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Discovering hosts from the inside

If you are inside the network one of the first things you will want to do is to discover other hosts. Depending on how much noise you can/want to do, different actions could be performed:

Passive

You can use these tools to passively discover hosts inside a connected network:
netdiscover -p
p0f -i eth0 -p -o /tmp/p0f.log
# Bettercap2
net.recon on/off
net.show
set net.show.meta true #more info

Active

Note that the techniques commented in Discovering hosts from the outside (TCP/HTTP/UDP/SCTP Port Discovery) can be also applied here. But, as you are in the same network as the other hosts, you can do more things:
#ARP discovery
nmap -sn <Network> #ARP Requests (Discover IPs)
netdiscover -r <Network> #ARP requests (Discover IPs)
#NBT discovery
nbtscan -r 192.168.0.1/24 #Search in Domain
# Bettercap2 (By default ARP requests are sent)
net.probe on/off #Activate all service discover and ARP
net.probe.mdns #Search local mDNS services (Discover local)
net.probe.nbns #Ask for NetBios name (Discover local)
net.probe.upnp # Search services (Discover local)
net.probe.wsd # Search Web Services Discovery (Discover local)
net.probe.throttle 10 #10ms between requests sent (Discover local)
#IPv6
alive6 <IFACE> # Send a pingv6 to multicast.

Active ICMP

Note that the techniques commented in Discovering hosts from the outside (ICMP) can be also applied here. But, as you are in the same network as the other hosts, you can do more things:
  • If you ping a subnet broadcast address the ping should be arrive to each host and they could respond to you: ping -b 10.10.5.255
  • Pinging the network broadcast address you could even find hosts inside other subnets: ping -b 255.255.255.255
  • Use the -PEPM flag of nmapto perform host discovery sending ICMPv4 echo, timestamp, and subnet mask requests: nmap -PEPM -sP –vvv -n 10.12.5.0/24

Wake On Lan

Wake On Lan is used to turn on computers through a network message. The magic packet used to turn on the computer is only a packet where a MAC Dst is provided and then it is repeated 16 times inside the same paket. Then this kind of packets are usually sent in an ethernet 0x0842 or in a UDP packet to port 9. If no [MAC] is provided, the packet is sent to broadcast ethernet (and the broadcast MAC will be the one being repeated).
#WOL (without MAC is used ff:...:ff)
wol.eth [MAC] #Send a WOL as a raw ethernet packet of type 0x0847
wol.udp [MAC] #Send a WOL as an IPv4 broadcast packet to UDP port 9
# Bettercap2 can also be used for this purpose