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Internet Domain: TCP, UDP, SSL, and TLS

PHP 4, PHP 5. ssl:// & tls:// since PHP 4.3.0 sslv2:// & sslv3:// since PHP 5.0.2

Nota: 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

Nota: 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.

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User Contributed Notes 4 notes

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2
pablo dot livardo at gmail dot com
4 years ago
I've been having a problem with a TLS connection.

<?php
$fp
= fsockopen("tls://mail.example.com", 587, $errno, $errstr);
?>

Which gives me an error of:

SSL operation failed with code 1. OpenSSL Error messages: error:1408F10B:SSL routines:SSL3_GET_RECORD:wrong version number

I believe this is caused by PHP not being able to start with an unencrypted connection and then switch to encryption even though the functionality is built into OpenSSL.

For Google Mail users you can avoid this by using port 465 instead of 587.
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2
stefan at example dot com
4 years ago
Actually, PHP is very able to start with an unencrypted connection and then switch to an encrypted one - refer to http://php.net/stream_socket_enable_crypto .
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1
christian at lantian dot eu
11 months ago
@pablo dot livardo  :  I think that the problem you found is caused by the difference between the client/server encryption methods used.

The 465 port is used for SMTPS, and the server starts the encryption immediately it receives your connection. So, your code will work.

The 587 port is used for Submission (MSA or Mail Submission Agent) which works like the port 25. The server accepts your connection and doesn't activate the encryption. If you want an encrypted connection on the port 587, you must connect on it without encryption, you must start to dialog with the server (with EHLO) and after that you must ask the server to start the encrypted connection using the STARTTLS command. The server starts the encryption and now you can start as well the encryption on your client.

So, in few words, you can not use :

<?php $fp = fsockopen("tls://mail.example.com", 587, $errno, $errstr);  ?> 

but you can use:

<?php $fp = stream_socket_client("mail.example.com:587", $errno, $errstr); ?> 

and after you send the STARTTLS command, you can enable the crypto:

<?php stream_socket_enable_crypto($fp, true, STREAM_CRYPTO_METHOD_SSLv23_CLIENT); ?>

P.S. My previous note on this page was totally wrong, so I ask the php.net admin to remove it.

:)
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-1
christian at lantian dot eu
11 months ago
@pablo dot livardo  :  I think that the problem you found is caused by the difference between the client/server encryption methods used.

You tried to access the port 587 using TLS encryption, but the server uses the SSLv3 encryption on this port.

You can communicate with the Google server on port 465 because on this port the communication is encrypted using TLS and your client is configured to recognize the TLS.

So, if you want to connect on the Google server over the port 587, you simply must write:

<?php
$fp
= fsockopen("ssl://mail.example.com", 587, $errno, $errstr);
?>

instead of:

<?php
$fp
= fsockopen("tls://mail.example.com", 587, $errno, $errstr);
?>

:)
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