zmq_getsockopt(3)

SYNOPSIS

int zmq_getsockopt (void *socket, int option_name, void *option_value, size_t *option_len);

DESCRIPTION

The zmq_getsockopt() function shall retrieve the value for the option +specified by the option_name argument for the ØMQ socket pointed to by the +socket argument, and store it in the buffer pointed to by the option_value +argument. The option_len argument is the size in bytes of the buffer pointed +to by option_value; upon successful completion zmq_getsockopt() shall +modify the option_len argument to indicate the actual size of the option +value stored in the buffer.

The following options can be retrieved with the zmq_getsockopt() function:

ZMQ_TYPE: Retrieve socket type

The ZMQ_TYPE option shall retrieve the socket type for the specified +socket. The socket type is specified at socket creation time and +cannot be modified afterwards.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +N/A + +
+Default value + +	+ +N/A + +
+Applicable socket types + +	+ +all + +

ZMQ_RCVMORE: More message data parts to follow

The ZMQ_RCVMORE option shall return True (1) if the message part last +received from the socket was a data part with more parts to follow. If there +are no data parts to follow, this option shall return False (0).

Refer to zmq_send(3) and zmq_recv(3) for a detailed description +of multi-part messages.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +boolean + +
+Default value + +	+ +N/A + +
+Applicable socket types + +	+ +all + +

ZMQ_SNDHWM: Retrieves high water mark for outbound messages

The ZMQ_SNDHWM option shall return the high water mark for outbound messages +on the specified socket. The high water mark is a hard limit on the maximum +number of outstanding messages ØMQ shall queue in memory for any single peer +that the specified socket is communicating with. A value of zero means no +limit.

If this limit has been reached the socket shall enter an exceptional state and +depending on the socket type, ØMQ shall take appropriate action such as +blocking or dropping sent messages. Refer to the individual socket descriptions +in zmq_socket(3) for details on the exact action taken for each socket +type.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +messages + +
+Default value + +	+ +1000 + +
+Applicable socket types + +	+ +all + +

ZMQ_RCVHWM: Retrieve high water mark for inbound messages

The ZMQ_RCVHWM option shall return the high water mark for inbound messages on +the specified socket. The high water mark is a hard limit on the maximum +number of outstanding messages ØMQ shall queue in memory for any single peer +that the specified socket is communicating with. A value of zero means no +limit.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +messages + +
+Default value + +	+ +1000 + +
+Applicable socket types + +	+ +all + +

ZMQ_AFFINITY: Retrieve I/O thread affinity

The ZMQ_AFFINITY option shall retrieve the I/O thread affinity for newly +created connections on the specified socket.

Affinity determines which threads from the ØMQ I/O thread pool associated with +the socket’s context shall handle newly created connections. A value of zero +specifies no affinity, meaning that work shall be distributed fairly among all +ØMQ I/O threads in the thread pool. For non-zero values, the lowest bit +corresponds to thread 1, second lowest bit to thread 2 and so on. For example, +a value of 3 specifies that subsequent connections on socket shall be handled +exclusively by I/O threads 1 and 2.

See also zmq_init(3) for details on allocating the number of I/O +threads for a specific context.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +uint64_t + +
+Option value unit + +	+ +N/A (bitmap) + +
+Default value + +	+ +0 + +
+Applicable socket types + +	+ +N/A + +

ZMQ_IDENTITY: Retrieve socket identity

The ZMQ_IDENTITY option shall retrieve the identity of the specified socket. +Socket identity is used only by request/reply pattern. Namely, it can be used +in tandem with ROUTER socket to route messages to the peer with specific +identity.

