Humble's Blog: wireless

Showing posts with label wireless. Show all posts

23 June 2015

Using PEAP for wireless authentication

PEAP creates an encrypted TLS tunnel between the client and the authentication server. The keys for this encryption are transported using the server's public key. The ensuing exchange of authentication information inside the tunnel to authenticate the client is then encrypted and user credentials are safe from eavesdropping.

Use a trusted certificate for authentication: The RADIUS server must be configured with a digital certificate that is signed by a trusted certificate authority (CA), using a private or a public CA.
Validate the server certificate on all clients: All PEAP clients must validate the server certificate for authentication. A Trusted Root CA, that issued the server certificate, must be installed in client.

Reference:
http://www.networkworld.com/columnists/2007/042307-wireless-security.html
http://revolutionwifi.blogspot.com/2010/09/peapv0-packet-flow-reference.html
http://www.keyboardlife.net/2010/06/8021x-port-based-authentication-wired.html

22 June 2015

SA Query

use case of SA Query procedure
A client might lose its encryption keys due to a card reset or reboot and needs to (re-)associate itself. Since he lost all his keys, he sends an unprotected Association Request Frame. The AP still has a valid association from the client with keys in his client table, so the AP will first of all reject the Association and tell the client to try again in “X” seconds. After that, the AP tries to find out if this is an attack and the actual client can still answer protected frames.

The mechanism for that check is the Source Address (SA) Query phase, which starts with a protected SA Query Request from the AP to the client. If the client is unable to answer them until the comeback timeout “X” expires, the AP will send out a protected Disassociate and discards the keys for the no longer valid association of the client. As of now, a new (unprotected) Association Request from the client will be accepted.

Reference:
https://wlan1nde.wordpress.com/2014/10/21/protected-management-frames-802-11w

01 November 2014

IEEE and Wi-Fi Alliance

>>> IEEE 802.11 standardizes WLAN technical specifications.
>>> The Wi-Fi Alliance creates certification programs for WLAN products.

Wi-Fi Direct (P2P) is a standard developed by the Wi-Fi Alliance. Wi-Fi Direct is not a standard created or maintained by the IEEE and as such there are no current plans to incorporate it into any IEEE standard.

Wi-Fi certification program formulation procedure:
1. Marketing TG (MTG) is established.
2. In the MTG, a Statement of Work (SoW) and a Marketing Requirements Document (MRD) are created.
3. Technical TG (TTG) is established and a Wi-Fi test plan is developed for the Wi-Fi certification.
4. Plugfest is held by member companies for testbed development, device selection, and connectivity verification.
5. Wi-Fi Certification, without waiting for the completion of IEEE 802.11 standards.

Reference:
https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr201004gls.html
http://networkengineering.stackexchange.com/questions/9675/does-ieee-802-11ac-imply-wi-fi-direct-compatibility

Fine Timing Measurement

distance = c * [ (t4-t1) – (t3-t2) ]
where “c” is speed of the light.

Reference:
https://mentor.ieee.org/802.11/dcn/13/11-13-0995-01-00ak-802-1as-synchronization-services-for-802-11ak-links.pptx
https://mentor.ieee.org/802.11/dcn/13/11-13-1178-00-000m-resolution-for-draft-1-0-lb-cid-s-cids-1424-1671-1418.docx

23 October 2012

802.11n deployment strategie

To achieve maximum output, a pure 802.11n 5 GHz network is recommended. The 5 GHz band has substantial capacity due to many non-overlapping radio channels and less radio interference as compared to the 2.4 GHz band. An 802.11n-only network may be impractical for many users because they need to support legacy equipment that still is 802.11b/g only. Consequently, it may be more practical in the short term to operate a mixed 802.11b/g/n network until 802.11n hardware becomes more prevalent.

