diff --git a/convert_client.c b/convert_client.c
index a320ec0..86fb9ac 100644
--- a/convert_client.c
+++ b/convert_client.c
@@ -76,7 +76,8 @@ static LIST_HEAD(socket_htbl_t, socket_state) _socket_htable[NUM_BUCKETS];
 static pthread_mutex_t _socket_htable_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 static struct addrinfo *_converter_addr;
-static const char *	_convert_port = CONVERT_PORT;
+static const char *	_convert_port	= CONVERT_PORT;
+static const char *	_convert_cookie = NULL;
 
 static FILE *		_log;
 static pthread_mutex_t	_log_mutex = PTHREAD_MUTEX_INITIALIZER;
@@ -175,6 +176,12 @@ _redirect_connect_tlv(uint8_t *buf, size_t buf_len, struct sockaddr *addr)
 
 	opts.flags = CONVERT_F_CONNECT;
 
+	if (_convert_cookie) {
+		opts.flags		|= CONVERT_F_COOKIE;
+		opts.cookie_len		= strlen(_convert_cookie);
+		opts.cookie_data	= (uint8_t *)_convert_cookie;
+	}
+
 	switch (addr->sa_family) {
 	case AF_INET: {
 		struct sockaddr_in *in = (struct sockaddr_in *)addr;
@@ -543,6 +550,7 @@ _validate_parameters(char *err_buf, size_t len)
 {
 	const char *	convert_addr	= getenv("CONVERT_ADDR");
 	const char *	convert_port	= getenv("CONVERT_PORT");
+	const char *	convert_cookie	= getenv("CONVERT_COOKIE");
 
 	if (!convert_addr) {
 		snprintf(err_buf, len,
@@ -565,6 +573,9 @@ _validate_parameters(char *err_buf, size_t len)
 			_convert_port = convert_port;
 	}
 
+	if (convert_cookie)
+		_convert_cookie = convert_cookie;
+
 	/* resolve address */
 	if (getaddrinfo(convert_addr, _convert_port, NULL,
 	                &_converter_addr) != 0) {
@@ -572,8 +583,10 @@ _validate_parameters(char *err_buf, size_t len)
 		return -1;
 	}
 
-	log_info("connecting to convert service at %s:%s",
-	         convert_addr, _convert_port);
+	log_info("connecting to convert service at %s:%s%s%s",
+	         convert_addr, _convert_port,
+	         _convert_cookie ? " with cookie: " : "",
+	         _convert_cookie ? : "");
 
 	return 0;
 }
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 9d77a2f..ca50e76 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -25,7 +25,7 @@ add_test(NAME check_convert_util
 set(TEST_WRAPPER "${PROJECT_SOURCE_DIR}/tests/test-wrapper")
 
 foreach(TEST_CMD "curl" "wget")
-    foreach(TEST_TYPE "test_ok" "test_error")
+    foreach(TEST_TYPE "test_ok" "test_error" "test_cookie_ok" "test_cookie_error")
         set (test_name "${TEST_CMD}-${TEST_TYPE}")
 
         add_test(NAME "${test_name}"
diff --git a/tests/check_convert_util.c b/tests/check_convert_util.c
index 0e69774..feef676 100644
--- a/tests/check_convert_util.c
+++ b/tests/check_convert_util.c
@@ -279,7 +279,7 @@ START_TEST (test_convert_parse_tlvs_cookie) {
 
 	for (i = 0; i < cookie_len; ++i)
 		ck_assert_msg(opts->cookie_data[i] == cookie->opaque[i],
-		              "Should return exact copy TCP options");
+		              "Should return exact cookie value");
 
 	convert_free_opts(opts);
 	free(buff);
diff --git a/tests/converter_mock.py b/tests/converter_mock.py
index 48fd046..0b09da3 100644
--- a/tests/converter_mock.py
+++ b/tests/converter_mock.py
@@ -53,7 +53,30 @@ def run(self, converter):
             converter.recv_end_seq += 1
         payload = pkt.getlayer(Raw)
         if payload:
-            converter.recv_end_seq += len(payload.load)
+            payload = payload.load
+
+            converter.recv_end_seq += len(payload)
+
+            # For the moment, we assume the TLV connect contains the header (4 bytes)
+            # and the TLV Connect (4 + 16 bytes). The cookie is then at the offset 24.
+            cookie_flag_offset = 24
+
+            # The cookie will only be received in the syn pkt.
+            if tcp.flags.S and len(payload) > cookie_flag_offset and bytes(payload)[cookie_flag_offset] == 0x16:
+
+                # The cookie TLV is as follows: 1 byte flag + 1 byte TLV length
+                # + 2 byte zeros, then Cookie data
+                cookie_size_offset = cookie_flag_offset + 1
+                cookie_data_offset = cookie_flag_offset + 4
+
+                # Length is given in 32-bit words, and includes flag byte + length
+                # byte and the 2 bytes of zeros.
+                cookie_data_size = (bytes(payload)[cookie_size_offset] - 1) * 4
+
+                cookie_data_offset_end = cookie_data_offset + cookie_data_size
+
+                cookie_bytes = bytes(payload)[cookie_data_offset:cookie_data_offset_end]
+                converter.cookie = cookie_bytes.decode('utf-8').rstrip('\x00')
 
 
 class RecvSyn(RecvPkt):
@@ -98,6 +121,18 @@ def run(self, converter):
         super(SendSynAck, self).run(converter)
 
