curl_setopt

Parameters

ch

A cURL handle returned by curl_init().

option

The CURLOPT_XXX option to set.

value

The value to be set on option.

value should be a bool for the following values of the option parameter:

Option	Set value to	Notes
CURLOPT_AUTOREFERER	TRUE to automatically set the Referer: field in requests where it follows a Location: redirect.
CURLOPT_BINARYTRANSFER	TRUE to return the raw output when CURLOPT_RETURNTRANSFER is used.	From PHP 5.1.3, this option has no effect: the raw output will always be returned when CURLOPT_RETURNTRANSFER is used.
CURLOPT_COOKIESESSION	TRUE to mark this as a new cookie "session". It will force libcurl to ignore all cookies it is about to load that are "session cookies" from the previous session. By default, libcurl always stores and loads all cookies, independent if they are session cookies or not. Session cookies are cookies without expiry date and they are meant to be alive and existing for this "session" only.
CURLOPT_CERTINFO	TRUE to output SSL certification information to STDERR on secure transfers.	Added in cURL 7.19.1. Available since PHP 5.3.2. Requires CURLOPT_VERBOSE to be on to have an effect.
CURLOPT_CONNECT_ONLY	TRUE tells the library to perform all the required proxy authentication and connection setup, but no data transfer. This option is implemented for HTTP, SMTP and POP3.	Added in 7.15.2. Available since PHP 5.5.0.
CURLOPT_CRLF	TRUE to convert Unix newlines to CRLF newlines on transfers.
CURLOPT_DNS_USE_GLOBAL_CACHE	TRUE to use a global DNS cache. This option is not thread-safe and is enabled by default.
CURLOPT_FAILONERROR	TRUE to fail verbosely if the HTTP code returned is greater than or equal to 400. The default behavior is to return the page normally, ignoring the code.
CURLOPT_SSL_FALSESTART	TRUE to enable TLS false start.	Added in cURL 7.42.0. Available since PHP 7.0.7.
CURLOPT_FILETIME	TRUE to attempt to retrieve the modification date of the remote document. This value can be retrieved using the CURLINFO_FILETIME option with curl_getinfo().
CURLOPT_FOLLOWLOCATION	TRUE to follow any "Location: " header that the server sends as part of the HTTP header (note this is recursive, PHP will follow as many "Location: " headers that it is sent, unless CURLOPT_MAXREDIRS is set).
CURLOPT_FORBID_REUSE	TRUE to force the connection to explicitly close when it has finished processing, and not be pooled for reuse.
CURLOPT_FRESH_CONNECT	TRUE to force the use of a new connection instead of a cached one.
CURLOPT_FTP_USE_EPRT	TRUE to use EPRT (and LPRT) when doing active FTP downloads. Use FALSE to disable EPRT and LPRT and use PORT only.
CURLOPT_FTP_USE_EPSV	TRUE to first try an EPSV command for FTP transfers before reverting back to PASV. Set to FALSE to disable EPSV.
CURLOPT_FTP_CREATE_MISSING_DIRS	TRUE to create missing directories when an FTP operation encounters a path that currently doesn't exist.
CURLOPT_FTPAPPEND	TRUE to append to the remote file instead of overwriting it.
CURLOPT_TCP_NODELAY	TRUE to disable TCP's Nagle algorithm, which tries to minimize the number of small packets on the network.	Available since PHP 5.2.1 for versions compiled with libcurl 7.11.2 or greater.
CURLOPT_FTPASCII	An alias of CURLOPT_TRANSFERTEXT. Use that instead.
CURLOPT_FTPLISTONLY	TRUE to only list the names of an FTP directory.
CURLOPT_HEADER	TRUE to include the header in the output.
CURLINFO_HEADER_OUT	TRUE to track the handle's request string.	Available since PHP 5.1.3. The CURLINFO_ prefix is intentional.
CURLOPT_HTTPGET	TRUE to reset the HTTP request method to GET. Since GET is the default, this is only necessary if the request method has been changed.
