0; i < 6; i++) {
-		int a, b;
 
-		a = hex2num(*txt++);
-		if (a < 0)
-			return -1;
-		b = hex2num(*txt++);
-		if (b < 0)
-			return -1;
-		*addr++ = (a << 4) | b;
-		if (i < 5 && *txt++ != ':')
+/**
+ * hwaddr_masked_aton - Convert ASCII string with optional mask to MAC address (colon-delimited format)
+ * @txt: MAC address with optional mask as a string (e.g., "00:11:22:33:44:55/ff:ff:ff:ff:00:00")
+ * @addr: Buffer for the MAC address (ETH_ALEN = 6 bytes)
+ * @mask: Buffer for the MAC address mask (ETH_ALEN = 6 bytes)
+ * @maskable: Flag to indicate whether a mask is allowed
+ * Returns: 0 on success, -1 on failure (e.g., string not a MAC address)
+ */
+int hwaddr_masked_aton(const char *txt, u8 *addr, u8 *mask, u8 maskable)
+{
+	const char *r;
+
+	/* parse address part */
+	r = hwaddr_parse(txt, addr);
+	if (!r)
+		return -1;
+
+	/* check for optional mask */
+	if (*r == '\0' || isspace(*r)) {
+		/* no mask specified, assume default */
+		os_memset(mask, 0xff, ETH_ALEN);
+	} else if (maskable && *r == '/') {
+		/* mask specified and allowed */
+		r = hwaddr_parse(r + 1, mask);
+		/* parser error? */
+		if (!r)
 			return -1;
+	} else {
+		/* mask specified but not allowed or trailing garbage */
+		return -1;
 	}
 
 	return 0;
 }
 
+
 /**
  * hwaddr_compact_aton - Convert ASCII string to MAC address (no colon delimitors format)
  * @txt: MAC address as a string (e.g., "001122334455")
@@ -144,6 +184,30 @@ int hexstr2bin(const char *hex, u8 *buf, size_t len)
 }
 
 
+int hwaddr_mask_txt(char *buf, size_t len, const u8 *addr, const u8 *mask)
+{
+	size_t i;
+	int print_mask = 0;
+	int res;
+
+	for (i = 0; i < ETH_ALEN; i++) {
+		if (mask[i] != 0xff) {
+			print_mask = 1;
+			break;
+		}
+	}
+
+	if (print_mask)
+		res = os_snprintf(buf, len, MACSTR "/" MACSTR,
+				  MAC2STR(addr), MAC2STR(mask));
+	else
+		res = os_snprintf(buf, len, MACSTR, MAC2STR(addr));
+	if (os_snprintf_error(len, res))
+		return -1;
+	return res;
+}
+
+
 /**
  * inc_byte_array - Increment arbitrary length byte array by one
  * @counter: Pointer to byte array
diff --git a/src/utils/common.h b/src/utils/common.h
index 14d9ad1..1127074 100644
--- a/src/utils/common.h
+++ b/src/utils/common.h
@@ -468,6 +468,7 @@ typedef u64 __bitwise le64;
 #endif /* __must_check */
 
 int hwaddr_aton(const char *txt, u8 *addr);
+int hwaddr_masked_aton(const char *txt, u8 *addr, u8 *mask, u8 maskable);
 int hwaddr_compact_aton(const char *txt, u8 *addr);
 int hwaddr_aton2(const char *txt, u8 *addr);
 int hex2byte(const char *hex);
@@ -478,6 +479,8 @@ int wpa_snprintf_hex(char *buf, size_t buf_size, const u8 *data, size_t len);
 int wpa_snprintf_hex_uppercase(char *buf, size_t buf_size, const u8 *data,
 			       size_t len);
 
