By Toradex秦海
1).?簡介
本文介紹基于ARM嵌入式平臺(tái)使用開源Hostapd軟件配置測試WiFi Access Point模式，也就是AP模式。
本文所使用的ARM嵌入式平臺(tái)來自于Toradex?基于NXP最新的iMX8 SoC（基于Cortex-A72+A53和Coretex-M4架構(gòu)）的ARM計(jì)算機(jī)模塊Apalis iMX8QM 4GB WB IT，模塊上面集成了AzureWave AW-CM276NF WiFi/BT?模塊，其具體WiFi參數(shù)如下：
2).?準(zhǔn)備
a).?Apalis iMX8QM?4GB WB IT ARM核心版配合Ioxra?載板，連接調(diào)試串口UART1（載板X22）到開發(fā)主機(jī)方便調(diào)試。
b). Apalis iMX8安裝Toradex Ycoto Linux Reference Multimedia image V5.0.0 2020Q3季度版本，詳細(xì)信息請參考這里。
c). WiFi模塊安裝標(biāo)準(zhǔn)WHF4接口天線，詳情請參考這里。
3). WiFi AP模式配置
a).?查看WiFi模塊AP模式端口uap0
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root@apalis-imx8:~# ifconfig -a |grep uap
uap0????? Link encap:Ethernet? HWaddr C0:E4:34:2F:C6:A1
-------------------------------
b).?配置Hostapd配置文件
./ file - /etc/hostapd.conf，Hostapd服務(wù)配置文件，里面預(yù)設(shè)了很多配置項(xiàng)目，這里只將必要的進(jìn)行修改，其他可以自行根據(jù)實(shí)際需要來配置。
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--- a/etc/hostapd.conf
+++ b/etc/hostapd.conf
@@ -5,7 +5,7 @@
?# management frames with the Host AP driver); wlan0 with many nl80211 drivers
?# Note: This attribute can be overridden by the values supplied with the '-i'
?# command line parameter.
-interface=wlan0
+interface=uap0
?# In case of atheros and nl80211 driver interfaces, an additional
?# configuration parameter, bridge, may be used to notify hostapd if the
@@ -85,7 +85,7 @@
?##### IEEE 802.11 related configuration #######################################
?# SSID to be used in IEEE 802.11 management frames
-ssid=test
+ssid=ap-apalis-imx8
?# Alternative formats for configuring SSID
?# (double quoted string, hexdump, printf-escaped string)
?#ssid2="test"
@@ -1234,7 +1234,7 @@
?# authentication with external ACL for MAC addresses, and accounting
?# The own IP address of the access point (used as NAS-IP-Address)
-own_ip_addr=127.0.0.1
+own_ip_addr=192.168.8.1
?# NAS-Identifier string for RADIUS messages. When used, this should be unique
?# to the NAS within the scope of the RADIUS server. Please note that hostapd
@@ -1464,7 +1464,7 @@
?# Note that WPA3 is also configured with bit1 since it uses RSN just like WPA2.
?# In other words, for WPA3, wpa=2 is used the configuration (and
?# wpa_key_mgmt=SAE for WPA3-Personal instead of wpa_key_mgmt=WPA-PSK).
-#wpa=2
+wpa=2
?# WPA pre-shared keys for WPA-PSK. This can be either entered as a 256-bit
?# secret in hex format (64 hex digits), wpa_psk, or as an ASCII passphrase
@@ -1473,7 +1473,7 @@
?# wpa_psk (dot11RSNAConfigPSKValue)
?# wpa_passphrase (dot11RSNAConfigPSKPassPhrase)
?#wpa_psk=0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef
-#wpa_passphrase=secret passphrase
+wpa_passphrase=MyPassword1234
?# Optionally, WPA PSKs can be read from a separate text file (containing list
?# of (PSK,MAC address) pairs. This allows more than one PSK to be configured.