CURLOPT_HTTPPROXYTUNNEL	TRUE to tunnel through a given HTTP proxy.
CURLOPT_MUTE	TRUE to be completely silent with regards to the cURL functions.	Removed in cURL 7.15.5 (You can use CURLOPT_RETURNTRANSFER instead)
CURLOPT_NETRC	TRUE to scan the ~/.netrc file to find a username and password for the remote site that a connection is being established with.
CURLOPT_NOBODY	TRUE to exclude the body from the output. Request method is then set to HEAD. Changing this to FALSE does not change it to GET.
CURLOPT_NOPROGRESS	TRUE to disable the progress meter for cURL transfers. Note: PHP automatically sets this option to TRUE, this should only be changed for debugging purposes.
CURLOPT_NOSIGNAL	TRUE to ignore any cURL function that causes a signal to be sent to the PHP process. This is turned on by default in multi-threaded SAPIs so timeout options can still be used.	Added in cURL 7.10.
CURLOPT_PATH_AS_IS	TRUE to not handle dot dot sequences.	Added in cURL 7.42.0. Available since PHP 7.0.7.
CURLOPT_PIPEWAIT	TRUE to wait for pipelining/multiplexing.	Added in cURL 7.43.0. Available since PHP 7.0.7.
CURLOPT_POST	TRUE to do a regular HTTP POST. This POST is the normal application/x-www-form-urlencoded kind, most commonly used by HTML forms.
CURLOPT_PUT	TRUE to HTTP PUT a file. The file to PUT must be set with CURLOPT_INFILE and CURLOPT_INFILESIZE.
CURLOPT_RETURNTRANSFER	TRUE to return the transfer as a string of the return value of curl_exec() instead of outputting it directly.
CURLOPT_SAFE_UPLOAD	TRUE to disable support for the @ prefix for uploading files in CURLOPT_POSTFIELDS, which means that values starting with @ can be safely passed as fields. CURLFile may be used for uploads instead.	Added in PHP 5.5.0 with FALSE as the default value. PHP 5.6.0 changes the default value to TRUE. PHP 7 removes this option; the CURLFile interface must be used to upload files.
CURLOPT_SASL_IR	TRUE to enable sending the initial response in the first packet.	Added in cURL 7.31.10. Available since PHP 7.0.7.
CURLOPT_SSL_ENABLE_ALPN	FALSE to disable ALPN in the SSL handshake (if the SSL backend libcurl is built to use supports it), which can be used to negotiate http2.	Added in cURL 7.36.0. Available since PHP 7.0.7.
CURLOPT_SSL_ENABLE_NPN	FALSE to disable NPN in the SSL handshake (if the SSL backend libcurl is built to use supports it), which can be used to negotiate http2.	Added in cURL 7.36.0. Available since PHP 7.0.7.
CURLOPT_SSL_VERIFYPEER	FALSE to stop cURL from verifying the peer's certificate. Alternate certificates to verify against can be specified with the CURLOPT_CAINFO option or a certificate directory can be specified with the CURLOPT_CAPATH option.	TRUE by default as of cURL 7.10. Default bundle installed as of cURL 7.10.
CURLOPT_SSL_VERIFYSTATUS	TRUE to verify the certificate's status.	Added in cURL 7.41.0. Available since PHP 7.0.7.
CURLOPT_TCP_FASTOPEN	TRUE to enable TCP Fast Open.	Added in cURL 7.49.0. Available since PHP 7.0.7.
CURLOPT_TFTP_NO_OPTIONS	TRUE to not send TFTP options requests.	Added in cURL 7.48.0. Available since PHP 7.0.7.
CURLOPT_TRANSFERTEXT	TRUE to use ASCII mode for FTP transfers. For LDAP, it retrieves data in plain text instead of HTML. On Windows systems, it will not set STDOUT to binary mode.
CURLOPT_UNRESTRICTED_AUTH	TRUE to keep sending the username and password when following locations (using CURLOPT_FOLLOWLOCATION), even when the hostname has changed.
CURLOPT_UPLOAD	TRUE to prepare for an upload.
CURLOPT_VERBOSE	TRUE to output verbose information. Writes output to STDERR, or the file specified using CURLOPT_STDERR.

