Interface(3)

NAME
Net::Interface - Perl extension to access network interfaces

SYNOPSIS
  use Net::Interface qw(
        cidr2mask
        full_inet_ntop
        ipV6compress
        mac_bin2hex
        mask2cidr
        net_symbols
        type
        scope
        inet_aton
        inet_ntoa
        inet_pton
        inet_ntop
        :afs
        :pfs
        :ifs
        :iffs
        :iffIN6
        :iftype
        :scope
        :constants
        :inet
        :all
        :lower
        :upper
  );

  TAGS
  Note: tags :afs, :pfs, :constants, :ifs
        include all AF_[family names], PF_[family names] and
        IFxxxx values that exist on this architecture.

        :iffs includes only IFF_xxx values
        :iffIN6 includes IN6_IFF_xxx values on BSD flavored OS's

        :inet includes inet_aton, inet_ntoa,
                inet_pton, inet_ntop

  On platforms that support IPV6, :iftype :scope
  provide additional attribute screening

  :constants is a deprecated synonym for :ifs

See Net::Interface::NetSymbols built specifically for this platform for a detailed list and description of all symbols available on this specific architecture and operating systems version.

By default Net::Interface functions and methods return string IPv6 addresses and MAC addresses in uppercase. To change that to lowercase:

  use Net::Interface qw(:lower);

To ensure the current string case behavior even if the default changes:

  use Net::Interface qw(:upper);

  FUNCTIONS and METHODS
  @all_ifs = Net::Interface->interfaces();

  $this_if    = Net::Interface->new('eth0');
  $refresh_if = $any_if->new();
  $refresh_if = $this_if->delete($naddr);

  $create_if  = Net::Interface->new(\%iface_spec);

  @ifnames     = "@all_ifs";
  $if_name_txt = $if->name;

  print $if,"\n";       # prints the name
  print "@all_ifs\n"    # prints all names

 ---------------------------------------------
        WARNING API CHANGE !

    $naddr = $if->address([$family],[$index]);
    $naddr = $if->netmask([$family],[$index]);
    $naddr = $if->destination([$family],[$index]);
        same as
    $naddr = $if->broadcast([$family],[$index]);

    @addresses = $if->address([$family]);
    @netmasks  = $if->netmask([$family]);
    @destinats = $if->destination([$family]);
        same as
    @broaddrs  = $if->broadcast([$family]);

    $bin_mac = $if->hwaddress($hwaddr);
 ---------------------------------------------

  $val = $if->flags($val);
  $val = $if->mtu ($val);
  $val = $if->metric($val);
  $val = $if=>index();

  $cidr = $if->mask2cidr([$naddmsk])
  $cidr = mask2cidr($naddrmsk);
  $naddrmsk = cidr2mask($cidr,[family])

  $mac_txt = if->mac_bin2hex();
  $mac_txt = mac_bin2hex($bin_mac);

  $naddr   = inet_aton($host or $dotquad);
  $dotquad = inet_ntoa($naddr);

  $info = $if->info();

    for ipV6 only
  $type  = $if->type([$naddr6]);
  $type  = type($naddr6);
  $scope = $if->scope([$naddr6]);
  $scope = scope($naddr6);

  $full_ipV6_txt = full_inet_ntop($naddr6);
  $ipV6_txt = inet_ntop($naddr6)
  $naddr6   = inet_pton($ipV6_txt);

DESCRIPTION
Net::Interface is a module that allows access to the host network interfaces in a manner similar to ifconfig(8). Version 1.00 is a complete re-write and includes support for IPV6 as well as the traditional IPV4.

Both read and write access to network device attributes including the creation of new logical and physical interfaces is available where supported by the OS and this module.

NOTE: if your OS is not supported, please feel free to contribute new capabilities, patches, etc.... see: Net::Interface::Developer

ANOTHER NOTE: Many of the operations of Net::Interface, particularly those that set interface values require privileged access to OS resources. Wherever possible, Net::Interface will simply fail softly when there are not adequate privileges to perform the requested operation or where the operation is not supported.

OPERATION
Net::Interface retrieves information about the network devices on its host in a fashion similar to ifconfig(8) running in a terminal window. With ifconfig(8), the information is returned to the screen and any additional activity on a particular network device goes on without the knowledge of the user. Similarly, Net::Interface only retrieves information about network devices when methods interfaces and new are invoked. Calls to interfaces retrieves information about all network devices known to the host. Calls to new make the same function call to the host library but rather than returning all the interface net device information to the user, it selects out only information for the specified device. The function call to the OS is the same. This information is cached in the object returned to the user interface and it is from this object that data is returned to the user program.

