Example knockd.conf file that creates and destroys iptables rules

knockd.conf

[options]
	logfile = /var/log/knockd.log

[openSSH]
   sequence    = 10000,20000,30000,40000
   seq_timeout = 45
   tcpflags    = syn
   command     = /sbin/iptables -I INPUT 15 -s %IP% -p tcp -m state --state NEW -m multiport --dports 22,80,443 -j ACCEPT -m comment --comment "knockd added `date +%F_%T` allowing access to SSH, HTTP and HTTPS : `dig -x %IP% +short`"

[closeSSH]
   sequence    = 40000,30000,20000,10000
   seq_timeout = 45
   tcpflags    = syn
   # https://gist.github.com/gene1wood/7489673
   command     = /usr/local/sbin/delete_knockd_iptables_rule %IP%