value should be an integer for the following values of the option parameter:

Option	Set value to	Notes
CURLOPT_BUFFERSIZE	The size of the buffer to use for each read. There is no guarantee this request will be fulfilled, however.	Added in cURL 7.10.
CURLOPT_CLOSEPOLICY	One of the CURLCLOSEPOLICY_* values. Note: This option is deprecated, as it was never implemented in cURL and never had any effect.	Removed in PHP 5.6.0.
CURLOPT_CONNECTTIMEOUT	The number of seconds to wait while trying to connect. Use 0 to wait indefinitely.
CURLOPT_CONNECTTIMEOUT_MS	The number of milliseconds to wait while trying to connect. Use 0 to wait indefinitely. If libcurl is built to use the standard system name resolver, that portion of the connect will still use full-second resolution for timeouts with a minimum timeout allowed of one second.	Added in cURL 7.16.2. Available since PHP 5.2.3.
CURLOPT_DNS_CACHE_TIMEOUT	The number of seconds to keep DNS entries in memory. This option is set to 120 (2 minutes) by default.
CURLOPT_EXPECT_100_TIMEOUT_MS	The timeout for Expect: 100-continue responses in milliseconds. Defaults to 1000 milliseconds.	Added in cURL 7.36.0. Available since PHP 7.0.7.
CURLOPT_FTPSSLAUTH	The FTP authentication method (when is activated): CURLFTPAUTH_SSL (try SSL first), CURLFTPAUTH_TLS (try TLS first), or CURLFTPAUTH_DEFAULT (let cURL decide).	Added in cURL 7.12.2.
CURLOPT_HEADEROPT	How to deal with headers. One of the following constants: CURLHEADER_UNIFIED: the headers specified in CURLOPT_HTTPHEADER will be used in requests both to servers and proxies. With this option enabled, CURLOPT_PROXYHEADER will not have any effect. CURLHEADER_SEPARATE: makes CURLOPT_HTTPHEADER headers only get sent to a server and not to a proxy. Proxy headers must be set with CURLOPT_PROXYHEADER to get used. Note that if a non-CONNECT request is sent to a proxy, libcurl will send both server headers and proxy headers. When doing CONNECT, libcurl will send CURLOPT_PROXYHEADER headers only to the proxy and then CURLOPT_HTTPHEADER headers only to the server. Defaults to CURLHEADER_SEPARATE as of cURL 7.42.1, and CURLHEADER_UNIFIED before.	Added in cURL 7.37.0. Available since PHP 7.0.7.
CURLOPT_HTTP_VERSION	CURL_HTTP_VERSION_NONE (default, lets CURL decide which version to use), CURL_HTTP_VERSION_1_0 (forces HTTP/1.0), or CURL_HTTP_VERSION_1_1 (forces HTTP/1.1).
CURLOPT_HTTPAUTH	The HTTP authentication method(s) to use. The options are: CURLAUTH_BASIC, CURLAUTH_DIGEST, CURLAUTH_GSSNEGOTIATE, CURLAUTH_NTLM, CURLAUTH_ANY, and CURLAUTH_ANYSAFE. The bitwise | (or) operator can be used to combine more than one method. If this is done, cURL will poll the server to see what methods it supports and pick the best one. CURLAUTH_ANY is an alias for CURLAUTH_BASIC | CURLAUTH_DIGEST | CURLAUTH_GSSNEGOTIATE | CURLAUTH_NTLM. CURLAUTH_ANYSAFE is an alias for CURLAUTH_DIGEST | CURLAUTH_GSSNEGOTIATE | CURLAUTH_NTLM.
CURLOPT_INFILESIZE	The expected size, in bytes, of the file when uploading a file to a remote site. Note that using this option will not stop libcurl from sending more data, as exactly what is sent depends on CURLOPT_READFUNCTION.