Identity should be at least one byte and at most 255 bytes long. Identities +starting with binary zero are reserved for use by ØMQ infrastructure.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +binary data + +
+Option value unit + +	+ +N/A + +
+Default value + +	+ +NULL + +
+Applicable socket types + +	+ +ZMQ_REP, ZMQ_REQ, ZMQ_ROUTER, ZMQ_DEALER. + +

ZMQ_RATE: Retrieve multicast data rate

The ZMQ_RATE option shall retrieve the maximum send or receive data rate for +multicast transports using the specified socket.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +kilobits per second + +
+Default value + +	+ +100 + +
+Applicable socket types + +	+ +all, when using multicast transports + +

ZMQ_RECOVERY_IVL: Get multicast recovery interval

The ZMQ_RECOVERY_IVL option shall retrieve the recovery interval for +multicast transports using the specified socket. The recovery interval +determines the maximum time in milliseconds that a receiver can be absent from a +multicast group before unrecoverable data loss will occur.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +milliseconds + +
+Default value + +	+ +10000 + +
+Applicable socket types + +	+ +all, when using multicast transports + +

ZMQ_SNDBUF: Retrieve kernel transmit buffer size

The ZMQ_SNDBUF option shall retrieve the underlying kernel transmit buffer +size for the specified socket. A value of zero means that the OS default is +in effect. For details refer to your operating system documentation for the +SO_SNDBUF socket option.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +bytes + +
+Default value + +	+ +0 + +
+Applicable socket types + +	+ +all + +

ZMQ_RCVBUF: Retrieve kernel receive buffer size

The ZMQ_RCVBUF option shall retrieve the underlying kernel receive buffer +size for the specified socket. A value of zero means that the OS default is +in effect. For details refer to your operating system documentation for the +SO_RCVBUF socket option.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +bytes + +
+Default value + +	+ +0 + +
+Applicable socket types + +	+ +all + +

ZMQ_LINGER: Retrieve linger period for socket shutdown

The ZMQ_LINGER option shall retrieve the linger period for the specified +socket. The linger period determines how long pending messages which have +yet to be sent to a peer shall linger in memory after a socket is closed with +zmq_close(3), and further affects the termination of the socket’s +context with zmq_term(3). The following outlines the different +behaviours:

+
+The default value of -1 specifies an infinite linger period. Pending + messages shall not be discarded after a call to zmq_close(); attempting to + terminate the socket’s context with zmq_term() shall block until all + pending messages have been sent to a peer. +
+
+
+The value of 0 specifies no linger period. Pending messages shall be + discarded immediately when the socket is closed with zmq_close(). +
+
+
+Positive values specify an upper bound for the linger period in milliseconds. + Pending messages shall not be discarded after a call to zmq_close(); + attempting to terminate the socket’s context with zmq_term() shall block + until either all pending messages have been sent to a peer, or the linger + period expires, after which any pending messages shall be discarded. +
+
+ + + + + + + + + + + + + + + + +
+Option value type +
+ +
+int +
+
+Option value unit +
+ +
+milliseconds +
+
+Default value +
+ +
+-1 (infinite) +
+
+Applicable socket types +
+ +
+all +
+
+

ZMQ_RECONNECT_IVL: Retrieve reconnection interval

The ZMQ_RECONNECT_IVL option shall retrieve the initial reconnection interval +for the specified socket. The reconnection interval is the period ØMQ shall +wait between attempts to reconnect disconnected peers when using +connection-oriented transports. The value -1 means no reconnection.

+ + + +

Note

The reconnection interval may be randomized by ØMQ to prevent +reconnection storms in topologies with a large number of peers per socket.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +milliseconds + +
+Default value + +	+ +100 + +
+Applicable socket types + +	+ +all, only for connection-oriented transports + +

ZMQ_RECONNECT_IVL_MAX: Retrieve maximum reconnection interval

The ZMQ_RECONNECT_IVL_MAX option shall retrieve the maximum reconnection +interval for the specified socket. This is the maximum period ØMQ shall wait +between attempts to reconnect. On each reconnect attempt, the previous interval +shall be doubled untill ZMQ_RECONNECT_IVL_MAX is reached. This allows for +exponential backoff strategy. Default value means no exponential backoff is +performed and reconnect interval calculations are only based on +ZMQ_RECONNECT_IVL.

