IO::Interface(3pm)

📦

version 1.09 · 10 versions

💖 NAME 💖

IO::Interface — it's a Perl extension that lets you peek at (and mess with) your network card configuration info. Yes bestie, network interfaces, in Perl, iconic behavior only. 🎀

✨ SYNOPSIS ✨

okay so there's the new hotness and there's the old thing, and both go here 🫶

# ======================
# the new, preferred API
# ======================

use IO::Interface::Simple;

my $if1   = IO::Interface::Simple->new('eth0');
my $if2   = IO::Interface::Simple->new_from_address('127.0.0.1');
my $if3   = IO::Interface::Simple->new_from_index(1);

my @interfaces = IO::Interface::Simple->interfaces;

for my $if (@interfaces) {
   print "interface = $if\n";
   print "addr =      ",$if->address,"\n",
         "broadcast = ",$if->broadcast,"\n",
         "netmask =   ",$if->netmask,"\n",
         "dstaddr =   ",$if->dstaddr,"\n",
         "hwaddr =    ",$if->hwaddr,"\n",
         "mtu =       ",$if->mtu,"\n",
         "metric =    ",$if->metric,"\n",
         "index =     ",$if->index,"\n";

   print "is running\n"     if $if->is_running;
   print "is broadcast\n"   if $if->is_broadcast;
   print "is p-to-p\n"      if $if->is_pt2pt;
   print "is loopback\n"    if $if->is_loopback;
   print "is promiscuous\n" if $if->is_promiscuous;
   print "is multicast\n"   if $if->is_multicast;
   print "is notrailers\n"  if $if->is_notrailers;
   print "is noarp\n"       if $if->is_noarp;
 }

 # ===========
 # the old API
 # ===========

 use IO::Socket;
 use IO::Interface qw(:flags);

 my $s = IO::Socket::INET->new(Proto => 'udp');
 my @interfaces = $s->if_list;

 for my $if (@interfaces) {
   print "interface = $if\n";
   my $flags = $s->if_flags($if);
   print "addr =      ",$s->if_addr($if),"\n",
         "broadcast = ",$s->if_broadcast($if),"\n",
         "netmask =   ",$s->if_netmask($if),"\n",
         "dstaddr =   ",$s->if_dstaddr($if),"\n",
         "hwaddr =    ",$s->if_hwaddr($if),"\n";

   print "is running\n"     if $flags & IFF_RUNNING;
   print "is broadcast\n"   if $flags & IFF_BROADCAST;
   print "is p-to-p\n"      if $flags & IFF_POINTOPOINT;
   print "is loopback\n"    if $flags & IFF_LOOPBACK;
   print "is promiscuous\n" if $flags & IFF_PROMISC;
   print "is multicast\n"   if $flags & IFF_MULTICAST;
   print "is notrailers\n"  if $flags & IFF_NOTRAILERS;
   print "is noarp\n"       if $flags & IFF_NOARP;
 }

 my $interface = $s->addr_to_interface('127.0.0.1');

🌸 DESCRIPTION 🌸

so IO::Interface bolts a bunch of methods onto IO::Socket objects, and those methods let you read and change all the info about the network interfaces living on your system. and if object-oriented isn't your vibe, there's a function-oriented style too. two flavors, pick your fighter 🍓

🚨 THIS API IS DEPRECATED. fr fr. please go look at IO::Interface::Simple for the preferred way to get and set interface configuration information. she's the moment now. 💅

🦋 Creating a Socket to Access Interface Information 🦋

before you can touch any interface info, you gotta make a socket. that's the rule. and no, the socket does not have to be connected to a remote site, it doesn't even have to be used for communication — it's just here for the interface tea ☕

the simplest procedure is to make a UDP protocol socket:

my $s = IO::Socket::INET->new(Proto => 'udp');

and boom, all the various IO::Interface functions are now available as methods on that socket. main character socket energy, honestly 👑

