Linux Disable Wireless Networking ( Wi-Fi )

We have over 20+ Dell Precision M6400 laptops pre installed with Red Hat Enterprise Linux version 5.x. I was asked to disable Wi-Fi on all laptops as it poses a serious security risk to our sensitive (classified) systems and networks. How do I disable wireless networking (802.11) under Linux?

You can easily disable Wi-Fi under Linux using the following techniques.

Remove Wireless Hardware

This is the best solution. Find out wireless hardware and if possible remove it. Refer to your laptops’s hardware manual which should contain information on its wireless capabilities. A mini-PCI card is typically accessible via a removable slot of the laptop. Some laptop comes with USB wireless device. Use the following commands to list installed devices (list PCI devices):
# lspci
List usb devices:
# lsusb

Disable Wireless in BIOS

Many laptops includes wireless support via BIOS. You can go to your BIOS setup and disable wireless. Again, read your laptops manual.

Disable Wireless Drivers

cd to /lib/modules/$(uname -r)/kernel/drivers/net/wireless and remove wireless driver. A simple solution as follows should work:
# mkdir -p /root/backup/
# mv /lib/modules/$(uname -r)/kernel/drivers/net/wireless /root/backup/
# reboot
Above will remove the kernel drivers that provide support for wireless devices and it will prevent users from easily activating the devices. Please note that you need to repeat above commands every time the kernel is upgraded.

Deactivate Wireless Interfaces ( Remove Config Files)

You can also deactive the wireless interfaces as normal user can not touch config file without root level access. Open terminal and type the following command to list the wireless interface:
# ifconfig -a
Usually, wireless interfaces may have names like wlan0, ath0, wifi0, or eth0:
Sample Outputs:

eth0      Link encap:Ethernet  HWaddr 00:19:d1:2a:ba:a8
          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)
          Memory:e3180000-e31a0000
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:16436  Metric:1
          RX packets:2475 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2475 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:330752 (330.7 KB)  TX bytes:330752 (330.7 KB)
ppp0      Link encap:Point-to-Point Protocol
          inet addr:10.1.3.49  P-t-P:10.0.31.18  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1496  Metric:1
          RX packets:230 errors:0 dropped:0 overruns:0 frame:0
          TX packets:496 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:37976 (37.9 KB)  TX bytes:47460 (47.4 KB)
wlan0     Link encap:Ethernet  HWaddr 00:1e:2a:47:42:8d
          inet addr:192.168.1.100  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::21e:2aff:fe47:428d/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:908222 errors:0 dropped:0 overruns:0 frame:0
          TX packets:837085 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:787222721 (787.2 MB)  TX bytes:322049568 (322.0 MB)
          Interrupt:18 Memory:e3000000-e3010000

Turn of wireless interfaces after identifying the same with ifdown command:
# ifdown interface
# ifdown wlan0
Finally, remove wireless configuration file /etc/sysconfig/network-scripts/ifcfg-interfaceName. In above example you should use interface config file /etc/sysconfig/network-scripts/ifcfg-wlan0:
# mv /etc/sysconfig/network-scripts/ifcfg-wlan0 /root/backup
OR just remove config file, enter:
# rm /etc/sysconfig/network-scripts/ifcfg-wlan0
Above will make sure wlan0 will not return after the next reboot.

How Do I Restore Wi-Fi Again?

Just copy back all files and reboot the system:
# mv /root/backup/ifcfg-wlan0 /etc/sysconfig/network-scripts/ifcfg-wlan0
# mv /root/backup/wireless /lib/modules/$(uname -r)/kernel/drivers/net/wireless
# reboot

A Note About Debian / Ubuntu Systems

You need to edit /etc/network/interfaces file to remove wireless configuration.
You need to remove /lib/modules/$(uname -r)/kernel/drivers/net/wireless directory.