Centos wireless Nic Configuration

Centos wireless Nic Configuration


I have a notebook that is not commonly used. It is a centos system. When I accidentally press Fn at a time, the network is no longer available. Afterwards, I finally got it and took a note.
1. Check whether the driver is still running
$ Lspci | grep Network
. 0 Network controller: Realtek semiconduco., Ltd. RTL8188CE 802.11b/g/n WiFi Adapter (rev 01)
If the NIC information appears, the driver is normal and the configuration is incorrect.

2. view the NIC status
$ Ifconfig wlan0
Wlan0 Link encap: Ethernet HWaddr 7c: 4f: b5: 73: b4: be
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 FIG: 1000
RX bytes: 0 (0.0 B) TX bytes: 0 (0.0 B)
$ Iwconfig wlan0
Wlan0 IEEE 802.11bgn ESSID: off/any
Mode: Managed Access Point: Not-Associated Tx-Power = 20 dBm
Retry long limit: 7 RTS thr = 2347 B Fragment thr: off
Power Management: off
Tips: If Tx-Power = off, You need to enable the wireless Nic Power.
Iwconfig wlan0 txpower on

3. Scan the network
$ Sudo iwlist wlan0 scan
Wlan0 Scan completed:
Edited to only show the relevant network
Cell 04-Address: 00: 16: 01: 12: E7: 5E
Channel: 6
Frequency: 2.437 GHz (Channel 6)
Quality = 64/70 Signal level =-46 dBm
Encryption key: off
ESSID: "aprk"
Bit Rates: 1 Mb/s, 2 Mb/s, 5.5 Mb/s, 11 Mb/s, 18 Mb/s
24 Mb/s; 36 Mb/s; 54 Mb/s
Bit Rates: 6 Mb/s; 9 Mb/s; 12 Mb/s; 48 Mb/s
Mode: Master
Extra: tsf = rj0000b6d6419d
Extra: Last beacon: 224 ms ago
IE: Unknown: 0009666f6f626172776133
IE: Unknown: 010882848B962430486C
IE: Unknown: 030106
IE: Unknown: 2A0102
IE: Unknown: 2F0102
IE: Unknown: 32040C121860
IE: Unknown: DD090010180201F0000000
IE: Unknown: dd180050f202010183163a4000027a40000000035e0062322f00

4. Set the network
$ Sudo iwconfig wlan0 essid "aprk"
Check whether the ssid is set successfully.
Wlan0 IEEE 802.11bgn ESSID: off/any
Mode: Managed Access Point: Not-Associated Tx-Power = 20 dBm
Retry long limit: 7 RTS thr = 2347 B Fragment thr: off
Encryption key: off
Power Management: off
Setting failed. This problem occurs repeatedly. Try to add parameters.
Sudo iwconfig wlan0 key open mode Managed essid "aprk" channel 6
Check whether the ssid is set successfully.
$ Sudo iwconfig wlan0 # check to see if settings took hold this time
Wlan0 IEEE 802.11bgn ESSID: "aprk"
Mode: Managed Frequency: 2.437 GHz Access Point: Not-Associated
Tx-Power = 20 dBm
Retry long limit: 7 RTS thr = 2347 B Fragment thr: off
Encryption key: off
Power Management: off
The network supports wep Encryption by default. We recommend that you set the network without a password and then add it again.

5. enable dhcp, get the ip address, and connect to it.
$ Sudo dhclient-v wlan0
Internet Systems Consortium DHCP Client 4.1.1-P1
Copyright 2004-2010 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/


Listening on LPF/wlan0/7c: 4f: b5: 73: b4: be
Sending on LPF/wlan0/7c: 4f: b5: 73: b4: be
Sending on Socket/fallback
DHCPDISCOVER on wlan0 to strongswan 255 port 67 interval 3
DHCPDISCOVER on wlan0 to strongswan 255 port 67 interval 6
DHCPDISCOVER on wlan0 to strongswan 255 port 67 interval 11
DHCPDISCOVER on wlan0 to strongswan 255 port 67 interval 17
DHCPDISCOVER on wlan0 to strongswan 255 port 67 interval 15
DHCPDISCOVER on wlan0 to strongswan 255 port 67 interval 9
No DHCPOFFERS already ed.
No working leases in persistent database-sleeping.


6. Networking successful
Install networkmanager, which can have a graphical interface.
$ Sudo yum install NetworkManager-gnome # adjust it based on your desktop environment

7. Last
The vro adds a password to the wifi and reboot the computer. Then the network settings icon will appear!