+int hwaddr_mask_txt(char *buf, size_t len, const u8 *addr, const u8 *mask);
+
 #ifdef CONFIG_NATIVE_WINDOWS
 void wpa_unicode2ascii_inplace(TCHAR *str);
 TCHAR * wpa_strdup_tchar(const char *str);
diff --git a/wpa_supplicant/config.c b/wpa_supplicant/config.c
index 8d1e1e0..7f742cb 100644
--- a/wpa_supplicant/config.c
+++ b/wpa_supplicant/config.c
@@ -235,6 +235,99 @@ static char * wpa_config_write_int(const struct parse_data *data,
 #endif /* NO_CONFIG_WRITE */
 
 
+static int wpa_config_parse_addr_list(const struct parse_data *data,
+				      int line, const char *value,
+				      u8 **list, size_t *num, char *name,
+				      u8 abort_on_error, u8 masked)
+{
+	const char *pos;
+	u8 *buf, *n, addr[2 * ETH_ALEN];
+	size_t count;
+
+	buf = NULL;
+	count = 0;
+
+	pos = value;
+	while (pos && *pos) {
+		while (*pos == ' ')
+			pos++;
+
+		if (hwaddr_masked_aton(pos, addr, &addr[ETH_ALEN], masked)) {
+			if (abort_on_error || count == 0) {
+				wpa_printf(MSG_ERROR,
+					   "Line %d: Invalid %s address '%s'",
+					   line, name, value);
+				os_free(buf);
+				return -1;
+			}
+			/* continue anyway since this could have been from a
+			 * truncated configuration file line */
+			wpa_printf(MSG_INFO,
+				   "Line %d: Ignore likely truncated %s address '%s'",
+				   line, name, pos);
+		} else {
+			n = os_realloc_array(buf, count + 1, 2 * ETH_ALEN);
+			if (n == NULL) {
+				os_free(buf);
+				return -1;
+			}
+			buf = n;
+			os_memmove(buf + 2 * ETH_ALEN, buf,
+				   count * 2 * ETH_ALEN);
+			os_memcpy(buf, addr, 2 * ETH_ALEN);
+			count++;
+			wpa_printf(MSG_MSGDUMP,
+				   "%s: addr=" MACSTR " mask=" MACSTR,
+				   name, MAC2STR(addr),
+				   MAC2STR(&addr[ETH_ALEN]));
+		}
+
+		pos = os_strchr(pos, ' ');
+	}
+
+	os_free(*list);
+	*list = buf;
+	*num = count;
+
+	return 0;
+}
+
+
+#ifndef NO_CONFIG_WRITE
+static char * wpa_config_write_addr_list(const struct parse_data *data,
+					 const u8 *list, size_t num, char *name)
+{
+	char *value, *end, *pos;
+	int res;
+	size_t i;
+
+	if (list == NULL || num == 0)
+		return NULL;
+
+	value = os_malloc(2 * 20 * num);
+	if (value == NULL)
+		return NULL;
+	pos = value;
+	end = value + 2 * 20 * num;
+
+	for (i = num; i > 0; i--) {
+		const u8 *a = list + (i - 1) * 2 * ETH_ALEN;
+		const u8 *m = a + ETH_ALEN;
+
+		if (i < num)
+			*pos++ = ' ';
+		res = hwaddr_mask_txt(pos, end - pos, a, m);
+		if (res < 0) {
+			os_free(value);
+			return NULL;
+		}
+		pos += res;
+	}
+
+	return value;
+}
+#endif /* NO_CONFIG_WRITE */
+
 static int wpa_config_parse_bssid(const struct parse_data *data,
 				  struct wpa_ssid *ssid, int line,
 				  const char *value)
@@ -280,6 +373,50 @@ static char * wpa_config_write_bssid(const struct parse_data *data,
 #endif /* NO_CONFIG_WRITE */
 
