Hello!

After proxying a REGISTER from a WebRTC client to our SIP backend, the backend starts sending keepalives. Every 30 seconds I get a log entry in Kamailio saying: “INFO: stun [kam_stun.c:169]: stun_parse_header(): INFO: stun_parse_header: incomplete header of STUN message”.

Here's one such packet:

No.     Time           Source                Destination           Protocol Length Info

      1 0.000000       xxx.xxx.xxx.xxx       yyy.yyy.yyy.yyy        UDP      60     5060 ? 15060 Len=4

Frame 1: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)

Ethernet II, Src: JuniperN_4f:3f:f0 (40:a6:77:4f:3f:f0), Dst: 02:81:64:58:cf:d1 (02:81:64:58:cf:d1)

Internet Protocol Version 4, Src: xxx.xxx.xxx.xxx, Dst: yyy.yyy.yyy.yyy

    0100 .... = Version: 4

    .... 0101 = Header Length: 20 bytes (5)

    Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)

    Total Length: 32

    Identification: 0x5bf5 (23541)

    Flags: 0x4000, Don't fragment

    Time to live: 56

    Protocol: UDP (17)

    Header checksum: 0x2fc3 [validation disabled]

    [Header checksum status: Unverified]

    Source: xxx.xxx.xxx.xxx

    Destination: yyy.yyy.yyy.yyy

User Datagram Protocol, Src Port: 5060, Dst Port: 15060

    Source Port: 5060

    Destination Port: 15060

    Length: 12

    Checksum: 0xfa28 [unverified]

    [Checksum Status: Unverified]

    [Stream index: 0]

Data (4 bytes)

0000  00 00 00 00                                       ....

    Data: 00000000

    [Length: 4]

I found this in kam_stun.c:

static int stun_parse_header(struct stun_msg* req, USHORT_T* error_code)

{

                if (sizeof(req->hdr) > req->msg.buf.len) {

                                /* the received message does not contain whole header */

                                LOG(L_INFO, "INFO: stun_parse_header: incomplete header of STUN message\n");

                                /* Any better solution? IMHO it's not possible to send error response

                                * because the transaction ID is not available.

                                */

                                return FATAL_ERROR;

                }

…

Could someone please explain what’s wrong?

Med vennlig hilsen
Pan B. Christensen
Utvikler

Phonect AS 
Brugata 19, PB 9156 Grønland, N-0133 Oslo, Norway
E-post: pan.christensen@phonect.no
Mobil: 41 88 88 00