At home, I have Ubuntu server with the UFW firewall. What command do I type to turn on local intranet access to my web server, but keep the outside world out from my DSL modem?
sudo ufw default deny sudo ufw allow from 192.168.1.0/24 to any port 80
Assuming the web server is on port 80 and 192.168.1.x is your home subnet. If you explicitly want exclude your router, then assuming it's 192.168.1.1, it would be:
sudo ufw deny from 192.168.1.1 to any port 80