To continually monitor a particular device, it is necessary to issue repeat calls to new.

SYMBOLS
Net::Interface provide a large number of network interface symbols with a module generated on its build host. These symbols include all of the available AF_xxxx, PF_xxx, IFF_xxx symbols and many more. For a detailed list of all of these symbols, see Net::Interface::NetSymbols.

  HINTS and TIPS for use SYMBOLS
Most of the symbols provided by Net::Interface have dual values.

1) a numeric value when use in arithmetic context and

2) a text value when used in string/text context

Symbols are actually calls to functions. Because of this certain usage rules apply that are not necessarily obvious.

If you make it a practice to build your Perl modules using:

  #!/usr/bin/perl
  use strict;

Then usage of symbols will require that they explicitly be called as functions. i.e.

  $functval = &AF_INET          is OK

  $functval = AF_INET()         is better

The first calling method allows the function to pick up the contents of @_. This works fine as long as @_ is empty. Since symbols do not take arguments, when @_ contains something the symbol call will fail with a message from Perl about inappropriate calling syntax.

If you do not "use strict;" (not recommended) then bare symbols will work just fine in your Perl scripts. You can also imbed your symbols in blocks where strict; is not enforced.

  {
        no strict;
        $functval = AF_INET
  }

Lastly, to access the numeric value of a symbol unconditionally:

  $numeric = 0 + AF_INET

WARNING - API CHANGES
The following changes have been made to the API. This may BREAK existing code. If you have been using a previous version of Net::Interface you should verify that these API changes do not break your code.

    NO LONGER SUPPORTED

    * $naddr=$if->address($naddr);

    * $naddr=$if->netmask($naddr);

    * $naddr=$if->destination($naddr);

    * $naddr=$if->broadcast($naddr);

    * $mac = $if-hwaddress($hwaddr);>

Setting address values was never implemented in previous versions of Net::Interface. With this version (where supported) changing an address will be implemented using a hash argument containing the required and optional elements in a manner similar to ifconfig(8). See:

        Net::Interface->new(\%iface_spec);

    NO LONGER SUPPORTED

    * ($sa_family,$size,$naddr)=$if->address($naddr);

On most platforms, multiple addresses and multiple address families can be assigned to the same interface. The returned data described above conflicts with the requirement to report multiple addresses for a particular interface. In addition, the returned information only reflected the attributes of the FIRST address assigned to the device where there could be many of mixed families. i.e. AF_INET, AF_INET6, and perhaps more as the capabilities of this module are enhanced to support additional address families.

The API has been changed to reflect this reality and the need to report multiple addresses on the same interface.

        @addresses = $if->address([$family]);

The new API is described in detail later in this document.

    NO LONGER SUPPORTED

    * ($sa_family,$size,$hwaddr)=$if->hwaddress($hwaddr);

As in the preceding case, it is not possible to accurately report the address family attributes of an interface which may support assignments of more than one address from differing address families.

        see: if->info();

METHODS
Brackets [] indicates an optional parameter.

The return value for SET attempts on systems that do not support the operation is not settled. Current practice is to silently ignore the set request. This may change so don't count on this behavior.

Unless otherwise specified, errors for all methods return either undef or and empty array depending on the expected return context.

•   ->interfaces();

    Returns a list of interface objects for each interface that supports IPV4 or IPV6.

    On failure, returns an empty list.

        usage:

            @all_ifs = Net::Interface->interfaces();

            foreach my $if (@all_ifs) {
              $if_name = $if->name;
                or
              print $if, "\n";      # (overloaded)
            }

        Get or Set (where supported)
            $old_mtu = $if->mtu($new_mtu);
            $old_metric = $if->metric($new_metric);
        etc...

•   ->new(); has multiple calling invocations.

    This method will refresh the data for an existing interface OR it can modify and existing interface OR it can create a new interface or alias.

    •   $this_if = ->new('eth0');

        Same as ->interfaces above except for a single known interface. An interface object is returned for the specific logical device requested.

        On failure return undef

    •   $refresh_if = ->new();

        The a new (refreshed) interface object is returned for the same logical device.

