Using wget to fetch a directory

wget -r --no-parent --reject "index.html*" http://mysite.com/configs/.vim/


Reference:
http://stackoverflow.com/questions/273743/using-wget-to-recursively-fetch-a-directory-with-arbitrary-files-in-it

How to make sure you have USB 3.0-capable hardware

Look for logo near the USB port

USB 2.0 logo

USB 3.0 logo

View device information in Device Manager
Next, confirm that Windows enumerated the host controller as a USB 3.0 controller. To confirm that, open Device Manager and locate the controller under the Universal Serial Bus controllers node. If Windows recognized it as a USB 3.0 controller, USB 3.0 eXtensible Host Controller is appended to the device description.

Reference:
http://blogs.msdn.com/b/usbcoreblog/archive/2012/06/27/how-to-determine-whether-a-usb-3-0-device-is-operating-at-superspeed.aspx

Why is 802.11ac 5 GHz only?

The most obvious place that speed comes from in 802.11ac is wider channels. Just as 802.11n provided a big speed boost by doubling channel width from 20 MHz to 40 MHz, 802.11ac uses 80 MHz and 160 MHz channels. With only 83 MHz of spectrum available at 2.4 GHz, there is only one channel available that too you are at the mercy all other devices keeping out of your way.

802.11ac’s second big feature to boost speed is 256-QAM, which requires clean spectrum to keep your error vectors small.

Reference:
http://blogs.aerohive.com/blog/the-wi-fi-security-blog/why-is-80211ac-5-ghz-only

Volume Serial Number

A volume serial number is created based on a fairly complex combination of the year, hour, month, second, and hundredth of a second that the drive was formatted. VSN will change each time the drive is formatted.

Since volume serial numbers are not generated at random and without knowledge of the volume serial numbers on other drives in the computer, there's a chance that two drives on the same computer could end up having the same volume serial number. However, the chance is infinitesimally small and isn't considered a concern.

A drive's volume serial number is not the same as the manufacture serial number of the drive.

C:\>vol
 Volume in drive C has no label.
 Volume Serial Number is A000-DC1E

C:\>vol d:
 Volume in drive D is DATA
 Volume Serial Number is F9AC-F19C

Reference:
http://pcsupport.about.com/od/termsv/g/volume-serial-number.htm
http://pcsupport.about.com/od/commandlinereference/p/vol-command.htm
http://www.wildpackets.com/support/activation_faqs

Linux Wireless

Wireless Extension: a generic driver API that allows user space configuration on Wireless LAN interface (IOCTL based).

cfg80211: Kernel side of configuration management for wireless device

nl80211: User-space side of configuration management for wireless devices. It is a Netlink-based user-space protocol.

iw: iw is a new nl80211 based CLI configuration utility for wireless devices.

MLME: MLME is the management entity where the Physical layer (PHY) MAC state machines reside. ex:- authenticate, disassociate etc...

FullMAC: FullMAC is a term used to describe a type of wireless card where the MLME is managed in hardware.

Reference:
http://wireless.kernel.org/en/developers/Documentation/Glossary
http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/Tools.html
http://wireless.kernel.org/en/developers/Documentation/Wireless-Extensions

RGMII,SGMII,XAUI

MII   - Media Independent Interface - 100 Mbps
GMII  - Gigabit MII - 1 Gbps (24 pins) (8TX - 8RX)
RGMII - Reduced GMII - 1 Gbps (12 pins) (4TX - 4RX)
SGMII - Serial GMII - 1 Gbps (8 pins) (2TX - 2RX)
XAUI  - XGMII Extender - 10 Gbps (XY pins) (8TX - 8RX)
SPI-4.2 - System Packet Interface Level 4, Phase 2 (16TX - 16RX)

The Media Independent Interface (MII) is a standard interface used to connect a Fast Ethernet (i.e. 100Mb/s) MAC-block to a PHY. The MII may connect to an external transceiver device via a pluggable connector or simply connect two chips on the same printed circuit board. Being media independent means that any of several different types of PHY devices can be used without redesigning or replacing the MAC hardware.

Gigabit Media Independent Interface (GMII) is an interface between the Media Access Control (MAC) device and the physical layer (PHY). The interface defines speeds up to 1000 Mbit/s, implemented using an eight bit data interface clocked at 125 MHz, and is backwards compatible with the Media Independent Interface (MII) specification.

Reduced Gigabit Media Independent Interface (RGMII) specifies a particular interface between an Ethernet MAC and PHY. RGMII uses half the number of pins as used in the GMII interface. This reduction is achieved by clocking data on both the rising and falling edges of the clock, and by eliminating non-essential signals (carrier-sense and collision-indication). Thus RGMII consists only of: RXC, RD[3:0], RX_CTL, TXC, TXD[3:0], and TX_CTL (12 pins, as opposed to GMII's 24).

The Serial Gigabit Media Independent Interface (SGMII) is a sequel of MII, a standard interface used to connect an Ethernet MAC-block to a PHY. It differs from GMII by its low-power and low pin count serial interface (commonly referred to as a SerDes).

XAUI is a standard for extending the XGMII (10 Gigabit Media Independent Interface) between the MAC and PHY layer of 10 Gigabit Ethernet (10GbE). XAUI is pronounced "zowie", a concatenation of the Roman numeral X, meaning ten, and the initials of "Attachment Unit Interface".

Reference:
http://uiway.blogspot.sg/2009/03/rgmiisgmiixaui.html
http://www.altera.com/technology/high_speed/protocols/spi_42/pro-spi_4.2.html