+ + + +

Note

Values less than ZMQ_RECONNECT_IVL will be ignored.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +milliseconds + +
+Default value + +	+ +0 (only use ZMQ_RECONNECT_IVL) + +
+Applicable socket types + +	+ +all, only for connection-oriented transport + +

ZMQ_BACKLOG: Retrieve maximum length of the queue of outstanding connections

The ZMQ_BACKLOG option shall retrieve the maximum length of the queue of +outstanding peer connections for the specified socket; this only applies to +connection-oriented transports. For details refer to your operating system +documentation for the listen function.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +connections + +
+Default value + +	+ +100 + +
+Applicable socket types + +	+ +all, only for connection-oriented transports + +

ZMQ_MAXMSGSIZE: Maximum acceptable inbound message size

The option shall retrieve limit for the inbound messages. If a peer sends +a message larger than ZMQ_MAXMSGSIZE it is disconnected. Value of -1 means +no limit.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int64_t + +
+Option value unit + +	+ +bytes + +
+Default value + +	+ +-1 + +
+Applicable socket types + +	+ +all + +

ZMQ_MULTICAST_HOPS: Maximum network hops for multicast packets

The option shall retrieve time-to-live used for outbound multicast packets. +The default of 1 means that the multicast packets don’t leave the local network.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +network hops + +
+Default value + +	+ +1 + +
+Applicable socket types + +	+ +all, when using multicast transports + +

ZMQ_RCVTIMEO: Maximum time before a socket operation returns with EAGAIN

Retrieve the timeout for recv operation on the socket. If the value is 0, +zmq_recv(3) will return immediately, with a EAGAIN error if there is no +message to receive. If the value is -1, it will block until a message is +available. For all other values, it will wait for a message for that amount +of time before returning with an EAGAIN error.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +milliseconds + +
+Default value + +	+ +-1 (infinite) + +
+Applicable socket types + +	+ +all + +

ZMQ_SNDTIMEO: Maximum time before a socket operation returns with EAGAIN

Retrieve the timeout for send operation on the socket. If the value is 0, +zmq_send(3) will return immediately, with a EAGAIN error if the message +cannot be sent. If the value is -1, it will block until the message is sent. +For all other values, it will try to send the message for that amount of time +before returning with an EAGAIN error.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +milliseconds + +
+Default value + +	+ +-1 (infinite) + +
+Applicable socket types + +	+ +all + +

ZMQ_IPV6: Retrieve IPv6 socket status

Retrieve the IPv6 option for the socket. A value of 1 means IPv6 is +enabled on the socket, while 0 means the socket will use only IPv4. +When IPv6 is enabled the socket will connect to, or accept connections +from, both IPv4 and IPv6 hosts.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +boolean + +
+Default value + +	+ +0 (false) + +
+Applicable socket types + +	+ +all, when using TCP transports. + +

ZMQ_IPV4ONLY: Retrieve IPv4-only socket override status

Retrieve the IPv4-only option for the socket. This option is deprecated. +Please use the ZMQ_IPV6 option.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +boolean + +
+Default value + +	+ +1 (true) + +
+Applicable socket types + +	+ +all, when using TCP transports. + +

ZMQ_IMMEDIATE: Retrieve attach-on-connect value

Retrieve the state of the attach on connect value. If set to 1, will delay the +attachment of a pipe on connect until the underlying connection has completed. +This will cause the socket to block if there are no other connections, but will +prevent queues from filling on pipes awaiting connection.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +boolean + +
+Default value + +	+ +0 (false) + +
+Applicable socket types + +	+ +all, primarily when using TCP/IPC transports. + +

ZMQ_FD: Retrieve file descriptor associated with the socket

The ZMQ_FD option shall retrieve the file descriptor associated with the +specified socket. The returned file descriptor can be used to integrate the +socket into an existing event loop; the ØMQ library shall signal any pending +events on the socket in an edge-triggered fashion by making the file +descriptor become ready for reading.

