archlinux - tricky wifi configuration

For some reason I cannot explain, the wireless adapter in my old laptop Compaq Presario V3000 gets both Soft and Hard blocked. As a result, the connection to a wireless access point is not possible either using # wifi-menu or # netctl.

The solution:

1. Check whether the wireless lan is blocked:

# rfkill list


2. In case it is hard blocked, then unblock it:

# rfkill unblock wifi

3. Run the wifi-menu, connect to the wlan and generate the profile (/etc/netctl/<profile_name>)

4. Make the netctl auto start at boot:

# netctl enable <profile_name>

To run all these commands, maybe it's necessary to install some packages:

- rfkill
- wpa_supplicant
- wpa_supplicant_gui
- iw
- wireless_tools
- dialog


References:
- https://wiki.archlinux.org/index.php/Wireless_network_configuration#Rfkill_caveat