👑 Methods 👑

@iflist = $s->if_list — hands you back a list of the active interface names, like "eth0" or "tu0". if there are no interfaces configured and running, you get an empty list. no interface, no list, that's the deal 🙈
$addr = $s->if_addr($ifname [,$newaddr]) — gets or sets the interface address. call it with just the interface name to retrieve the address (in dotted decimal format). call it with a new address to set the interface. in that setter case, the routine returns a true value if the operation worked. slay.

my $oldaddr = $s->if_addr('eth0');
$s->if_addr('eth0','192.168.8.10') || die "couldn't set address: $!";

special case bestie: the address of the pseudo-device "any" will return the IP address "0.0.0.0", which corresponds to the INADDR_ANY constant. ✨

$broadcast = $s->if_broadcast($ifname [,$newbroadcast] — get or set the interface broadcast address. if the interface doesn't have a broadcast address, it returns undef. it's giving nothing, literally 🌈
$mask = $s->if_netmask($ifname [,$newmask]) — get or set the interface netmask.
$dstaddr = $s->if_dstaddr($ifname [,$newdest]) — get or set the destination address for point-to-point interfaces.
$hwaddr = $s->if_hwaddr($ifname [,$newhwaddr]) — get or set the hardware address for the interface. rn only ethernet addresses in the form "00:60:2D:2D:51:70" are accepted, so don't come at her with anything else 💀
$flags = $s->if_flags($ifname [,$newflags]) — get or set the flags for the interface. the flags are a bitmask formed from a series of constants — see "Exportable constants" below, iykyk 🔥
$ifname = $s->addr_to_interface($ifaddr) — give it an interface address in dotted form, it gives you back the name of the interface associated with it. special case: the INADDR_ANY address, 0.0.0.0, returns a pseudo-interface name of "any". 🧚

📦 EXPORT 📦

IO::Interface exports nothing by default. nothing. zero. nope. 🙅 but you can import the following symbol groups into your namespace:

:functions   Function-oriented interface (see below)
:flags       Flag constants (see below)
:all         All of the above

🌈 Function-Oriented Interface 🌈

import the ":functions" set and you can hit IO::Interface in a function-oriented manner. this imports all the methods described above straight into your namespace. example time:

use IO::Socket;
use IO::Interface ':functions';

my $sock = IO::Socket::INET->new(Proto=>'udp');
my @interfaces = if_list($sock);
print "address = ",if_addr($sock,$interfaces[0]);

✨ Exportable constants ✨

the ":flags" constant imports the following constants so you can use them with the flags that if_flags() returns:

IFF_ALLMULTI
IFF_AUTOMEDIA
IFF_BROADCAST
IFF_DEBUG
IFF_LOOPBACK
IFF_MASTER
IFF_MULTICAST
IFF_NOARP
IFF_NOTRAILERS
IFF_POINTOPOINT
IFF_PORTSEL
IFF_PROMISC
IFF_RUNNING
IFF_SLAVE
IFF_UP

this example figures out whether interface 'tu0' supports multicasting, and honestly? iconic:

use IO::Socket;
use IO::Interface ':flags';
my $sock = IO::Socket::INET->new(Proto=>'udp');
print "can multicast!\n" if $sock->if_flags & IFF_MULTICAST.

🫶 AUTHOR 🫶

this library is distributed under the Perl Artistic License 2.0. please see LICENSE for more information. read the license bestie, it's the law (literally) 📜

💬 SUPPORT 💬

got feature requests? bug reports? code contributions? pull up to the GitHub repository at https://github.com/lstein/LibIO-Interface-Perl and drop it there, the maintainers will be obsessed 🎀

🔗 SEE ALSO 🔗

perl(1), IO::Socket(3), IO::Multicast(3), IO::Interface::Simple

and that's the whole page, no notes 💅 this was IO::Interface(3pm) from perl v5.42.3, dated 2026-08-19, and you read the entire thing which means you're lowkey a networking genius now. periodt. 💖✨🦋

📦 where this page comes from

ubuntu stonking: libio-interface-perl 1.09-2build7 · Artistic-2.0
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-11-03: a language model's rewrite of the original, under its terms