 
+static int wpa_config_parse_bssid_blacklist(const struct parse_data *data,
+					    struct wpa_ssid *ssid, int line,
+					    const char *value)
+{
+	return wpa_config_parse_addr_list(data, line, value,
+					  &ssid->bssid_blacklist,
+					  &ssid->num_bssid_blacklist,
+					  "bssid_blacklist", 1, 1);
+}
+
+
+#ifndef NO_CONFIG_WRITE
+static char * wpa_config_write_bssid_blacklist(const struct parse_data *data,
+					       struct wpa_ssid *ssid)
+{
+	return wpa_config_write_addr_list(data, ssid->bssid_blacklist,
+					  ssid->num_bssid_blacklist,
+					  "bssid_blacklist");
+}
+#endif /* NO_CONFIG_WRITE */
+
+
+static int wpa_config_parse_bssid_whitelist(const struct parse_data *data,
+					    struct wpa_ssid *ssid, int line,
+					    const char *value)
+{
+	return wpa_config_parse_addr_list(data, line, value,
+					  &ssid->bssid_whitelist,
+					  &ssid->num_bssid_whitelist,
+					  "bssid_whitelist", 1, 1);
+}
+
+
+#ifndef NO_CONFIG_WRITE
+static char * wpa_config_write_bssid_whitelist(const struct parse_data *data,
+					       struct wpa_ssid *ssid)
+{
+	return wpa_config_write_addr_list(data, ssid->bssid_whitelist,
+					  ssid->num_bssid_whitelist,
+					  "bssid_whitelist");
+}
+#endif /* NO_CONFIG_WRITE */
+
+
 static int wpa_config_parse_psk(const struct parse_data *data,
 				struct wpa_ssid *ssid, int line,
 				const char *value)
@@ -1435,53 +1572,10 @@ static int wpa_config_parse_p2p_client_list(const struct parse_data *data,
 					    struct wpa_ssid *ssid, int line,
 					    const char *value)
 {
-	const char *pos;
-	u8 *buf, *n, addr[ETH_ALEN];
-	size_t count;
-
-	buf = NULL;
-	count = 0;
-
-	pos = value;
-	while (pos && *pos) {
-		while (*pos == ' ')
-			pos++;
-
-		if (hwaddr_aton(pos, addr)) {
-			if (count == 0) {
-				wpa_printf(MSG_ERROR, "Line %d: Invalid "
-					   "p2p_client_list address '%s'.",
-					   line, value);
-				os_free(buf);
-				return -1;
-			}
-			/* continue anyway since this could have been from a
-			 * truncated configuration file line */
-			wpa_printf(MSG_INFO, "Line %d: Ignore likely "
-				   "truncated p2p_client_list address '%s'",
-				   line, pos);
-		} else {
-			n = os_realloc_array(buf, count + 1, ETH_ALEN);
-			if (n == NULL) {
-				os_free(buf);
-				return -1;
-			}
-			buf = n;
-			os_memmove(buf + ETH_ALEN, buf, count * ETH_ALEN);
-			os_memcpy(buf, addr, ETH_ALEN);
-			count++;
-			wpa_hexdump(MSG_MSGDUMP, "p2p_client_list",
-				    addr, ETH_ALEN);
-		}
-
-		pos = os_strchr(pos, ' ');
-	}
-
-	os_free(ssid->p2p_client_list);
-	ssid->p2p_client_list = buf;
-	ssid->num_p2p_clients = count;
-
-	return 0;
+	return wpa_config_parse_addr_list(data, line, value,
+					  &ssid->p2p_client_list,
+					  &ssid->num_p2p_clients,
+					  "p2p_client_list", 0, 0);
 }
 
