GlassFish 4 is running by default at port number 8080 as you want to run at port 80 we can change it.

Open your GlassFish administration interface with port : 4848 (by default).

Click on "Configurations" link on the left menu,

Then select the appropriate configuration, Click on "server-config"

Then click on "Network Config"

Then click on "Network Listeners"

Choose the appropriate listener, probably "http-listener-1"

By default port fixed 8080, Change the Port value to 80 

Finally Save and retart your glassfish server according to your needs.