Port Knocking

After finding the knock sequence in /etc/knockd.conf, send packets to each port in order to unlock the hidden service.

• Just replace 571 290 911, key, user, and IP accordingly.

Using Nmap to SSH

for i in 571 290 911; do nmap -Pn --host-timeout 100 --max-retries 0 -p $i <IP> >/dev/null; done; ssh -i key USER@IP

UDP knocks (check /etc/knockd.conf for protocol type)

for i in 571 290 911; do nmap -sU -Pn -p $i IP >/dev/null; done; ssh -i key user@IP

Using knock tool

knock IP 571 290 911 && ssh -i key user@IP

Using netcat

for i in 571 290 911; do nc -w 1 IP $i; done; ssh -i key user@IP

Using hping3 (for strict SYN-only knockd configs)

for i in 571 290 911; do hping3 -S -p $i -c 1 IP; done; ssh -i key user@IP

Port knocking - ArchWikiwiki.archlinux.org