CURLOPT_LOW_SPEED_LIMIT	The transfer speed, in bytes per second, that the transfer should be below during the count of CURLOPT_LOW_SPEED_TIME seconds before PHP considers the transfer too slow and aborts.
CURLOPT_LOW_SPEED_TIME	The number of seconds the transfer speed should be below CURLOPT_LOW_SPEED_LIMIT before PHP considers the transfer too slow and aborts.
CURLOPT_MAXCONNECTS	The maximum amount of persistent connections that are allowed. When the limit is reached, CURLOPT_CLOSEPOLICY is used to determine which connection to close.
CURLOPT_MAXREDIRS	The maximum amount of HTTP redirections to follow. Use this option alongside CURLOPT_FOLLOWLOCATION.
CURLOPT_PORT	An alternative port number to connect to.
CURLOPT_POSTREDIR	A bitmask of 1 (301 Moved Permanently), 2 (302 Found) and 4 (303 See Other) if the HTTP POST method should be maintained when CURLOPT_FOLLOWLOCATION is set and a specific type of redirect occurs.	Added in cURL 7.19.1. Available since PHP 5.3.2.
CURLOPT_PROTOCOLS	Bitmask of CURLPROTO_* values. If used, this bitmask limits what protocols libcurl may use in the transfer. This allows you to have a libcurl built to support a wide range of protocols but still limit specific transfers to only be allowed to use a subset of them. By default libcurl will accept all protocols it supports. See also CURLOPT_REDIR_PROTOCOLS. Valid protocol options are: CURLPROTO_HTTP, CURLPROTO_HTTPS, CURLPROTO_FTP, CURLPROTO_FTPS, CURLPROTO_SCP, CURLPROTO_SFTP, CURLPROTO_TELNET, CURLPROTO_LDAP, CURLPROTO_LDAPS, CURLPROTO_DICT, CURLPROTO_FILE, CURLPROTO_TFTP, CURLPROTO_ALL	Added in cURL 7.19.4.
CURLOPT_PROXYAUTH	The HTTP authentication method(s) to use for the proxy connection. Use the same bitmasks as described in CURLOPT_HTTPAUTH. For proxy authentication, only CURLAUTH_BASIC and CURLAUTH_NTLM are currently supported.	Added in cURL 7.10.7.
CURLOPT_PROXYPORT	The port number of the proxy to connect to. This port number can also be set in CURLOPT_PROXY.
CURLOPT_PROXYTYPE	Either CURLPROXY_HTTP (default), CURLPROXY_SOCKS4, CURLPROXY_SOCKS5, CURLPROXY_SOCKS4A or CURLPROXY_SOCKS5_HOSTNAME.	Added in cURL 7.10.
CURLOPT_REDIR_PROTOCOLS	Bitmask of CURLPROTO_* values. If used, this bitmask limits what protocols libcurl may use in a transfer that it follows to in a redirect when CURLOPT_FOLLOWLOCATION is enabled. This allows you to limit specific transfers to only be allowed to use a subset of protocols in redirections. By default libcurl will allow all protocols except for FILE and SCP. This is a difference compared to pre-7.19.4 versions which unconditionally would follow to all protocols supported. See also CURLOPT_PROTOCOLS for protocol constant values.	Added in cURL 7.19.4.
CURLOPT_RESUME_FROM	The offset, in bytes, to resume a transfer from.
CURLOPT_SSL_OPTIONS	Set SSL behavior options, which is a bitmask of any of the following constants: CURLSSLOPT_ALLOW_BEAST: do not attempt to use any workarounds for a security flaw in the SSL3 and TLS1.0 protocols. CURLSSLOPT_NO_REVOKE: disable certificate revocation checks for those SSL backends where such behavior is present.	Added in cURL 7.25.0. Available since PHP 7.0.7.
