这里我们假定中继器完成下面这样的一个功能：
Wired Network ---> Wireless Network ---> 上级无线路由器
即从外部插入一个网线，通过imx6UL上面的无线网卡将数据转发到上级的路由器上面， 当然也可以完成下面这样的传送：
Wireless Network（AP mode） --> Wireless Network（Client） --> 上级无线路由器
即设立一个AP热点，相当于一个路由器，然后再将这个AP的数据通过另外一个无线网卡转发到上一级的路由器或者WLAN上面。
用图片来表示如下：
要完成这些功能， 我们需要：
1. 驱动无线网卡2. 建立AP热点3. 其中一个wired或者wireless介入到上一级路由器或者WLAN中4. 使用IPTables来对数据包进行转发
对于1，我们在前面已经完成，对于Wired Network访问WLAN我们也已经在前面完成。所以这篇我们将完成2与3， 以及4。
建立AP热点，我们使用经典的Hostapd工具来完成， 这个在OpenWRT中已经存在， 直接选上，然后build即可。
然后我们可以查看对应的使用帮助
root@(none):/# hostapd --help hostapd: invalid option -- '-' hostapd v2.5 User space daemon for IEEE 802.11 AP management, IEEE 802.1X/WPA/WPA2/EAP/RADIUS Authenticator Copyright (c) 2002-2015, Jouni Malinen <j@w1.fi> and contributors usage: hostapd [-hdBKtv] [-P <PID file>] [-e <entropy file>] \ [-g <global ctrl_iface>] [-G <group>] \ <configuration file(s)> options: -h show this usage -d show more debug messages (-dd for even more) -B run daemon in the background -e entropy file -g global control interface path -G group for control interfaces -P PID file -K include key data in debug messages -t include timestamps in some debug messages -v show hostapd version 因此可以确定需要一个config文件， 这个configuration file我们如下填写：
root@(none):/# cat /etc/hostapd_ori.conf interface=wlan1 ssid=TonyOpenWRT channel=9 hw_mode=g ignore_broadcast_ssid=0 auth_algs=1 wpa=3 wpa_passphrase=TonyHo123456 wpa_key_mgmt=WPA-PSK wpa_pairwise=TKIP rsn_pairwise=CCMP即我们创建一个SSID为TonyOpenWRT的热点， wpa_passphrase为密码， 后面的为加密方式， 然后还选择了channel， 这个channel可以通过前面的iw list来查看， 例如其中一个为：
Frequencies: * 2412 MHz [1] (20.0 dBm) * 2417 MHz [2] (20.0 dBm) * 2422 MHz [3] (20.0 dBm) * 2427 MHz [4] (20.0 dBm) * 2432 MHz [5] (20.0 dBm) * 2437 MHz [6] (20.0 dBm) * 2442 MHz [7] (20.0 dBm) * 2447 MHz [8] (20.0 dBm) * 2452 MHz [9] (20.0 dBm) * 2457 MHz [10] (20.0 dBm) * 2462 MHz [11] (20.0 dBm) * 2467 MHz [12] (disabled) * 2472 MHz [13] (disabled) * 2484 MHz [14] (disabled) 后面的【】中的就是channel了。
然后我们使用后台运行的方式启动hostapd，并且打开debug信息，便于我们查看：
root@(none):/# hostapd -B -d /etc/hostapd_ori.conf random: Trying to read entropy from /dev/random Configuration file: /etc/hostapd_ori.conf rfkill: Cannot open RFKILL control device nl80211: RFKILL status not available nl80211: TDLS supported nl80211: TDLS external setup nl80211: Supported cipher 00-0f-ac:1 nl80211: Supported cipher 00-0f-ac:5 nl80211: Supported cipher 00-0f-ac:2 nl80211: Supported cipher 00-0f-ac:4 nl80211: Supported cipher 00-0f-ac:6 nl80211: Using driver-based off-channel TX nl80211: Use separate P2P group interface (driver advertised support) nl80211: interface wlan1 in phy phy1 nl80211: Set mode ifindex 9 iftype 3 (AP) nl80211: Setup AP(wlan1) - device_ap_sme=0 use_monitor=0 nl80211: Subscribe to mgmt frames with AP handle 0xcfd5d8 nl80211: Register frame type=0xb0 (WLAN_FC_STYPE_AUTH) nl_handle=0xcfd5d8 match= nl80211: Register frame type=0x0 (WLAN_FC_STYPE_ASSOC_REQ) nl_handle=0xcfd5d8 match= nl80211: Register frame