 
@@ -1489,34 +1583,9 @@ static int wpa_config_parse_p2p_client_list(const struct parse_data *data,
 static char * wpa_config_write_p2p_client_list(const struct parse_data *data,
 					       struct wpa_ssid *ssid)
 {
-	char *value, *end, *pos;
-	int res;
-	size_t i;
-
-	if (ssid->p2p_client_list == NULL || ssid->num_p2p_clients == 0)
-		return NULL;
-
-	value = os_malloc(20 * ssid->num_p2p_clients);
-	if (value == NULL)
-		return NULL;
-	pos = value;
-	end = value + 20 * ssid->num_p2p_clients;
-
-	for (i = ssid->num_p2p_clients; i > 0; i--) {
-		res = os_snprintf(pos, end - pos, MACSTR " ",
-				  MAC2STR(ssid->p2p_client_list +
-					  (i - 1) * ETH_ALEN));
-		if (res < 0 || res >= end - pos) {
-			os_free(value);
-			return NULL;
-		}
-		pos += res;
-	}
-
-	if (pos > value)
-		pos[-1] = '\0';
-
-	return value;
+	return wpa_config_write_addr_list(data, ssid->p2p_client_list,
+					  ssid->num_p2p_clients,
+					  "p2p_client_list");
 }
 #endif /* NO_CONFIG_WRITE */
 
@@ -1667,6 +1736,8 @@ static const struct parse_data ssid_fields[] = {
 	{ STR_RANGE(ssid, 0, MAX_SSID_LEN) },
 	{ INT_RANGE(scan_ssid, 0, 1) },
 	{ FUNC(bssid) },
+	{ FUNC(bssid_blacklist) },
+	{ FUNC(bssid_whitelist) },
 	{ FUNC_KEY(psk) },
 	{ FUNC(proto) },
 	{ FUNC(key_mgmt) },
@@ -1971,6 +2042,8 @@ void wpa_config_free_ssid(struct wpa_ssid *ssid)
 	os_free(ssid->freq_list);
 	os_free(ssid->bgscan);
 	os_free(ssid->p2p_client_list);
+	os_free(ssid->bssid_blacklist);
+	os_free(ssid->bssid_whitelist);
 #ifdef CONFIG_HT_OVERRIDES
 	os_free(ssid->ht_mcs);
 #endif /* CONFIG_HT_OVERRIDES */
diff --git a/wpa_supplicant/config_ssid.h b/wpa_supplicant/config_ssid.h
index a4910d0..7443207 100644
--- a/wpa_supplicant/config_ssid.h
+++ b/wpa_supplicant/config_ssid.h
@@ -128,6 +128,18 @@ struct wpa_ssid {
 	u8 bssid[ETH_ALEN];
 
 	/**
+	 * bssid_blacklist - List of inacceptable BSSIDs
+	 */
+	u8 *bssid_blacklist;
+	size_t num_bssid_blacklist;
+
+	/**
+	 * bssid_blacklist - List of acceptable BSSIDs
+	 */
+	u8 *bssid_whitelist;
+	size_t num_bssid_whitelist;
+
+	/**
 	 * bssid_set - Whether BSSID is configured for this network
 	 */
 	int bssid_set;
diff --git a/wpa_supplicant/events.c b/wpa_supplicant/events.c
index 6761c1a..855653c 100644
--- a/wpa_supplicant/events.c
+++ b/wpa_supplicant/events.c
@@ -703,6 +703,33 @@ static int bss_is_ess(struct wpa_bss *bss)
 }
 
 
+static int match_mac_mask(const u8 *addr_a, const u8 *addr_b, const u8 *mask)
+{
+	size_t i;
+
+	for (i = 0; i < ETH_ALEN; i++) {
+		if ((addr_a[i] & mask[i]) != (addr_b[i] & mask[i]))
+			return 0;
+	}
+	return 1;
+}
+
+
+static int addr_in_list(const u8 *addr, const u8 *list, size_t num)
+{
+	size_t i;
+
+	for (i = 0; i < num; i++) {
+		const u8 *a = list + i * ETH_ALEN * 2;
+		const u8 *m = a + ETH_ALEN;
+
+		if (match_mac_mask(a, addr, m))
+			return 1;
+	}
+	return 0;
+}
+
+
 static struct wpa_ssid * wpa_scan_res_match(struct wpa_supplicant *wpa_s,
 					    int i, struct wpa_bss *bss,
 					    struct wpa_ssid *group,
@@ -827,6 +854,24 @@ static struct wpa_ssid * wpa_scan_res_match(struct wpa_supplicant *wpa_s,
 			continue;
 		}
 
