implemented IKEv2 force_encap connection parameter

enforces UDP encapsulation by faking NAT detection payloads
  to hurdle restrictive firewalls

src/charon/config/backends/sqlite_backend.c

@@ -192,6 +192,7 @@ static peer_cfg_t *process_peer_cfg_row(private_sqlite_backend_t *this,
 			sqlite3_column_int(stmt, 10),				/* jitter */
 			sqlite3_column_int(stmt, 13),				/* reauth */
 			sqlite3_column_int(stmt, 14),				/* mobike */
+			FALSE,										/* force_encap */
 			sqlite3_column_int(stmt, 11),				/* dpd_delay */
 			sqlite3_column_int(stmt, 12),				/* dpd_action */
 			local_vip, remote_vip);

src/charon/config/peer_cfg.c

@@ -140,6 +140,11 @@ struct private_peer_cfg_t {
 	 */
 	bool use_mobike;
 	
+	/**
+	 * enforce UDP encapsulation
+	 */
+	bool force_encap;
+	
 	/**
 	 * Time before an SA gets invalid
 	 */
@@ -365,6 +370,14 @@ static bool use_mobike(private_peer_cfg_t *this)
 	return this->use_mobike;
 }
 	
+/**
+ * Implementation of peer_cfg_t.force_encap.
+ */
+static bool force_encap_meth(private_peer_cfg_t *this)
+{
+	return this->force_encap;
+}
+
 /**
  * Implements peer_cfg_t.get_dpd_delay
  */
@@ -452,7 +465,7 @@ peer_cfg_t *peer_cfg_create(char *name, u_int ike_version, ike_cfg_t *ike_cfg,
 							auth_method_t auth_method, eap_type_t eap_type,
 							u_int32_t keyingtries, u_int32_t lifetime,
 							u_int32_t rekeytime, u_int32_t jitter,
-							bool reauth, bool mobike,
+							bool reauth, bool mobike, bool force_encap,
 							u_int32_t dpd_delay, dpd_action_t dpd_action,
 							host_t *my_virtual_ip, host_t *other_virtual_ip)
 {
@@ -477,6 +490,7 @@ peer_cfg_t *peer_cfg_create(char *name, u_int ike_version, ike_cfg_t *ike_cfg,
 	this->public.get_lifetime = (u_int32_t (*) (peer_cfg_t *, bool rekey))get_lifetime;
 	this->public.use_reauth = (bool (*) (peer_cfg_t *))use_reauth;
 	this->public.use_mobike = (bool (*) (peer_cfg_t *))use_mobike;
+	this->public.force_encap = (bool (*) (peer_cfg_t *))force_encap_meth;
 	this->public.get_dpd_delay = (u_int32_t (*) (peer_cfg_t *))get_dpd_delay;
 	this->public.get_dpd_action = (dpd_action_t (*) (peer_cfg_t *))get_dpd_action;
 	this->public.get_my_virtual_ip = (host_t* (*) (peer_cfg_t *))get_my_virtual_ip;
@@ -504,6 +518,7 @@ peer_cfg_t *peer_cfg_create(char *name, u_int ike_version, ike_cfg_t *ike_cfg,
 	this->jitter = jitter;
 	this->use_reauth = reauth;
 	this->use_mobike = mobike;
+	this->force_encap = force_encap;
 	this->dpd_delay = dpd_delay;
 	this->dpd_action = dpd_action;
 	this->my_virtual_ip = my_virtual_ip;

src/charon/config/peer_cfg.h

@@ -273,6 +273,14 @@ struct peer_cfg_t {
 	 */
 	bool (*use_mobike) (peer_cfg_t *this);
 	
