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Network Functions



No external libraries are needed to build this extension.


There is no installation needed to use these functions; they are part of the PHP core.

Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Network Configuration Options
Name Default Changeable Changelog
define_syslog_variables "0" PHP_INI_ALL  
For further details and definitions of the PHP_INI_* constants, see the php.ini directives.

Here's a short explanation of the configuration directives.

define_syslog_variables boolean

Whether or not to define the various syslog variables (e.g. $LOG_PID, $LOG_CRON, etc.). Turning it off is a good idea performance-wise. At runtime, you can define these variables by calling define_syslog_variables().

Resource Types

This extension defines a file pointer resource returned by fsockopen() and pfsockopen().

Predefined Constants

The constants below are always available as part of the PHP core.

openlog() Options
Constant Description
LOG_CONS if there is an error while sending data to the system logger, write directly to the system console
LOG_NDELAY open the connection to the logger immediately
LOG_ODELAY (default) delay opening the connection until the first message is logged
LOG_PERROR print log message also to standard error
LOG_PID include PID with each message
openlog() Facilities
Constant Description
LOG_AUTH security/authorization messages (use LOG_AUTHPRIV instead in systems where that constant is defined)
LOG_AUTHPRIV security/authorization messages (private)
LOG_CRON clock daemon (cron and at)
LOG_DAEMON other system daemons
LOG_KERN kernel messages
LOG_LOCAL0 ... LOG_LOCAL7 reserved for local use, these are not available in Windows
LOG_LPR line printer subsystem
LOG_MAIL mail subsystem
LOG_NEWS USENET news subsystem
LOG_SYSLOG messages generated internally by syslogd
LOG_USER generic user-level messages
LOG_UUCP UUCP subsystem
syslog() Priorities (in descending order)
Constant Description
LOG_EMERG system is unusable
LOG_ALERT action must be taken immediately
LOG_CRIT critical conditions
LOG_ERR error conditions
LOG_WARNING warning conditions
LOG_NOTICE normal, but significant, condition
LOG_INFO informational message
LOG_DEBUG debug-level message
dns_get_record() Options
Constant Description
DNS_A IPv4 Address Resource
DNS_MX Mail Exchanger Resource
DNS_CNAME Alias (Canonical Name) Resource
DNS_NS Authoritative Name Server Resource
DNS_PTR Pointer Resource
DNS_HINFO Host Info Resource (See IANA's » Operating System Names for the meaning of these values)
DNS_SOA Start of Authority Resource
DNS_TXT Text Resource
DNS_ANY Any Resource Record. On most systems this returns all resource records, however it should not be counted upon for critical uses. Try DNS_ALL instead.
DNS_AAAA IPv6 Address Resource
DNS_ALL Iteratively query the name server for each available record type.

Table of Contents

  • checkdnsrr — Check DNS records corresponding to a given Internet host name or IP address
  • closelog — Close connection to system logger
  • debugger_off — Disable internal PHP debugger (PHP 3)
  • debugger_on — Enable internal PHP debugger (PHP 3)
  • define_syslog_variables — Initializes all syslog related constants
  • dns_check_record — Alias of checkdnsrr
  • dns_get_mx — Alias of getmxrr
  • dns_get_record — Fetch DNS Resource Records associated with a hostname
  • fsockopen — Open Internet or Unix domain socket connection
  • gethostbyaddr — Get the Internet host name corresponding to a given IP address
  • gethostbyname — Get the IP address corresponding to a given Internet host name
  • gethostbynamel — Get a list of IP addresses corresponding to a given Internet host name
  • getmxrr — Get MX records corresponding to a given Internet host name
  • getprotobyname — Get protocol number associated with protocol name
  • getprotobynumber — Get protocol name associated with protocol number
  • getservbyname — Get port number associated with an Internet service and protocol
  • getservbyport — Get Internet service which corresponds to port and protocol
  • header — Send a raw HTTP header
  • headers_list — Returns a list of response headers sent (or ready to send)
  • headers_sent — Checks if or where headers have been sent
  • inet_ntop — Converts a packed internet address to a human readable representation
  • inet_pton — Converts a human readable IP address to its packed in_addr representation
  • ip2long — Converts a string containing an (IPv4) Internet Protocol dotted address into a proper address
  • long2ip — Converts an (IPv4) Internet network address into a string in Internet standard dotted format
  • openlog — Open connection to system logger
  • pfsockopen — Open persistent Internet or Unix domain socket connection
  • setcookie — Send a cookie
  • setrawcookie — Send a cookie without urlencoding the cookie value
  • socket_get_status — Alias of stream_get_meta_data
  • socket_set_blocking — Alias of stream_set_blocking
  • socket_set_timeout — Alias of stream_set_timeout
  • syslog — Generate a system log message