In a mixed-mode system, an optimal solution would be to use a dual-radio access point and place the 802.11b/g traffic on the 2.4 GHz radio and the 802.11n traffic on the 5 GHz radio. This setup assumes that all the 802.11n clients are 5 GHz capable. A technique called "band steering" is used to send 802.11n clients to the 5 GHz band, leaving the 2.4 GHz band for legacy clients. Band steering works by responding only to 5 GHz association requests and not the 2.4 GHz requests from dual-band clients.

802.11n protection mechanisms kick in as soon as an access point hears a legacy device transmitting on the same channel. The legacy device does not have to be associated to the 802.11n access point; the access point just needs to hear it on the same channel. 802.11n standardized support for increased data rate, short guard interval (800us to 400us), 40 MHz channels etc...

MIMO techniques:
- Spatial Multiplexing - this requires MIMO client capable of receiving and de-multiplexing N spatial streams. a 3x3:2 MIMO access point can transmit and receive 2 data streams on its 3 antennas.
- Maximal Ratio Combining (MRC) - MRC is a receive-side MIMO technique that takes RF signals from multiple receive antennas and combines them within the radio to effectively boost the signal strength.
- Transmit Beamforming (TxBF) - focus RF energy toward the target receiver (only supported for 802.11n clients). client send special frequency characteristics and channel response information to the access point. This information is used by the AP in calculating the phase adjustment for its next transmission.

Frame Aggregation Techniques:
- MSDU Aggregation (A-MSDU) - The maximum A-MSDU size allowed by 802.11n is 8192 bytes. The disadvantage of aggregating A-MSDU is that each frame is only protected by a single checksum and the overhead of having to retransmit the entire A-MSDU again.
- MPDU Aggregation with Block ACKs - MPDU (MAC Protocol Data Unit) aggregation gathers 802.11 frames, which each already have an 802.11 header for the same destination and transmits them as a single frame. One of the disadvantages of MPDU aggregation is that each 802.11 frame needs to be encrypted separately, adding encryption overhead.
- Reduced Interframe Spacing (RIFS)

Reference:
http://en.wikipedia.org/wiki/IEEE_802.11n-2009#Deployment_strategies
http://mcsindex.com/
http://www.motorola.com/web/Business/_Documents/White%20Paper/_Static%20files/802%2011nDEM_WP_v4_0209.pdf

20 July 2011

VLAN Advanced

On a large, flat, switched network with thousands of computers, performance suffers and security concerns increase.

Using VLANs to divide a growing network can help with manageability, performance and security.

The VLAN structure makes it easier for administrators to manage network resources. Users can be grouped logically with the resources(servers, printers, etc.) that they need. When a user's computer physically moves to a different location (for example, with a laptop computer), the VLAN management software can recognize the computer and automatically assign it to the VLAN to which it's supposed to belong.

VLANs reduce the need to have routers deployed on a network to contain broadcast traffic. VLANs are separated by switches that divide the network into multiple broadcast domains, to reduce the amount of traffic going to all devices and thus increase performance.

By confining the broadcast domains, end-stations on a VLAN can be isolated from listening to or receiving broadcasts not intended for them. Moreover, if a router is not connected between the VLANs, the end-stations of a VLAN cannot communicate with the end-stations of the other VLANs.

Reference:
http://thebestechblog.blogspot.com/2009/06/vlan.html
http://www.frokwon.net/essays/VLAN.htm
http://net21.ucdavis.edu/newvlan.htm
http://www.techrepublic.com/article/scaling-your-network-with-vlans/5779489

wpa_passphrase

WPA-PSK uses pre-shared key as a passphrase of 8 to 63 printable ASCII characters or as a string of 64 hexadecimal digits.

If ASCII characters are used, the 256 bit key is calculated by applying the PBKDF2 key derivation function to the passphrase, using the SSID as the salt and 4096 iterations of HMAC-SHA1.

wpa_passphrase -- utility for generating a 256-bit pre-shared WPA key from an ASCII passphrase. You can download wpa_passphrase.tar.gz from here.