+ + + +

Note

The ability to read from the returned file descriptor does not +necessarily indicate that messages are available to be read from, or can be +written to, the underlying socket; applications must retrieve the actual event +state with a subsequent retrieval of the ZMQ_EVENTS option.

+ + + +

Note

The returned file descriptor is also used internally by the zmq_send +and zmq_recv functions. As the descriptor is edge triggered, applications +must update the state of ZMQ_EVENTS after each invocation of zmq_send +or zmq_recv.To be more explicit: after calling zmq_send the socket may +become readable (and vice versa) without triggering a read event on the +file descriptor.

+ + + +

Caution

The returned file descriptor is intended for use with a poll or +similar system call only. Applications must never attempt to read or write data +to it directly, neither should they try to close it.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int on POSIX systems, SOCKET on Windows + +
+Option value unit + +	+ +N/A + +
+Default value + +	+ +N/A + +
+Applicable socket types + +	+ +all + +

ZMQ_EVENTS: Retrieve socket event state

The ZMQ_EVENTS option shall retrieve the event state for the specified +socket. The returned value is a bit mask constructed by OR’ing a combination +of the following event flags:

+ZMQ_POLLIN +: +
+Indicates that at least one message may be received from the specified socket +without blocking. +
+
+ZMQ_POLLOUT +: +
+Indicates that at least one message may be sent to the specified socket without +blocking. +
+

The combination of a file descriptor returned by the ZMQ_FD option being +ready for reading but no actual events returned by a subsequent retrieval of +the ZMQ_EVENTS option is valid; applications should simply ignore this case +and restart their polling operation/event loop.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +N/A (flags) + +
+Default value + +	+ +N/A + +
+Applicable socket types + +	+ +all + +

ZMQ_LAST_ENDPOINT: Retrieve the last endpoint set

The ZMQ_LAST_ENDPOINT option shall retrieve the last endpoint bound for +TCP and IPC transports. The returned value will be a string in the form of +a ZMQ DSN. Note that if the TCP host is INADDR_ANY, indicated by a *, then +the returned address will be 0.0.0.0 (for IPv4).

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +NULL-terminated character string + +
+Option value unit + +	+ +N/A + +
+Default value + +	+ +NULL + +
+Applicable socket types + +	+ +all, when binding TCP or IPC transports + +

ZMQ_TCP_KEEPALIVE: Override SO_KEEPALIVE socket option

Override SO_KEEPALIVE socket option(where supported by OS). +The default value of -1 means to skip any overrides and leave it to OS default.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +-1,0,1 + +
+Default value + +	+ +-1 (leave to OS default) + +
+Applicable socket types + +	+ +all, when using TCP transports. + +

ZMQ_TCP_KEEPALIVE_IDLE: Override TCP_KEEPCNT(or TCP_KEEPALIVE on some OS)

Override TCP_KEEPCNT(or TCP_KEEPALIVE on some OS) socket option (where +supported by OS). The default value of -1 means to skip any overrides and +leave it to OS default.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +-1,>0 + +
+Default value + +	+ +-1 (leave to OS default) + +
+Applicable socket types + +	+ +all, when using TCP transports. + +

ZMQ_TCP_KEEPALIVE_CNT: Override TCP_KEEPCNT socket option

Override TCP_KEEPCNT socket option(where supported by OS). +The default value of -1 means to skip any overrides and leave it to OS default.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +-1,>0 + +
+Default value + +	+ +-1 (leave to OS default) + +
+Applicable socket types + +	+ +all, when using TCP transports. + +

ZMQ_TCP_KEEPALIVE_INTVL: Override TCP_KEEPINTVL socket option

Override TCP_KEEPINTVL socket option(where supported by OS). +The default value of -1 means to skip any overrides and leave it to OS default.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +-1,>0 + +
+Default value + +	+ +-1 (leave to OS default) + +
+Applicable socket types + +	+ +all, when using TCP transports. + +

