diff --git a/ChangeLog b/ChangeLog
index dc2acf7..96fa9f3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,6 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
-= mbed TLS x.x.x branch released xxxx-xx-xx
+= mbed TLS 2.16.6 branch released 2020-04-14
 
 Security
    * Fix side channel in ECC code that allowed an adversary with access to
@@ -14,6 +14,8 @@
 Bugfix
    * Fix compilation failure when both MBEDTLS_SSL_PROTO_DTLS and
      MBEDTLS_SSL_HW_RECORD_ACCEL are enabled.
+   * Fix a function name in a debug message. Contributed by Ercan Ozturk in
+     #3013.
 
 = mbed TLS 2.16.5 branch released 2020-02-20
 
diff --git a/Makefile b/Makefile
index 1ae6bd9..0a9640f 100644
--- a/Makefile
+++ b/Makefile
@@ -123,8 +123,10 @@
 
 ## Editor navigation files
 C_SOURCE_FILES = $(wildcard include/*/*.h library/*.[hc] programs/*/*.[hc] tests/suites/*.function)
+# Exuberant-ctags invocation. Other ctags implementations may require different options.
+CTAGS = ctags --langmap=c:+.h.function -o
 tags: $(C_SOURCE_FILES)
-	ctags -o $@ $(C_SOURCE_FILES)
+	$(CTAGS) $@ $(C_SOURCE_FILES)
 TAGS: $(C_SOURCE_FILES)
 	etags -o $@ $(C_SOURCE_FILES)
 GPATH GRTAGS GSYMS GTAGS: $(C_SOURCE_FILES)
diff --git a/doxygen/input/doc_mainpage.h b/doxygen/input/doc_mainpage.h
index bc55d13..db5bb49 100644
--- a/doxygen/input/doc_mainpage.h
+++ b/doxygen/input/doc_mainpage.h
@@ -24,7 +24,7 @@
  */
 
 /**
- * @mainpage mbed TLS v2.16.5 source code documentation
+ * @mainpage mbed TLS v2.16.6 source code documentation
  *
  * This documentation describes the internal structure of mbed TLS.  It was
  * automatically generated from specially formatted comment blocks in
diff --git a/doxygen/mbedtls.doxyfile b/doxygen/mbedtls.doxyfile
index d0b1744..1edc9ce 100644
--- a/doxygen/mbedtls.doxyfile
+++ b/doxygen/mbedtls.doxyfile
@@ -28,7 +28,7 @@
 # identify the project. Note that if you do not use Doxywizard you need
 # to put quotes around the project name if it contains spaces.
 
-PROJECT_NAME           = "mbed TLS v2.16.5"
+PROJECT_NAME           = "mbed TLS v2.16.6"
 
 # The PROJECT_NUMBER tag can be used to enter a project or revision number.
 # This could be handy for archiving the generated documentation or
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index d076c23..93de091 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -546,6 +546,23 @@
 #error "MBEDTLS_SSL_PROTO_TLS1_2 defined, but not all prerequisites"
 #endif
 
+#if (defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) ||  \
+     defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)) && \
+    !(defined(MBEDTLS_KEY_EXCHANGE_RSA_ENABLED) ||                          \
+      defined(MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED) ||                      \
+      defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED) ||                    \
+      defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) ||                  \
+      defined(MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED) ||                     \
+      defined(MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED) ||                   \
+      defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED) ||                          \
+      defined(MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED) ||                      \
+      defined(MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED) ||                      \
+      defined(MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED) ||                    \
+      defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED) )
+#error "One or more versions of the TLS protocol are enabled " \
+        "but no key exchange methods defined with MBEDTLS_KEY_EXCHANGE_xxxx"
+#endif
+
 #if defined(MBEDTLS_SSL_PROTO_DTLS)     && \
     !defined(MBEDTLS_SSL_PROTO_TLS1_1)  && \
     !defined(MBEDTLS_SSL_PROTO_TLS1_2)
@@ -669,6 +686,10 @@
 #error "MBEDTLS_X509_CREATE_C defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_CERTS_C) && !defined(MBEDTLS_X509_USE_C)
+#error "MBEDTLS_CERTS_C defined, but not all prerequisites"
+#endif
+
 #if defined(MBEDTLS_X509_CRT_PARSE_C) && ( !defined(MBEDTLS_X509_USE_C) )
 #error "MBEDTLS_X509_CRT_PARSE_C defined, but not all prerequisites"
 #endif
diff --git a/include/mbedtls/version.h b/include/mbedtls/version.h
index 8e2ce03..e0a2e7f 100644
--- a/include/mbedtls/version.h
+++ b/include/mbedtls/version.h
@@ -40,16 +40,16 @@
  */
 #define MBEDTLS_VERSION_MAJOR  2
 #define MBEDTLS_VERSION_MINOR  16
-#define MBEDTLS_VERSION_PATCH  5
+#define MBEDTLS_VERSION_PATCH  6
 