    •   $new_if = ->new(%iface_spec);

    •   $new_if = ->new(\%iface_spec);

        A logical device is created or updated. The specification is contained in a hash table that is passed to new either directly or as a reference.

        The interface specification is architecture dependent. For example, adding an address to an existing interface.

                i.e.    Linux

          $iface_spec = {
                name      => 'eth0:0',
                address   => inet_aton('192.168.1.2'),
                netmask   => inet_aton('255.255.255.0),
          # netmask may be optionally specified as:
          #     cidr      => 24,
                broadcast => inet_aton('192.168.1.255),
          # optional values, defaults shown
                metric    => 1,
                mtu       => 1500,
          };

        The address family is determined by inspection of the size of the address.

                i.e.    BSD variants

          $iface_spec = {
                name      => 'eth0',    # primary interface
                alias     => inet_aton('192.168.1.2'),
                netmask   => inet_aton('255.255.255.255),
          # netmask may be optionally specified as:
          #     cidr      => 32,
          # optional values, defaults shown
                metric    => 1,
                mtu       => 1500,
          };

        The keyword alias says not to change the primary interface but instead to add an address to the interface.

    •   $refresh_if = ->delete($naddr);

        Removes and address from an interface where supported.

    •   ->name();

        Return the name of the interface.

    •   ->address([$family],[$index]);

        SCALAR context

        Get the interface specified by the optional $family and $index.

        Absent a $family and $index, the first available interface for the family AF_INET (or if not present AF_INET6) will be returned.

        NOTE: this is not a definitive response. The OS may report the interfaces in any order. Usually the primary interface is reported first but this is not guaranteed. Use ARRAY context instead to get all addresses.

        ARRAY context

        Returns a list of addresses assigned to this interface.

        If a $family is not specified then AF_INET is assumed or AF_INET6 if there are no AF_INET addresses present.

    •   ->netmask([$family],[$index]);

        Similar to ->address([$family],[$index]); above. Netmasks are reported in the same order as the addresses above, in matching positions in the returned array.

    •   ->destination([$family],[$index]);

    •   ->broadcast([$family],[$index]);

        These to methods are identical in execution. The returned address attribute(s) will be destination or broadcast addresses depending on the status of the POINTOPOINT flag.

        Similar to ->address([$family],[$index]); above. If an address attribute is unknown, the array slot will contain undef.

    •   ->hwaddress([$hwaddr]);

        Returns the binary value of the MAC address for the interface. Optionally, where supported, it allows setting of the MAC address.

          i.e.  $old_binmac = $if->hwaddress($new_binmac);
                $new_binmac = $if->hwaddress();

    •   ->flags([$new_flags]);

        Get or Set (where supported) the flags on the interface.

                i.e. down an interface.
                $flags  = $if->flags();
                $mask   = ~IFF_UP;
                $old_fg = $if->flags($flags & $mask);
                $flags  = $if->flags();

                UPDATES the if object

        NOTE: returns undef if the interface is down or not configured.

    •   ->mtu([$new_mtu]);

        Get or Set (where supported) the mtu of the interface.

                $mtu = $if->mtu();
                $old_mtu = $if->mtu($new_mtu);

                UPDATES the if object

        NOTE: returns undef if the interface is down or not configured.

    •   ->metric([$new_metric]);

        Get or Set (where supported) the metric for the interface.

                $metric = $if->metric();
                $old_metric = $if->metric($new_metric);

                UPDATES the if object

        NOTE: returns undef if the interface is down or not configured.

    •   ->index();

        Get the interface index, not to be confused with the index number of the IP assigned to a particular index.

        There is no provision to SET the index.

                $index = $if->index();

    •   ->mask2cidr([$naddrmsk]);

    •   $cidr = mask2cidr($naddrmsk);

        Returns the CIDR (prefix length) for the netmask $naddrmsk.

        When no $naddrmsk is specified the method will return the first address in the first family starting with AF_INET, AF_INET6, etc... This is particularly useful for interfaces with only a single address assigned.

        May be called as a METHOD or a FUNCTION.

    •   ->mac_bin2hex();

    •   $mac_txt = mac_bin2hex($bin_mac);

        Converts a binary MAC address into hex text.

          i.e. A1:B2:C3:D4:E5:F6

        May be called as a METHOD or a FUNCTION.