type=0x20 (WLAN_FC_STYPE_REASSOC_REQ) nl_handle=0xcfd5d8 match= nl80211: Register frame type=0xa0 (WLAN_FC_STYPE_DISASSOC) nl_handle=0xcfd5d8 match= nl80211: Register frame type=0xc0 (WLAN_FC_STYPE_DEAUTH) nl_handle=0xcfd5d8 match= nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0xcfd5d8 match= nl80211: Register frame type=0x40 (WLAN_FC_STYPE_PROBE_REQ) nl_handle=0xcfd5d8 match= [ 495.443813] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready nl80211: Add own interface ifindex 9 nl80211: if_indices[16]: 9 phy: phy1 BSS count 1, BSSID mask 00:00:00:00:00:00 (0 bits) nl80211: Regulatory information - country=00 nl80211: 2402-2472 @ 40 MHz 20 mBm nl80211: 2457-2482 @ 40 MHz 20 mBm (no IR) nl80211: 2474-2494 @ 20 MHz 20 mBm (no OFDM) (no IR) nl80211: 5170-5250 @ 160 MHz 20 mBm (no IR) nl80211: 5250-5330 @ 160 MHz 20 mBm (DFS) (no IR) nl80211: 5490-5730 @ 160 MHz 20 mBm (DFS) (no IR) nl80211: Added 802.11b mode based on 802.11g information Completing interface initialization Mode: IEEE 802.11g Channel: 9 Frequency: 2452 MHz DFS 0 channels required radar detection nl80211: Set freq 2452 (ht_enabled=0, vht_enabled=0, bandwidth=20 MHz, cf1=2452 MHz, cf2=0 MHz) * freq=2452 * vht_enabled=0 * ht_enabled=0 RATE[0] rate=10 flags=0x1 RATE[1] rate=20 flags=0x1 RATE[2] rate=55 flags=0x1 RATE[3] rate=110 flags=0x1 RATE[4] rate=60 flags=0x0 RATE[5] rate=90 flags=0x0 RATE[6] rate=120 flags=0x0 RATE[7] rate=180 flags=0x0 RATE[8] rate=240 flags=0x0 RATE[9] rate=360 flags=0x0 RATE[10] rate=480 flags=0x0 RATE[11] rate=540 flags=0x0 hostapd_setup_bss(hapd=0xcfcf50 (wlan1), first=1) wlan1: Flushing old station entries nl80211: flush -> DEL_STATION wlan1 (all) wlan1: Deauthenticate all stations nl80211: send_mlme - da= ff:ff:ff:ff:ff:ff noack=0 freq=0 no_cck=0 offchanok=0 wait_time=0 fc=0xc0 (WLAN_FC_STYPE_DEAUTH) nlmode=3 nl80211: send_mlme -> send_frame nl80211: send_frame - Use bss->freq=2452 nl80211: send_frame -> send_frame_cmd nl80211: Frame command failed: ret=-16 (Device or resource busy) (freq=2452 wait=0) wpa_driver_nl80211_set_key: ifindex=9 (wlan1) alg=0 addr=(nil) key_idx=0 set_tx=0 seq_len=0 key_len=0 wpa_driver_nl80211_set_key: ifindex=9 (wlan1) alg=0 addr=(nil) key_idx=1 set_tx=0 seq_len=0 key_len=0 wpa_driver_nl80211_set_key: ifindex=9 (wlan1) alg=0 addr=(nil) key_idx=2 set_tx=0 seq_len=0 key_len=0 wpa_driver_nl80211_set_key: ifindex=9 (wlan1) alg=0 addr=(nil) key_idx=3 set_tx=0 seq_len=0 key_len=0 Using interface wlan1 with hwaddr 94:0c:6d:7c:12:f6 and ssid "TonyOpenWRT" Deriving WPA PSK based on passphrase SSID - hexdump_ascii(len=11): 54 6f 6e 79 4f 70 65 6e 57 52 54 TonyOpenWRT PSK (ASCII passphrase) - hexdump_ascii(len=12): [REMOVED] PSK (from passphrase) - hexdump(len=32): [REMOVED] random: Got 15/20 bytes from /dev/random random: Only 15/20 bytes of strong random data available from /dev/random random: Not enough entropy pool available for secure operations WPA: Not enough entropy in random