 /**
  * The single version number has the following structure:
  *    MMNNPP00
  *    Major version | Minor version | Patch version
  */
-#define MBEDTLS_VERSION_NUMBER         0x02100500
-#define MBEDTLS_VERSION_STRING         "2.16.5"
-#define MBEDTLS_VERSION_STRING_FULL    "mbed TLS 2.16.5"
+#define MBEDTLS_VERSION_NUMBER         0x02100600
+#define MBEDTLS_VERSION_STRING         "2.16.6"
+#define MBEDTLS_VERSION_STRING_FULL    "mbed TLS 2.16.6"
 
 #if defined(MBEDTLS_VERSION_C)
 
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 5c67d5b..93ce7b8 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -165,15 +165,15 @@
 
 if(USE_SHARED_MBEDTLS_LIBRARY)
     add_library(mbedcrypto SHARED ${src_crypto})
-    set_target_properties(mbedcrypto PROPERTIES VERSION 2.16.5 SOVERSION 3)
+    set_target_properties(mbedcrypto PROPERTIES VERSION 2.16.6 SOVERSION 3)
     target_link_libraries(mbedcrypto ${libs})
 
     add_library(mbedx509 SHARED ${src_x509})
-    set_target_properties(mbedx509 PROPERTIES VERSION 2.16.5 SOVERSION 0)
+    set_target_properties(mbedx509 PROPERTIES VERSION 2.16.6 SOVERSION 0)
     target_link_libraries(mbedx509 ${libs} mbedcrypto)
 
     add_library(mbedtls SHARED ${src_tls})
-    set_target_properties(mbedtls PROPERTIES VERSION 2.16.5 SOVERSION 12)
+    set_target_properties(mbedtls PROPERTIES VERSION 2.16.6 SOVERSION 12)
     target_link_libraries(mbedtls ${libs} mbedx509)
 
     install(TARGETS mbedtls mbedx509 mbedcrypto
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 65f59fb..cbec74f 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4005,17 +4005,23 @@
 
     if( ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED )
     {
+        int send_ret;
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "sending HelloVerifyRequest" ) );
+        MBEDTLS_SSL_DEBUG_BUF( 4, "output record sent to network",
+                                  ssl->out_buf, len );
         /* Don't check write errors as we can't do anything here.
          * If the error is permanent we'll catch it later,
          * if it's not, then hopefully it'll work next time. */
-        (void) ssl->f_send( ssl->p_bio, ssl->out_buf, len );
+        send_ret = ssl->f_send( ssl->p_bio, ssl->out_buf, len );
+        MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_send", send_ret );
+        (void) send_ret;
 
         return( MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED );
     }
 
     if( ret == 0 )
     {
-        /* Got a valid cookie, partially reset context */
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "cookie is valid, resetting context" ) );
         if( ( ret = ssl_session_reset_int( ssl, 1 ) ) != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "reset", ret );
diff --git a/library/x509.c b/library/x509.c
index 2e0b0e8..4d25303 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -1063,7 +1063,7 @@
     mbedtls_x509_crt_free( &clicert );
 #else
     ((void) verbose);
-#endif /* MBEDTLS_CERTS_C && MBEDTLS_SHA1_C */
+#endif /* MBEDTLS_CERTS_C && MBEDTLS_SHA256_C */
     return( ret );
 }
 