CURLOPT_SSL_VERIFYHOST	1 to check the existence of a common name in the SSL peer certificate. 2 to check the existence of a common name and also verify that it matches the hostname provided. 0 to not check the names. In production environments the value of this option should be kept at 2 (default value).	Support for value 1 removed in cURL 7.28.1.
CURLOPT_SSLVERSION	One of CURL_SSLVERSION_DEFAULT (0), CURL_SSLVERSION_TLSv1 (1), CURL_SSLVERSION_SSLv2 (2), CURL_SSLVERSION_SSLv3 (3), CURL_SSLVERSION_TLSv1_0 (4), CURL_SSLVERSION_TLSv1_1 (5) or CURL_SSLVERSION_TLSv1_2 (6). Note: Your best bet is to not set this and let it use the default. Setting it to 2 or 3 is very dangerous given the known vulnerabilities in SSLv2 and SSLv3.
CURLOPT_STREAM_WEIGHT	Set the numerical stream weight (a number between 1 and 256).	Added in cURL 7.46.0. Available since PHP 7.0.7.
CURLOPT_TIMECONDITION	How CURLOPT_TIMEVALUE is treated. Use CURL_TIMECOND_IFMODSINCE to return the page only if it has been modified since the time specified in CURLOPT_TIMEVALUE. If it hasn't been modified, a "304 Not Modified" header will be returned assuming CURLOPT_HEADER is TRUE. Use CURL_TIMECOND_IFUNMODSINCE for the reverse effect. CURL_TIMECOND_IFMODSINCE is the default.
CURLOPT_TIMEOUT	The maximum number of seconds to allow cURL functions to execute.
CURLOPT_TIMEOUT_MS	The maximum number of milliseconds to allow cURL functions to execute. If libcurl is built to use the standard system name resolver, that portion of the connect will still use full-second resolution for timeouts with a minimum timeout allowed of one second.	Added in cURL 7.16.2. Available since PHP 5.2.3.
CURLOPT_TIMEVALUE	The time in seconds since January 1st, 1970. The time will be used by CURLOPT_TIMECONDITION. By default, CURL_TIMECOND_IFMODSINCE is used.
CURLOPT_MAX_RECV_SPEED_LARGE	If a download exceeds this speed (counted in bytes per second) on cumulative average during the transfer, the transfer will pause to keep the average rate less than or equal to the parameter value. Defaults to unlimited speed.	Added in cURL 7.15.5. Available since PHP 5.4.0.
CURLOPT_MAX_SEND_SPEED_LARGE	If an upload exceeds this speed (counted in bytes per second) on cumulative average during the transfer, the transfer will pause to keep the average rate less than or equal to the parameter value. Defaults to unlimited speed.	Added in cURL 7.15.5. Available since PHP 5.4.0.
CURLOPT_SSH_AUTH_TYPES	A bitmask consisting of one or more of CURLSSH_AUTH_PUBLICKEY, CURLSSH_AUTH_PASSWORD, CURLSSH_AUTH_HOST, CURLSSH_AUTH_KEYBOARD. Set to CURLSSH_AUTH_ANY to let libcurl pick one.	Added in cURL 7.16.1.
CURLOPT_IPRESOLVE	Allows an application to select what kind of IP addresses to use when resolving host names. This is only interesting when using host names that resolve addresses using more than one version of IP, possible values are CURL_IPRESOLVE_WHATEVER, CURL_IPRESOLVE_V4, CURL_IPRESOLVE_V6, by default CURL_IPRESOLVE_WHATEVER.	Added in cURL 7.10.8.
CURLOPT_FTP_FILEMETHOD	Tell curl which method to use to reach a file on a FTP(S) server. Possible values are CURLFTPMETHOD_MULTICWD, CURLFTPMETHOD_NOCWD and CURLFTPMETHOD_SINGLECWD.	Added in cURL 7.15.1. Available since PHP 5.3.0.

