개발 이야기

1.wifi 켜기

# ifconfig wlan0 up

# ifconfig

wlan0 Link encap:Ethernet HWaddr 58:86:94:F7:68:56

UP BROADCAST MULTICAST MTU:1500 Metric:1

RX packets:0 errors:0 dropped:0 overruns:0 frame:0

TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

2.wifi 검색

# iwlist wlan0 scanning | more

Cell 08 - Address: 70:5D:CC:D6:70:C4

ESSID:"iptime"

Protocol:IEEE 802.11bgn

Mode:Master

Frequency:2.442 GHz (Channel 7)

Encryption key:off -> 암호사용 여부

Bit Rates:300 Mb/s

IE: Unknown: DD7A0050F204104A00011010440001021041000100103B000103104700104D73C5C27E6B5243D6440AAB1719670B10210006697054494D4510230008697054494D4541501024000A31323334353637383930104200033336301054000800060050F204000110110008697054494D454150100800020084103C000101

Quality=36/100 Signal level=60/100

Extra:fm=0003

3.wifi 연결

(ESSID이름이 iptime이라면)

# iwconfig wlan0 essid "iptime" 또는 iw dev wlan0 connect iptime

4.wifi 연결 상태 확인

# iw wlan0 link

Connected to 70:5d:cc:d6:70:c4 (on wlan0)

SSID: iptime

freq: 2427

signal: -40 dBm

tx bitrate: 150.0 MBit/s

5.wifi ip 할당

# dhcpcd wlan0

DUID 00:01:00:01:28:01:2d:a0:02:e2:e4:67:2a:e4

wlan0: IAID 94:f7:68:56

wlan0: soliciting a DHCP lease

wlan0: soliciting an IPv6 router

wlan0: offered 192.168.0.7 from 192.168.0.1

wlan0: probing address 192.168.0.7/24

wlan0: leased 192.168.0.7 for 7200 seconds

wlan0: adding route to 192.168.0.0/24

wlan0: adding default route via 192.168.0.1

forked to background, child pid 25434

6.인터넷 연결 테스트

# ping www.google.co.kr

PING www.google.co.kr (172.217.31.163): 56 data bytes

64 bytes from 172.217.31.163: seq=0 ttl=52 time=40.399 ms

64 bytes from 172.217.31.163: seq=1 ttl=52 time=35.684 ms

7.wifi ip 연결 정보

# ip a 또는 ip addr show

15: wlan0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq qlen 1000

link/ether 58:86:94:f7:68:56 brd ff:ff:ff:ff:ff:ff

8.wifi 설정 및 연결 스크립트

위의 순서를 스크립트를 활용하여 한번에 처리

#wpa_supplicant -B -i wlan0 -c /etc/wpa_supplicant.conf

#wpa_cli -i wlan0 reconfigure

스크립트 구성

network={

ssid=공유기이름

psk=공유기 접속 비밀번호

scan_ssid=1 -> 숨겨진 ssid에 접속하기 위해서는 1로 설정해야 함

}

참고)

https://www.daemon-systems.org/man/wpa_supplicant.conf.5.html

https://gist.github.com/windows98SE/8a8a59cc5d5d9d0b2ed2

https://webnautes.tistory.com/141

https://hiseon.me/linux/command/linux-wifi-command-line/

https://jung-max.github.io/2021/04/08/%EB%9D%BC%EC%A6%88%EB%B2%A0%EB%A6%AC%ED%8C%8C%EC%9D%B4-%EC%88%A8%EA%B2%A8%EC%A7%84(%ED%9E%88%EB%93%A0)%EC%99%80%EC%9D%B4%ED%8C%8C%EC%9D%B4-%EC%84%A4%EC%A0%95/

https://www.linuxbabe.com/command-line/ubuntu-server-16-04-wifi-wpa-supplicant

https://www.linuxadictos.com/ko/como-conectarnos-a-una-red-wi-fi-oculta-desde-nuestra-raspberry-pi.html

https://webstory.postach.io/post/rajeuberipai-rajeubian-wifi-keomaendeu-rain-setingbangbeob

https://wikidocs.net/3200

https://mandoo12.tistory.com/entry/wpasupplicant%EB%A5%BC-%EC%9D%B4%EC%9A%A9%ED%95%9C-WiFi-%EC%A0%91%EC%86%8D

https://www.lesstif.com/lpt/linux-tee-89556049.html

9.기타 명령어

• • wifi ip 연결 정보

# wpa_cli status

Selected interface 'wlan0'

bssid=70:5d:cc:d6:70:c4

freq=2427

ssid=iptime

id=0

id_str=school

mode=station

pairwise_cipher=CCMP

group_cipher=CCMP

key_mgmt=WPA2-PSK

wpa_state=COMPLETED

ip_address=192.168.0.7 : 외부와 통신이 안될 때는 ip_address가 보이지 않는다.

