场景：
openwrtWIFI当做sta，连接上级AP，其他外设比如手机、pc设备连接到openwrt的局域网，通过openwrt访问外网。
dhcp配置：
config dnsmasq
option domainneeded 1
option boguspriv 1
option filterwin2k 0 # enable for dial on demand
option localise_queries 1
option rebind_protection 1 # disable if upstream must serve RFC1918 addresses
option rebind_localhost 1 # enable for RBL checking and similar services
#list rebind_domain example.lan # whitelist RFC1918 responses for domains
option local '/lan/'
option domain 'lan'
option expandhosts 1
option nonegcache 0
option authoritative 1
option readethers 1
option leasefile '/tmp/dhcp.leases'
option resolvfile '/tmp/resolv.conf.auto'
#list server '/mycompany.local/1.2.3.4'
option nonwildcard 1 # bind to & keep track of interfaces
#list interface br-lan
#list notinterface lo
#list bogusnxdomain '64.94.110.11'
option localservice 1 # disable to allow DNS requests from non-local subnets
config dhcp lan
option interface lan
option start 100
option limit 150
option leasetime 12h
config dhcp wan
option interface wan
option ignore 1
network配置：
config interface 'loopback'
option ifname 'lo'
option proto 'static'
option ipaddr '127.0.0.1'
option netmask '255.0.0.0'
config globals 'globals'
option ula_prefix 'fd41:6975:8c8b::/48'
config interface 'wan'
option ifname 'eth0.1'
option proto 'dhcp'
config interface 'Wwan'
option proto 'dhcp'
config device 'wan_dev'
option name 'eth0.1'
option macaddr '00:0c:24:09:76:28'
config interface 'wan6'
option ifname 'eth0.1'
option proto 'dhcpv6'
config interface 'lan'
option type 'bridge'
option ifname 'eth0.2'
option proto 'static'
option ipaddr '10.10.10.254'
option netmask '255.255.255.0'
option ip6assign '60'
config device 'lan_dev'
option name 'eth0.2'
option macaddr '00:0c:24:09:76:27'
config switch
option name 'switch0'
option reset '1'
option enable_vlan '1'
config switch_vlan
option device 'switch0'
option vlan '1'
option ports '0 6t'
config switch_vlan
option device 'switch0'
option vlan '2'
option ports '1 2 3 4 6t'
wireless配置
config wifi-device 'radio0'
option type 'mac80211'
option channel '11'
option hwmode '11g'
option path 'platform/10300000.wmac'
option htmode 'HT20'
option disabled '0'
config wifi-iface 'default_radio0'
option device 'radio0'
option network 'Wwan'
option mode 'sta'
option encryption 'psk2'
option ssid 'ssid—name'
option key 'password'
firewall配置
config defaults
option syn_flood 1
option input ACCEPT
option output ACCEPT
option forward REJECT
# Uncomment this line to disable ipv6 rules
# option disable_ipv6 1
config zone
option name lan
list network 'lan'
option input ACCEPT
option output ACCEPT
option forward ACCEPT
config zone
option name wan
list network 'wan'
list network 'wan6'
list network 'Wwan'
option input REJECT
option output ACCEPT
option forward REJECT
option masq 1
option mtu_fix 1
config forwarding
option src lan
option dest wan
# We need to accept udp packets on port 68,
# see https://dev.openwrt.org/ticket/4108
config rule
option name Allow-DHCP-Renew
option src wan
option proto udp
option dest_port 68
option target ACCEPT
option family ipv4
# Allow IPv4 ping
config rule
option name Allow-Ping
option src wan
option proto icmp
option icmp_type echo-request
option family ipv4
option target ACCEPT
config rule
option name Allow-IGMP
option src wan
option proto igmp
option family ipv4
option target ACCEPT
# Allow DHCPv6 replies
# see https://dev.openwrt.org/ticket/10381
config rule
option name Allow-DHCPv6
option src wan
option proto udp
option src_ip fc00::/6
option dest_ip fc00::/6
option dest_port 546
option family ipv6
option target ACCEPT
config rule
option name Allow-MLD
option src wan
option proto icmp