    •   ->info();

        Returns a pointer to a hash containing information about the interface as follows:

          $info = {
                name    => 'eth0',
                index   => 1,
                mtu     => 1500,
                metric  => 1,
                flags   => 1234,
                mac     => binary_mac_address,
                $fam0   => {
                        number  => of_addresses,
                        size    => of_address,
                },
                $fam1   => etc....
          };

          where $famX is one of AF_INET, AF_INET6, etc...

    •   ->type([$naddr6]);

    •   $type = type($naddr6);

        ipV6 method. Returns attributes of an IPV6 address that may be tested with these bit masks:

          IPV6_ADDR_ANY                 unknown
          IPV6_ADDR_UNICAST             unicast
          IPV6_ADDR_MULTICAST           multicast
          IPV6_ADDR_ANYCAST             anycast
          IPV6_ADDR_LOOPBACK            loopback
          IPV6_ADDR_LINKLOCAL           link-local
          IPV6_ADDR_SITELOCAL           site-local
          IPV6_ADDR_COMPATv4            compat-v4
          IPV6_ADDR_SCOPE_MASK          scope-mask
          IPV6_ADDR_MAPPED              mapped
          IPV6_ADDR_RESERVED            reserved
          IPV6_ADDR_ULUA                uniq-lcl-unicast
          IPV6_ADDR_6TO4                6to4
          IPV6_ADDR_6BONE               6bone
          IPV6_ADDR_AGU                 global-unicast
          IPV6_ADDR_UNSPECIFIED         unspecified
          IPV6_ADDR_SOLICITED_NODE      solicited-node
          IPV6_ADDR_ISATAP              ISATAP
          IPV6_ADDR_PRODUCTIVE          productive
          IPV6_ADDR_6TO4_MICROSOFT      6to4-ms
          IPV6_ADDR_TEREDO              teredo
          IPV6_ADDR_ORCHID              orchid
          IPV6_ADDR_NON_ROUTE_DOC       non-routeable-doc

            i.e.  if ($type & $mask) {
                      print $mask,"\n";
                  ...

        ... will print the string shown to the right of the bit mask.

        When no $naddr6 is specified the method will return the first AF_INET6 address found. This is particularly useful for interfaces with only a single address assigned.

        May be called as a METHOD or a FUNCTION with an $naddr6 argument.

    •   ->scope([$naddr6]);

    •   $scope = scope($naddr6);

        Returns the RFC-2373 scope of an IPV6 address that may be equated to these constants.

          RFC2373_GLOBAL        global-scope    0xE
          RFC2373_ORGLOCAL      org-local       0x8
          RFC2373_SITELOCAL     site-local      0x5
          RFC2373_LINKLOCAL     link-local      0x2
          RFC2373_NODELOCAL     loopback        0x1

        One additional constant is provided as there is an out of band scope value mapped returned when determining scope. If you want standard RFC2373 scope only, && the return value with 0xF

          LINUX_COMPATv4        lx-compat-v4    0x10

            i.e.  if ($scope = $const) {
                      print $const,"\n";
                  ...

        ... will print the string shown to the right of the constant.

        When no $naddr6 is specified the method will return the first AF_INET6 address found. This is particularly useful for interfaces with only a single address assigned.

        May be called as a METHOD or a FUNCTION with an $naddr6 argument.

FUNCTIONS
Unless otherwise specified, errors for all methods return either undef or and empty array depending on the expected return context.

•   $naddr = inet_aton($host or $dotquad);

    Converts a hostname or dotquad ipV4 address into a packed network address.

•   $dotquad = inet_ntoa($naddr);

    Convert a binary IPV4 address into a dotquad text string.

•   $ipV6_txt = full_inet_ntop($naddr6);

      Returns an uncompressed text string for a net6 address.

      i.e.   FE80:02A0:0000:0000:0000:0000:0123:4567

•   $minimized = ipV6compress($ipV6_txt);

    Compress an ipV6 address to the minimum RFC-1884 format

      i.e.  FE80:02A0:0000:0000:0000:0000:0123:4567
      to    FE80:2A0::123:4567

•   $ipV6_txt = inet_ntop($naddr6)

      Returns a minimized RFC-1884 IPV6 address

•   $naddr6 = inet_pton($ipV6_txt);

    Takes an IPv6 text address of the form described in rfc1884 and returns a naddr6 128 bit binary address string in network order.

