Provided by: libzmq3-dev_4.2.5-1ubuntu0.2_amd64 bug

NAME

       zmq_setsockopt - set 0MQ socket options

SYNOPSIS

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

       Caution: All options, with the exception of ZMQ_SUBSCRIBE, ZMQ_UNSUBSCRIBE, ZMQ_LINGER,
       ZMQ_ROUTER_HANDOVER, ZMQ_ROUTER_MANDATORY, ZMQ_PROBE_ROUTER, ZMQ_XPUB_VERBOSE,
       ZMQ_XPUB_VERBOSER, ZMQ_REQ_CORRELATE, ZMQ_REQ_RELAXED, ZMQ_SNDHWM and ZMQ_RCVHWM, only
       take effect for subsequent socket bind/connects.

       Specifically, security options take effect for subsequent bind/connect calls, and can be
       changed at any time to affect subsequent binds and/or connects.

DESCRIPTION

       The zmq_setsockopt() function shall set the option specified by the option_name argument
       to the value pointed to by the option_value argument for the 0MQ socket pointed to by the
       socket argument. The option_len argument is the size of the option value in bytes. For
       options taking a value of type "character string", the provided byte data should either
       contain no zero bytes, or end in a single zero byte (terminating ASCII NUL character).

       The following socket options can be set with the zmq_setsockopt() function:

   ZMQ_AFFINITY: Set I/O thread affinity
       The ZMQ_AFFINITY option shall set the I/O thread affinity for newly created connections on
       the specified socket.

       Affinity determines which threads from the 0MQ 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 0MQ 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_BACKLOG: Set maximum length of the queue of outstanding connections
       The ZMQ_BACKLOG option shall set 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_BINDTODEVICE: Set name of device to bind the socket to
       The ZMQ_BINDTODEVICE option binds this socket to a particular device, eg. an interface or
       VRF. If a socket is bound to an interface, only packets received from that particular
       interface are processed by the socket. If device is a VRF device, then subsequent
       binds/connects to that socket use addresses in the VRF routing table.

           Note
           requires setting CAP_NET_RAW on the compiled program. NOTE: in DRAFT state, not yet
           available in stable releases.

       Option value type         character string

       Option value unit         N/A

       Default value             not set

       Applicable socket types   all, when using TCP or UDP
                                 transports.

   ZMQ_CONNECT_RID: Assign the next outbound connection id
       This option name is now deprecated. Use ZMQ_CONNECT_ROUTING_ID instead. ZMQ_CONNECT_RID
       remains as an alias for now.

   ZMQ_CONNECT_ROUTING_ID: Assign the next outbound routing id
       The ZMQ_CONNECT_ROUTING_ID option sets the peer id of the peer connected via the next
       zmq_connect() call, such that that connection is immediately ready for data transfer with
       the given routing id. This option applies only to the first subsequent call to
       zmq_connect(), zmq_connect() calls thereafter use the default connection behaviour.

       Typical use is to set this socket option ahead of each zmq_connect() call. Each connection
       MUST be assigned a unique routing id. Assigning a routing id that is already in use is not
       allowed.

       Useful when connecting ROUTER to ROUTER, or STREAM to STREAM, as it allows for immediate
       sending to peers. Outbound routing id framing requirements for ROUTER and STREAM sockets
       apply.

       The routing id must be from 1 to 255 bytes long and MAY NOT start with a zero byte (such
       routing ids are reserved for internal use by the 0MQ infrastructure).

       Option value type         binary data

       Option value unit         N/A

       Default value             NULL

       Applicable socket types   ZMQ_ROUTER, ZMQ_STREAM

   ZMQ_CONFLATE: Keep only last message
       If set, a socket shall keep only one message in its inbound/outbound queue, this message
       being the last message received/the last message to be sent. Ignores ZMQ_RCVHWM and
       ZMQ_SNDHWM options. Does not support multi-part messages, in particular, only one part of
       it is kept in the socket internal queue.

       Option value type         int

       Option value unit         boolean

       Default value             0 (false)

       Applicable socket types   ZMQ_PULL, ZMQ_PUSH, ZMQ_SUB,
                                 ZMQ_PUB, ZMQ_DEALER

   ZMQ_CONNECT_TIMEOUT: Set connect() timeout
       Sets how long to wait before timing-out a connect() system call. The connect() system call
       normally takes a long time before it returns a time out error. Setting this option allows
       the library to time out the call at an earlier interval.

       Option value type         int

       Option value unit         milliseconds

       Default value             0 (disabled)

       Applicable socket types   all, when using TCP transports.