+	/**
+	 * @brief Enforce UDP encapsulation by faking NATD notifies?
+	 * 
+	 * @param this		calling object
+	 * @return			TRUE to enfoce UDP encapsulation
+	 */
+	bool (*force_encap) (peer_cfg_t *this);
+	
 	/**
 	 * @brief Get the DPD check interval.
 	 * 
@@ -364,8 +372,9 @@ struct peer_cfg_t {
  * @param lifetime			lifetime before deleting an SA
  * @param rekeytime			lifetime before rekeying an SA
  * @param jitter			range of random to substract from rekeytime
- * @param use_reauth		sould be done reauthentication instead of rekeying?
+ * @param reauth			sould be done reauthentication instead of rekeying?
- * @param use_mobike		use MOBIKE (RFC4555) if peer supports it
+ * @param mobike			use MOBIKE (RFC4555) if peer supports it
+ * @param force_encap		enforce UDP encapsulation by faking NATD notify
  * @param dpd_delay			after how many seconds of inactivity to check DPD
  * @param dpd_action		what to do with CHILD_SAs when detected a dead peer
  * @param my_virtual_ip		virtual IP for local host, or NULL
@@ -381,7 +390,7 @@ peer_cfg_t *peer_cfg_create(char *name, u_int ikev_version, ike_cfg_t *ike_cfg,
 							auth_method_t auth_method, eap_type_t eap_type,
 							u_int32_t keyingtries, u_int32_t lifetime,
 							u_int32_t rekeytime, u_int32_t jitter,
-							bool reauth, bool mobike,
+							bool reauth, bool mobike, bool force_encap,
 							u_int32_t dpd_delay, dpd_action_t dpd_action,
 							host_t *my_virtual_ip, host_t *other_virtual_ip);
 

src/charon/control/interfaces/stroke_interface.c

@@ -572,7 +572,8 @@ static void stroke_add_conn(stroke_msg_t *msg, FILE *out)
 					msg->add_conn.rekey.ike_lifetime - msg->add_conn.rekey.margin,
 					msg->add_conn.rekey.margin * msg->add_conn.rekey.fuzz / 100, 
 					msg->add_conn.rekey.reauth, msg->add_conn.mobike, 
-					msg->add_conn.dpd.delay, msg->add_conn.dpd.action, my_vip, other_vip);
+					msg->add_conn.force_encap, msg->add_conn.dpd.delay,
+					msg->add_conn.dpd.action, my_vip, other_vip);
 	}
 	
 	child_cfg = child_cfg_create(

src/charon/sa/child_sa.c

@@ -822,6 +822,8 @@ static status_t update_hosts(private_child_sa_t *this,
 								policy->other_ts, policy->my_ts, POLICY_FWD);
 		
 			/* check wether we have to update a "dynamic" traffic selector */
+			DBG1(DBG_IKE, "--- my: %H, %H, %R", me, this->me.addr, policy->my_ts);
+			DBG1(DBG_IKE, "--- ot: %H, %H, %R", other, this->other.addr, policy->other_ts);
 			if (!me->ip_equals(me, this->me.addr) &&
 				policy->my_ts->is_host(policy->my_ts, this->me.addr))
 			{
@@ -832,6 +834,8 @@ static status_t update_hosts(private_child_sa_t *this,
 			{
 				policy->other_ts->set_address(policy->other_ts, other);
 			}
+			DBG1(DBG_IKE, "--- my: %H, %H, %R", me, this->me.addr, policy->my_ts);
+			DBG1(DBG_IKE, "--- ot: %H, %H, %R", other, this->other.addr, policy->other_ts);
 			
 			/* we reinstall the virtual IP to handle interface romaing
 			 * correctly */

src/charon/sa/ike_sa.c

@@ -495,6 +495,10 @@ static void set_condition(private_ike_sa_t *this, ike_condition_t condition,
 					DBG1(DBG_IKE, "remote host is behind NAT");
 					this->conditions |= COND_NAT_ANY;
 					break;
+				case COND_NAT_FAKE:
+					DBG1(DBG_IKE, "faked NAT situation to enforce UDP encapsulation");
+					this->conditions |= COND_NAT_ANY;
+					break;
 				default:
 					break;
 			}
@@ -508,10 +512,12 @@ static void set_condition(private_ike_sa_t *this, ike_condition_t condition,
 					DBG1(DBG_IKE, "new route to %H found", this->other_host);
 					break;
 				case COND_NAT_HERE:
+				case COND_NAT_FAKE:
 				case COND_NAT_THERE:
 					set_condition(this, COND_NAT_ANY,
 								  has_condition(this, COND_NAT_HERE) ||
-								  has_condition(this, COND_NAT_THERE));
+								  has_condition(this, COND_NAT_THERE) ||
+								  has_condition(this, COND_NAT_FAKE));
 					break;
 				default:
 					break;