option src_ip fe80::/10
list icmp_type '130/0'
list icmp_type '131/0'
list icmp_type '132/0'
list icmp_type '143/0'
option family ipv6
option target ACCEPT
# Allow essential incoming IPv6 ICMP traffic
config rule
option name Allow-ICMPv6-Input
option src wan
option proto icmp
list icmp_type echo-request
list icmp_type echo-reply
list icmp_type destination-unreachable
list icmp_type packet-too-big
list icmp_type time-exceeded
list icmp_type bad-header
list icmp_type unknown-header-type
list icmp_type router-solicitation
list icmp_type neighbour-solicitation
list icmp_type router-advertisement
list icmp_type neighbour-advertisement
option limit 1000/sec
option family ipv6
option target ACCEPT
# Allow essential forwarded IPv6 ICMP traffic
config rule
option name Allow-ICMPv6-Forward
option src wan
option dest *
option proto icmp
list icmp_type echo-request
list icmp_type echo-reply
list icmp_type destination-unreachable
list icmp_type packet-too-big
list icmp_type time-exceeded
list icmp_type bad-header
list icmp_type unknown-header-type
option limit 1000/sec
option family ipv6
option target ACCEPT
config rule
option name Allow-IPSec-ESP
option src wan
option dest lan
option proto esp
option target ACCEPT
config rule
option name Allow-ISAKMP
option src wan
option dest lan
option dest_port 500
option proto udp
option target ACCEPT
# include a file with users custom iptables rules
config include
option path /etc/firewall.user
### EXAMPLE CONFIG SECTIONS
# do not allow a specific ip to access wan
#config rule
# option src lan
# option src_ip 192.168.45.2
# option dest wan
# option proto tcp
# option target REJECT
# block a specific mac on wan
#config rule
# option dest wan
# option src_mac 00:11:22:33:44:66
# option target REJECT
# block incoming ICMP traffic on a zone
#config rule
# option src lan
# option proto ICMP
# option target DROP
# port redirect port coming in on wan to lan
#config redirect
# option src wan
# option src_dport 80
# option dest lan
# option dest_ip 192.168.16.235
# option dest_port 80
# option proto tcp
# port redirect of remapped ssh port (22001) on wan
#config redirect
# option src wan
# option src_dport 22001
# option dest lan
# option dest_port 22
# option proto tcp
### FULL CONFIG SECTIONS
#config rule
# option src lan
# option src_ip 192.168.45.2
# option src_mac 00:11:22:33:44:55
# option src_port 80
# option dest wan
# option dest_ip 194.25.2.129
# option dest_port 120
# option proto tcp
# option target REJECT
#config redirect
# option src lan
# option src_ip 192.168.45.2
# option src_mac 00:11:22:33:44:55
# option src_port 1024
# option src_dport 80
# option dest_ip 194.25.2.129
# option dest_port 120
# option proto tcp
config rule
option name 'Allow-SSH'
option target ACCEPT
option src 'wan'
option dest_port '22'
option proto 'tcp'
option family 'ipv4'
config rule
option name 'Allow-http'
option src wan
option dest_port 80
option target ACCEPT
option proto tcp
配置基本完成，作为sta连接到ap，需要不同的加密方式，比如none、wep、wpa、wpa2等，如果仅仅是none、wep格式直接用iw connect即可完成连接，其他的加密方式，则需要用到 wpa_supplicant，使用方法如下：
wpa_supplicant -Dnl80211 -iwlan0 -c/etc/wpa_supplicant.conf -B
-B是后台进行wifi的连接，
-c/etc/wpa_supplicant.conf 是要连接的ap的配置信息，比如ssid名，key等，因此再运行这条命令之前需要在/etc目录下建立wpa_supplicant.conf 文件输入以下内容：
network{
ssid=“ssid—name”
psk=“password”
}
或者用以下命令自动生成这个配置文件
wpa_passphrase "<wifi_ssid>" "<password>" >> /etc/wpa_supplicant.conf
最后可以使用如下命令来查看wifi连接状态
iw dev wlan0 link
注：wlan0是本人开发板上的wifi设备。
至此，所有连接到openwrt局域网内的设备，均可以通过openwrt访问上级ap，若是上级ap可以访问外网，则openwrt局域网内的所有设备均可以访问外网，相当于openwrt是个无线网卡；
该配置有个缺点是：当wifi连接后，再断开wifi，通过有线连接openwrt开发板的wan口，另一端连接上级ap的lan口，此时openwrt不能访问外网，但是可以访问上级ap的局域网；也就是不能完成有线wan口和sta模式共存……