diff --git a/src/eap_peer/eap.c b/src/eap_peer/eap.c
index db46d95..d23556d 100644
--- a/src/eap_peer/eap.c
+++ b/src/eap_peer/eap.c
@@ -1731,6 +1731,9 @@
 		wpa_hexdump_ascii(MSG_DEBUG,
 				  "EAP: using IMSI privacy anonymous identity",
 				  identity, identity_len);
+	} else if (config->strict_conservative_peer_mode) {
+		wpa_printf(MSG_DEBUG, "EAP: never use real identity in conservative peer mode.");
+		return NULL;
 	} else {
 		identity = config->identity;
 		identity_len = config->identity_len;
@@ -2816,6 +2819,24 @@
 	return config->identity;
 }
 
+
+/**
+ * eap_get_config_strict_conservative_peer_mode - get the value of
+ * strict conservative peer mode in eap_peer_config.
+ * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
+*/
+int eap_get_config_strict_conservative_peer_mode(struct eap_sm *sm)
+{
+	struct eap_peer_config *config;
+	config = eap_get_config(sm);
+	if (config) {
+		return config->strict_conservative_peer_mode;
+	}
+
+	return 0;
+}
+
+
 static const u8 * strnchr(const u8 *str, size_t len, u8 needle) {
 	const u8 *cur = str;
 
diff --git a/src/eap_peer/eap.h b/src/eap_peer/eap.h
index aae1a41..06654ce 100644
--- a/src/eap_peer/eap.h
+++ b/src/eap_peer/eap.h
@@ -371,6 +371,7 @@
 const u8 * eap_get_eapSessionId(struct eap_sm *sm, size_t *len);
 const u8 * eap_get_eapKeyData(struct eap_sm *sm, size_t *len);
 struct wpabuf * eap_get_eapRespData(struct eap_sm *sm);
+int eap_get_config_strict_conservative_peer_mode(struct eap_sm *sm);
 void eap_register_scard_ctx(struct eap_sm *sm, void *ctx);
 void eap_invalidate_cached_session(struct eap_sm *sm);
 
diff --git a/src/eap_peer/eap_aka.c b/src/eap_peer/eap_aka.c
index 7f660e6..fc2b16f 100644
--- a/src/eap_peer/eap_aka.c
+++ b/src/eap_peer/eap_aka.c
@@ -708,6 +708,11 @@
 		identity_len = data->pseudonym_len;
 		eap_aka_clear_identities(sm, data, CLEAR_REAUTH_ID);
 	} else if (id_req != NO_ID_REQ) {
+		if (id_req == PERMANENT_ID && eap_get_config_strict_conservative_peer_mode(sm)) {
+			wpa_printf(MSG_INFO,
+				   "EAP-AKA: reject permanent identity in conservative peer mode");
+			return eap_aka_client_error(data, id, EAP_AKA_UNABLE_TO_PROCESS_PACKET);
+		}
 		identity = eap_get_config_identity(sm, &identity_len);
 		if (identity) {
 			int ids = CLEAR_PSEUDONYM | CLEAR_REAUTH_ID;
diff --git a/src/eap_peer/eap_config.h b/src/eap_peer/eap_config.h
index 26744ab..e28ebad 100644
--- a/src/eap_peer/eap_config.h
+++ b/src/eap_peer/eap_config.h
@@ -338,6 +338,18 @@
 	char *imsi_privacy_attr;
 
 	/**
+	 * strict_conservative_peer_mode - Whether the strict conservative peer
+	 * mode is enabled or not
+	 *
+	 * This field is used to handle the reponse of AT_PERMANENT_ID_REQ
+	 * for EAP-SIM/AKA/AKA', in convervative peer mode, a client error would
+	 * be sent to the server, but it allows to send the permanent identity
+	 * in some special cases according to 4.6.2 of RFC 4187; With the strict
+	 * mode, it never send the permanent identity to server for privacy concern.
+	 */
+	int strict_conservative_peer_mode;
+
+	/**
 	 * machine_identity - EAP Identity for machine credential
 	 *
 	 * This field is used to set the machine identity or NAI for cases where
diff --git a/src/eap_peer/eap_sim.c b/src/eap_peer/eap_sim.c
index 71e9108..0ccb9a8 100644
--- a/src/eap_peer/eap_sim.c
+++ b/src/eap_peer/eap_sim.c
@@ -576,6 +576,11 @@
 		identity_len = data->pseudonym_len;
 		eap_sim_clear_identities(sm, data, CLEAR_REAUTH_ID);
 	} else if (id_req != NO_ID_REQ) {
+		if (id_req == PERMANENT_ID && eap_get_config_strict_conservative_peer_mode(sm)) {
+			wpa_printf(MSG_INFO,
+				   "EAP-SIM: reject permanent identity in conservative peer mode");
+			return  eap_sim_client_error(data, id, EAP_SIM_UNABLE_TO_PROCESS_PACKET);
+		}
 		identity = eap_get_config_identity(sm, &identity_len);
 		if (identity) {
 			int ids = CLEAR_PSEUDONYM | CLEAR_REAUTH_ID;