3-2 host discovery - layer 3 discovery

The three-tier host finds the advantages and disadvantages

Layer 3 host discovery refers to ： utilize OSI Host discovery based on the protocol in the network . In general use ICMP agreement .

advantage ：

1、 You can find remote hosts , Routed hosts , It makes up for the fact that we cannot find hosts of different subnets in layer 2

2、 The speed is relatively fast

shortcoming ：

1、 Often filtered by firewall ,icmp Often filtered by firewall

2、 The speed is slower than that of the second floor

Found on the third floor -ping Tools

ping Tools in linux and windows All have their own , There are different ways to bring these tools ,linux Next ping If you don't specify -c Parameters , Keep scanning .windows By default, four probes are performed .

ifconfig
ping 192.168.42.1

Because we have a firewall on this computer , Let's close it

ping 192.168.42.1
ctrl+z

ping 192.168.42.1 -c 4

ipconfig
ping 192.168.42.128

We are in the process of detection , It will also discover the survivability of the host of the probe subnet , Use layer 3 to discover , Then you can't achieve your goal directly

Found on the third floor -fping Tools

kali linux The self-contained tools in the lower layer can perform corresponding three-tier host discovery . Host discovery can be performed simultaneously for multiple hosts

Host discovery refers to the active or surviving hosts in the current network

CIDR No inter domain address translation ,/24 This way of writing

fping -g 192.168.42.0/24

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After the probe was completed , Will re detect

Found on the third floor -hping3 Tools

kali linux Bring their own tools hping3 Perform three-tier host discovery on the target . characteristic ： Send custom ICMP Data packets

We can also specify other packet types

clear
hping3 --help

We found that we could modify icmp Parameters

hping3 -c 3 -1 192.168.42.1

hping3 -c 3 -1 192.168.42.1 --icmpcode 1

Of course , We can also modify it icmp Contents of other data packets , To perform more detailed operations , So that we can bypass some specific firewalls , Perform corresponding host discovery