When your target systems are located on the same network as your attacking machine, you can enumerate systems by performing an ARP scan. Naturally, Metasploit has a module that can help you out.

msf > use auxiliary/scanner/discovery/arp_sweep
msf auxiliary(arp_sweep) > show options

Module options (auxiliary/scanner/discovery/arp_sweep):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   INTERFACE                   no        The name of the interface
   RHOSTS                      yes       The target address range or CIDR identifier
   SHOST                       no        Source IP Address
   SMAC                        no        Source MAC Address
   THREADS    1                yes       The number of concurrent threads
   TIMEOUT    5                yes       The number of seconds to wait for new data

Due to the manner in which ARP scanning is performed, you need to pass your MAC address and source IP address to the scanner in order for it to function properly.

msf auxiliary(arp_sweep) > set RHOSTS 192.168.1.200-254
RHOSTS => 192.168.1.200-254
msf auxiliary(arp_sweep) > set SHOST 192.168.1.101
SHOST => 192.168.1.101
msf auxiliary(arp_sweep) > set SMAC d6:46:a7:38:15:65
SMAC => d6:46:a7:38:15:65
msf auxiliary(arp_sweep) > set THREADS 55
THREADS => 55
msf auxiliary(arp_sweep) > run

[*] 192.168.1.201 appears to be up.
[*] 192.168.1.203 appears to be up.
[*] 192.168.1.205 appears to be up.
[*] 192.168.1.206 appears to be up.
[*] 192.168.1.250 appears to be up.
[*] Scanned 55 of 55 hosts (100% complete)
[*] Auxiliary module execution completed
msf auxiliary(arp_sweep) >

As you will see when running this module, ARP scanning is very fast.

The ipv6_neighbor auxiliary module probes the local network for IPv6 hosts that respond to Neighbor Solicitations with a link-local address. This module, like the arp_sweep one, will generally only work within the attacking machine’s broadcast domain.

msf > use auxiliary/scanner/discovery/ipv6_neighbor
msf auxiliary(ipv6_neighbor) > show options

Module options:

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   INTERFACE                   no        The name of the interface
   PCAPFILE                    no        The name of the PCAP capture file to process
   RHOSTS                      yes       The target address range or CIDR identifier
   SHOST                       yes       Source IP Address
   SMAC                        yes       Source MAC Address
   THREADS    1                yes       The number of concurrent threads
   TIMEOUT    500              yes       The number of seconds to wait for new data

In addition to setting our RHOSTS value, we also need to set our source MAC address(SMAC) and source host(SHOST) IP address. We then set our RHOSTS and THREADS values and let the scanner run.

msf auxiliary(ipv6_neighbor) > set RHOSTS 192.168.1.2-254
RHOSTS => 192.168.1.200-254
msf auxiliary(ipv6_neighbor) > set SHOST 192.168.1.101
SHOST => 192.168.1.101
msf auxiliary(ipv6_neighbor) > set SMAC d6:46:a7:38:15:65
SMAC => d6:46:a7:38:15:65
msf auxiliary(ipv6_neighbor) > set THREADS 55
THREADS => 55
msf auxiliary(ipv6_neighbor) > run

[*] IPv4 Hosts Discovery
[*] 192.168.1.10 is alive.
[*] 192.168.1.11 is alive.
[*] 192.168.1.2 is alive.
[*] 192.168.1.69 is alive.
[*] 192.168.1.109 is alive.
[*] 192.168.1.150 is alive.
[*] 192.168.1.61 is alive.
[*] 192.168.1.201 is alive.
[*] 192.168.1.203 is alive.
[*] 192.168.1.205 is alive.
[*] 192.168.1.206 is alive.
[*] 192.168.1.99 is alive.
[*] 192.168.1.97 is alive.
[*] 192.168.1.250 is alive.
[*] IPv6 Neighbor Discovery
[*] 192.168.1.69 maps to IPv6 link local address fe80::5a55:caff:fe14:1e61
[*] 192.168.1.99 maps to IPv6 link local address fe80::5ab0:35ff:fe6a:4ecc
[*] 192.168.1.97 maps to IPv6 link local address fe80::7ec5:37ff:fef9:a96a
[*] Scanned 253 of 253 hosts (100% complete)
[*] Auxiliary module execution completed
msf auxiliary(ipv6_neighbor) >

Looking at the module output, you can see that this scanner serves the dual-purpose of showing what hosts are online similar to arp_sweep and then performs the IPv6 Neighbor Discovery.