   ZMQ_CURVE_PUBLICKEY: Set CURVE public key
       Sets the socket’s long term public key. You must set this on CURVE client sockets, see
       zmq_curve(7). You can provide the key as 32 binary bytes, or as a 40-character string
       encoded in the Z85 encoding format and terminated in a null byte. The public key must
       always be used with the matching secret key. To generate a public/secret key pair, use
       zmq_curve_keypair(3). To derive the public key from a secret key, use zmq_curve_public(3).

           Note
           an option value size of 40 is supported for backwards compatibility, though is
           deprecated.

       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: Set CURVE secret key
       Sets the socket’s long term secret key. You must set this on both CURVE client and server
       sockets, see zmq_curve(7). You can provide the key as 32 binary bytes, or as a
       40-character string encoded in the Z85 encoding format and terminated in a null byte. To
       generate a public/secret key pair, use zmq_curve_keypair(3). To derive the public key from
       a secret key, use zmq_curve_public(3).

           Note
           an option value size of 40 is supported for backwards compatibility, though is
           deprecated.

       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_SERVER: Set CURVE server role
       Defines whether the socket will act as server for CURVE security, see zmq_curve(7). A
       value of 1 means the socket will act as CURVE server. A value of 0 means the socket will
       not act as CURVE server, and its security role then depends on other option settings.
       Setting this to 0 shall reset the socket security to NULL. When you set this you must also
       set the server’s secret key using the ZMQ_CURVE_SECRETKEY option. A server socket does not
       need to know its own public key.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   all, when using TCP transport

   ZMQ_CURVE_SERVERKEY: Set CURVE server key
       Sets the socket’s long term server key. You must set this on CURVE client sockets, see
       zmq_curve(7). You can provide the key as 32 binary bytes, or as a 40-character string
       encoded in the Z85 encoding format and terminated in a null byte. This key must have been
       generated together with the server’s secret key. To generate a public/secret key pair, use
       zmq_curve_keypair(3).

           Note
           an option value size of 40 is supported for backwards compatibility, though is
           deprecated.

       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_GSSAPI_PLAINTEXT: Disable GSSAPI encryption
       Defines whether communications on the socket will be encrypted, see zmq_gssapi(7). A value
       of 1 means that communications will be plaintext. A value of 0 means communications will
       be encrypted.

       Option value type         int

       Option value unit         0, 1

       Default value             0 (false)

       Applicable socket types   all, when using TCP transport

   ZMQ_GSSAPI_PRINCIPAL: Set name of GSSAPI principal
       Sets the name of the principal for whom GSSAPI credentials should be acquired.

       Option value type         character string

       Option value unit         N/A

       Default value             not set

       Applicable socket types   all, when using TCP transport

   ZMQ_GSSAPI_SERVER: Set GSSAPI server role
       Defines whether the socket will act as server for GSSAPI security, see zmq_gssapi(7). A
       value of 1 means the socket will act as GSSAPI server. A value of 0 means the socket will
       act as GSSAPI client.

       Option value type         int

       Option value unit         0, 1

       Default value             0 (false)

       Applicable socket types   all, when using TCP transport

   ZMQ_GSSAPI_SERVICE_PRINCIPAL: Set name of GSSAPI service principal
       Sets the name of the principal of the GSSAPI server to which a GSSAPI client intends to
       connect.

       Option value type         character string

       Option value unit         N/A

       Default value             not set

       Applicable socket types   all, when using TCP transport

   ZMQ_GSSAPI_SERVICE_PRINCIPAL_NAMETYPE: Set name type of service principal
       Sets the name type of the GSSAPI service principal. A value of ZMQ_GSSAPI_NT_HOSTBASED (0)
       means the name specified with ZMQ_GSSAPI_SERVICE_PRINCIPAL is interpreted as a host based
       name. A value of ZMQ_GSSAPI_NT_USER_NAME (1) means it is interpreted as a local user name.
       A value of ZMQ_GSSAPI_NT_KRB5_PRINCIPAL (2) means it is interpreted as an unparsed
       principal name string (valid only with the krb5 GSSAPI mechanism).

           Note
           in DRAFT state, not yet available in stable releases.

       Option value type         int

       Option value unit         0, 1, 2

       Default value             0 (ZMQ_GSSAPI_NT_HOSTBASED)

       Applicable socket types   all, when using TCP or IPC
                                 transport

   ZMQ_GSSAPI_PRINCIPAL_NAMETYPE: Set name type of principal
       Sets the name type of the GSSAPI principal. A value of ZMQ_GSSAPI_NT_HOSTBASED (0) means
       the name specified with ZMQ_GSSAPI_PRINCIPAL is interpreted as a host based name. A value
       of ZMQ_GSSAPI_NT_USER_NAME (1) means it is interpreted as a local user name. A value of
       ZMQ_GSSAPI_NT_KRB5_PRINCIPAL (2) means it is interpreted as an unparsed principal name
       string (valid only with the krb5 GSSAPI mechanism).

