how to open a port

[znx]

ACCEPT udp -- anywhere anywhere udp spt:bootps state ESTABLISHED

 

This says, accept UDP, from any host, to any host FROM the source port (spt) of bootps with the an established state.

 

So, no your port isn't "open". Instead, only when your system has a connection already active, will it accept access from port 67 on the remote host.