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上面是配置2.4GHz頻段的AP，如果需要配置5GHz頻段，則需要修改下面內(nèi)容：
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hw_mode=a
channel=40
ieee80211n=1
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./?文件?- /etc/systemd/network/hostapd.network，用于配置AP?固定IP以及DHCP服務(wù)
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[Match]
Name=<IF_NAME>
[Network]
Address=192.168.8.1/24
DHCPServer=yes
-------------------------------
c).?配置相關(guān)systemd啟動(dòng)服務(wù)
./?開機(jī)自動(dòng)啟動(dòng)WiFi服務(wù)，當(dāng)然Linux BSP已經(jīng)包含了?/lib/systemd/system/enable-wifi.service?服務(wù)文件，只需要后面通過systemctl命令使能即可。
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[Unit]
Description=Enable Wifi
BindsTo=sys-subsystem-net-devices-uap0.device
After=sys-subsystem-net-devices-uap0.device
[Service]
Type=oneshot
ExecStart=/usr/bin/connmanctl enable wifi
ExecStop=
RemainAfterExit=yes
[Install]
WantedBy=multi-user.target
-------------------------------
./?修改默認(rèn)的?Hostapd?服務(wù)文件，使其確定在Wifi服務(wù)以及uap0端口起來后再啟動(dòng)，避免出現(xiàn)啟動(dòng)失敗。
-------------------------------
--- a/lib/systemd/system/hostapd.service
+++ b/lib/systemd/system/hostapd.service
@@ -1,6 +1,7 @@
?[Unit]
?Description=Hostapd IEEE 802.11 AP, IEEE 802.1X/WPA/WPA2/EAP/RADIUS Authenticator
-After=network.target
+BindsTo=sys-subsystem-net-devices-uap0.device
+After=sys-subsystem-net-devices-uap0.device
?[Service]
?Type=forking
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./?重載并使能上述修改的服務(wù)然后重新啟動(dòng)
-------------------------------
$ systemctl --system daemon-reload
$ systemctl enable hostapd
$ systemctl enable enable-wifi.service
$ reboot
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c).?測試AP配置
./?重啟后，通過PC WiFi網(wǎng)卡掃描可以找到?ap-apalis-imx8 AP設(shè)備，使用上面配置文件設(shè)定的密碼連接后，ping通訊正常
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// on apalis imx8 linux
root@apalis-imx8:~# ifconfig uap0
uap0????? Link encap:Ethernet? HWaddr C0:E4:34:2F:C6:A1?
????????? inet addr:192.168.8.1? Bcast:192.168.8.255? Mask:255.255.255.0
????? ????inet6 addr: fe80::c2e4:34ff:fe2f:c6a1/64 Scope:Link
????????? UP BROADCAST RUNNING MULTICAST? MTU:1500? Metric:1
????????? RX packets:78 errors:0 dropped:0 overruns:0 frame:0
????????? TX packets:100 errors:39 dropped:0 overruns:0 carrier:0
????????? collisions:0 txqueuelen:1000
????????? RX bytes:11466 (11.1 KiB)? TX bytes:5792 (5.6 KiB)
// on Ubuntu desktop
$ ifconfig wlo1
wlo1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>? mtu 1500
??????? inet 192.168.8.72? netmask 255.255.255.0? broadcast 192.168.8.255
??????? inet6 fe80::8f97:db63:7329:9efb? prefixlen 64? scopeid 0x20<link>
ether 3c:f0:11:6f:d0:47? txqueuelen 1000? (以太網(wǎng))
??????? RX packets 951788? bytes 722874574 (722.8 MB)
??????? RX errors 0? dropped 0? overruns 0? frame 0
??????? TX packets 99168? bytes 16375180 (16.3 MB)
??????? TX errors 0? dropped 0 overruns 0? carrier 0? collisions 0
$ ping 192.168.8.1
PING 192.168.8.1 (192.168.8.1) 56(84) bytes of data.
64 bytes from 192.168.8.1: icmp_seq=1 ttl=64 time=5.82 ms
64 bytes from 192.168.8.1: icmp_seq=2 ttl=64 time=4.13 ms
64 bytes from 192.168.8.1: icmp_seq=3 ttl=64 time=4.15 ms
^C
--- 192.168.8.1 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2001ms
rtt min/avg/max/mdev = 4.138/4.705/5.824/0.793 ms
-------------------------------
4).?網(wǎng)絡(luò)共享功能配置
a).?將WiFi模塊Client模式端口連接到可連接互聯(lián)網(wǎng)的WiFi網(wǎng)絡(luò)，用于作為下面AP端口網(wǎng)絡(luò)共享的端口
./?查看WiFi模塊client模式端口
-------------------------------
root@apalis-imx8:~# ifconfig |grep mlan
mlan0???? Link encap:Ethernet? HWaddr C0:E4:34:2F:C4:A1
-------------------------------
./?參考這里的說明，連接WiFi網(wǎng)絡(luò)，連接后狀態(tài)如下：
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root@apalis-imx8:~# ifconfig mlan0?????
mlan0???? Link encap:Ethernet? HWaddr C0:E4:34:2F:C4:A1?
