| SO_DEBUG | Reports whether debugging information is being recorded. | int |
| SO_BROADCAST | Reports whether transmission of broadcast messages is supported. | int |
| SO_REUSEADDR | Reports whether local addresses can be reused. | int |
| SO_KEEPALIVE | Reports whether connections are kept active with periodic transmission of messages. If the connected socket fails to respond to these messages, the connection is broken and processes writing to that socket are notified with a SIGPIPE signal. | int |
| SO_LINGER | Reports whether the socket lingers on socket_close() if data is present. By default, when the socket is closed, it attempts to send all unsent data. In the case of a connection-oriented socket, socket_close() will wait for its peer to acknowledge the data. If l_onoff is non-zero and l_linger is zero, all the unsent data will be discarded and RST (reset) is sent to the peer in the case of a connection-oriented socket. On the other hand, if l_onoff is non-zero and l_linger is non-zero, socket_close() will block until all the data is sent or the time specified in l_linger elapses. If the socket is non-blocking, socket_close() will fail and return an error. | array. The array will contain two keys: l_onoff and l_linger. |
| SO_OOBINLINE | Reports whether the socket leaves out-of-band data inline. | int |
| SO_SNDBUF | Reports the size of the send buffer. | int |
| SO_RCVBUF | Reports the size of the receive buffer. | int |
| SO_ERROR | Reports information about error status and clears it. | int (cannot be set by socket_set_option()) |
| SO_TYPE | Reports the socket type (e.g. SOCK_STREAM). | int (cannot be set by socket_set_option()) |
| SO_DONTROUTE | Reports whether outgoing messages bypass the standard routing facilities. | int |
| SO_RCVLOWAT | Reports the minimum number of bytes to process for socket input operations. | int |
| SO_RCVTIMEO | Reports the timeout value for input operations. | array. The array will contain two keys: sec which is the seconds part on the timeout value and usec which is the microsecond part of the timeout value. |
| SO_SNDTIMEO | Reports the timeout value specifying the amount of time that an output function blocks because flow control prevents data from being sent. | array. The array will contain two keys: sec which is the seconds part on the timeout value and usec which is the microsecond part of the timeout value. |
| SO_SNDLOWAT | Reports the minimum number of bytes to process for socket output operations. | int |