           Note
           in DRAFT state, not yet available in stable releases.

       Option value type         int

       Option value unit         0, 1, 2

       Default value             0 (ZMQ_GSSAPI_NT_HOSTBASED)

       Applicable socket types   all, when using TCP or IPC
                                 transport

   ZMQ_HANDSHAKE_IVL: Set maximum handshake interval
       The ZMQ_HANDSHAKE_IVL option shall set the maximum handshake interval for the specified
       socket. Handshaking is the exchange of socket configuration information (socket type,
       routing id, security) that occurs when a connection is first opened, only for
       connection-oriented transports. If handshaking does not complete within the configured
       time, the connection shall be closed. The value 0 means no handshake time limit.

       Option value type         int

       Option value unit         milliseconds

       Default value             30000

       Applicable socket types   all but ZMQ_STREAM, only for
                                 connection-oriented transports

   ZMQ_HEARTBEAT_IVL: Set interval between sending ZMTP heartbeats
       The ZMQ_HEARTBEAT_IVL option shall set the interval between sending ZMTP heartbeats for
       the specified socket. If this option is set and is greater than 0, then a PING ZMTP
       command will be sent every ZMQ_HEARTBEAT_IVL milliseconds.

       Option value type         int

       Option value unit         milliseconds

       Default value             0

       Applicable socket types   all, when using
                                 connection-oriented transports

   ZMQ_HEARTBEAT_TIMEOUT: Set timeout for ZMTP heartbeats
       The ZMQ_HEARTBEAT_TIMEOUT option shall set how long to wait before timing-out a connection
       after sending a PING ZMTP command and not receiving any traffic. This option is only valid
       if ZMQ_HEARTBEAT_IVL is also set, and is greater than 0. The connection will time out if
       there is no traffic received after sending the PING command, but the received traffic does
       not have to be a PONG command - any received traffic will cancel the timeout.

       Option value type         int

       Option value unit         milliseconds

       Default value             0

       Applicable socket types   all, when using
                                 connection-oriented transports

   ZMQ_HEARTBEAT_TTL: Set the TTL value for ZMTP heartbeats
       The ZMQ_HEARTBEAT_TTL option shall set the timeout on the remote peer for ZMTP heartbeats.
       If this option is greater than 0, the remote side shall time out the connection if it does
       not receive any more traffic within the TTL period. This option does not have any effect
       if ZMQ_HEARTBEAT_IVL is not set or is 0. Internally, this value is rounded down to the
       nearest decisecond, any value less than 100 will have no effect.

       Option value type         int

       Option value unit         milliseconds

       Default value             0

       Applicable socket types   all, when using
                                 connection-oriented transports

   ZMQ_IDENTITY: Set socket identity
       This option name is now deprecated. Use ZMQ_ROUTING_ID instead. ZMQ_IDENTITY remains as an
       alias for now.

   ZMQ_IMMEDIATE: Queue messages only to completed connections
       By default queues will fill on outgoing connections even if the connection has not
       completed. This can lead to "lost" messages on sockets with round-robin routing (REQ,
       PUSH, DEALER). If this option is set to 1, messages shall be queued only to completed
       connections. 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, only for
                                 connection-oriented transports.

   ZMQ_INVERT_MATCHING: Invert message filtering
       Reverses the filtering behavior of PUB-SUB sockets, when set to 1.

       On PUB and XPUB sockets, this causes messages to be sent to all connected sockets except
       those subscribed to a prefix that matches the message. On SUB sockets, this causes only
       incoming messages that do not match any of the socket’s subscriptions to be received by
       the user.

       Whenever ZMQ_INVERT_MATCHING is set to 1 on a PUB socket, all SUB sockets connecting to it
       must also have the option set to 1. Failure to do so will have the SUB sockets reject
       everything the PUB socket sends them. XSUB sockets do not need to do this because they do
       not filter incoming messages.

       Option value type         int

       Option value unit         0,1

       Default value             0

       Applicable socket types   ZMQ_PUB, ZMQ_XPUB, ZMQ_SUB

   ZMQ_IPV6: Enable IPv6 on socket
       Set 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_LINGER: Set linger period for socket shutdown
       The ZMQ_LINGER option shall set 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 disconnected with zmq_disconnect(3) or closed with
       zmq_close(3), and further affects the termination of the socket’s context with
       zmq_ctx_term(3). The following outlines the different behaviours:

       •   A value of -1 specifies an infinite linger period. Pending messages shall not be
           discarded after a call to zmq_disconnect() or zmq_close(); attempting to terminate the
           socket’s context with zmq_ctx_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 after a call to zmq_disconnect() or 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_disconnect() or zmq_close();
           attempting to terminate the socket’s context with zmq_ctx_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_MAXMSGSIZE: Maximum acceptable inbound message size
       Limits the size of the inbound message. 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_METADATA: Add application metadata properties to a socket
       The ZMQ_METADATA option shall add application metadata to the specified socket, the
       metadata is exchanged with peers during connection setup. A metadata property is specfied
       as a string, delimited by a colon, starting with the metadata property followed by the
       metadata value, for example "X-key:value". Property names are restrited to maximum 255
       characters and must be prefixed by "X-". Multiple application metadata properties can be
       added to a socket by executing zmq_setsockopt() multiple times. As the argument is a
       null-terminated string, binary data must be encoded before it is added e.g. using Z85
       (zmq_z85_encode(3)).

