zmq_unbind - Man Page

Stop accepting connections on a socket


int zmq_unbind (void *socket, const char *endpoint);


The zmq_unbind() function shall unbind a socket specified by the socket argument from the endpoint specified by the endpoint argument.

Addionally the incoming message queue associated with the endpoint will be discarded. This means that after unbinding an endpoint it is possible to received messages originating from that same endpoint if they were already present in the incoming message queue before unbinding.

The endpoint argument is as described in zmq_bind(3)

Unbinding wild-card address from a socket

When wild-card * endpoint (described in zmq_tcp(7), zmq_ipc(7), zmq_udp(7) and zmq_vmci(7)) was used in zmq_bind(), the caller should use real endpoint obtained from the ZMQ_LAST_ENDPOINT socket option to unbind this endpoint from a socket.

Return Value

The zmq_unbind() function shall return zero if successful. Otherwise it shall return -1 and set errno to one of the values defined below.



The endpoint supplied is invalid.


The 0MQ context associated with the specified socket was terminated.


The provided socket was invalid.


The endpoint supplied was not previously bound.


Unbind a subscriber socket from a TCP transport.

/* Create a ZMQ_SUB socket */
void *socket = zmq_socket (context, ZMQ_SUB);
assert (socket);
/* Connect it to the host server001, port 5555 using a TCP transport */
rc = zmq_bind (socket, "tcp://");
assert (rc == 0);
/* Disconnect from the previously connected endpoint */
rc = zmq_unbind (socket, "tcp://");
assert (rc == 0);

Unbind wild-card * binded socket.

/* Create a ZMQ_SUB socket */
void *socket = zmq_socket (context, ZMQ_SUB);
assert (socket);
/* Bind it to the system-assigned ephemeral port using a TCP transport */
rc = zmq_bind (socket, "tcp://*");
assert (rc == 0);
/* Obtain real endpoint */
const size_t buf_size = 32;
char buf[buf_size];
rc = zmq_getsockopt (socket, ZMQ_LAST_ENDPOINT, buf, (size_t *)&buf_size);
assert (rc == 0);
/* Unbind socket by real endpoint */
rc = zmq_unbind (socket, buf);
assert (rc == 0);


Note that while the implementation is similar to zmq_disconnect(), the semantics are different and the two functions should not be used interchangeably. Bound sockets should be unbound, and connected sockets should be disconnected.

See Also

zmq_bind(3) zmq_socket(3) zmq(7)


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08/13/2020 0MQ 4.3.3 0MQ Manual