diff --git a/webrtc/dtls.nim b/webrtc/dtls.nim
index a904011..0e38b89 100644
--- a/webrtc/dtls.nim
+++ b/webrtc/dtls.nim
@@ -8,7 +8,7 @@
 # those terms.
 
 import std/times
-import chronos
+import chronos, chronicles
 import webrtc_connection
 
 import mbedtls/ssl
@@ -22,6 +22,10 @@ import mbedtls/x509_crt
 import mbedtls/bignum
 import mbedtls/error
 import mbedtls/net_sockets
+import mbedtls/timing
+
+logScope:
+  topics = "webrtc dtls"
 
 type
   DtlsConn* = ref object of WebRTCConn
@@ -31,6 +35,7 @@ type
 
     entropy: mbedtls_entropy_context
     ctr_drbg: mbedtls_ctr_drbg_context
+    timer: mbedtls_timing_delay_context
 
     config: mbedtls_ssl_config
     ssl: mbedtls_ssl_context
@@ -57,7 +62,6 @@ proc generateCertificate(self: DtlsConn): mbedtls_x509_crt =
     time_from = times.now().format(time_format)
     time_to = (times.now() + times.years(1)).format(time_format)
 
-
   var issuer_key = self.generateKey()
   var write_cert: mbedtls_x509write_cert
   var serial_mpi: mbedtls_mpi
@@ -78,14 +82,15 @@ proc generateCertificate(self: DtlsConn): mbedtls_x509_crt =
   mb_x509_crt_parse(result, buf)
 
 proc dtlsSend*(ctx: pointer, buf: ptr byte, len: uint): cint {.cdecl.} =
-  echo "dtlsSend: "
+  echo "Send: ", len
   let self = cast[ptr DtlsConn](ctx)
   self.sendEvent.fire()
 
 proc dtlsRecv*(ctx: pointer, buf: ptr byte, len: uint): cint {.cdecl.} =
-  echo "dtlsRecv: "
+  echo "Recv: ", len
   let self = cast[ptr DtlsConn](ctx)[]
-  self.recvEvent.fire()
+
+  let x = self.read()
 
 method init*(self: DtlsConn, conn: WebRTCConn, address: TransportAddress) {.async.} =
   await procCall(WebRTCConn(self).init(conn, address))
@@ -110,7 +115,10 @@ method init*(self: DtlsConn, conn: WebRTCConn, address: TransportAddress) {.asyn
   mb_ssl_conf_read_timeout(self.config, 10000) # in milliseconds
   mb_ssl_conf_ca_chain(self.config, srvcert.next, nil)
   mb_ssl_conf_own_cert(self.config, srvcert, pkey)
-  # cookies ?
+  mbedtls_ssl_set_timer_cb(addr self.ssl, cast[pointer](addr self.timer),
+                           mbedtls_timing_set_delay,
+                           mbedtls_timing_get_delay)
+  # cookie ?
   mb_ssl_setup(self.ssl, self.config)
   mb_ssl_session_reset(self.ssl)
   mb_ssl_set_bio(self.ssl, cast[pointer](addr selfvar),
@@ -118,25 +126,21 @@ method init*(self: DtlsConn, conn: WebRTCConn, address: TransportAddress) {.asyn
   while true:
     mb_ssl_handshake(self.ssl)
 
-method close*(self: DtlsConn) {.async.} =
-  discard
-
 method write*(self: DtlsConn, msg: seq[byte]) {.async.} =
   var buf = msg
   self.sendEvent.clear()
-  discard mbedtls_ssl_write(addr self.ssl, cast[ptr byte](buf.cstring), buf.len())
+  discard mbedtls_ssl_write(addr self.ssl, cast[ptr byte](addr buf[0]), buf.len().uint)
   await self.sendEvent.wait()
 
 method read*(self: DtlsConn): Future[seq[byte]] {.async.} =
-  var res = newString(4096)
-  self.recvEvent.clear()
-  discard mbedtls_ssl_read(addr self.ssl, cast[ptr byte](res.cstring), 4096)
-  await self.recvEvent.wait()
+  return await self.conn.read()
+
+method close*(self: DtlsConn) {.async.} =
+  discard
 
 proc main {.async.} =
   let laddr = initTAddress("127.0.0.1:" & "4242")
   var dtls = DtlsConn()
   await dtls.init(nil, laddr)
-  let cert = dtls.generateCertificate()
 
 waitFor(main())
diff --git a/webrtc/sctp.nim b/webrtc/sctp.nim
index d86833d..78e6004 100644
--- a/webrtc/sctp.nim
+++ b/webrtc/sctp.nim
@@ -8,7 +8,7 @@
 # those terms.
 