value should be a string for the following values of the option parameter:

Option	Set value to	Notes
CURLOPT_CAINFO	The name of a file holding one or more certificates to verify the peer with. This only makes sense when used in combination with CURLOPT_SSL_VERIFYPEER.	Might require an absolute path.
CURLOPT_CAPATH	A directory that holds multiple CA certificates. Use this option alongside CURLOPT_SSL_VERIFYPEER.
CURLOPT_COOKIE	The contents of the "Cookie: " header to be used in the HTTP request. Note that multiple cookies are separated with a semicolon followed by a space (e.g., "fruit=apple; colour=red")
CURLOPT_COOKIEFILE	The name of the file containing the cookie data. The cookie file can be in Netscape format, or just plain HTTP-style headers dumped into a file. If the name is an empty string, no cookies are loaded, but cookie handling is still enabled.
CURLOPT_COOKIEJAR	The name of a file to save all internal cookies to when the handle is closed, e.g. after a call to curl_close.
CURLOPT_CUSTOMREQUEST	A custom request method to use instead of "GET" or "HEAD" when doing a HTTP request. This is useful for doing "DELETE" or other, more obscure HTTP requests. Valid values are things like "GET", "POST", "CONNECT" and so on; i.e. Do not enter a whole HTTP request line here. For instance, entering "GET /index.html HTTP/1.0\r\n\r\n" would be incorrect. Note: Don't do this without making sure the server supports the custom request method first.
CURLOPT_DEFAULT_PROTOCOL	The default protocol to use if the URL is missing a scheme name.	Added in cURL 7.45.0. Available since PHP 7.0.7.
CURLOPT_DNS_INTERFACE	Set the name of the network interface that the DNS resolver should bind to. This must be an interface name (not an address).	Added in cURL 7.33.0. Available since PHP 7.0.7.
CURLOPT_DNS_LOCAL_IP4	Set the local IPv4 address that the resolver should bind to. The argument should contain a single numerical IPv4 address as a string.	Added in cURL 7.33.0. Available since PHP 7.0.7.
CURLOPT_DNS_LOCAL_IP6	Set the local IPv6 address that the resolver should bind to. The argument should contain a single numerical IPv6 address as a string.	Added in cURL 7.33.0. Available since PHP 7.0.7.
CURLOPT_EGDSOCKET	Like CURLOPT_RANDOM_FILE, except a filename to an Entropy Gathering Daemon socket.
CURLOPT_ENCODING	The contents of the "Accept-Encoding: " header. This enables decoding of the response. Supported encodings are "identity", "deflate", and "gzip". If an empty string, "", is set, a header containing all supported encoding types is sent.	Added in cURL 7.10.
CURLOPT_FTPPORT	The value which will be used to get the IP address to use for the FTP "PORT" instruction. The "PORT" instruction tells the remote server to connect to our specified IP address. The string may be a plain IP address, a hostname, a network interface name (under Unix), or just a plain '-' to use the systems default IP address.
CURLOPT_INTERFACE	The name of the outgoing network interface to use. This can be an interface name, an IP address or a host name.
CURLOPT_KEYPASSWD	The password required to use the CURLOPT_SSLKEY or CURLOPT_SSH_PRIVATE_KEYFILE private key.	Added in cURL 7.16.1.
CURLOPT_KRB4LEVEL	The KRB4 (Kerberos 4) security level. Any of the following values (in order from least to most powerful) are valid: "clear", "safe", "confidential", "private".. If the string does not match one of these, "private" is used. Setting this option to NULL will disable KRB4 security. Currently KRB4 security only works with FTP transactions.
CURLOPT_LOGIN_OPTIONS	Can be used to set protocol specific login options, such as the preferred authentication mechanism via "AUTH=NTLM" or "AUTH=*", and should be used in conjunction with the CURLOPT_USERNAME option.	Added in cURL 7.34.0. Available since PHP 7.0.7.
CURLOPT_PINNEDPUBLICKEY	Set the pinned public key. The string can be the file name of your pinned public key. The file format expected is "PEM" or "DER". The string can also be any number of base64 encoded sha256 hashes preceded by "sha256//" and separated by ";".	Added in cURL 7.39.0. Available since PHP 7.0.7.