 
+class SendSynAckCheckCookie(SendSynAck):
+    def __init__(self, payload, cookie):
+        SendSynAck.__init__(self, payload=payload)
+        self.cookie = cookie
+
+    def run(self, converter):
+        # Check cookie value
+        if self.cookie != converter.cookie:
+            raise Exception("Wrong cookie '{}' instead of '{}'".format(converter.cookie, self.cookie))
+        super(SendSynAckCheckCookie, self).run(converter)
+
+
 class SendHTTPResp(SendPkt):
     def __init__(self, data):
         payload = "HTTP/1.1 200 OK\r\n"
diff --git a/tests/test-wrapper b/tests/test-wrapper
index 49b62cf..92e737f 100755
--- a/tests/test-wrapper
+++ b/tests/test-wrapper
@@ -13,6 +13,7 @@ export TEST_CONVERT_LOG=convert.log
 export TEST_OUTPUT_LOG=output.log
 export TEST_CONVERT_MOCK_LOG=convert_mock.log
 export TEST_VALIDATE_LOG=validate.log
+export TEST_CONVERT_COOKIE="cookie"
 
 SCAPY_PID=
 
@@ -60,7 +61,11 @@ sleep 1
 
 
 COMMAND=$(test_step run_cmd)
-CONVERT_LOG=${TEST_CONVERT_LOG} CONVERT_ADDR=127.0.0.1 LD_PRELOAD="../libconvert_client.so" ${COMMAND} > ${TEST_OUTPUT_LOG} 2>&1 || true
+CONVERT_LOG=${TEST_CONVERT_LOG} \
+    CONVERT_ADDR=127.0.0.1 \
+    CONVERT_COOKIE=${TEST_CONVERT_COOKIE} \
+    LD_PRELOAD="../libconvert_client.so" \
+        ${COMMAND} > ${TEST_OUTPUT_LOG} 2>&1 || true
 
 ret=$(test_step validate 2>&1 | tee ${TEST_VALIDATE_LOG})
 [ "${ret}" == "" ] && RETURN_CODE=0
diff --git a/tests/test_cookie_error.py b/tests/test_cookie_error.py
new file mode 100755
index 0000000..03a84d4
--- /dev/null
+++ b/tests/test_cookie_error.py
@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+
+from converter_mock import *
+from test_lib import *
+
+
+class TestCookieError(TestInstance):
+    def run(self):
+        converter = Convert(tlvs=[ConvertTLV_Error(error_code=3)])
+        print(converter.build())
+        cookie = self.get_cookie()
+
+        class MockConverterCookieError(MockConverter):
+            actions = [RecvSyn(), SendSynAckCheckCookie(converter.build(), cookie), Wait(1), SendPkt(flags='R')]
+        MockConverterCookieError()
+
+    def validate(self):
+        self.assert_log_contains("received TLV error: 3")
+
+
+TestCookieError()
diff --git a/tests/test_cookie_ok.py b/tests/test_cookie_ok.py
new file mode 100755
index 0000000..c9bfc7e
--- /dev/null
+++ b/tests/test_cookie_ok.py
@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+
+from converter_mock import *
+from test_lib import *
+
+
+class TestCookieOK(TestInstance):
+    def run(self):
+        cookie = self.get_cookie()
+        class MockConverterCookieOK(MockConverter):
+            actions = [RecvSyn(), SendSynAckCheckCookie(Convert().build(), cookie), RecvHTTPGet(
+            ), SendHTTPResp("HELLO, WORLD!"), SendPkt(flags='RA')]
+        MockConverterCookieOK()
+
+    def validate(self):
+        self.assert_result("HELLO, WORLD!")
+
+
+TestCookieOK()
diff --git a/tests/test_lib.py b/tests/test_lib.py
index 773ea78..9134ed6 100644
--- a/tests/test_lib.py
+++ b/tests/test_lib.py
@@ -35,6 +35,9 @@ def _get_log(self):
         with open(os.environ["TEST_CONVERT_LOG"]) as f:
             return f.read()
 
+    def get_cookie(self):
+        return os.environ["TEST_CONVERT_COOKIE"]
+
     def assert_result(self, result):
         assert result in self._get_result(), "Couldn't find '{}' in output".format(result)