Wifi扩展器、中继器及桥接配置

在本文中，您将看到如何将您的设备配置为WiFi扩展器/中继器/桥接。

在某些情况下,因为OpenWrt所用的开源无线驱动不支持“链路层(2层)“客户端模式下的桥接，所以LAN和无线客户端之间的流量只能用路由的方式来合并到一起，然后在其中广播比如DHCP和mDNS等本链路上的不可路由的消息。

relayd包借由DHCP和广播中继在仅IPv4的环境下实现了类似桥接的行为。此配置可以通过SSH（远程终端）和Luci图形界面完成。

简单起见，我们将把配置的设备称为“wifi扩展器”。

上图展示了一个示例配置。Wi-Fi扩展器的LAN接口必须配置为不同的子网，否则realyd无法正常工作（因为它需要两个不同的子网来进行路由）。

因为有线端口和无线网络均属于同一个LAN接口，所有连接至Wi-Fi扩展器有线端口和无线网络的客户端将由relayd进行路由，进而连接到您的主网。

LAN接口所配置的子网将只被用作“管理”网段，而连接到Wi-Fi扩展器的设备则会被分配到主网段。您必须给您的PC设置一个和LAN接口同网段的静态IP地址（比如192.168.2.10）以便再次连接到Wi-Fi扩展器的管理界面或SSH。

relayd包当然是必装的。如果您想使用Luci图形界面来配置您的wifi扩展器，还需要安装luci-proto-relay包。

As shown in the image above, the LAN interface must be set in a different subnet than the Wi-Fi network you are connecting to.

Begin by configuring and enabling the normal Wi-Fi network and configure it as you want it.
If you are making a simple Wi-Fi repeater (a device that extends the same Wi-Fi network's coverage) it's a good choice to set this Wi-Fi network to be the same as the one of your main router, same name, encryption, password, and so on. This way, devices connected to your (wider) network will automatically stay connected to the best Wi-Fi network.
But you can also choose to have a different name/encryption/password if you prefer to.
Setting up a Wi-Fi network at this stage is not necessary if you want a “Wi-Fi bridge”, a device designed to connect ethernet-only devices to your existing Wi-Fi network.

• Set LAN protocol as static address
• Assign an IP address in a different subnet (e.g. 192.168.2.1)
• Disable DHCP for the LAN interface (as it does prevent relayd from working).
• (May be required in certain case) set Gateway address and Use custom DNS servers using IP address of the primary router (e.g. 192.168.1.1)
• Save and Apply.

Set your PC's ethernet or Wi-Fi settings at static IP 192.168.2.10 and default gateway 192.168.2.1, then connect again to the wifi repeater (through ethernet or wifi). When you finish all of the following steps, remember to reset your PC's IP address back to the original address (or DHCP), otherwise you won't have Internet access. The repeater won't route traffic from the 192.168.2.0/24 subnet.

We will now set up the client Wi-Fi network, the configuration needed to connect to another Wi-Fi network.
Once you are connected again to the Wi-Fi extender, go in the wireless networks page, and click on Scan button.

Choose the Wi-Fi network you want to connect to from the page and click “Join Network”.

Enter the Wi-Fi password, leave the “name of new network” as “wwan” and select lan firewall zone. Click Save.

You will land in the client Wi-Fi settings page, set other things as needed.
The most important settings are on the Operating Frequency line.
Set the Mode to Legacy if you are connecting to a Wi-Fi g network (like in my example) or N if you are connecting to a Wi-Fi n (and so on).
Set the Width to the same value that you set on the Wi-Fi you are connecting to (to avoid bottlenecking the connection for no reason).

Go in the Interfaces page, we will now add the relayd interface that will join the lan and wwan interfaces.
Click on Add New Interface.

Write a name for it (repeater_bridge is the name I used in the example), and then choose Relay bridge in the Protocol of the new interface field. Click Submit.

You may need to reboot your device before the Relay bridge option appears.

In this new interface's setting page, select both lan and wwan in the Relay between networks list.

This “Local IPv4 address” (empty in above screen shot, sorry, I don't have enough rights to upload a new screen shot) needs to match the IP address assigned by the Wifi-network (eg. from 192.168.1.0/24 range, but do not enter the netmask here!) otherwise this bridge will not be accessible from the clients connected directly to the primary router and the relayd-daemon will not start. It makes sense to either fix the IP in the DHCP servers MAC-IP mapping table or configure then WWAN interface of OpenWRT to a fix IP which is not being used in Wifi-networks DHCP-range (I used 192.168.1.2, as my DHCP server only serves IP addresses higher than 192.168.1.100).