src/charon/sa/ike_sa.h

@@ -94,7 +94,7 @@ enum ike_extension_t {
 enum ike_condition_t {
 	
 	/**
-	 * Connection is natted somewhere
+	 * Connection is natted (or faked) somewhere
 	 */
 	COND_NAT_ANY = (1<<0),
 	
@@ -108,10 +108,15 @@ enum ike_condition_t {
 	 */
 	COND_NAT_THERE = (1<<2),
 	
+	/**
+	 * Faking NAT to enforce UDP encapsulation
+	 */
+	COND_NAT_FAKE = (1<<3),
+
 	/**
 	 * peer is currently not reachable (due missing route, ...)
 	 */
-	COND_STALE = (1<<3),
+	COND_STALE = (1<<4),
 };
 
 /**

src/charon/sa/tasks/ike_natd.c

@@ -113,6 +113,25 @@ static chunk_t generate_natd_hash(private_ike_natd_t *this,
 	return natd_hash;
 }
 
+/**
+ * build a faked NATD payload to enforce UDP encap
+ */
+static chunk_t generate_natd_hash_faked(private_ike_natd_t *this)
+{
+	randomizer_t *randomizer;
+	chunk_t chunk;
+	
+	randomizer = randomizer_create();
+	if (randomizer->allocate_pseudo_random_bytes(randomizer, HASH_SIZE_SHA1,
+												 &chunk) != SUCCESS)
+	{
+		DBG1(DBG_IKE, "unable to get random bytes for NATD fake");
+		chunk = chunk_empty;
+	}
+	randomizer->destroy(randomizer);
+	return chunk;
+}
+
 /**
  * Build a NAT detection notify payload.
  */
@@ -122,11 +141,20 @@ static notify_payload_t *build_natd_payload(private_ike_natd_t *this,
 	chunk_t hash;
 	notify_payload_t *notify;	
 	ike_sa_id_t *ike_sa_id;
+	peer_cfg_t *config;
 	
 	ike_sa_id = this->ike_sa->get_id(this->ike_sa);
+	config = this->ike_sa->get_peer_cfg(this->ike_sa);
 	notify = notify_payload_create();
 	notify->set_notify_type(notify, type);
-	hash = generate_natd_hash(this, ike_sa_id, host);
+	if (config->force_encap(config) && type == NAT_DETECTION_SOURCE_IP)
+	{
+		hash = generate_natd_hash_faked(this);
+	}
+	else
+	{
+		hash = generate_natd_hash(this, ike_sa_id, host);
+	}
 	notify->set_notification_data(notify, hash);
 	chunk_free(&hash);
 	
@@ -144,6 +172,7 @@ static void process_payloads(private_ike_natd_t *this, message_t *message)
 	chunk_t hash, src_hash, dst_hash;
 	ike_sa_id_t *ike_sa_id;
 	host_t *me, *other;
+	peer_cfg_t *config;
 	
 	/* Precompute NAT-D hashes for incoming NAT notify comparison */
 	ike_sa_id = message->get_ike_sa_id(message);
@@ -210,6 +239,11 @@ static void process_payloads(private_ike_natd_t *this, message_t *message)
 									!this->dst_matched);
 		this->ike_sa->set_condition(this->ike_sa, COND_NAT_THERE,
 									!this->src_matched);		
+		config = this->ike_sa->get_peer_cfg(this->ike_sa);
+		if (config->force_encap(config))
+		{
+			this->ike_sa->set_condition(this->ike_sa, COND_NAT_FAKE, TRUE);	
+		}
 	}
 }
 

src/pluto/constants.h

@@ -876,6 +876,7 @@ extern const char *prettypolicy(lset_t policy);
 #define POLICY_DONT_REAUTH	LELEM(21)	/* don't reauthenticate on rekeying, IKEv2 only */
 #define POLICY_BEET		LELEM(22)	/* bound end2end tunnel, IKEv2 */
 #define POLICY_MOBIKE		LELEM(23)	/* enable MOBIKE for IKEv2  */
+#define POLICY_FORCE_ENCAP	LELEM(24)	/* force UDP encapsulation (IKEv2)  */
 