The udp_probe module scans a given range of hosts for common UDP services. Note: This module is deprecated and may disappear at any time.

msf > use auxiliary/scanner/discovery/udp_probe

[!] ******************************************************************************************
[!] *                 The module scanner/discovery/udp_probe is deprecated!                  *
[!] *                       It will be removed on or about 2016-11-23                        *
[!] *                   Use auxiliary/scanner/discovery/udp_sweep instead                    *
[!] ******************************************************************************************
msf auxiliary(udp_probe) > show options

Module options (auxiliary/scanner/discovery/udp_probe):

   Name     Current Setting  Required  Description
   ----     ---------------  --------  -----------
   CHOST                     no        The local client address
   RHOSTS                    yes       The target address range or CIDR identifier
   THREADS  1                yes       The number of concurrent threads

There are very few required settings for this module so we just configure the RHOSTS and THREADS values and let it run.

msf auxiliary(udp_probe) > set RHOSTS 192.168.1.2-254
RHOSTS => 192.168.1.2-254
msf auxiliary(udp_probe) > set THREADS 253
THREADS => 253
msf auxiliary(udp_probe) > run

[*] Discovered SNMP on 192.168.1.2:161 (GSM7224 L2 Managed Gigabit Switch)
[*] Discovered SNMP on 192.168.1.2:161 (GSM7224 L2 Managed Gigabit Switch)
[*] Discovered NetBIOS on 192.168.1.109:137 (SAMSUNG::U :SAMSUNG::U :00:15:99:3f:40:bd)
[*] Discovered NetBIOS on 192.168.1.150:137 (XEN-WIN7-PROD::U :WORKGROUP::G :XEN-WIN7-PROD::U :WORKGROUP::G :aa:e3:27:6e:3b:a5)
[*] Discovered SNMP on 192.168.1.109:161 (Samsung CLX-3160 Series; OS V1.01.01.16 02-25-2008;Engine 6.01.00;NIC V4.03.08(CLX-3160) 02-25-2008;S/N 8Y61B1GP400065Y.)
[*] Discovered NetBIOS on 192.168.1.206:137 (XEN-XP-PATCHED::U :XEN-XP-PATCHED::U :HOTZONE::G :HOTZONE::G :12:fa:1a:75:b8:a5)
[*] Discovered NetBIOS on 192.168.1.203:137 (XEN-XP-SPLOIT::U :WORKGROUP::G :XEN-XP-SPLOIT::U :WORKGROUP::G :3e:ff:3c:4c:89:67)
[*] Discovered NetBIOS on 192.168.1.201:137 (XEN-XP-SP2-BARE::U :HOTZONE::G :XEN-XP-SP2-BARE::U :HOTZONE::G :HOTZONE::U :__MSBROWSE__::G :c6:ce:4e:d9:c9:6e)
[*] Discovered SNMP on 192.168.1.109:161 (Samsung CLX-3160 Series; OS V1.01.01.16 02-25-2008;Engine 6.01.00;NIC V4.03.08(CLX-3160) 02-25-2008;S/N 8Y61B1GP400065Y.)
[*] Discovered NTP on 192.168.1.69:123 (NTP v4)
[*] Discovered NetBIOS on 192.168.1.250:137 (FREENAS::U :FREENAS::U :FREENAS::U :__MSBROWSE__::G :WORKGROUP::U :WORKGROUP::G :WORKGROUP::G :00:00:00:00:00:00)
[*] Discovered NTP on 192.168.1.203:123 (Microsoft NTP)
[*] Discovered MSSQL on 192.168.1.206:1434 (ServerName=XEN-XP-PATCHED InstanceName=SQLEXPRESS IsClustered=No Version=9.00.4035.00 tcp=1050 np=\\XEN-XP-PATCHED\pipe\MSSQL$SQLEXPRESS\sql\query )
[*] Discovered NTP on 192.168.1.206:123 (Microsoft NTP)
[*] Discovered NTP on 192.168.1.201:123 (Microsoft NTP)
[*] Scanned 029 of 253 hosts (011% complete)
[*] Scanned 052 of 253 hosts (020% complete)
[*] Scanned 084 of 253 hosts (033% complete)
[*] Scanned 114 of 253 hosts (045% complete)
[*] Scanned 140 of 253 hosts (055% complete)
[*] Scanned 160 of 253 hosts (063% complete)
[*] Scanned 184 of 253 hosts (072% complete)
[*] Scanned 243 of 253 hosts (096% complete)
[*] Scanned 250 of 253 hosts (098% complete)
[*] Scanned 253 of 253 hosts (100% complete)
[*] Auxiliary module execution completed
msf auxiliary(udp_probe) >

As you can see in the above output, our quick little scan discovered many services running on a wide variety of platforms.