Move to the Firewall tab of this interface settings page and select lan. Click on Save and Apply.

After you have done this, it might be necessary to reboot the Wi-Fi extender.

This is the final result. Note how the client network has a ? instead of a IP address.

The following part of the configuration should not be necessary (already default options or changed automatically), in case something isn't working check this too.

Under the Network tab, click on the Firewall tab. Under Zones, change the forwarding for lan and wwan to accept

if you are doing this with a device that has a single radio, both Wi-Fi networks will stay on the same channel, and total bandwidth will be halved as the same radio is used for 2 different Wi-Fi networks.

Before doing any actual configuration, the Wi-Fi interface must be enabled in order to scan for networks in the vicinity:

uci set wireless.@wifi-device[0].disabled="0"
uci commit wireless
wifi

• Set the disabled option to 0 (to enable wireless)
• Save changed configuration file
• Start wireless using the wifi command

Now we can list networks in range using iw dev wlan0 scan, substituting your actual wireless interface for wlan0 if different (ifconfig lists all available interfaces to find how your wlan is called)

iw dev wlan0 scan output example:

# iw dev wlan0 scan
BSS c8:d5:fe:c8:61:b0(on wlan0) -- associated
        TSF: 24324848870 usec (0d, 06:45:24)
        freq: 2412
        beacon interval: 100 TUs
        capability: ESS (0x0411)
        signal: -72.00 dBm
        last seen: 140 ms ago
        Information elements from Probe Response frame:
        SSID: Violetta
        RSN:     * Version: 1
                 * Group cipher: CCMP
                 * Pairwise ciphers: CCMP
                 * Authentication suites: PSK
                 * Capabilities: 1-PTKSA-RC 1-GTKSA-RC (0x0000)
BSS f8:35:dd:eb:20:f8(on wlan0)
        TSF: 24225790925 usec (0d, 06:43:45)
        freq: 2457
        beacon interval: 100 TUs
        capability: ESS (0x0431)
        signal: -90.00 dBm
        last seen: 1450 ms ago
        Information elements from Probe Response frame:
        SSID: GOinternet_EB20FB
        HT capabilities:
                Capabilities: 0x11ee
                        HT20/HT40
                        SM Power Save disabled
                        RX HT20 SGI
                        RX HT40 SGI
                        TX STBC
                        RX STBC 1-stream
                        Max AMSDU length: 3839 bytes
                        DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 4 usec (0x05)
                HT RX MCS rate indexes supported: 0-15, 32
                HT TX MCS rate indexes are undefined
        HT operation:
                 * primary channel: 10
                 * secondary channel offset: below
                 * STA channel width: any
        RSN:     * Version: 1
                 * Group cipher: TKIP
                 * Pairwise ciphers: TKIP CCMP
                 * Authentication suites: PSK
                 * Capabilities: 1-PTKSA-RC 1-GTKSA-RC (0x0000)

In the example, there are two networks, a Wi-Fi g one called Violetta and a Wi-Fi n one called GOinternet_EB20FB. The device was configured to connect to the one called Violetta.

These are the uci values that were added or changed by the configuration procedure.
For SSID, BSSID, and encryption you must use the info you got from the Wi-Fi scan above.
For an explanation of why these values were changed, please read the luci tutorial above.

network.lan.ipaddr='192.168.2.1'
network.repeater_bridge=interface
network.repeater_bridge.proto='relay'
network.repeater_bridge.network='lan wwan'
network.wwan=interface
network.wwan.proto='dhcp'
firewall.@zone[0].network='lan repeater_bridge wwan'
dhcp.lan.ignore='1'
wireless.radio0.hwmode='11g'
wireless.radio0.country='00'
wireless.radio0.channel='1'
wireless.radio0.disabled='0'
wireless.@wifi-iface[0]=wifi-iface
wireless.@wifi-iface[0].device='radio0'
wireless.@wifi-iface[0].mode='ap'
wireless.@wifi-iface[0].encryption='none'
wireless.@wifi-iface[0].ssid='OpenWrt'
wireless.@wifi-iface[0].network='lan'
wireless.@wifi-iface[1]=wifi-iface
wireless.@wifi-iface[1].network='wwan'
wireless.@wifi-iface[1].ssid='Violetta'
wireless.@wifi-iface[1].encryption='psk2'
wireless.@wifi-iface[1].device='radio0'
wireless.@wifi-iface[1].mode='sta'
wireless.@wifi-iface[1].bssid='C8:D5:FE:C8:61:B0'
wireless.@wifi-iface[1].key='myWifiPasswordHere'

