Routed AP
In the default configuration, OpenWrt bridges the wireless network to the LAN of the device. The advantage of bridging is that broadcast traffic from Wireless to LAN and vice versa works without further changes.
In order to separate the wireless network from LAN, a new network with the corresponding DHCP and firewall settings must be created. This document outlines the steps necessary to implement such a setup.
Configuration
The changes below assume an OpenWrt default configuration, the relevant files are:
Step 1: Define a new network
Edit /etc/config/network
and define a new interface
section:
config 'interface' 'wifi' option 'proto' 'static' option 'ipaddr' '192.168.2.1' option 'netmask' '255.255.255.0'
Note that no ifname/device
option is set here, it is not required since the wireless network will reference this section later.
Make sure that the chosen IP address is in a different subnet than the one used by the lan interface. For instance, if your lan is in 192.168.1.x space, the wifi must be in the 192.168.2; be aware that the same restrictions may apply regarding your WAN interface |
Step 2: Change the existing wireless network
In /etc/config/wireless
, locate the existing wifi-iface
section and change its network option to point to the newly created interface section.
config 'wifi-iface' option 'device' 'wl0' option 'network' 'wifi' option 'mode' 'ap' option 'ssid' 'OpenWrt' option 'encryption' 'none'
In the existing section, network
was changed to point to the wifi
interface defined in the previous step.
Optionally change the last line for option encryption 'psk2
' and add the line option key 'secret key
' to enable WPA encryption
Step 3: Define a new DHCP pool (optional)
Since wireless is not bridged to LAN anymore, no DHCP leases are served to wireless clients yet.
In order to support DHCP on wireless as well, a new dhcp
pool must be defined in /etc/config/dhcp
:
config 'dhcp' 'wifi' option 'interface' 'wifi' option 'start' '100' option 'limit' '150' option 'leasetime' '12h'
Step 4: Adjust firewall settings
By default, traffic originating from the wireless network is not allowed to reach the WAN or the LAN interface. There is also no firewall zone defined for it yet, so only the default policies apply to the wireless network.
Edit /etc/config/firewall
and add new zone
section covering the wifi
interface:
config zone option name wifi list network 'wifi' option input ACCEPT option output ACCEPT option forward REJECT
Now that the zone is defined, traffic forwarding control for the wireless network can be implemented.
To allow wireless clients to use the WAN interface, add the following forwarding
section:
config 'forwarding' option 'src' 'wifi' option 'dest' 'wan'
If LAN clients should be able to contact wireless clients, add the following forwarding:
config 'forwarding' option 'src' 'lan' option 'dest' 'wifi'
To allow wireless clients to reach the LAN network, add the reversed rule below as well:
config 'forwarding' option 'src' 'wifi' option 'dest' 'lan'
To allow replies from wan to wifi client add option masq 1 to the lan 'lan' firewall option:
config zone option name lan list network 'lan' option input ACCEPT option output ACCEPT option forward ACCEPT option masq 1
Apply changes
- Enable the new wireless network
ifup wifi wifi
- Restart the firewall
/etc/init.d/firewall restart
- Restart the DHCP service
/etc/init.d/dnsmasq restart
IPv6 prefix delegation
If you are using IPv6 prefix delegation for subnetting on the LAN side, you might have to adjust the interface parameter ip6assign
, which sets
the prefix size delegated downstream.
For each of lan
and wifi
in the example, a value of ip6assign
must be chosen such that the combined size of these subnets does not exceed the size of the IPv6 prefix available from upstream. Otherwise, one of the assignments would fail.
The IPv6 page explains downstream configuration in more detail.
More tweaks
- In some case, you cannot access Internet from “wifi” network clients (though you can do from the router), then you can replace the firewall setting with this https://forum.openwrt.org/viewtopic.php?pid=166701#p166701