Debian 8 (Jessie)：更新後無法連接到 WIFI

我最近更新了我的 Debian 8 作業系統。從那以後，我一直無法連接到wifi。LAN 工作正常。請參閱下面的命令輸出範例：

frank@debian8:~$ sudo iwlist wlan0 scan
wlan0     Interface doesn't support scanning.


frank@debian8:~$ sudo iwconfig
lo        no wireless extensions.
eth0      no wireless extensions.


frank@debian8:~$ sudo ifconfig -a
eth0      Link encap:Ethernet  HWaddr 34:e6:d7:1e:50:21  
         inet addr:10.68.77.173  Bcast:10.68.77.255  Mask:255.255.255.128
         inet6 addr: fe80::36e6:d7ff:fe1e:5021/64 Scope:Link
         UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
         RX packets:9246 errors:0 dropped:0 overruns:0 frame:0
         TX packets:9323 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000 
         RX bytes:7078862 (6.7 MiB)  TX bytes:2001113 (1.9 MiB)
         Interrupt:20 Memory:f7400000-f7420000 

lo        Link encap:Local Loopback  
         inet addr:127.0.0.1  Mask:255.0.0.0
         inet6 addr: ::1/128 Scope:Host
         UP LOOPBACK RUNNING  MTU:65536  Metric:1
         RX packets:925 errors:0 dropped:0 overruns:0 frame:0
         TX packets:925 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1 
         RX bytes:104194 (101.7 KiB)  TX bytes:104194 (101.7 KiB)

frank@debian8:~$ lspci -vnn | grep -i net
00:19.0 Ethernet controller [0200]: Intel Corporation Ethernet Connection I218-LM [8086:155a] (rev 04)
02:00.0 Network controller [0280]: Intel Corporation Wireless 7260 [8086:08b1] (rev 73)


frank@debian8:~$ sudo dmesg|grep 'firmw\|wl'
[    4.588961] iwlwifi 0000:02:00.0: firmware: failed to load iwlwifi-7260-17.ucode (-2)
[    4.589058] iwlwifi 0000:02:00.0: Direct firmware load for iwlwifi-7260-17.ucode failed with error -2


frank@debian8:~$ sudo rfkill unblock all ; sudo ip link set wlan0 up
Cannot find device "wlan0"


frank@debian8:~$ lspci -knn | grep Net -A2
02:00.0 Network controller [0280]: Intel Corporation Wireless 7260 [8086:08b1] (rev 73)
   Subsystem: Intel Corporation Dual Band Wireless-AC 7260 [8086:4470]
03:00.0 3D controller [0302]: NVIDIA Corporation GF117M [GeForce 610M/710M/820M / GT 620M/625M/630M/720M] [10de:1140] (rev a1)


frank@debian8:~$ sudo rfkill list
1: dell-wifi: Wireless LAN
   Soft blocked: no
   Hard blocked: no
2: dell-bluetooth: Bluetooth
   Soft blocked: no
   Hard blocked: no
3: hci0: Bluetooth
   Soft blocked: no
   Hard blocked: no

我使用的是戴爾 Latitude E5440。

更新：

更多命令輸出：

frank@debian8:~$ lsmod | grep dell
dell_laptop            20480  0 
dell_smbios            16384  1 dell_laptop
dcdbas                 16384  1 dell_smbios
dell_smm_hwmon         16384  0 
video                  40960  3 dell_laptop,nouveau,i915
dell_smo8800           16384  0 
dell_rbtn              16384  1 
rfkill                 24576  5 bluetooth,dell_laptop,dell_rbtn,cfg80211

根據Intel的說法，Intel® Dual Band Wireless-AC 7260應該可以在核心版本 4.1 及更高版本上執行。

添加backports到您的/etc/apt/sources.list：

deb http://deb.debian.org/debian jessie-backports main contrib non-free

從 backports 保存並安裝新核心：

sudo apt-get update
sudo apt-get install linux-image-4.9.0-0.bpo.3-amd64
sudo reboot
sudo modprobe -r iwlwifi
sudo modprobe iwlwifi

缺少的依賴項應該通過apt-get install -t jessie-backports package-name.

從後端安裝韌體並執行這些命令為我做了。

apt-get install -t jessie-backports firmware-iwlwifi
modprobe iwlwifi
rfkill unblock all

重新啟動後，我可以使用wlan0.

引用自：https://unix.stackexchange.com/questions/395161