+		/* check blacklist */
+		if (ssid->num_bssid_blacklist &&
+		    addr_in_list(bss->bssid, ssid->bssid_blacklist,
+				 ssid->num_bssid_blacklist)) {
+			wpa_dbg(wpa_s, MSG_DEBUG,
+				"   skip - BSSID blacklisted");
+			continue;
+		}
+
+		/* if there is a whitelist, only accept those APs */
+		if (ssid->num_bssid_whitelist &&
+		    !addr_in_list(bss->bssid, ssid->bssid_whitelist,
+				  ssid->num_bssid_whitelist)) {
+			wpa_dbg(wpa_s, MSG_DEBUG,
+				"   skip - BSSID not in whitelist");
+			continue;
+		}
+
 		if (!wpa_supplicant_ssid_bss_match(wpa_s, ssid, bss))
 			continue;
 
diff --git a/wpa_supplicant/p2p_supplicant.c b/wpa_supplicant/p2p_supplicant.c
index 8cd43df..60dcb5d 100644
--- a/wpa_supplicant/p2p_supplicant.c
+++ b/wpa_supplicant/p2p_supplicant.c
@@ -831,7 +831,7 @@ static void wpas_p2p_add_persistent_group_client(struct wpa_supplicant *wpa_s,
 		return;
 
 	for (i = 0; s->p2p_client_list && i < s->num_p2p_clients; i++) {
-		if (os_memcmp(s->p2p_client_list + i * ETH_ALEN, addr,
+		if (os_memcmp(s->p2p_client_list + i * 2 * ETH_ALEN, addr,
 			      ETH_ALEN) != 0)
 			continue;
 
@@ -839,32 +839,42 @@ static void wpas_p2p_add_persistent_group_client(struct wpa_supplicant *wpa_s,
 			return; /* already the most recent entry */
 
 		/* move the entry to mark it most recent */
-		os_memmove(s->p2p_client_list + i * ETH_ALEN,
-			   s->p2p_client_list + (i + 1) * ETH_ALEN,
-			   (s->num_p2p_clients - i - 1) * ETH_ALEN);
+		os_memmove(s->p2p_client_list + i * 2 * ETH_ALEN,
+			   s->p2p_client_list + (i + 1) * 2 * ETH_ALEN,
+			   (s->num_p2p_clients - i - 1) * 2 * ETH_ALEN);
 		os_memcpy(s->p2p_client_list +
-			  (s->num_p2p_clients - 1) * ETH_ALEN, addr, ETH_ALEN);
+			  (s->num_p2p_clients - 1) * 2 * ETH_ALEN, addr,
+			  ETH_ALEN);
+		os_memset(s->p2p_client_list +
+			  (s->num_p2p_clients - 1) * 2 * ETH_ALEN + ETH_ALEN,
+			  0xff, ETH_ALEN);
 		found = 1;
 		break;
 	}
 
 	if (!found && s->num_p2p_clients < P2P_MAX_STORED_CLIENTS) {
 		n = os_realloc_array(s->p2p_client_list,
-				     s->num_p2p_clients + 1, ETH_ALEN);
+				     s->num_p2p_clients + 1, 2 * ETH_ALEN);
 		if (n == NULL)
 			return;
-		os_memcpy(n + s->num_p2p_clients * ETH_ALEN, addr, ETH_ALEN);
+		os_memcpy(n + s->num_p2p_clients * 2 * ETH_ALEN, addr,
+			  ETH_ALEN);
+		os_memset(n + s->num_p2p_clients * 2 * ETH_ALEN + ETH_ALEN,
+			  0xff, ETH_ALEN);
 		s->p2p_client_list = n;
 		s->num_p2p_clients++;
 	} else if (!found && s->p2p_client_list) {
 		/* Not enough room for an additional entry - drop the oldest
 		 * entry */
 		os_memmove(s->p2p_client_list,
-			   s->p2p_client_list + ETH_ALEN,
-			   (s->num_p2p_clients - 1) * ETH_ALEN);
+			   s->p2p_client_list + 2 * ETH_ALEN,
+			   (s->num_p2p_clients - 1) * 2 * ETH_ALEN);
 		os_memcpy(s->p2p_client_list +
-			  (s->num_p2p_clients - 1) * ETH_ALEN,
+			  (s->num_p2p_clients - 1) * 2 * ETH_ALEN,
 			  addr, ETH_ALEN);
+		os_memset(s->p2p_client_list +
+			  (s->num_p2p_clients - 1) * 2 * ETH_ALEN + ETH_ALEN,
+			  0xff, ETH_ALEN);
 	}
 
