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.
Note: 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.
(available only when openssl support is compiled into PHP) are extensions
tcp:// transport which include SSL encryption.
ssl:// will attempt to negotiate an SSL V2,
or SSL V3 connection depending on the capabilities and preferences
of the remote host.
sslv3:// will select the SSL V2 or SSL V3