CURLOPT_POSTFIELDS	The full data to post in a HTTP "POST" operation. To post a file, prepend a filename with @ and use the full path. The filetype can be explicitly specified by following the filename with the type in the format ';type=mimetype'. This parameter can either be passed as a urlencoded string like 'para1=val1&para2=val2&...' or as an array with the field name as key and field data as value. If value is an array, the Content-Type header will be set to multipart/form-data. As of PHP 5.2.0, value must be an array if files are passed to this option with the @ prefix. As of PHP 5.5.0, the @ prefix is deprecated and files can be sent using CURLFile. The @ prefix can be disabled for safe passing of values beginning with @ by setting the CURLOPT_SAFE_UPLOAD option to TRUE.
CURLOPT_PRIVATE	Any data that should be associated with this cURL handle. This data can subsequently be retrieved with the CURLINFO_PRIVATE option of curl_getinfo(). cURL does nothing with this data. When using a cURL multi handle, this private data is typically a unique key to identify a standard cURL handle.	Added in cURL 7.10.3.
CURLOPT_PROXY	The HTTP proxy to tunnel requests through.
CURLOPT_PROXY_SERVICE_NAME	The proxy authentication service name.	Added in cURL 7.34.0. Available since PHP 7.0.7.
CURLOPT_PROXYUSERPWD	A username and password formatted as "[username]:[password]" to use for the connection to the proxy.
CURLOPT_RANDOM_FILE	A filename to be used to seed the random number generator for SSL.
CURLOPT_RANGE	Range(s) of data to retrieve in the format "X-Y" where X or Y are optional. HTTP transfers also support several intervals, separated with commas in the format "X-Y,N-M".
CURLOPT_REFERER	The contents of the "Referer: " header to be used in a HTTP request.
CURLOPT_SERVICE_NAME	The authentication service name.	Added in cURL 7.43.0. Available since PHP 7.0.7.
CURLOPT_SSH_HOST_PUBLIC_KEY_MD5	A string containing 32 hexadecimal digits. The string should be the MD5 checksum of the remote host's public key, and libcurl will reject the connection to the host unless the md5sums match. This option is only for SCP and SFTP transfers.	Added in cURL 7.17.1.
CURLOPT_SSH_PUBLIC_KEYFILE	The file name for your public key. If not used, libcurl defaults to $HOME/.ssh/id_dsa.pub if the HOME environment variable is set, and just "id_dsa.pub" in the current directory if HOME is not set.	Added in cURL 7.16.1.
CURLOPT_SSH_PRIVATE_KEYFILE	The file name for your private key. If not used, libcurl defaults to $HOME/.ssh/id_dsa if the HOME environment variable is set, and just "id_dsa" in the current directory if HOME is not set. If the file is password-protected, set the password with CURLOPT_KEYPASSWD.	Added in cURL 7.16.1.
CURLOPT_SSL_CIPHER_LIST	A list of ciphers to use for SSL. For example, RC4-SHA and TLSv1 are valid cipher lists.
CURLOPT_SSLCERT	The name of a file containing a PEM formatted certificate.
CURLOPT_SSLCERTPASSWD	The password required to use the CURLOPT_SSLCERT certificate.
CURLOPT_SSLCERTTYPE	The format of the certificate. Supported formats are "PEM" (default), "DER", and "ENG".	Added in cURL 7.9.3.
CURLOPT_SSLENGINE	The identifier for the crypto engine of the private SSL key specified in CURLOPT_SSLKEY.
CURLOPT_SSLENGINE_DEFAULT	The identifier for the crypto engine used for asymmetric crypto operations.
CURLOPT_SSLKEY	The name of a file containing a private SSL key.
CURLOPT_SSLKEYPASSWD	The secret password needed to use the private SSL key specified in CURLOPT_SSLKEY. Note: Since this option contains a sensitive password, remember to keep the PHP script it is contained within safe.
CURLOPT_SSLKEYTYPE	The key type of the private SSL key specified in CURLOPT_SSLKEY. Supported key types are "PEM" (default), "DER", and "ENG".
CURLOPT_UNIX_SOCKET_PATH	Enables the use of Unix domain sockets as connection endpoint and sets the path to the given string.	Added in cURL 7.40.0. Available since PHP 7.0.7.
CURLOPT_URL	The URL to fetch. This can also be set when initializing a session with curl_init().
CURLOPT_USERAGENT	The contents of the "User-Agent: " header to be used in a HTTP request.
CURLOPT_USERNAME	The user name to use in authentication.	Added in cURL 7.19.1. Available since PHP 5.5.0.
CURLOPT_USERPWD	A username and password formatted as "[username]:[password]" to use for the connection.
CURLOPT_XOAUTH2_BEARER	Specifies the OAuth 2.0 access token.	Added in cURL 7.33.0. Available since PHP 7.0.7.