           Note
           in DRAFT state, not yet available in stable releases.

       Option value type         character string

       Option value unit         N/A

       Default value             not set

       Applicable socket types   all

   ZMQ_MULTICAST_HOPS: Maximum network hops for multicast packets
       Sets the time-to-live field in every multicast packet sent from this socket. The default
       is 1 which 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_MULTICAST_MAXTPDU: Maximum transport data unit size for multicast packets
       Sets the maximum transport data unit size used for outbound multicast packets.

       This must be set at or below the minimum Maximum Transmission Unit (MTU) for all network
       paths over which multicast reception is required.

       Option value type         int

       Option value unit         bytes

       Default value             1500

       Applicable socket types   all, when using multicast
                                 transports

   ZMQ_PLAIN_PASSWORD: Set PLAIN security password
       Sets the password for outgoing connections over TCP or IPC. If you set this to a non-null
       value, the security mechanism used for connections shall be PLAIN, see zmq_plain(7). If
       you set this to a null value, the security mechanism used for connections shall be NULL,
       see zmq_null(3).

       Option value type         character string

       Option value unit         N/A

       Default value             not set

       Applicable socket types   all, when using TCP transport

   ZMQ_PLAIN_SERVER: Set PLAIN server role
       Defines whether the socket will act as server for PLAIN security, see zmq_plain(7). A
       value of 1 means the socket will act as PLAIN server. A value of 0 means the socket will
       not act as PLAIN server, and its security role then depends on other option settings.
       Setting this to 0 shall reset the socket security to NULL.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   all, when using TCP transport

   ZMQ_PLAIN_USERNAME: Set PLAIN security username
       Sets the username for outgoing connections over TCP or IPC. If you set this to a non-null
       value, the security mechanism used for connections shall be PLAIN, see zmq_plain(7). If
       you set this to a null value, the security mechanism used for connections shall be NULL,
       see zmq_null(3).

       Option value type         character string

       Option value unit         N/A

       Default value             not set

       Applicable socket types   all, when using TCP transport

   ZMQ_USE_FD: Set the pre-allocated socket file descriptor
       When set to a positive integer value before zmq_bind is called on the socket, the socket
       shall use the corresponding file descriptor for connections over TCP or IPC instead of
       allocating a new file descriptor. Useful for writing systemd socket activated services. If
       set to -1 (default), a new file descriptor will be allocated instead (default behaviour).

           Note
           if set after calling zmq_bind, this option shall have no effect. NOTE: the file
           descriptor passed through MUST have been ran through the "bind" and "listen" system
           calls beforehand. Also, socket option that would normally be passed through
           zmq_setsockopt like TCP buffers length, IP_TOS or SO_REUSEADDR MUST be set beforehand
           by the caller, as they must be set before the socket is bound.

       Option value type         int

       Option value unit         file descriptor

       Default value             -1

       Applicable socket types   all bound sockets, when using
                                 IPC or TCP transport

   ZMQ_PROBE_ROUTER: bootstrap connections to ROUTER sockets
       When set to 1, the socket will automatically send an empty message when a new connection
       is made or accepted. You may set this on REQ, DEALER, or ROUTER sockets connected to a
       ROUTER socket. The application must filter such empty messages. The ZMQ_PROBE_ROUTER
       option in effect provides the ROUTER application with an event signaling the arrival of a
       new peer.

           Note
           do not set this option on a socket that talks to any other socket types: the results
           are undefined.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   ZMQ_ROUTER, ZMQ_DEALER, ZMQ_REQ

   ZMQ_RATE: Set multicast data rate
       The ZMQ_RATE option shall set the maximum send or receive data rate for multicast
       transports such as zmq_pgm(7) 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_RCVBUF: Set kernel receive buffer size
       The ZMQ_RCVBUF option shall set the underlying kernel receive buffer size for the socket
       to the specified size in bytes. A value of -1 means leave the OS default unchanged. For
       details refer to your operating system documentation for the SO_RCVBUF socket option.

