The following is a list of the various URL style socket transports that PHP has built-in for use with the streams based socket functions such as fsockopen(), and stream_socket_client(). These transports do not apply to the Sockets Extension.
For a list of transports installed in your version of PHP use stream_get_transports().
PHP 3, PHP 4, PHP 5. ssl:// & tls:// since PHP 4.3.0 sslv2:// & sslv3:// since PHP 5.0.2
Note: If no transport is specified, tcp:// will be assumed.
Internet Domain sockets expect a port number in addition to a target address. In the case of fsockopen() this is specified in a second parameter and therefore does not impact the formatting of transport URL. With stream_socket_client() and related functions as with traditional URLs however, the port number is specified as a suffix of the transport URL delimited by a colon.
IPv6 numeric addresses with port numbers: In the second example above, while the IPv4 and hostname examples are left untouched apart from the addition of their colon and portnumber, the IPv6 address is wrapped in square brackets: [fe80::1]. This is to distinguish between the colons used in an IPv6 address and the colon used to delimit the portnumber.
The ssl:// and tls:// transports (available only when openssl support is compiled into PHP) are extensions of the tcp:// transport which include SSL encryption. Since PHP 4.3.0 OpenSSL support must be statically compiled into PHP, since PHP 5.0.0 it may be compiled as a module or statically.
ssl:// will attempt to negotiate an SSL V2, or SSL V3 connection depending on the capabilities and preferences of the remote host. sslv2:// and sslv3:// will select the SSL V2 or SSL V3 protocol explicitly.
Table P-1. Context options for ssl:// and tls:// transports (since PHP 4.3.2)
|verify_peer||TRUE or FALSE. Require verification of SSL certificate used.||FALSE|
|allow_self_signed||TRUE or FALSE. Allow self-signed certificates.||FALSE|
|cafile||Location of Certificate Authority file on local filesystem which should be used with the verify_peer context option to authenticate the identity of the remote peer.|
|capath||If cafile is not specified or if the certificate is not found there, the directory pointed to by capath is searched for a suitable certificate. capath must be a correctly hashed certificate directory.|
|local_cert||Path to local certificate file on filesystem. It must be a PEM encoded file which contains your certificate and private key. It can optionally contain the certificate chain of issuers.|
|passphrase||Passphrase with which your local_cert file was encoded.|
|CN_match||Common Name we are expecting. PHP will perform limited wildcard matching. If the Common Name does not match this, the connection attempt will fail.|