ZeroMQ: PUB socket binding problems - sockets

Question

I have a simple PUB/SUB messaging program. I'm trying to bind it to tcp://*:5556 range to publish at all available ips with the port. When a socket is binding the error is returning:
Resource temporarily unavailable.
I'm trying to start the publisher thread first. The port is free.
What is wrong with the binding process?
Publisher:
int main (void) {
void *context = zmq_ctx_new();
void *publisher = zmq_socket(context, ZMQ_PUB);
zmq_bind(publisher, "tcp://*:5556");
printf("Binding: %s\n", zmq_strerror(errno));
srandom((unsigned) time(NULL));
while(true) {
char update[20];
sprintf(update, "%05d %d %d", randof(10000), randof(215) - 80, randof(50) + 10);
sleep(1);
zmq_send(publisher, update, strlen(update), 0);
printf("Sending: %s", zmq_strerror(errno));
}
zmq_close(publisher);
zmq_ctx_destroy(context);
return 0;
}
Subscriber:
int main () {
void *context = zmq_ctx_new();
void *subscriber = zmq_socket(context, ZMQ_SUB);
zmq_connect(subscriber, "tcp://localhost:5556");
printf("Connection: %s\n", zmq_strerror(errno));
while(true) {
char update[20];
zmq_recv(subscriber, update, 20, 0);
printf("Receiving: %s\n", zmq_strerror(errno));
printf("Message: %s\n", update);
}
zmq_close(subscriber);
zmq_ctx_destroy(context);
return 0;
}

Answer 1

From the info given, most likely something else is already bound to that socket. Is there already an instance of your program running on your machine? Or another process using that port no.
Try replacing tcp with ipc. For writing these sample programs it can avoid problems like that.
Also: your SUB socket isn't subscribed to anything, so even if the bind works the SUB will receive nothing.