Please note that the Wi-Fi network generated by the device in this example (the one called OpenWrt) has no password nor encryption.
This was done because the focus of this article was getting the relay bridge up and running.
You will likely want to set up your device's Wi-Fi network in a more secure way, as explained in the Wi-Fi setup page here.

If you find the OpenWrt device itself is only accessible from those computers directly connected to the W-LAN AP, not from the ones connected to the OpenWrt W-LAN client, when in the 192.168.1.0 subnet, Make sure the Local IPv4 address setting in the Relay bridge interface matches the ip address of the wireless uplink. (The alternative is tedious: It is possible to access the OpenWrt box via its 192.168.2.1 address if you manually configure your computer to that subnet.)

Activate IPv6 support on your Internet box, this will get you a public IPv6 prefix. We will now activate IPv6 on our Wi-Fi extender to allow for Stateless Address Autoconfiguration (SLAAC) of your public IPv6 addresses and IPv6 traffic.

1. Go to Network / Interfaces and create a new interface. Name it WWAN6, using protocol DHCPv6, cover the WWAN interface. In the Common Configuration of the new interface, configure: Request IPv6 address: disabled. In the Firewall settings: check that the “lan / repeater bridge…” line is selected. Leave the other settings by default, especially, leave the “Custom delegated IPv6-prefix” field empty. On the Interfaces / overwiew page check that the WWAN interface gets a public IPv6 address.

2. Edit the LAN interface settings, DHCP server / IPv6 settings: check/modify the following settings: Router Advertisement Service: relay mode, DHCPv6 service: disabled, NDP-Proxy: relay mode.

3. Open a SSH session on your OpenWrt device. Issue the following commands:

uci set dhcp.wan.interface=wwan
uci set dhcp.wan.ra=relay
uci set dhcp.wan.ndp=relay
uci set dhcp.wan.master=1
uci commit

We suppose that you created a wwan interface when you joined to the other Wi-Fi network as suggested earlier in this guide; otherwise, change the dhcp.wan.interface=… line accordingly.

That's it. Restart ophcpd (LuCI System/Starup page, or /etc/init.d/odhcpd restart) and your IPv6-network should begin to configure itself. Connected IPv6-enabled devices should get their public IPv6 addresses, derived from your public IPv6 prefix, and IPv6 traffic should go through your Wi-Fi extender.

Here are a list of some recently reported issues:

1. DHCP issue caused by Access Point. OWrt forum
2. Extremely poor upstream transfer speeds with some MT762x devices. Owrt forum Bug Report FS#2816
3. Need additional instruction for backdoor to router since once dhcp is disabled on LAN, the router become unreachable

这个方法就是单纯的将第二个无线路由配置在第一个的层级之下。
就好像用一根网线把Wifi扩展器的WAN接口连到主路由的LAN接口。Wifi扩展器在自身和连接至它的客户端之间创建了新的网络。此网络可以访问互联网以及主路由所在的子网。只不过我们是用无线网络来达成这个目的。

先决条件: - 路由必须由两个初始接口（lan，wan）

使用luci图形界面进行设置：

• 至网络 → 接口页面，点击lan接口的编辑按钮，
• 设置LAN的静态IPv4地址为192.168.x.1。（x取决于您通过wifi连入的网络的配置）
• 至网络 → Wifi界面, 点击扫描，并选择对应的网络连接，点击“加入网络”。
• 输入wifi密码，保留“新网络名称”为”wwan”并选择wwan(或wan)防火墙区域，点击保存，
• 至网络 → 接口页面，点击wwan接口的编辑按钮，
• 至防火墙标签页，点击保存并应用。
• 至网络 → 防火墙页面, 点击wan区域的编辑按钮，在“covered networks”中勾选wan和wwan。点击保存并应用。

至此，您已经正确的将wwan绑定至wan，也就是建立了wwan至lan的通路