man Net::Interface (3): 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
);

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...
```

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 <[email protected]>

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

        Jerrad Pierce [email protected]

on the maintenance and improvements to the original version.

Thanks also go to

        Jens Rehsack <[email protected]>

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.

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.

SYNOPSIS

TAGS

FUNCTIONS and METHODS

DESCRIPTION

OPERATION

SYMBOLS

HINTS and TIPS for use SYMBOLS

WARNING - API CHANGES

METHODS

FUNCTIONS

ACKNOWLEDGEMENTS

COPYRIGHT 2008-2009 Michael Robinton <[email protected]>

SEE ALSO

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