 import tables, bitops, posix, strutils, sequtils
-import chronos, chronicles, stew/ranges/ptr_arith
+import chronos, chronicles, stew/[ranges/ptr_arith, byteutils]
 import usrsctp
 
 export chronicles
@@ -101,10 +101,13 @@ proc write*(self: SctpConnection, buf: seq[byte]) {.async.} =
   self.sctp.sentConnection = self
   self.sctp.sentAddress = self.address
   let sendvErr = self.sctp.usrsctpAwait:
-    self.sctpSocket.usrsctp_sendv(addr buf[0], buf.len.uint,
+    self.sctpSocket.usrsctp_sendv(unsafeAddr buf[0], buf.len.uint,
                                   nil, 0, nil, 0,
                                   SCTP_SENDV_NOINFO, 0)
 
+proc write*(self: SctpConnection, s: string) {.async.} =
+  await self.write(s.toBytes())
+
 proc close*(self: SctpConnection) {.async.} =
   self.sctp.usrsctpAwait: self.sctpSocket.usrsctp_close()
 
@@ -143,7 +146,7 @@ proc handleUpcall(sock: ptr socket, data: pointer, flags: cint) {.cdecl.} =
       if bitand(flags, MSG_NOTIFICATION) != 0:
         trace "Notification received", length = n
       else:
-        conn.dataRecv = conn.dataRecv.concat(buffer[0..n])
+        conn.dataRecv = conn.dataRecv.concat(buffer[0..<n])
         conn.recvEvent.fire()
   else:
     warn "Handle Upcall unexpected event", events
@@ -237,7 +240,7 @@ proc startServer*(self: Sctp, sctpPort: uint16 = 5000) =
   doAssert 0 == sock.usrsctp_set_upcall(handleAccept, cast[pointer](self))
   self.sockServer = sock
 
-proc closeServer(self: Sctp) =
+proc stopServer*(self: Sctp) =
   if not self.isServer:
     trace "Try to close a client"
     return
@@ -254,7 +257,7 @@ proc new*(T: typedesc[Sctp], port: uint16 = 9899): T =
   proc onReceive(udp: DatagramTransport, address: TransportAddress) {.async, gcsafe.} =
     let
       msg = udp.getMessage()
-      data = usrsctp_dumppacket(addr msg[0], uint(msg.len), SCTP_DUMP_INBOUND)
+      data = usrsctp_dumppacket(unsafeAddr msg[0], uint(msg.len), SCTP_DUMP_INBOUND)
     if data != nil:
       if sctp.isServer:
         trace "onReceive (server)", data = data.packetPretty(), length = msg.len(), address
@@ -264,12 +267,12 @@ proc new*(T: typedesc[Sctp], port: uint16 = 9899): T =
 
     if sctp.isServer:
       sctp.sentAddress = address
-      usrsctp_conninput(cast[pointer](sctp), addr msg[0], uint(msg.len), 0)
+      usrsctp_conninput(cast[pointer](sctp), unsafeAddr msg[0], uint(msg.len), 0)
     else:
       let conn = await sctp.getOrCreateConnection(udp, address)
       sctp.sentConnection = conn
       sctp.sentAddress = address
-      usrsctp_conninput(cast[pointer](sctp), addr msg[0], uint(msg.len), 0)
+      usrsctp_conninput(cast[pointer](sctp), unsafeAddr msg[0], uint(msg.len), 0)
   let
     localAddr = TransportAddress(family: AddressFamily.IPv4, port: Port(port))
     laddr = initTAddress("127.0.0.1:" & $port)
@@ -285,6 +288,10 @@ proc new*(T: typedesc[Sctp], port: uint16 = 9899): T =
 
