How to raise Apache and bring it to the network, if you open only port 21?

You can, in the config of Apache and put port 21. (this port for anything else to work should not)
On another machine, put the proxy which will pass from your 80 port 21 port of your machine. Refer to the IP toraymyxin and see the content from the first. Can second car lift nginx and configure the second machine as the backend.