Port Knocking

Config file can be found at

/etc/knockd.conf

File found from Directory traversal

knock 192.168.156.209 9842 8475 7469

for i in 9842 8475 7469; do nmap -Pn --host-timeout 201 --max-retries 0 -p $i 192.168.156.209; done

for i in 9842 8475 7469; do nc 192.168.156.209 $i -v; done

It's possible to sniff traffic and find the sequence