pool for secure operations - update keys later when the first station connects GMK - hexdump(len=32): [REMOVED] Key Counter - hexdump(len=32): [REMOVED] WPA: Delay group state machine start until Beacon frames have been configured nl80211: Set beacon (beacon_set=0) nl80211: Beacon head - hexdump(len=62): 80 00 00 00 ff ff ff ff ff ff 94 0c 6d 7c 12 f6 94 0c 6d 7c 12 f6 00 00 00 00 00 00 00 00 00 00 64 00 11 04 00 0b 54 6f 6e 79 4f 70 65 6e 57 52 54 01 08 82 84 8b 96 0c 12 1y 01 09 nl80211: Beacon tail - hexdump(len=65): 2a 01 04 32 04 30 48 60 6c 30 14 01 00 00 0f ac 02 01 00 00 0f ac 04 01 00 00 0f ac 02 00 00 dd 16 00 50 f2 01 01 00 00 50 f2 02 01 00 00 50 f2 02 01 00 00 50 f2 02 7f 08 00 nl80211: ifindex=9 nl80211: beacon_int=100 nl80211: dtim_period=2 nl80211: ssid - hexdump_ascii(len=11): 54 6f 6e 79 4f 70 65 6e 57 52 54 TonyOpenWRT * beacon_int=100 nl80211: hidden SSID not in use nl80211: privacy=1 nl80211: auth_algs=0x1 nl80211: wpa_version=0x3 nl80211: key_mgmt_suites=0x2 nl80211: pairwise_ciphers=0x18 nl80211: group_cipher=0x8 nl80211: SMPS mode - off nl80211: beacon_ies - hexdump(len=10): 7f 08 00 00 00 00 00 00 00 40 nl80211: proberesp_ies - hexdump(len=10): 7f 08 00 00 00 00 00 00 00 40 nl80211: assocresp_ies - hexdump(len=10): 7f 08 00 00 00 00 00 00 00 40 WPA: Start group state machine to set initial keys WPA: group state machine entering state GTK_INIT (VLAN-ID 0) GTK - hexdump(len=32): [REMOVED] WPA: group state machine entering state SETKEYSDONE (VLAN-ID 0) wpa_driver_nl80211_set_key: ifindex=9 (wlan1) alg=2 addr=0x8dc74 key_idx=1 set_tx=1 seq_len=0 key_len=32 nl80211: KEY_DATA - hexdump(len=32): [REMOVED] broadcast key nl80211: Set wlan1 operstate 0->1 (UP) netlink: Operstate: ifindex=9 linkmode=-1 (no change), operstate=6 (IF_OPER_UP) wlan1: interface state UNINITIALIZED->ENABLED wlan1: AP-ENABLED wlan1: Setup of interface done. ctrl_iface not configured! 其中里面用到了加密时候需要的随机数，这个是使用内核中的random节点来生成的，所以我们在内核这两个还需要添加random驱动。
在验证之前，我们需要给我们的这个网卡自己一个IP地址， 因此直接：
root@(none):/# ifconfig wlan1 192.168.2.1 root@(none):/# ifconfig wlan1 wlan1 Link encap:Ethernet HWaddr 94:0c:6d:7c:12:f6 inet addr:192.168.2.1 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::960c:6dff:fe7c:12f6/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:131 errors:0 dropped:0 overruns:0 frame:0 TX packets:106 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:20162 (19.6 KiB) TX bytes:20954 (20.4 KiB) 然后我们打开手机查看是否可以看到我们的热点：
然后我们使用手动配置IP方式连接热点
连接完成后， 我们可以看到已经连接的状态：
然后在手机上面可以Ping一把确定是否连通：
然后在iMX6UL上面也来ping一把这个手机：
root@(none):/# ping 192.168.2.111 PING 192.168.2.111 (192.168.2.111): 56 data bytes 64 bytes from 192.168.2.111: seq=0 ttl=64 time=90.952 ms 64 bytes from 192.168.2.111: seq=1 ttl=64 time=143.093 ms 64 bytes from 192.168.2.111: seq=2 ttl=64 time=4.508 ms 64 bytes from 192.168.2.111: seq=3 ttl=64 time=46.859 ms 64 bytes from 192.168.2.111: seq=4 ttl=64 time=2.539 ms 64 bytes from 192.168.2.111: seq=5 ttl=64 time=2.697 ms ^C --- 192.168.2.111 ping statistics --- 6 packets transmitted, 6 packets received, 0% packet loss round-trip min/avg/max = 2.539/48.441/143.093 ms 至此，基本的连接就好了， 如果想要自动获取IP地址，那么我们还需要配置DHCPD。