       Option value type         int

       Option value unit         bytes

       Default value             -1

       Applicable socket types   all

   ZMQ_RCVHWM: Set high water mark for inbound messages
       The ZMQ_RCVHWM option shall set 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
       0MQ 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, 0MQ 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_RCVTIMEO: Maximum time before a recv operation returns with EAGAIN
       Sets the timeout for receive 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_RECONNECT_IVL: Set reconnection interval
       The ZMQ_RECONNECT_IVL option shall set the initial reconnection interval for the specified
       socket. The reconnection interval is the period 0MQ 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 0MQ 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: Set maximum reconnection interval
       The ZMQ_RECONNECT_IVL_MAX option shall set the maximum reconnection interval for the
       specified socket. This is the maximum period 0MQ 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 transports

   ZMQ_RECOVERY_IVL: Set multicast recovery interval
       The ZMQ_RECOVERY_IVL option shall set 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.

           Caution
           Exercise care when setting large recovery intervals as the data needed for recovery
           will be held in memory. For example, a 1 minute recovery interval at a data rate of
           1Gbps requires a 7GB in-memory buffer.

       Option value type         int

       Option value unit         milliseconds

       Default value             10000

       Applicable socket types   all, when using multicast
                                 transports

   ZMQ_REQ_CORRELATE: match replies with requests
       The default behaviour of REQ sockets is to rely on the ordering of messages to match
       requests and responses and that is usually sufficient. When this option is set to 1, the
       REQ socket will prefix outgoing messages with an extra frame containing a request id. That
       means the full message is (request id, 0, user frames...). The REQ socket will discard all
       incoming messages that don’t begin with these two frames.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   ZMQ_REQ

   ZMQ_REQ_RELAXED: relax strict alternation between request and reply
       By default, a REQ socket does not allow initiating a new request with zmq_send(3) until
       the reply to the previous one has been received. When set to 1, sending another message is
       allowed and previous replies will be discarded if any. The request-reply state machine is
       reset and a new request is sent to the next available peer.

       If set to 1, also enable ZMQ_REQ_CORRELATE to ensure correct matching of requests and
       replies. Otherwise a late reply to an aborted request can be reported as the reply to the
       superseding request.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   ZMQ_REQ

   ZMQ_ROUTER_HANDOVER: handle duplicate client routing ids on ROUTER sockets
       If two clients use the same routing id when connecting to a ROUTER, the results shall
       depend on the ZMQ_ROUTER_HANDOVER option setting. If that is not set (or set to the
       default of zero), the ROUTER socket shall reject clients trying to connect with an
       already-used routing id. If that option is set to 1, the ROUTER socket shall hand-over the
       connection to the new client and disconnect the existing one.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   ZMQ_ROUTER

   ZMQ_ROUTER_MANDATORY: accept only routable messages on ROUTER sockets
       Sets the ROUTER socket behaviour when an unroutable message is encountered. A value of 0
       is the default and discards the message silently when it cannot be routed or the peers
       SNDHWM is reached. A value of 1 returns an EHOSTUNREACH error code if the message cannot
       be routed or EAGAIN error code if the SNDHWM is reached and ZMQ_DONTWAIT was used. Without
       ZMQ_DONTWAIT it will block until the SNDTIMEO is reached or a spot in the send queue opens
       up.

       When ZMQ_ROUTER_MANDATORY is set to 1, ZMQ_POLLOUT events will be generated if one or more
       messages can be sent to at least one of the peers. If ZMQ_ROUTER_MANDATORY is set to 0,
       the socket will generate a ZMQ_POLLOUT event on every call to zmq_poll.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   ZMQ_ROUTER

   ZMQ_ROUTER_RAW: switch ROUTER socket to raw mode
       Sets the raw mode on the ROUTER, when set to 1. When the ROUTER socket is in raw mode, and
       when using the tcp:// transport, it will read and write TCP data without 0MQ framing. This
       lets 0MQ applications talk to non-0MQ applications. When using raw mode, you cannot set
       explicit identities, and the ZMQ_SNDMORE flag is ignored when sending data messages. In
       raw mode you can close a specific connection by sending it a zero-length message
       (following the routing id frame).

           Note
           This option is deprecated, please use ZMQ_STREAM sockets instead.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   ZMQ_ROUTER

   ZMQ_ROUTING_ID: Set socket routing id
       The ZMQ_ROUTING_ID option shall set the routing id of the specified socket when connecting
       to a ROUTER socket.

       A routing id must be at least one byte and at most 255 bytes long. Identities starting
       with a zero byte are reserved for use by the 0MQ infrastructure.

       If two clients use the same routing id when connecting to a ROUTER, the results shall
       depend on the ZMQ_ROUTER_HANDOVER option setting. If that is not set (or set to the
       default of zero), the ROUTER socket shall reject clients trying to connect with an
       already-used routing id. If that option is set to 1, the ROUTER socket shall hand-over the
       connection to the new client and disconnect the existing one.

