In the TGS_REQ packet, KDC_REQ_BODY is missing

[Surendra Babu]

Hi Team,

Thank you for your information. Thaks a lot for your guidance. COuld you
please let me know your thoughts on ..How TGS_REQ packet generation happens,
What steps should be followed? In my TGS_REQ packet, KDC_REQ_BODY fileds are
missing.

Please find attached my capture file. Please have a look at the TGS_REQ
packet. It is saying that short frame. (I am using TCP and working with MIT
code and UNIX KDC.) In that packet, KDC_REQ_BODY is missing and giving the
probelm from there onwards.

Could you please throw some light on this issue?

I followed the beloew mentioned steps to form the TGS_REQ packet. Please let
me know if I miss something.

============================================================
krb5_error_code *krb5_FormTGSReq*(krb5_kdc_req *tgs_req, krb5_context
context)
{

  krb5_data     *scratch=NULL;
  krb5_checksum        checksum;
  krb5_authenticator  authent;
  krb5_timestamp   tgt_exptime;
  krb5_error_code   retval, iRet;
  char          server_name[500] = {0, };

*  // copy the TGT Expiration time to tmp variable
*   tgt_exptime =   kdc_server_time+36000; //as_reply->enc_part2->
times.endtime;

*//Fillup the tgs_req fields*

  tgs_req->magic = KV5M_KDC_REQ;
  tgs_req->msg_type = KRB5_TGS_REQ;
  tgs_req->kdc_options = KDC_OPT_RENEWABLE_OK;
  tgs_req->client = NULL;  // Optional


  //Assign the SMTP Server principal name

  sprintf(ServiceName, "%s@%s","host/dpdniclin1.sisodomain.com",
auth_user_data.realm_domain);



  iRet = krb5_parse_name(context,ServiceName,&(tgs_req->server));
 if(iRet != NULL)
  {
   return -1;
  }

     tgs_req->from =  NULL;      // Optional
  tgs_req->till = tgt_exptime;    //Till the tgt expiration time
  tgs_req->rtime = NULL;
  tgs_req->nonce = rand();      //put some no for testing purpose -Gopi

  if(krb5_make_clientaddr(&(tgs_req->addresses)) != KERB_SUCCESS)
  {
   DEBUG_KERB_PRINT("[kerberos_formTgsReq] Client Addr Failed");
   return KERB_FAILURE;
  }

  tgs_req->unenc_authdata = NULL; // Optional
  tgs_req->second_ticket = NULL;  // Optional

  tgs_req->ktype = (krb5_enctype *) malloc(sizeof(get_in_tkt_enctypes));
  memcpy(tgs_req->ktype,get_in_tkt_enctypes,sizeof(get_in_tkt_enctypes));

*//filling up with Encryption types suported*
  tgs_req->nktypes = (sizeof(get_in_tkt_enctypes)/sizeof(krb5_enctype));


*  // Encode the TGS-REQ body into scratch to calculate checksum
*  retval = encode_krb5_kdc_req_body(tgs_req,&scratch);
  if(retval)
  {
   if(scratch)
    krb5_free_data(NULL, scratch);
   return KERB_FAILURE;
  }


*  // Calculate the Checksum using the scratch
*  if ((retval = krb5_c_make_checksum(NULL, CKSUMTYPE_RSA_MD5,
           as_reply->enc_part2->session,
           KRB5_KEYUSAGE_TGS_REQ_AUTH_CKSUM,
           scratch, &checksum)))
  {
   free(checksum.contents);
   if(scratch)
    krb5_free_data(NULL, scratch);

   return(KERB_FAILURE);
     }
  // DO the clean Up here

  if(scratch)
   krb5_free_data(NULL,scratch);

*//Form the PA Data.*

  if(KERB_SUCCESS != Form_PAData(&(tgs_req->padata),&checksum, context))
  {
   free(checksum.contents);
   return KERB_FAILURE;
  }

  return KERB_SUCCESS;
 }
=========================================================
With the above client code, I could generate the PA_DATA in the TGS_REQ
packet but I could not generate the KDC_REQ_BODY fileds, though I filled up
the tgs_req fields.

If you look at the second attached network capture, it shows the correct
TGS_REQ packet. It contains the KDC_REQ_BODY fileds also. This is taken from
MS-windows client code. BUt with my client code's TGS_REQ packet,
KDC_REQ_BODY fileds are missing.

Could you please let me know your thoughts after going through the attached
network capture.

Appreciate your thoughts. Thank you.
-Surendra