IO::Interface - Perl extension for access to network card configuration information use IO::Socket; use IO::Interface qw(:flags); my $s = IO::Socket::INET->new(Proto => 'udp'); my @interfaces = $s->if_list; for my $f (@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'); IO::Interface adds methods to IO::Socket objects that allows them to be used to retrieve and change information about the network interfaces on your system. In addition to the object-oriented access methods, you can use a function-oriented style.

Creating a Socket to Access Interface Information
You must create a socket before you can access interface information. The socket does not have to be connected to a remote site, or even used for communication. The simplest procedure is to create a UDP protocol socket: my $s = IO::Socket::INET->new(Proto => 'udp'); The various IO::Interface functions will now be available as methods on this socket.

Methods
The if_list() method will return a list of active interface names, for example "eth0" or "tu0". If no interfaces are configured and running, returns an empty list. if_addr() gets or sets the interface address. Call with the interface name to retrieve the address (in dotted decimal format). Call with a new address to set the interface. In the latter case, the routine will return a true value if the operation was successful. my $oldaddr = $s->if_addr('eth0'); $s->if_addr('eth0','192.168.8.10') || die "couldn't set address: $!"; Special case: the address of the pseudo-device "any" will return the IP address "0.0.0.0", which corresponds to the INADDR_ANY constant. Get or set the interface broadcast address. If the interface does not have a broadcast address, returns undef. Get or set the interface netmask. Get or set the destination address for point-to-point interfaces. Get or set the hardware address for the interface. Currently only ethernet addresses in the form "00:60:2D:2D:51:70" are accepted. Get or set the flags for the interface. The flags are a bitmask formed from a series of constants. See "Exportable constants" below. Given an interface address in dotted form, returns the name of the interface associated with it. Special case: the INADDR_ANY address, 0.0.0.0 will return a pseudo-interface name of "any".

EXPORT
IO::Interface exports nothing by default. However, 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
By importing the ":functions" set, you can access IO::Interface in a function-oriented manner. This imports all the methods described above into your namespace. Example: 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 for use with the flags returned by if_flags(): 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 determines whether interface 'tu0' supports multicasting: 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. Lincoln Stein <lstein@cshl.org> This module is distributed under the same license as Perl itself. perl(1), IO::Socket(3), IO::Multicast(3)