Block an IP Address
iptables -I FORWARD -s 18.104.22.168 -j ACCEPT iptables -I FORWARD -s 22.214.171.124 -j DROP
What connections are Established
To view what connections are established on our host we use lsof (list open files).
# lsof | grep ESTA
To avoid DNS resultion, that slows down we use the -n option (numerical).
# lsof -n | grep ESTA
Explore your Network
First we send some Traffic to the connected hosts in our Network, hopefully they do respond
# ping -b 192.168.0.255
Now we look if some hosts did reply.
# arp -a