Appendix Q. List of Supported Socket Transports

Table of Contents
Internet Domain: TCP, UDP, SSL, and TLS
Unix Domain: Unix and UDG

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().

Internet Domain: TCP, UDP, SSL, and TLS

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.

127.0.0.1
fe80::1
www.example.com
tcp://127.0.0.1
tcp://fe80::1
tcp://www.example.com
udp://www.example.com
ssl://www.example.com
sslv2://www.example.com
sslv3://www.example.com
tls://www.example.com

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.

tcp://127.0.0.1:80
tcp://[fe80::1]:80
tcp://www.example.com:80

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 Q-1. Context options for ssl:// and tls:// transports (since PHP 4.3.2)

Name	Usage	Default
`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.

Note: Because ssl:// is the underlying transport for the https:// and ftps:// wrappers, any context options which apply to ssl:// also apply to https:// and ftps://.