diff --git a/programs/test/udp_proxy.c b/programs/test/udp_proxy.c
index e96e91b..4be0865 100644
--- a/programs/test/udp_proxy.c
+++ b/programs/test/udp_proxy.c
@@ -130,6 +130,7 @@
     "    bad_ad=0/1          default: 0 (don't add bad ApplicationData)\n"  \
     "    protect_hvr=0/1     default: 0 (don't protect HelloVerifyRequest)\n" \
     "    protect_len=%%d      default: (don't protect packets of this size)\n" \
+    "    inject_clihlo=0/1   default: 0 (don't inject fake ClientHello)\n"  \
     "\n"                                                                    \
     "    seed=%%d             default: (use current time)\n"                \
     USAGE_PACK                                                              \
@@ -162,6 +163,7 @@
     int bad_ad;                 /* inject corrupted ApplicationData record  */
     int protect_hvr;            /* never drop or delay HelloVerifyRequest   */
     int protect_len;            /* never drop/delay packet of the given size*/
+    int inject_clihlo;          /* inject fake ClientHello after handshake  */
     unsigned pack;              /* merge packets into single datagram for
                                  * at most \c merge milliseconds if > 0     */
     unsigned int seed;          /* seed for "random" events                 */
@@ -304,6 +306,12 @@
             if( opt.protect_len < 0 )
                 exit_usage( p, q );
         }
+        else if( strcmp( p, "inject_clihlo" ) == 0 )
+        {
+            opt.inject_clihlo = atoi( q );
+            if( opt.inject_clihlo < 0 || opt.inject_clihlo > 1 )
+                exit_usage( p, q );
+        }
         else if( strcmp( p, "seed" ) == 0 )
         {
             opt.seed = atoi( q );
@@ -503,11 +511,41 @@
     fflush( stdout );
 }
 
+/*
+ * In order to test the server's behaviour when receiving a ClientHello after
+ * the connection is established (this could be a hard reset from the client,
+ * but the server must not drop the existing connection before establishing
+ * client reachability, see RFC 6347 Section 4.2.8), we memorize the first
+ * ClientHello we see (which can't have a cookie), then replay it after the
+ * first ApplicationData record - then we're done.
+ *
+ * This is controlled by the inject_clihlo option.
+ *
+ * We want an explicit state and a place to store the packet.
+ */
+typedef enum {
+    ICH_INIT,       /* haven't seen the first ClientHello yet */
+    ICH_CACHED,     /* cached the initial ClientHello */
+    ICH_INJECTED,   /* ClientHello already injected, done */
+} inject_clihlo_state_t;
+
+static inject_clihlo_state_t inject_clihlo_state;
+static packet initial_clihlo;
+
 int send_packet( const packet *p, const char *why )
 {
     int ret;
     mbedtls_net_context *dst = p->dst;
 
+    /* save initial ClientHello? */
+    if( opt.inject_clihlo != 0 &&
+        inject_clihlo_state == ICH_INIT &&
+        strcmp( p->type, "ClientHello" ) == 0 )
+    {
+        memcpy( &initial_clihlo, p, sizeof( packet ) );
+        inject_clihlo_state = ICH_CACHED;
+    }
+
     /* insert corrupted ApplicationData record? */
     if( opt.bad_ad &&
         strcmp( p->type, "ApplicationData" ) == 0 )
@@ -553,6 +591,23 @@
         }
     }
 
+    /* Inject ClientHello after first ApplicationData */
+    if( opt.inject_clihlo != 0 &&
+        inject_clihlo_state == ICH_CACHED &&
+        strcmp( p->type, "ApplicationData" ) == 0 )
+    {
+        print_packet( &initial_clihlo, "injected" );
+
+        if( ( ret = dispatch_data( dst, initial_clihlo.buf,
+                                        initial_clihlo.len ) ) <= 0 )
+        {
+            mbedtls_printf( "  ! dispatch returned %d\n", ret );
+            return( ret );
+        }
+
+        inject_clihlo_state = ICH_INJECTED;
+    }
+
     return( 0 );
 }
 