ZMQ_MECHANISM: Retrieve current security mechanism

The ZMQ_MECHANISM option shall retrieve the current security mechanism +for the socket.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +ZMQ_NULL, ZMQ_PLAIN, or ZMQ_CURVE + +
+Default value + +	+ +ZMQ_NULL + +
+Applicable socket types + +	+ +all, when using TCP or IPC transports + +

ZMQ_PLAIN_SERVER: Retrieve current PLAIN server role

Returns the ZMQ_PLAIN_SERVER option, if any, previously set on the socket.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +int + +
+Option value unit + +	+ +0, 1 + +
+Default value + +	+ +int + +
+Applicable socket types + +	+ +all, when using TCP or IPC transports + +

ZMQ_PLAIN_USERNAME: Retrieve current PLAIN username

The ZMQ_PLAIN_USERNAME option shall retrieve the last username set for +the PLAIN security mechanism. The returned value shall be a NULL-terminated +string and MAY be empty. The returned size SHALL include the terminating +null byte.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +NULL-terminated character string + +
+Option value unit + +	+ +N/A + +
+Default value + +	+ +null string + +
+Applicable socket types + +	+ +all, when using TCP or IPC transports + +

ZMQ_PLAIN_PASSWORD: Retrieve current password

The ZMQ_PLAIN_PASSWORD option shall retrieve the last password set for +the PLAIN security mechanism. The returned value shall be a NULL-terminated +string and MAY be empty. The returned size SHALL include the terminating +null byte.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +NULL-terminated character string + +
+Option value unit + +	+ +N/A + +
+Default value + +	+ +null string + +
+Applicable socket types + +	+ +all, when using TCP or IPC transports + +

ZMQ_CURVE_PUBLICKEY: Retrieve current CURVE public key

Retrieves the current long term public key for the socket. You can +provide either a 32 byte buffer, to retrieve the binary key value, or +a 41 byte buffer, to retrieve the key in a printable Z85 format. +NOTE: to fetch a printable key, the buffer must be 41 bytes large +to hold the 40-char key value and one null byte.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +binary data or Z85 text string + +
+Option value size + +	+ +32 or 41 + +
+Default value + +	+ +null + +
+Applicable socket types + +	+ +all, when using TCP transport + +

ZMQ_CURVE_SECRETKEY: Retrieve current CURVE secret key

Retrieves the current long term secret key for the socket. You can +provide either a 32 byte buffer, to retrieve the binary key value, or +a 41 byte buffer, to retrieve the key in a printable Z85 format.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +binary data or Z85 text string + +
+Option value size + +	+ +32 or 41 + +
+Default value + +	+ +null + +
+Applicable socket types + +	+ +all, when using TCP transport + +

ZMQ_CURVE_SERVERKEY: Retrieve current CURVE server key

Retrieves the current server key for the client socket. You can +provide either a 32 byte buffer, to retrieve the binary key value, or +a 40 byte buffer, to retrieve the key in a printable Z85 format.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +binary data or Z85 text string + +
+Option value size + +	+ +32 or 41 + +
+Default value + +	+ +null + +
+Applicable socket types + +	+ +all, when using TCP transport + +

ZMQ_ZAP_DOMAIN: Retrieve RFC 27 authentication domain

The ZMQ_ZAP_DOMAIN option shall retrieve the last ZAP domain set for +the socket. The returned value shall be a NULL-terminated string and MAY +be empty. The returned size SHALL include the terminating null byte.