 /* Any IPsec policy?  If not, a connection description
  * is only for ISAKMP SA, not IPSEC SA.  (A pun, I admit.)

src/starter/args.c

@@ -194,6 +194,7 @@ static const token_info_t token_info[] =
     { ARG_MISC, 0, NULL  /* KW_AUTHBY */                                           },
     { ARG_MISC, 0, NULL  /* KW_EAP */                                              },
     { ARG_MISC, 0, NULL  /* KW_MOBIKE */                                           },
+    { ARG_MISC, 0, NULL  /* KW_FORCE_ENCAP */                                      },
     { ARG_TIME, offsetof(starter_conn_t, sa_ike_life_seconds), NULL                },
     { ARG_TIME, offsetof(starter_conn_t, sa_ipsec_life_seconds), NULL              },
     { ARG_TIME, offsetof(starter_conn_t, sa_rekey_margin), NULL                    },

src/starter/confread.c

@@ -554,6 +554,9 @@ load_conn(starter_conn_t *conn, kw_list_t *kw, starter_config_t *cfg)
 		case KW_MOBIKE:
 			KW_POLICY_FLAG("yes", "no", POLICY_MOBIKE)
 			break;
+		case KW_FORCE_ENCAP:
+			KW_POLICY_FLAG("yes", "no", POLICY_FORCE_ENCAP)
+			break;
 		case KW_MODECONFIG:
 			KW_POLICY_FLAG("push", "pull", POLICY_MODECFG_PUSH)
 			break;

src/starter/ipsec.conf.5

@@ -365,6 +365,11 @@ for the connection, e.g.
 (encryption-integrity-[dh-group]). If dh-group is specified, CHILD_SA setup
 and rekeying include a separate diffe hellman exchange (IKEv2 only).
 .TP
+.B force_encap
+Force UDP encapsulation for ESP packets even if no NAT situation is detected.
+This may help to hurdle restrictive firewalls. To enforce the peer to 
+encapsulate packets, NAT detection payloads are faked (IKEv2 only).
+.TP
 .B ike
 IKE/ISAKMP SA encryption/authentication algorithm to be used, e.g.
 .B aes128-sha1-modp2048

src/starter/keywords.h

@@ -71,6 +71,7 @@ typedef enum {
     KW_AUTHBY,
     KW_EAP,
     KW_MOBIKE,
+    KW_FORCE_ENCAP,
     KW_IKELIFETIME,
     KW_KEYLIFE,
     KW_REKEYMARGIN,

src/starter/keywords.txt

@@ -50,6 +50,7 @@ virtual_private,   KW_VIRTUAL_PRIVATE
 eap,               KW_EAP
 eapdir,            KW_EAPDIR
 mobike,	           KW_MOBIKE
+force_encap,       KW_FORCE_ENCAP
 pkcs11module,      KW_PKCS11MODULE
 pkcs11initargs,    KW_PKCS11INITARGS
 pkcs11keepstate,   KW_PKCS11KEEPSTATE

src/stroke/stroke.c

@@ -110,6 +110,7 @@ static int add_connection(char *name,
 	msg.add_conn.eap_type = 0;
 	msg.add_conn.mode = 1;
 	msg.add_conn.mobike = 1;
+	msg.add_conn.force_encap = 0;
 	
 	msg.add_conn.rekey.reauth = 0;
 	msg.add_conn.rekey.ipsec_lifetime = 0;

src/stroke/stroke.h

@@ -183,6 +183,7 @@ struct stroke_msg_t {
 			int eap_type;
 			int mode;
 			int mobike;
+			int force_encap;
 			struct {
 				char *ike;
 				char *esp;