You can not hide IP adresses because that are "the" adresses. Even when using domain names, that will be resolved to IP adresses using DNS.
Compare with telephone numbers: They must be known to call. If you don't know a specific number, you can't call the recipient. Your phone book is like DNS: It provides the number for a specific name.
An example:
If you enter "http://www.codeproject.com" into the address field of your web browser, the browser will query DNS servers to get the correspoding IP and uses that to connect to the server.
You can also enter "http://76.74.234.210" into the address field instead.
To get the IP number for a known server, you can use the command line tool
nslookup (with Linux use
dig instead):
nslookup www.codeproject.com
Server: 127.0.0.1
Address: 127.0.0.1#53
Non-authoritative answer:
Name: www.codeproject.com
Address: 76.74.234.210
So everybody can get your IP address when you publish your domain name.