????????? inet addr:10.20.1.123? Bcast:10.20.1.255? Mask:255.255.255.0
????????? inet6 addr: fe80::c2e4:34ff:fe2f:c4a1/64 Scope:Link
????????? UP BROADCAST RUNNING MULTICAST? MTU:1500? Metric:1
????????? RX packets:18613 errors:0 dropped:39 overruns:0 frame:0
????????? TX packets:12421 errors:0 dropped:0 overruns:0 carrier:0
????????? collisions:0 txqueuelen:1000
????????? RX bytes:20897583 (19.9 MiB)? TX bytes:1621867 (1.5 MiB)
-------------------------------
b).?使能Packet Forwarding
文件?- /etc/sysctl.d/30-ipforward.conf
-------------------------------
net.ipv4.ip_forward=1
net.ipv6.conf.default.forwarding=1
net.ipv6.conf.all.forwarding=1
-------------------------------
c).?使能NAT
./?首先需要kernel包含下面驅(qū)動(dòng)，直接編譯到kernel或者編譯成kernel modules都可以，當(dāng)前測試BSP是已經(jīng)編譯為kernel modules，如果沒有包含則需要重新編譯kernel添加進(jìn)入
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root@apalis-imx8:~# zcat /proc/config.gz |grep CONFIG_IP_NF_IPTABLES????????????????????????????????????
CONFIG_IP_NF_IPTABLES=m
root@apalis-imx8:~# zcat /proc/config.gz |grep CONFIG_NETFILTER_XT_MATCH_CONNTRACK
CONFIG_NETFILTER_XT_MATCH_CONNTRACK=m
-------------------------------
./?使用iptables使能NAT，首先創(chuàng)建下面iptables?規(guī)則
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iptables -t nat -A POSTROUTING -o mlan0 -j MASQUERADE
iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i uap0 -o mlan0 -j ACCEPT
-------------------------------
./?將上面設(shè)置的規(guī)則保存到配置文件
-------------------------------
$ iptables-save > /etc/iptables/iptables.rules
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./?使能iptable服務(wù)，當(dāng)前BSP已經(jīng)包含服務(wù)文件?/lib/systemd/system/iptables.service
-------------------------------
$ systemctl enable iptables
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d).?重啟后上述配置生效，然后啟動(dòng)后可以通過systemctl查看相關(guān)服務(wù)是否都啟動(dòng)正常
-------------------------------
$ systemctl status hostapd
$ systemctl status enable-wifi
$ systemctl status iptables
-------------------------------
e).?同樣使用Ubuntu desktop連接ap-apalis-imx8 AP后，如下測試可以正常連接互聯(lián)網(wǎng)了，證明網(wǎng)絡(luò)共享配置成功
-------------------------------
$ ifconfig wlo1
wlo1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>? mtu 1500
??????? inet 192.168.8.72? netmask 255.255.255.0? broadcast 192.168.8.255
??????? inet6 fe80::8f97:db63:7329:9efb? prefixlen 64? scopeid 0x20<link>
ether 3c:f0:11:6f:d0:47? txqueuelen 1000? (以太網(wǎng))
??????? RX packets 967881? bytes 745946717 (745.9 MB)
??????? RX errors 0? dropped 0? overruns 0? frame 0
??????? TX packets 103940? bytes 17087302 (17.0 MB)
??????? TX errors 0? dropped 0 overruns 0? carrier 0? collisions 0
# ping?百度網(wǎng)址，因?yàn)锳P默認(rèn)沒有設(shè)定DNS配置，因此連接后需要手動(dòng)指定一個(gè)有效的DNS地址才能進(jìn)行DNS解析
$ ping www.baidu.com
PING www.a.shifen.com (180.101.49.11) 56(84) bytes of data.
64 bytes from 180.101.49.11 (180.101.49.11): icmp_seq=1 ttl=51 time=8.97 ms
64 bytes from 180.101.49.11 (180.101.49.11): icmp_seq=2 ttl=51 time=11.2 ms
64 bytes from 180.101.49.11 (180.101.49.11): icmp_seq=3 ttl=51 time=10.8 ms
^C
--- www.a.shifen.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 8.972/10.369/11.276/1.005 ms
-------------------------------
5).?總結(jié)
本文在iMX8嵌入式平臺(tái)下使用Linux開源工具測試了WiFi?模塊AP模式以及網(wǎng)絡(luò)共享功能。
參考文檔
https://developer.toradex.cn/knowledge-base/wi-fi-access-point-mode