+ + + + + + + + + + + + + + + + +

+Option value type + +	+ +character string + +
+Option value unit + +	+ +N/A + +
+Default value + +	+ +not set + +
+Applicable socket types + +	+ +all, when using TCP transport + +

RETURN VALUE

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

ERRORS

+EINVAL +: +
+The requested option option_name is unknown, or the requested option_len or +option_value is invalid, or the size of the buffer pointed to by +option_value, as specified by option_len, is insufficient for storing the +option value. +
+
+ETERM +: +
+The ØMQ context associated with the specified socket was terminated. +
+
+ENOTSOCK +: +
+The provided socket was invalid. +
+
+EINTR +: +
+The operation was interrupted by delivery of a signal. +
+

EXAMPLE

Retrieving the high water mark for outgoing messages

/* Retrieve high water mark into sndhwm */
+int sndhwm;
+size_t sndhwm_size = sizeof (sndhwm);
+rc = zmq_getsockopt (socket, ZMQ_SNDHWM, &sndhwm, &sndhwm_size);
+assert (rc == 0);

AUTHORS

This page was written by the ØMQ community. To make a change please +read the ØMQ Contribution Policy at http://www.zeromq.org/docs:contributing.

+zmq_getsockopt(3) Manual Page +

NAME

SYNOPSIS

DESCRIPTION

ZMQ_TYPE: Retrieve socket type

ZMQ_RCVMORE: More message data parts to follow

ZMQ_SNDHWM: Retrieves high water mark for outbound messages

ZMQ_RCVHWM: Retrieve high water mark for inbound messages

ZMQ_AFFINITY: Retrieve I/O thread affinity

ZMQ_IDENTITY: Retrieve socket identity

ZMQ_RATE: Retrieve multicast data rate

ZMQ_RECOVERY_IVL: Get multicast recovery interval

ZMQ_SNDBUF: Retrieve kernel transmit buffer size

ZMQ_RCVBUF: Retrieve kernel receive buffer size

ZMQ_LINGER: Retrieve linger period for socket shutdown

ZMQ_RECONNECT_IVL: Retrieve reconnection interval

ZMQ_RECONNECT_IVL_MAX: Retrieve maximum reconnection interval

ZMQ_BACKLOG: Retrieve maximum length of the queue of outstanding connections

ZMQ_MAXMSGSIZE: Maximum acceptable inbound message size

ZMQ_MULTICAST_HOPS: Maximum network hops for multicast packets

ZMQ_RCVTIMEO: Maximum time before a socket operation returns with EAGAIN

ZMQ_SNDTIMEO: Maximum time before a socket operation returns with EAGAIN

ZMQ_IPV6: Retrieve IPv6 socket status

ZMQ_IPV4ONLY: Retrieve IPv4-only socket override status

ZMQ_IMMEDIATE: Retrieve attach-on-connect value

ZMQ_FD: Retrieve file descriptor associated with the socket

ZMQ_EVENTS: Retrieve socket event state

ZMQ_LAST_ENDPOINT: Retrieve the last endpoint set

ZMQ_TCP_KEEPALIVE: Override SO_KEEPALIVE socket option

ZMQ_TCP_KEEPALIVE_IDLE: Override TCP_KEEPCNT(or TCP_KEEPALIVE on some OS)

ZMQ_TCP_KEEPALIVE_CNT: Override TCP_KEEPCNT socket option

ZMQ_TCP_KEEPALIVE_INTVL: Override TCP_KEEPINTVL socket option

ZMQ_MECHANISM: Retrieve current security mechanism

ZMQ_PLAIN_SERVER: Retrieve current PLAIN server role

ZMQ_PLAIN_USERNAME: Retrieve current PLAIN username

ZMQ_PLAIN_PASSWORD: Retrieve current password

ZMQ_CURVE_PUBLICKEY: Retrieve current CURVE public key

ZMQ_CURVE_SECRETKEY: Retrieve current CURVE secret key

ZMQ_CURVE_SERVERKEY: Retrieve current CURVE server key

ZMQ_ZAP_DOMAIN: Retrieve RFC 27 authentication domain

RETURN VALUE

ERRORS

EXAMPLE

SEE ALSO

AUTHORS