The udp_sweep module scans across a given range of hosts to detect commonly available UDP services.

msf > use auxiliary/scanner/discovery/udp_sweep
msf auxiliary(udp_sweep) > show options

Module options (auxiliary/scanner/discovery/udp_sweep):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   BATCHSIZE  256              yes       The number of hosts to probe in each set
   RHOSTS                      yes       The target address range or CIDR identifier
   THREADS    10               yes       The number of concurrent threads

To configure this module, we just need to set the RHOSTS and THREADS values and run it.

msf auxiliary(udp_sweep) > set RHOSTS 192.168.1.2-254
RHOSTS => 192.168.1.2-254
msf auxiliary(udp_sweep) > set THREADS 253
THREADS => 253
msf auxiliary(udp_sweep) > run

[*] Sending 10 probes to 192.168.1.2->192.168.1.254 (253 hosts)
[*] Discovered NetBIOS on 192.168.1.109:137 (SAMSUNG::U :SAMSUNG::U :00:15:99:3f:40:bd)
[*] Discovered NetBIOS on 192.168.1.150:137 (XEN-WIN7-PROD::U :WORKGROUP::G :XEN-WIN7-PROD::U :WORKGROUP::G :aa:e3:27:6e:3b:a5)
[*] Discovered NetBIOS on 192.168.1.203:137 (XEN-XP-SPLOIT::U :WORKGROUP::G :XEN-XP-SPLOIT::U :WORKGROUP::G :3e:ff:3c:4c:89:67)
[*] Discovered NetBIOS on 192.168.1.201:137 (XEN-XP-SP2-BARE::U :HOTZONE::G :XEN-XP-SP2-BARE::U :HOTZONE::G :HOTZONE::U :__MSBROWSE__::G :c6:ce:4e:d9:c9:6e)
[*] Discovered NetBIOS on 192.168.1.206:137 (XEN-XP-PATCHED::U :XEN-XP-PATCHED::U :HOTZONE::G :HOTZONE::G :12:fa:1a:75:b8:a5)
[*] Discovered NetBIOS on 192.168.1.250:137 (FREENAS::U :FREENAS::U :FREENAS::U :__MSBROWSE__::G :WORKGROUP::U :WORKGROUP::G :WORKGROUP::G :00:00:00:00:00:00)
[*] Discovered SNMP on 192.168.1.2:161 (GSM7224 L2 Managed Gigabit Switch)
[*] Discovered SNMP on 192.168.1.109:161 (Samsung CLX-3160 Series; OS V1.01.01.16 02-25-2008;Engine 6.01.00;NIC V4.03.08(CLX-3160) 02-25-2008;S/N 8Y61B1GP400065Y.)
[*] Discovered NTP on 192.168.1.69:123 (NTP v4)
[*] Discovered NTP on 192.168.1.99:123 (NTP v4)
[*] Discovered NTP on 192.168.1.201:123 (Microsoft NTP)
[*] Discovered NTP on 192.168.1.203:123 (Microsoft NTP)
[*] Discovered NTP on 192.168.1.206:123 (Microsoft NTP)
[*] Discovered MSSQL on 192.168.1.206:1434 (ServerName=XEN-XP-PATCHED InstanceName=SQLEXPRESS IsClustered=No Version=9.00.4035.00 tcp=1050 np=\\XEN-XP-PATCHED\pipe\MSSQL$SQLEXPRESS\sql\query )
[*] Discovered SNMP on 192.168.1.2:161 (GSM7224 L2 Managed Gigabit Switch)
[*] Discovered SNMP on 192.168.1.109:161 (Samsung CLX-3160 Series; OS V1.01.01.16 02-25-2008;Engine 6.01.00;NIC V4.03.08(CLX-3160) 02-25-2008;S/N 8Y61B1GP400065Y.)
[*] Scanned 253 of 253 hosts (100% complete)
[*] Auxiliary module execution completed
msf auxiliary(udp_sweep) >

With minimal effort, we have once again identified a wide range of services running on many different platforms within our network.