I have a rather different approach. I wanted to use port 80 for a node.js server. I was unable to do it since Node.js was installed for a non-sudo user. I tried to use symlinks, but it didn't work for me.

Then I got to know that I can forward connections from one port to another port. So I started the server on port 3000 and set up a port forward from port 80 to port 3000.

This link provides the actual commands which can be used to do this. Here're the commands -

localhost/loopback

sudo iptables -t nat -I OUTPUT -p tcp -d 127.0.0.1 --dport 80 -j REDIRECT --to-ports 3000

external

sudo iptables -t nat -I PREROUTING -p tcp --dport 80 -j REDIRECT --to-ports 3000

I have used the second command and it worked for me. So I think this is a middle ground for not allowing user-process to access the lower ports directly, but giving them access using port-forwarding.