   return sctp
 
+proc stop*(self: Sctp) {.async.} =
+  discard self.usrsctpAwait usrsctp_finish()
+  self.udp.close()
+
 proc listen*(self: Sctp): Future[SctpConnection] {.async.} =
   if not self.isServer:
     raise newSctpError("Not a server")
diff --git a/webrtc/stun.nim b/webrtc/stun/stun.nim
similarity index 99%
rename from webrtc/stun.nim
rename to webrtc/stun/stun.nim
index 344195c..fdd685f 100644
--- a/webrtc/stun.nim
+++ b/webrtc/stun/stun.nim
@@ -13,7 +13,7 @@ import chronos,
        binary_serialization,
        stew/objects,
        stew/byteutils
-import stunattributes
+import stun_attributes
 
 export binary_serialization
 
diff --git a/webrtc/stunattributes.nim b/webrtc/stun/stun_attributes.nim
similarity index 99%
rename from webrtc/stunattributes.nim
rename to webrtc/stun/stun_attributes.nim
index bf2b471..bb8ebd2 100644
--- a/webrtc/stunattributes.nim
+++ b/webrtc/stun/stun_attributes.nim
@@ -11,7 +11,7 @@ import sequtils, typetraits
 import binary_serialization,
        stew/byteutils,
        chronos
-import utils
+import ../utils
 
 type
   StunAttributeEncodingError* = object of CatchableError
diff --git a/webrtc/stun_connection.nim b/webrtc/stun/stun_connection.nim
similarity index 93%
rename from webrtc/stun_connection.nim
rename to webrtc/stun/stun_connection.nim
index f8482c9..e0d3a04 100644
--- a/webrtc/stun_connection.nim
+++ b/webrtc/stun/stun_connection.nim
@@ -8,7 +8,7 @@
 # those terms.
 
 import chronos
-import webrtc_connection, stun
+import ../webrtc_connection, stun
 
 type
   StunConn* = ref object of WebRTCConn
@@ -24,8 +24,8 @@ proc handles(self: StunConn) {.async.} =
       if res.isSome():
         await self.conn.write(res.get())
     else:
-      recvData.add(msg)
-      recvEvent.fire()
+      self.recvData.add(msg)
+      self.recvEvent.fire()
 
 method init(self: StunConn, conn: WebRTCConn, address: TransportAddress) {.async.} =
   await procCall(WebRTCConn(self).init(conn, address))
diff --git a/webrtc/udp_connection.nim b/webrtc/udp_connection.nim
index 25f3ba4..49d20b6 100644
--- a/webrtc/udp_connection.nim
+++ b/webrtc/udp_connection.nim
@@ -7,9 +7,12 @@
 # This file may not be copied, modified, or distributed except according to
 # those terms.
 
-import chronos
+import chronos, chronicles
 import webrtc_connection
 
+logScope:
+  topics = "webrtc udp"
+
 type
   UdpConn* = ref object of WebRTCConn
     udp: DatagramTransport
@@ -25,7 +28,7 @@ method init(self: UdpConn, conn: WebRTCConn, address: TransportAddress) {.async.
     self.recvEvent.fire()
 
   self.recvEvent = newAsyncEvent()
-  self.udp = newDatagramTransport(onReceive)
+  self.udp = newDatagramTransport(onReceive, local = address)
 
 method close(self: UdpConn) {.async.} =
   self.udp.close()
diff --git a/webrtc/webrtc.nim b/webrtc/webrtc.nim
index ce8eb0b..f8cdc36 100644
--- a/webrtc/webrtc.nim
+++ b/webrtc/webrtc.nim
@@ -8,7 +8,7 @@
 # those terms.
 
 import chronos, chronicles
-import stun
+import stun/stun
 
 logScope:
   topics = "webrtc"
diff --git a/webrtc/webrtc_connection.nim b/webrtc/webrtc_connection.nim
index eae2b1b..5cdf63c 100644
--- a/webrtc/webrtc_connection.nim
+++ b/webrtc/webrtc_connection.nim
@@ -11,8 +11,8 @@ import chronos
 
 type
   WebRTCConn* = ref object of RootObj
-    conn: WebRTCConn
-    address: TransportAddress
+    conn*: WebRTCConn
+    address*: TransportAddress
     # isClosed: bool
     # isEof: bool