I configured a separate network with a separate interface on a different subnet than the LAN network that I only use for IP cameras.
I do not want to give the cameras network access to the internet or to the LAN devices to avoid the cameras to access internet through WAN interface (phoning home). It can be done by just creating a firewall rule that reject forward traffic to WAN interface from the specific camera IP addresses (if on LAN network).
But since I also do not want the cameras to be able to sniff/manipulate LAN traffic, I chose to create a new interface that uses a completely isolated physical network port (that on my device is its own NIC, not a VLAN). The only traffic I let through is DHCP and NTP for synchronizing the camera's time with the NTP server in OpenWrt. I created a firewall zone only for the camera network.
But now I have some questions about the function of the firewall rules. To be able to get DHCP server to hand out IP addresses properly, I set up a firewall rule allowing DHCP on port 67-68 as per the tutorial on guest WLANs.
Please explain to me in what order those rules are executed? For this rule to work i had to set Output=accept in the settings for the
cam zone. Why is this?
When output is set to accept, it seems like only the traffic that is specified in a firewall rule gets through? Isn't it supposed to be the opposite, that a specific firewall rule can override the rules set for the firewall zone settings?
config zone option name 'cam' list network 'cam' option output 'ACCEPT' option input 'REJECT' option forward 'REJECT' config rule option name 'Allow-DHCP-Cam' list proto 'udp' option src 'cam' option dest_port '67-68' option target 'ACCEPT' config rule option name 'Allow-NTP-Cam' option src 'cam' option dest_port '123' option target 'ACCEPT' config forwarding option src 'lan' option dest 'cam'
It must be correct that output=ACCEPT means the devices in the specific zone can initiate a connection to the OpenWrt device (for DHCP and NTP in my case)?
But, for the cam zone input is set to REJECT. I can still ping all the cameras from the OpenWrt router's shell console, and reach the camera web interface from a computer in the LAN zone. Wouldn't traffic originationg from OpenWrt device be rejected since there is no specific rule set for that?
Is it because I have set forward to ACCEPT and that the OpenWrt device is in the LAN zone that is possible?
I find it quite a bit confusing and the documentation is not very clear how everything works together.