 	if (wpa_s->parent->conf->update_config &&
@@ -3276,7 +3286,7 @@ static void wpas_remove_persistent_peer(struct wpa_supplicant *wpa_s,
 		return;
 
 	for (i = 0; ssid->p2p_client_list && i < ssid->num_p2p_clients; i++) {
-		if (os_memcmp(ssid->p2p_client_list + i * ETH_ALEN, peer,
+		if (os_memcmp(ssid->p2p_client_list + i * 2 * ETH_ALEN, peer,
 			      ETH_ALEN) == 0)
 			break;
 	}
@@ -3296,9 +3306,9 @@ static void wpas_remove_persistent_peer(struct wpa_supplicant *wpa_s,
 		   "group %d client list%s",
 		   MAC2STR(peer), ssid->id,
 		   inv ? " due to invitation result" : "");
-	os_memmove(ssid->p2p_client_list + i * ETH_ALEN,
-		   ssid->p2p_client_list + (i + 1) * ETH_ALEN,
-		   (ssid->num_p2p_clients - i - 1) * ETH_ALEN);
+	os_memmove(ssid->p2p_client_list + i * 2 * ETH_ALEN,
+		   ssid->p2p_client_list + (i + 1) * 2 * ETH_ALEN,
+		   (ssid->num_p2p_clients - i - 1) * 2 * ETH_ALEN);
 	ssid->num_p2p_clients--;
 	if (wpa_s->parent->conf->update_config &&
 	    wpa_config_write(wpa_s->parent->confname, wpa_s->parent->conf))
@@ -6925,7 +6935,7 @@ struct wpa_ssid * wpas_p2p_get_persistent(struct wpa_supplicant *wpa_s,
 		if (s->mode != WPAS_MODE_P2P_GO || s->p2p_client_list == NULL)
 			continue;
 		for (i = 0; i < s->num_p2p_clients; i++) {
-			if (os_memcmp(s->p2p_client_list + i * ETH_ALEN,
+			if (os_memcmp(s->p2p_client_list + i * 2 * ETH_ALEN,
 				      addr, ETH_ALEN) == 0)
 				return s; /* peer is P2P client in persistent
 					   * group */
diff --git a/wpa_supplicant/wpa_supplicant.conf b/wpa_supplicant/wpa_supplicant.conf
index 0e8a28a..4bc08db 100644
--- a/wpa_supplicant/wpa_supplicant.conf
+++ b/wpa_supplicant/wpa_supplicant.conf
@@ -1408,6 +1408,21 @@ network={
 	key_mgmt=NONE
 }
 
+# Example configuration blacklisting two APs - these will be ignored
+# for this network.
+network={
+	ssid="example"
+	psk="very secret passphrase"
+	bssid_blacklist=02:11:22:33:44:55 02:22:aa:44:55:66
+}
+
+# Example configuration limiting AP selection to a specific set of APs;
+# any other AP not matching the masked address will be ignored.
+network={
+	ssid="example"
+	psk="very secret passphrase"
+	bssid_whitelist=02:55:ae:bc:00:00/ff:ff:ff:ff:00:00 00:00:77:66:55:44/00:00:ff:ff:ff:ff
+}
 
 # Example config file that will only scan on channel 36.
 freq_list=5180
-- 
2.1.3