You want traffic on the "vnc" port whitelisted. For this to work, you have to specify the correct port number. See here for a list of port numbers.
It's very confusing that iptables (the part of your system that is used for the port whitelisting) accepts some "service names" like http and https, which leeds users erroneously to the assumption that they can use all names. So I suggest to always use only the numbers (except for http and https because of a bug in mobloquer, which gets confused there if you specify 80 and 443).
BTW: Please have a look at my signature --> post output in CODE tags.