前面我们使用其中一个网卡，配置好了AP， 接下来我们使用另外一个Wireless作为上一级router的接入设备。 这个可以参考我以前写的文章: Yocto i.MX6 (TQIMX6) (03) : wifi网卡的相关工具wpa_supplicant与dhcp 但是wpa_supplicant的版本升级后， 和hostapd的使用基本一致起来， 因此以前的使用方法稍微有些不同了。
创建一个配置文件，写明需要接入的SSID，密码等信息：
root@(none):/# cat /etc/wpa.conf ctrl_interface=/var/run/wpa_supplicant network={ ssid="XXX" proto=WPA key_mgmt=WPA-PSK pairwise=TKIP group=TKIP psk="PASSWORD" } 其中XXX是路由器的热点名字， psk填写Password， 加密方式TKIP需要根据实际情况填写，不明白可以看我以前的文章，或者直接man。
先创建一个runtime目录：
root@(none):/# mkdir /var/run/wpa_supplicant 然后直接在后台运行：
root@(none):/# wpa_supplicant -B -iwlan0 -c /etc/wpa.conf Successfully initialized wpa_supplicant rfkill: Cannot open RFKILL contro[ 172.506937] ieee80211 phy0: rt2x00lib_request_firmware: Info - Loading firmware file 'rt2870.bin' l device [ 172.527112] ieee80211 phy0: rt2x00lib_request_firmware: Info - Firmware detected - version: 0.29 [ 173.083412] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready root@(none):/# [ 174.937567] wlan0: authenticate with bc:d1:77:a0:4f:3c [ 175.073446] wlan0: send auth to bc:d1:77:a0:4f:3c (try 1/3) [ 175.082318] wlan0: authenticated [ 175.087051] rt2800usb 1-1.2.1:1.0 wlan0: disabling HT/VHT due to WEP/TKIP use [ 175.098735] wlan0: associate with bc:d1:77:a0:4f:3c (try 1/3) [ 175.108018] wlan0: RX AssocResp from bc:d1:77:a0:4f:3c (capab=0x411 status=0 aid=5) [ 175.129960] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready [ 175.136678] wlan0: associated [ 176.069997] IPv6: wlan0: IPv6 duplicate address fe80::7edd:90ff:feb2:73b1 detected!
使用wpa_cli看查看连接的状态
root@(none):/# wpa_cli status Selected interface 'wlan0' bssid=bc:d1:77:a0:4f:3c freq=2412 ssid=XXX id=0 mode=station pairwise_cipher=TKIP group_cipher=TKIP key_mgmt=WPA-PSK wpa_state=COMPLETED address=7c:dd:90:b2:73:b1 uuid=1e82e362-f927-544e-aa4d-1a229533944cstatus为COMPLETED那么表示连接上了， 然后我们获取IP地址， 并尝试ping国内的某个网站：
root@(none):/# udhcpc -i wlan0 udhcpc (v1.24.1) started Sending discover... Sending select for 192.168.1.112... Lease of 192.168.1.112 obtained, lease time 86400 /etc/udhcpc.d/50default: Adding DNS 192.168.1.1 /etc/udhcpc.d/50default: Adding DNS 0.0.0.0 root@(none):/# ping meitu.com PING meitu.com (42.62.69.156): 56 data bytes 64 bytes from 42.62.69.156: seq=0 ttl=42 time=44.499 ms 64 bytes from 42.62.69.156: seq=1 ttl=42 time=44.956 ms 64 bytes from 42.62.69.156: seq=2 ttl=42 time=43.122 ms 64 bytes from 42.62.69.156: seq=3 ttl=42 time=43.387 ms 64 bytes from 42.62.69.156: seq=4 ttl=42 time=46.467 ms 64 bytes from 42.62.69.156: seq=5 ttl=42 time=46.267 ms 64 bytes from 42.62.69.156: seq=6 ttl=42 time=43.843 ms ^C --- meitu.com ping statistics --- 7 packets transmitted, 7 packets received, 0% packet loss round-trip min/avg/max = 43.122/44.648/46.467 ms 至此， 我们就完成了基本的配置工作。
