There is a small defect in iperf_api.c in iperf-3.0b5 version. After invoke mkstemp, u guys forgot to invoke unlink and here i offer an example.

/* unlink temp file otherwise it would be remained in /tmp */ 
if(0 != unlink(template)) {         
    i_errno = IECREATESTREAM;   /* here is not quite right */   
    return NULL; 
} 

Thanks; fixed now.

u are welcome.