value should be an array for the following values of the option parameter:

Option	Set value to	Notes
CURLOPT_CONNECT_TO	Connect to a specific host and port instead of the URL's host and port. Accepts an array of strings with the format HOST:PORT:CONNECT-TO-HOST:CONNECT-TO-PORT.	Added in cURL 7.49.0. Available since PHP 7.0.7.
CURLOPT_HTTP200ALIASES	An array of HTTP 200 responses that will be treated as valid responses and not as errors.	Added in cURL 7.10.3.
CURLOPT_HTTPHEADER	An array of HTTP header fields to set, in the format array('Content-type: text/plain', 'Content-length: 100')
CURLOPT_POSTQUOTE	An array of FTP commands to execute on the server after the FTP request has been performed.
CURLOPT_PROXYHEADER	An array of custom HTTP headers to pass to proxies.	Added in cURL 7.37.0. Available since PHP 7.0.7.
CURLOPT_QUOTE	An array of FTP commands to execute on the server prior to the FTP request.
CURLOPT_RESOLVE	Provide a custom address for a specific host and port pair. An array of hostname, port, and IP address strings, each element separated by a colon. In the format: array("example.com:80:127.0.0.1")	Added in cURL 7.21.3. Available since PHP 5.5.0.

value should be a stream resource (using fopen(), for example) for the following values of the option parameter:

Option	Set value to
CURLOPT_FILE	The file that the transfer should be written to. The default is STDOUT (the browser window).
CURLOPT_INFILE	The file that the transfer should be read from when uploading.
CURLOPT_STDERR	An alternative location to output errors to instead of STDERR.
CURLOPT_WRITEHEADER	The file that the header part of the transfer is written to.

value should be the name of a valid function or a Closure for the following values of the option parameter:

Option	Set value to
CURLOPT_HEADERFUNCTION	A callback accepting two parameters. The first is the cURL resource, the second is a string with the header data to be written. The header data must be written by this callback. Return the number of bytes written.
CURLOPT_PASSWDFUNCTION	A callback accepting three parameters. The first is the cURL resource, the second is a string containing a password prompt, and the third is the maximum password length. Return the string containing the password.
CURLOPT_PROGRESSFUNCTION	A callback accepting five parameters. The first is the cURL resource, the second is the total number of bytes expected to be downloaded in this transfer, the third is the number of bytes downloaded so far, the fourth is the total number of bytes expected to be uploaded in this transfer, and the fifth is the number of bytes uploaded so far. Note: The callback is only called when the CURLOPT_NOPROGRESS option is set to FALSE. Return a non-zero value to abort the transfer. In which case, the transfer will set a CURLE_ABORTED_BY_CALLBACK error.
CURLOPT_READFUNCTION	A callback accepting three parameters. The first is the cURL resource, the second is a stream resource provided to cURL through the option CURLOPT_INFILE, and the third is the maximum amount of data to be read. The callback must return a string with a length equal or smaller than the amount of data requested, typically by reading it from the passed stream resource. It should return an empty string to signal EOF.
CURLOPT_WRITEFUNCTION	A callback accepting two parameters. The first is the cURL resource, and the second is a string with the data to be written. The data must be saved by this callback. It must return the exact number of bytes written or the transfer will be aborted with an error.

Other values:

Option	Set value to
CURLOPT_SHARE	A result of curl_share_init(). Makes the cURL handle to use the data from the shared handle.