Manully configure OpenWRT to block outgoing connections

• Login to your router from the web with your favorite webrowser ( the default address is http://192.168.1.1 )
• Select the "System" tab then then "File Editor" sub tab.
• the file you want to edit is in /etc/firewall.user
• click the "Edit" button near the firewall.user file
• scroll to the end of this file and paste the following:
  • for blocking from the entire LAN ("-i $LAN" part selects all interfaces on the LAN side)

iptables -A forwarding_rule -p udp -i $LAN --dport 5121 -j DROP

• • if we are using wifi split from the bridge, we can add this rule:

[ -n "$WIFI" ] && iptables -A forwarding_rule -p udp -i $WIFI --dport 5121 -j DROP

• • to block a port from one machine on the LAN (example is 192.168.1.101) from reaching outside the router:

iptables -A forwarding_rule -p udp -s 192.168.1.101 --dport 5121 -j DROP

• save changes
• apply changes