Perl & Net::SNMP::Interfaces::Details, how to get mac address?

Question

for my internship i have to code a network supervisor. I'm writting perl scripts to find all informations (speed, mac address, duplex...) from an interface name on the switch. There is a function "ifPhysAddress" in this module, but it returns the switch interface mac address, not the mac address of the device connected to it. How can I find the mac address please ? Thanks

Here what I've started :

#!/usr/bin/perl
use strict;
use warnings;
use Getopt::Long;
use SnmpTable;
use Net::MAC;
use Net::SNMP;
use Net::SNMP::Interfaces;

my $ifname;
my $hostname;
my $community;
my $version = 1;

GetOptions( "ifname=s"      => \$ifname,
            "host=s"        => \$hostname,
            "community=s"   => \$community,
            "protocol:s"    => \$version);

my $interfaces = Net::SNMP::Interfaces->new(Hostname => $hostname, Community => $community);
my $inter = $interfaces->interface($ifname);

#On récupere l'identifiant de l'interface $ifname
my $ifindex = $inter->index();
#Vitesse
my $vitesse = $inter->ifHighSpeed();
#Alias
my $ifalias = $inter->ifAlias();


#Recherche des VLANs
my $numeroportbridge;
my $vlan_trouve;

my $oid_cisco_vlans = "1.3.6.1.4.1.9.9.46.1.3.1.1.2.1";
my $vlans = SnmpTable->new($hostname, $oid_cisco_vlans, $community);
$vlans->connexion();
my %vl = $vlans->requete();
my @tab = keys(%vl);

foreach my $i (@tab) {
    if ($i<1000) {
        my $comvlan = $community."@".$i;
        print $comvlan."\n";
    }
}
printf "Nom de l'interface : %s --> ifindex = %s, Vitesse = %s, Alias = %s\n", $ifname, $ifindex, $vitesse, $ifalias;

Answer 1

Ok, i found how to do, if someone need to do it...

#We get the index of $ifname
my $ifindex = $inter->index();
#Speed
my $vitesse = $inter->ifHighSpeed();
#Alias
my $ifalias = $inter->ifAlias();
#Finding VLANs
my $vlan_trouve;

#Listing all VLANs on the switch
my $vmVlan = "1.3.6.1.4.1.9.9.68.1.2.2.1.2";
my $vlans = SnmpTable->new($hostname, $vmVlan, $community);
$vlans->connexion();
my %vl = $vlans->requete();

#Getting the good VLAN
$vlan_trouve = $vl{$ifindex};

#Listing ports of VLAN <-> @mac
my $dot1dTpFdbAddress = "1.3.6.1.2.1.17.4.3.1.1";
my $dot = SnmpTable->new($hostname, $dot1dTpFdbAddress, $community."@".$vlan_trouve);
$dot->connexion();
my %dot1address = $dot->requete();

#Listing numPortBridge <-> ports of VLAN
my $dot1dTpFdbPort = "1.3.6.1.2.1.17.4.3.1.2";
my $dot2 = SnmpTable->new($hostname, $dot1dTpFdbPort, $community."@".$vlan_trouve);
$dot2->connexion();
my %portdot = reverse($dot2->requete());

#Listing num Port bridge <-> ID port switch
my $dot1dBasePortIfIndex = "1.3.6.1.2.1.17.1.4.1.2";
my $dot3 = SnmpTable->new($hostname, $dot1dBasePortIfIndex, $community."@".$vlan_trouve);
$dot3->connexion();
my %dotindex = reverse($dot3->requete());

my $numportbridge = $dotindex{$ifindex};
if (!defined($numportbridge)) {
    print "Erreur : $ifindex non trouvé dans la liste : num Port bridge <-> ID port switch\n";
    exit 2;
}
my $portVlan = $portdot{$numportbridge};
if (!defined($portVlan)) {
    print "Erreur : $numportbridge non trouvé dans la liste : numPortBridge <-> ports du VLAN\n";
    exit 3;
}
my $add = $dot1address{$portVlan};
if (!defined($add)) {
    print "Erreur : $portVlan non trouvé dans la liste : ports du VLAN <-> \@mac\n";
    exit 4;
}
$add =~ s/0x//g;
printf "Interface : $ifname sur $hostname <=> ifindex : $ifindex sur VLAN : $vlan_trouve <=> \@mac : $add\nVitesse=$vitesse, Alias=$ifalias, Duplex=--\n";

I created a class SnmpTable.pm, using Net::SNMP, it just does :
$session->get_table( -baseoid => $this->{oid} )
and returns it in a hash.

That's all. Bye.

Answer 2

You need to follow certain Network Topology algorithms.

For finding connection between a Host machine and a Switch/Router, you have to fist get subnet information from the host machine. Then find out from which switch, the subnet is created. If switch is found with that subnet then the host is connected to that switch.

1. Find ifIndex for you interface using ifTable.
   --> 53
2. Get ipRouteDest using ipRouteTable. It will get some ip addresses. It is primary key for the table.
   -->10.0.0.1, 192.168.1.1, 8.8.8.1
3. Now, find ifIndex for each hop using ipRouteIfIndex+"ip found in step 2." It will get if indexes for each hop.
   -->1.3.6.1.2.1.4.21.1.2(ipRouteIfIndex)+10.0.0.1 = 1.3.6.1.2.1.4.21.1.2.10.0.0.1
   --> In response of queries in step 3, you will get if index for that IP. Match inIndex from step one. The correnspoding IP will be the IP at that interface. You can get MAC by directly querying that IP.

Thanks.