       Option value type         binary data

       Option value unit         N/A

       Default value             NULL

       Applicable socket types   ZMQ_REQ, ZMQ_REP, ZMQ_ROUTER,
                                 ZMQ_DEALER.

   ZMQ_SNDBUF: Set kernel transmit buffer size
       The ZMQ_SNDBUF option shall set the underlying kernel transmit buffer size for the socket
       to the specified size in bytes. A value of -1 means leave the OS default unchanged. For
       details please refer to your operating system documentation for the SO_SNDBUF socket
       option.

       Option value type         int

       Option value unit         bytes

       Default value             -1

       Applicable socket types   all

   ZMQ_SNDHWM: Set high water mark for outbound messages
       The ZMQ_SNDHWM option shall set 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
       0MQ 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, 0MQ 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.

           Note
           0MQ does not guarantee that the socket will accept as many as ZMQ_SNDHWM messages, and
           the actual limit may be as much as 90% lower depending on the flow of messages on the
           socket.

       Option value type         int

       Option value unit         messages

       Default value             1000

       Applicable socket types   all

   ZMQ_SNDTIMEO: Maximum time before a send operation returns with EAGAIN
       Sets 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_SOCKS_PROXY: Set SOCKS5 proxy address
       Sets the SOCKS5 proxy address that shall be used by the socket for the TCP connection(s).
       Does not support SOCKS5 authentication. If the endpoints are domain names instead of
       addresses they shall not be resolved and they shall be forwarded unchanged to the SOCKS
       proxy service in the client connection request message (address type 0x03 domain name).

       Option value type         character string

       Option value unit         N/A

       Default value             not set

       Applicable socket types   all, when using TCP transport

   ZMQ_STREAM_NOTIFY: send connect and disconnect notifications
       Enables connect and disconnect notifications on a STREAM socket, when set to 1. When
       notifications are enabled, the socket delivers a zero-length message when a peer connects
       or disconnects.

       Option value type         int

       Option value unit         0, 1

       Default value             1

       Applicable socket types   ZMQ_STREAM

   ZMQ_SUBSCRIBE: Establish message filter
       The ZMQ_SUBSCRIBE option shall establish a new message filter on a ZMQ_SUB socket. Newly
       created ZMQ_SUB sockets shall filter out all incoming messages, therefore you should call
       this option to establish an initial message filter.

       An empty option_value of length zero shall subscribe to all incoming messages. A non-empty
       option_value shall subscribe to all messages beginning with the specified prefix. Multiple
       filters may be attached to a single ZMQ_SUB socket, in which case a message shall be
       accepted if it matches at least one filter.

       Option value type         binary data

       Option value unit         N/A

       Default value             N/A

       Applicable socket types   ZMQ_SUB

   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_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_IDLE: Override TCP_KEEPIDLE (or TCP_KEEPALIVE on some OS)
       Override TCP_KEEPIDLE (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_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_TCP_MAXRT: Set TCP Maximum Retransmit Timeout
       On OSes where it is supported, sets how long before an unacknowledged TCP retransmit times
       out. The system normally attempts many TCP retransmits following an exponential backoff
       strategy. This means that after a network outage, it may take a long time before the
       session can be re-established. Setting this option allows the timeout to happen at a
       shorter interval.

       Option value type         int

       Option value unit         milliseconds

       Default value             0 (leave to OS default)

       Applicable socket types   all, when using TCP transports.

   ZMQ_TOS: Set the Type-of-Service on socket
       Sets the ToS fields (Differentiated services (DS) and Explicit Congestion Notification
       (ECN) field of the IP header. The ToS field is typically used to specify a packets
       priority. The availability of this option is dependent on intermediate network equipment
       that inspect the ToS field and provide a path for low-delay, high-throughput,
       highly-reliable service, etc.

       Option value type         int

       Option value unit         >0

       Default value             0

       Applicable socket types   all, only for
                                 connection-oriented transports

   ZMQ_UNSUBSCRIBE: Remove message filter
       The ZMQ_UNSUBSCRIBE option shall remove an existing message filter on a ZMQ_SUB socket.
       The filter specified must match an existing filter previously established with the
       ZMQ_SUBSCRIBE option. If the socket has several instances of the same filter attached the
       ZMQ_UNSUBSCRIBE option shall remove only one instance, leaving the rest in place and
       functional.

       Option value type         binary data

       Option value unit         N/A

       Default value             N/A

       Applicable socket types   ZMQ_SUB

   ZMQ_XPUB_VERBOSE: pass duplicate subscribe messages on XPUB socket
       Sets the XPUB socket behaviour on new duplicated subscriptions. If enabled, the socket
       passes all subscribe messages to the caller. If disabled, only the first subscription to
       each filter will be passed. The default is 0 (disabled).