•   $cidr = mask2cidr($naddrmsk);

•   ->mask2cidr($naddrmsk);

    Returns the CIDR (prefix length) for the netmask $naddrmsk.

    May be called as a FUNCTION or a METHOD.

•   $mac_txt = mac_bin2hex($bin_mac);

•   ->mac_bin2hex();

    Converts a binary MAC address into hex text.

      i.e. A1:B2:C3:D4:E5:F6

    May be called as a FUNCTION or a METHOD.

•   $type = type($naddr6);

•   ->type($naddr6);

    ipV6 method. Returns attributes of an IPV6 address that may be tested with the bit masks described in detail in the METHOD section above.

    May be called as a FUNCTION or a METHOD with an $naddr6 argument.

•   $scope = scope($naddr6);

•   ->scope($naddr6);

    Returns the RFC-2373 scope of an IPV6 address that may be equated module constants described in detail in the METHOD section above.

    May be called as a FUNCTION or a METHOD with an $naddr6 argument.

•   $symbolptr = net_symbols();

    Returns a hash containing most of the network symbols available for this architecture.

      where $symbolptr = {
            SYMBOL_TEXT => value,
            ...
      };

    Most all of these symbols have both a numeric and text value. Perl does the right thing and uses the numeric value in all logic and arithmetic operations and provides the text value for print requests.

    To print the numeric value:

      print (0 + &SYMBOL),"\n";

      i.e.  print (0 + AF_INET()),"\n";

    results in the digit 2 being printed, whereas:

            print AF_INET,"\n";

    results in the string "inet" being printed.

      NOTE: that many symbols are OS dependent. Do not use
            numeric values in your code, instead use the symbol.

      i.e. AF_INET, AF_INET6, AF_LINK, etc...

PREREQUISITES
To build Net::Interface, it is necessary to have kernel development libriaries installed on the build system. Systems such as Ubuntu, FreeBSD, etc... do NOT come with these libraries installed.

Your build system must have a fully populated directory

    /usr/include/sys

Missing header files in the above directory will produce errors saying that symbols such as AF_INET and PF_INET are missing.

ACKNOWLEDGEMENTS
This version of Net::Interface has been completely rewritten and updated to include support for IPV6. Credit should be given to the original author

        Stephen Zander <gibreel@pobox.com>

for conceiving the idea behind Net::Interface and to the work done by

        Jerrad Pierce jpierce@cpan.org

on the maintenance and improvements to the original version.

Thanks also go to

        Jens Rehsack <rehsack@web.de>

for inspiring me to create this updated version and for his assistance in vetting the design concepts and loads of other helpful things.

The following functions are used in whole or in part as include files to Interface.xs. The copyright (same as Perl itself) is include in the file.

    file:              functions:

  miniSocketXS.c  inet_aton, inet_ntoa

inet_aton, inet_ntoa are from the perl-5.8.0 release by Larry Wall, copyright 1989-2002. inet_aton, inet_ntoa code is current through perl-5.9.3 release. Thank you Larry for making PERL possible for all of us.

COPYRIGHT 2008-2016 Michael Robinton <michael@bizsystems.com>
All rights reserved.

This program is free software; you can redistribute it and/or modify it under the terms of either:

  a) the GNU General Public License as published by the Free
  Software Foundation; either version 2, or (at your option) any
  later version, or

  b) the "Artistic License" which comes with this distribution.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See either the GNU General Public License or the Artistic License for more details.

You should have received a copy of the Artistic License with this distribution, in the file named "Artistic". If not, I'll be glad to provide one.

You should also have received a copy of the GNU General Public License along with this program in the file named "Copying". If not, write to the

        Free Software Foundation, Inc.
        59 Temple Place, Suite 330
        Boston, MA  02111-1307, USA

or visit their web page on the internet at:

        http://www.gnu.org/copyleft/gpl.html.

SEE ALSO
ifconfig(8), Net::Interface::NetSymbols, Net::Interface::Developer

POD ERRORS
Hey! The above document had some coding errors, which are explained below:

Around line 340:
    You can't have =items (as at line 344) unless the first thing after the =over is an =item

Around line 363:
    You can't have =items (as at line 367) unless the first thing after the =over is an =item

Around line 387:
    You can't have =items (as at line 391) unless the first thing after the =over is an =item

Around line 476:
    '=item' outside of any '=over'

Around line 850:
    You forgot a '=back' before '=head1'