# 設定無線基地台(AP)

## 所需套件

從安裝所需的套件開始。

```
$ sudo apt-get install hostapd dnsmasq
```

## 設定網路介面

為了防止樹莓派的Wi-Fi介面重新向DHCP索取動態IP位址，與原有的固定IP位址發生衝突，需修正/etc/dhcpcd.conf的檔案內容。在檔案結尾處加入此行。

```
denyinterfaces wlan0
```

接著修改/etc/network/interfaces檔案中的Wi-Fi介面設定，設定成靜態的固定IP位址。我們選擇 10.0.0.1作為MoodleBox的地址。

這個檔案的wlan0部份，看起來像這樣：

```
allow-hotplug wlan0
iface wlan0 inet static
    address 10.0.0.1
    netmask 255.255.255.0
    network 10.0.0.0
    broadcast 10.0.0.255
#  wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
```

檔案的其他部分不需要修改。

## 設定基地台(AP，hostapd)

接下來修正hostapd.conf檔案，在此訂定Wi-Fi網路連線名稱 (SSID)、連線密碼和其他選項，例如廣播通道。 網路連線名稱是 MoodleBox 密碼為 moodlebox。

/etc/hostapd/hostapd.conf檔案內容：

```
# Set country code
country_code=TW
# Name of the Wi-Fi interface
interface=wlan0
# Use the nl80211 driver
driver=nl80211
# Wi-Fi network name
ssid=MoodleBox
# Use the 2.4GHz band
hw_mode=g
# Use channel 11
channel=11
# Enable 802.11n
ieee80211n=1
# Enable WMM
wmm_enabled=1
# Enable 40 MHz channels with short guard interval for 20 Mhz
ht_capab=[HT40][SHORT-GI-20][DSSS_CCK-40]
# Accept all MAC addresses
macaddr_acl=0
# Use WPA authentication
auth_algs=1
# Use WPA2
wpa=2
# Use a pre-shared key
wpa_key_mgmt=WPA-PSK
# The network passphrase
wpa_passphrase=moodlebox
# Use AES, instead of TKIP
rsn_pairwise=CCMP
# Enable hostapd_cli
ctrl_interface=/var/run/hostapd
ctrl_interface_group=0
```

***驗證***

```
啟動 hostapd：
$ sudo /usr/sbin/hostapd /etc/hostapd/hostapd.conf
會有錯誤顯示(因為設定還沒有完成)，但是會自動由 wlan0:AP-ENABLED 終止。就可以掃瞄到 MoodleBox 的Wi-Fi網路連線了。
```

接著要定義 hostapd所需的啟動設定，即修改/etc/default/hostapd檔案。

用 DAEMON\_CONF="/etc/hostapd/hostapd.conf" 取代 #DAEMON\_CONF=""。

## 設定DHCP伺服器和DNS伺服器

修改 /etc/dnsmasq.conf 檔案 。 內容如下：

```
interface=wlan0         # Use interface wlan0
listen-address=127.0.0.1     # Explicitly specify the address to listen on
listen-address=10.0.0.1     # Explicitly specify the address to listen on
bind-interfaces             # Make sure we aren't sending things elsewhere
server=209.244.0.3         # Forward DNS requests to Level3 DNS
server=209.244.0.4         # Forward DNS requests to Level3 DNS
domain-needed             # Don't forward short names
bogus-priv             # Don't forward addresses in the non-routed spaces
domain=home             # Set private domain name to 'home'
local=/home/             # Don't forward queries for private domain 'home'
expand-hosts             # Add private domain name to hostnames
dhcp-range=wifi,10.0.0.100,10.0.0.199,255.255.255.0,12h # Assign IP addresses with12h lease, subnet name 'wifi'
dhcp-option=wifi,6,10.0.0.1 # Set DNS server for subnet wifi
# log-facility=/var/log/dnsmasq.log # Enable log
```

然後修改 /etc/hosts檔案，更換最後一行，由127.0.0.1開頭，取代為下面的內容：

```
10.0.0.1  moodlebox
```

此設定允許任何類型的設備，即使是那些不屬於zeroconf的技術科技，也可以使用地址 <http://moodlebox.home/> 存取MoodleBox。

## 路由配置

修改 /etc/sysctl.conf檔案，取消註釋（或增加）此行

```
net.ipv4.ip_forward=1
```

在介面中加入這些行:

```
$ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
$ sudo iptables -A FORWARD -i eth0 -o wlan0 -m state --state RELATED,ESTABLISHED -j ACCEPT
$ sudo iptables -A FORWARD -i wlan0 -o eth0 -j ACCEPT
$ sudo sh -c "iptables-save > /etc/iptables.ipv4.nat"
$ sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
```

接著，新建一個檔案 /lib/dhcpcd/dhcpcd-hooks/70-ipv4-nat。它的內容如下:

```
iptables-restore < /etc/iptables.ipv4.nat
```

最後，重新啟動樹莓派即完成。

```
$ sudo reboot
```

## 測試無線基地台

***驗證***

```
在啟動樹莓派時，客戶端應該可以透過連線名稱為MoodleBox、密碼moodlebox的Wi-Fi基地台連上網際網路。
```

## mDNS服務

為了在網路上可以看見MoodleBox提供的網路服務，新建/etc/avahi/services/moodlebox.service 檔案，內容如下：

```
<?xml version="1.0" standalone='no'?>
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
<name replace-wildcards="yes">%h</name>
    <service>
        <type>_device-info._tcp</type>
        <port>0</port>
        <txt-record>model=MoodleBox</txt-record>
    </service>
    <service>
        <type>_ssh._tcp</type>
        <port>22</port>
    </service>
    <service>
        <type>_sftp-ssh._tcp</type>
        <port>22</port>
    </service>
    <service>
        <type>_http._tcp</type>
        <port>80</port>
    </service>
</service-group>
```


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