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   ZMQ_XPUB

   ZMQ_XPUB_VERBOSER: pass duplicate subscribe and unsubscribe messages on XPUB socket
       Sets the XPUB socket behaviour on new duplicated subscriptions and unsubscriptions. If
       enabled, the socket passes all subscribe and unsubscribe messages to the caller. If
       disabled, only the first subscription to each filter and the last unsubscription from each
       filter will be passed. The default is 0 (disabled).

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   ZMQ_XPUB

   ZMQ_XPUB_MANUAL: change the subscription handling to manual
       Sets the XPUB socket subscription handling mode manual/automatic. A value of 0 is the
       default and subscription requests will be handled automatically. A value of 1 will change
       the subscription requests handling to manual, with manual mode subscription requests are
       not added to the subscription list. To add subscription the user need to call setsockopt
       with ZMQ_SUBSCRIBE on XPUB socket.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   ZMQ_XPUB

   ZMQ_XPUB_NODROP: do not silently drop messages if SENDHWM is reached
       Sets the XPUB socket behaviour to return error EAGAIN if SENDHWM is reached and the
       message could not be send.

       A value of 0 is the default and drops the message silently when the peers SNDHWM is
       reached. A value of 1 returns an EAGAIN error code if the SNDHWM is reached and
       ZMQ_DONTWAIT was used.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   ZMQ_XPUB, ZMQ_PUB

   ZMQ_XPUB_WELCOME_MSG: set welcome message that will be received by subscriber when connecting
       Sets a welcome message the will be recieved by subscriber when connecting. Subscriber must
       subscribe to the Welcome message before connecting. Welcome message will also be sent on
       reconnecting. For welcome message to work well user must poll on incoming subscription
       messages on the XPUB socket and handle them.

       Use NULL and lenght of zero to disable welcome message.

       Option value type         binary data

       Option value unit         N/A

       Default value             NULL

       Applicable socket types   ZMQ_XPUB

   ZMQ_ZAP_DOMAIN: Set RFC 27 authentication domain
       Sets the domain for ZAP (ZMQ RFC 27) authentication. A ZAP domain must be specified to
       enable authentication. When the ZAP domain is empty, which is the default, ZAP
       authentication is disabled. This is not compatible with previous versions of libzmq, so it
       can be controlled by ZMQ_ZAP_ENFORCE_DOMAIN which for now is disabled by default. See
       http://rfc.zeromq.org/spec:27 for more details.

       Option value type         character string

       Option value unit         N/A

       Default value             empty

       Applicable socket types   all, when using TCP transport

   ZMQ_ZAP_ENFORCE_DOMAIN: Set ZAP domain handling to strictly adhere the RFC
       The ZAP (ZMQ RFC 27) authentication protocol specifies that a domain must always be set.
       Older versions of libzmq did not follow the spec and allowed an empty domain to be set.
       This option can be used to enabled or disable the stricter, backward incompatible
       behaviour. For now it is disabled by default, but in a future version it will be enabled
       by default.

       Option value type         int

       Option value unit         0, 1

       Default value             0

       Applicable socket types   all, when using ZAP

   ZMQ_TCP_ACCEPT_FILTER: Assign filters to allow new TCP connections
       Assign an arbitrary number of filters that will be applied for each new TCP transport
       connection on a listening socket. If no filters are applied, then the TCP transport allows
       connections from any IP address. If at least one filter is applied then new connection
       source ip should be matched. To clear all filters call zmq_setsockopt(socket,
       ZMQ_TCP_ACCEPT_FILTER, NULL, 0). Filter is a null-terminated string with ipv6 or ipv4
       CIDR.

           Note
           This option is deprecated, please use authentication via the ZAP API and IP address
           whitelisting / blacklisting.

       Option value type         binary data

       Option value unit         N/A

       Default value             no filters (allow from all)

       Applicable socket types   all listening sockets, when
                                 using TCP transports.

   ZMQ_IPC_FILTER_GID: Assign group ID filters to allow new IPC connections
       Assign an arbitrary number of filters that will be applied for each new IPC transport
       connection on a listening socket. If no IPC filters are applied, then the IPC transport
       allows connections from any process. If at least one UID, GID, or PID filter is applied
       then new connection credentials should be matched. To clear all GID filters call
       zmq_setsockopt(socket, ZMQ_IPC_FILTER_GID, NULL, 0).

           Note
           GID filters are only available on platforms supporting SO_PEERCRED or LOCAL_PEERCRED
           socket options (currently only Linux and later versions of OS X).

           Note
           This option is deprecated, please use authentication via the ZAP API and IPC
           whitelisting / blacklisting.

       Option value type         gid_t

       Option value unit         N/A

       Default value             no filters (allow from all)

       Applicable socket types   all listening sockets, when
                                 using IPC transports.