p2p_device_address=58:86:94:f7:68:56

address=58:86:94:f7:68:56

uuid=f97f4363-d017-5f52-8af7-63941e8d1418

• • wifi ip 연결 정보

# ip r

default via 192.168.0.1 dev wlan0 src 192.168.0.7 metric 304

192.168.0.0/24 dev wlan0 src 192.168.0.7 metric 304

• • wifi 특정 공유기 grep

# iwlist wlan0 scanning | grep ESSID:\"iptime\" -A9

ESSID:"iptime"

Protocol:IEEE 802.11bgn

Mode:Master

Frequency:2.427 GHz (Channel 4)

Encryption key:off

Bit Rates:300 Mb/s

IE: Unknown: DD7A0050F204104A00011010440001021041000100103B000103104700104D73C5C27E6B5243D6440AAB1719670B10210006697054494D4510230008697054494D4541501024000A31323334353637383930104200033336301054000800060050F204000110110008697054494D454150100800020084103C000101

Quality=91/100 Signal level=63/100

Extra:fm=0003

• • wifi 동작상태

# cat /sys/class/net/wlan0/operstate

동작상태에 따라 down 또는 up이라고 표시됨

• • wifi 검색

# iwlist wlan0 scanning | more

• • wifi 하드웨어 검색

# iw dev

phy#11

Interface wlan0

ifindex 15

wdev 0xb00000001

addr 58:86:94:f7:68:56

type managed

• • wifi 상태 검색

# iwconfig

wlan0 unassociated Nickname:"<WIFI@REALTEK>"

Mode:Managed Frequency=2.412 GHz Access Point: Not-Associated

Sensitivity:0/0

Retry:off RTS thr:off Fragment thr:off

Encryption key:off

Power Management:off

Link Quality:0 Signal level:0 Noise level:0

Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0

Tx excessive retries:0 Invalid misc:0 Missed beacon:0

sit0 no wireless extensions.

lo no wireless extensions.

eth0 no wireless extensions.

//-----------------------------------

1.참고사이트

https://easylinuxtipsproject.blogspot.com/p/realtek.html?m=1

https://stackoverflow.com/questions/56619504/can-i-get-ssid-and-mac-address-from-c-code-in-linux

SIOCGIWESSID

https://hiseon.me/linux/command/linux-wifi-command-line/

https://changun516.tistory.com/120

http://blog.ajhodges.com/2011/10/using-ioctl-to-gather-wifi-information.html

https://webnautes.tistory.com/141

https://wiki.gentoo.org/wiki/Network_management_using_DHCPCD/ko

https://raspberrypi.stackexchange.com/questions/84277/failed-to-connect-to-non-global-ctrl-ifname-wlan0-error-no-such-file-or-direct

2. iwconfig

https://markspeople.tistory.com/72

3. dhcpcd

https://blog-jooso.tistory.com/4

https://webterror.net/2012/02/19/866/

https://wiki.archlinux.org/title/wpa_supplicant

https://hybridego.net/entry/iw-wpasupplicant

https://www.ibm.com/docs/ko/aix/7.2?topic=d-dhcpcd-daemon

https://hybridego.net/entry/iw-wpasupplicant

https://m.blog.naver.com/PostView.naver?isHttpsRedirect=true&blogId=sigsaly&logNo=220409271175

https://m.blog.naver.com/21ahn/221308950395

http://eve24.tistory.com/1

https://blog.naver.com/damtaja/222974920693

https://hybridego.net/entry/iw-wpasupplicant

https://android.googlesource.com/platform/external/wpa_supplicant_8/+/master/wpa_supplicant/wpa_supplicant.conf

3. rssi

https://blog.naver.com/PostView.nhn?isHttpsRedirect=true&blogId=ddol213&logNo=90023933458