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 9fbf592..24c8616 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -5759,8 +5759,8 @@
 
 not_with_valgrind # spurious resend
 run_test    "DTLS client reconnect from same port: reference" \
-            "$P_SRV dtls=1 exchanges=2 read_timeout=1000" \
-            "$P_CLI dtls=1 exchanges=2 debug_level=2 hs_timeout=500-1000" \
+            "$P_SRV dtls=1 exchanges=2 read_timeout=20000 hs_timeout=10000-20000" \
+            "$P_CLI dtls=1 exchanges=2 debug_level=2 hs_timeout=10000-20000" \
             0 \
             -C "resend" \
             -S "The operation timed out" \
@@ -5768,8 +5768,8 @@
 
 not_with_valgrind # spurious resend
 run_test    "DTLS client reconnect from same port: reconnect" \
-            "$P_SRV dtls=1 exchanges=2 read_timeout=1000" \
-            "$P_CLI dtls=1 exchanges=2 debug_level=2 hs_timeout=500-1000 reconnect_hard=1" \
+            "$P_SRV dtls=1 exchanges=2 read_timeout=20000 hs_timeout=10000-20000" \
+            "$P_CLI dtls=1 exchanges=2 debug_level=2 hs_timeout=10000-20000 reconnect_hard=1" \
             0 \
             -C "resend" \
             -S "The operation timed out" \
@@ -5798,6 +5798,14 @@
             -s "The operation timed out" \
             -S "Client initiated reconnection from same port"
 
+run_test    "DTLS client reconnect from same port: attacker-injected" \
+            -p "$P_PXY inject_clihlo=1" \
+            "$P_SRV dtls=1 exchanges=2 debug_level=1" \
+            "$P_CLI dtls=1 exchanges=2" \
+            0 \
+            -s "possible client reconnect from the same port" \
+            -S "Client initiated reconnection from same port"
+
 # Tests for various cases of client authentication with DTLS
 # (focused on handshake flows and message parsing)
 
@@ -6867,8 +6875,8 @@
 not_with_valgrind # spurious resend due to timeout
 run_test    "DTLS proxy: reference" \
             -p "$P_PXY" \
-            "$P_SRV dtls=1 debug_level=2" \
-            "$P_CLI dtls=1 debug_level=2" \
+            "$P_SRV dtls=1 debug_level=2 hs_timeout=10000-20000" \
+            "$P_CLI dtls=1 debug_level=2 hs_timeout=10000-20000" \
             0 \
             -C "replayed record" \
             -S "replayed record" \
@@ -6883,8 +6891,8 @@
 not_with_valgrind # spurious resend due to timeout
 run_test    "DTLS proxy: duplicate every packet" \
             -p "$P_PXY duplicate=1" \
-            "$P_SRV dtls=1 dgram_packing=0 debug_level=2" \
-            "$P_CLI dtls=1 dgram_packing=0 debug_level=2" \
+            "$P_SRV dtls=1 dgram_packing=0 debug_level=2 hs_timeout=10000-20000" \
+            "$P_CLI dtls=1 dgram_packing=0 debug_level=2 hs_timeout=10000-20000" \
             0 \
             -c "replayed record" \
             -s "replayed record" \
diff --git a/tests/suites/test_suite_asn1write.function b/tests/suites/test_suite_asn1write.function
index 57a9741..7601439 100644
--- a/tests/suites/test_suite_asn1write.function
+++ b/tests/suites/test_suite_asn1write.function
@@ -78,7 +78,7 @@
 }
 /* END_CASE */
 
-/* BEGIN_CASE depends_on:MBEDTLS_ASN1PARSE_C */
+/* BEGIN_CASE depends_on:MBEDTLS_ASN1_PARSE_C */
 void mbedtls_asn1_write_len( int len, data_t * asn1, int buf_len,
                              int result )
 {
diff --git a/tests/suites/test_suite_version.data b/tests/suites/test_suite_version.data
index f8a2918..54c1220 100644
--- a/tests/suites/test_suite_version.data
+++ b/tests/suites/test_suite_version.data
@@ -1,8 +1,8 @@
 Check compiletime library version
-check_compiletime_version:"2.16.5"
+check_compiletime_version:"2.16.6"
 
 Check runtime library version
-check_runtime_version:"2.16.5"
+check_runtime_version:"2.16.6"
 
 Check for MBEDTLS_VERSION_C
 check_feature:"MBEDTLS_VERSION_C":0