   ZMQ_IPC_FILTER_PID: Assign process ID filters to allow new IPC connections
       Assign an arbitrary number of filters that will be applied for each new IPC transport
       connection on a listening socket. If no IPC filters are applied, then the IPC transport
       allows connections from any process. If at least one UID, GID, or PID filter is applied
       then new connection credentials should be matched. To clear all PID filters call
       zmq_setsockopt(socket, ZMQ_IPC_FILTER_PID, NULL, 0).

           Note
           PID filters are only available on platforms supporting the SO_PEERCRED socket option
           (currently only Linux).

           Note
           This option is deprecated, please use authentication via the ZAP API and IPC
           whitelisting / blacklisting.

       Option value type         pid_t

       Option value unit         N/A

       Default value             no filters (allow from all)

       Applicable socket types   all listening sockets, when
                                 using IPC transports.

   ZMQ_IPC_FILTER_UID: Assign user ID filters to allow new IPC connections
       Assign an arbitrary number of filters that will be applied for each new IPC transport
       connection on a listening socket. If no IPC filters are applied, then the IPC transport
       allows connections from any process. If at least one UID, GID, or PID filter is applied
       then new connection credentials should be matched. To clear all UID filters call
       zmq_setsockopt(socket, ZMQ_IPC_FILTER_UID, NULL, 0).

           Note
           UID filters are only available on platforms supporting SO_PEERCRED or LOCAL_PEERCRED
           socket options (currently only Linux and later versions of OS X).

           Note
           This option is deprecated, please use authentication via the ZAP API and IPC
           whitelisting / blacklisting.

       Option value type         uid_t

       Option value unit         N/A

       Default value             no filters (allow from all)

       Applicable socket types   all listening sockets, when
                                 using IPC transports.

   ZMQ_IPV4ONLY: Use IPv4-only on socket
       Set 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_VMCI_BUFFER_SIZE: Set buffer size of the VMCI socket
       The ZMQ_VMCI_BUFFER_SIZE option shall set the size of the underlying buffer for the
       socket. Used during negotiation before the connection is established.

       Option value type         uint64_t

       Option value unit         bytes

       Default value             65546

       Applicable socket types   all, when using VMCI transport

   ZMQ_VMCI_BUFFER_MIN_SIZE: Set min buffer size of the VMCI socket
       The ZMQ_VMCI_BUFFER_MIN_SIZE option shall set the min size of the underlying buffer for
       the socket. Used during negotiation before the connection is established.

       Option value type         uint64_t

       Option value unit         bytes

       Default value             128

       Applicable socket types   all, when using VMCI transport

   ZMQ_VMCI_BUFFER_MAX_SIZE: Set max buffer size of the VMCI socket
       The ZMQ_VMCI_BUFFER_MAX_SIZE option shall set the max size of the underlying buffer for
       the socket. Used during negotiation before the connection is established.

       Option value type         uint64_t

       Option value unit         bytes

       Default value             262144

       Applicable socket types   all, when using VMCI transport

   ZMQ_VMCI_CONNECT_TIMEOUT: Set connection timeout of the VMCI socket
       The ZMQ_VMCI_CONNECT_TIMEOUT option shall set connection timeout for the socket.

       Option value type         int

       Option value unit         milliseconds

       Default value             -1

       Applicable socket types   all, when using VMCI transport

RETURN VALUE

       The zmq_setsockopt() 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.

       ETERM
           The 0MQ 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

       Subscribing to messages on a ZMQ_SUB socket.

           /* Subscribe to all messages */
           rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "", 0);
           assert (rc == 0);
           /* Subscribe to messages prefixed with "ANIMALS.CATS" */
           rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "ANIMALS.CATS", 12);

       Setting I/O thread affinity.

           int64_t affinity;
           /* Incoming connections on TCP port 5555 shall be handled by I/O thread 1 */
           affinity = 1;
           rc = zmq_setsockopt (socket, ZMQ_AFFINITY, &affinity, sizeof (affinity));
           assert (rc);
           rc = zmq_bind (socket, "tcp://lo:5555");
           assert (rc);
           /* Incoming connections on TCP port 5556 shall be handled by I/O thread 2 */
           affinity = 2;
           rc = zmq_setsockopt (socket, ZMQ_AFFINITY, &affinity, sizeof (affinity));
           assert (rc);
           rc = zmq_bind (socket, "tcp://lo:5556");
           assert (rc);

SEE ALSO

       zmq_getsockopt(3) zmq_socket(3) zmq_plain(7) zmq_curve(7) zmq(7)

AUTHORS

       This page was written by the 0MQ community. To make a change please read the 0MQ
       Contribution Policy at http://www.zeromq.org/docs:contributing.