# tar xzvf wpa_passphrase.tar.gz
# make
# ./wpa_passphrase humble mypassword
network={
        ssid="humble"
        #psk="mypassword"
        psk=aa382e1c4ac62580c25ee2b33a1cf6179176baad4a5cffc43be9c8d2b103f4aa
}

AP can be configured with ASCII passphrase or HEX digits
Which enables the windows client to uses either of the above key

For home and small office networks its preferred to use WPA2-personal authentication method which also uses CCMP, AES based encryption.
Each wireless network device authenticates with the access point using the same 256-bit key.

Reference:
http://www.hautespot.net/wpapsk.html
http://fuse4bsd.creo.hu/localcgi/man-cgi.cgi?wpa_passphrase+8

23 August 2010

Solution to flashing wifi light in fedora 13

I have Compaq nc6400 laptop which have built-in wireless card.
(Intel Corporation PRO/Wireless 3945ABG)

1. I have enabled wireless and a blue WiFi light started flashing non-stop with traffic.

echo "#add to /etc/modprobe.d/wlan.conf" > /etc/modprobe.d/wlan.conf
echo "options iwlcore led_mode=1" >> /etc/modprobe.d/wlan.conf

2. Restart the machine

Reference:
http://forums.linuxmint.com/viewtopic.php?f=90&t=44829&start=0
http://linuxfocus.org/~guido/gentoo-x301/

How to install WPA2-PSK in Fedoa 13

I have Compaq nc6400 laptop which have built-in wireless card.
(Intel Corporation PRO/Wireless 3945ABG)(iwl3945)

1. service NetworkManager restart

OR

1. edit wpa_supplicant config file
=> /etc/wpa_supplicant/wpa_supplicant.conf

ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=0
ap_scan=1

network={
        ssid="my_network"
        proto=RSN
        key_mgmt=WPA-PSK
        pairwise=CCMP TKIP
        group=CCMP TKIP
        psk="secret_password"
}

2. create "/bin/wireless"

#!/bin/sh

rmmod iwl3945
modprobe iwl3945
sleep 3
ifconfig wlan0 0.0.0.0
wpa_supplicant -d -c/etc/wpa_supplicant/wpa_supplicant.conf -iwlan0 -Dwext

3. sudo wireless
4. sudo ifup wlan0

Reference:
http://hostap.epitest.fi/wpa_supplicant/
http://www.thinkwiki.org/wiki/Wpa_supplicant
http://fedoraproject.org/wiki/NetworkManager_in_Fedora_13
http://ftp.gnome.org/pub/GNOME/sources/NetworkManager/0.8/

21 August 2010

Reliance Netconnect in Fedora 13

you need root permission and wvdial software to use reliance netconnect in fedora.

1. connect reliance data card
2. run the command "wvdialconf"

$ sudo wvdialconf 
Editing `/etc/wvdial.conf'.

Scanning your serial ports for a modem.

Modem Port Scan<*1>: S0   S1   S2   S3   
WvModem<*1>: Cannot get information for serial port.
ttyUSB0<*1>: ATQ0 V1 E1 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 Z -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK
ttyUSB0<*1>: Modem Identifier: ATI -- Manufacturer: +GMI: HUAWEI TECHNOLOGIES CO., LTD
ttyUSB0<*1>: Speed 9600: AT -- OK
ttyUSB0<*1>: Max speed is 9600; that should be safe.
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK
WvModem<*1>: Cannot get information for serial port.
ttyUSB1<*1>: ATQ0 V1 E1 -- failed with 2400 baud, next try: 9600 baud
ttyUSB1<*1>: ATQ0 V1 E1 -- failed with 9600 baud, next try: 9600 baud
ttyUSB1<*1>: ATQ0 V1 E1 -- and failed too at 115200, giving up.
WvModem<*1>: Cannot get information for serial port.
ttyUSB2<*1>: ATQ0 V1 E1 -- OK
ttyUSB2<*1>: ATQ0 V1 E1 Z -- OK
ttyUSB2<*1>: ATQ0 V1 E1 S0=0 -- OK
ttyUSB2<*1>: ATQ0 V1 E1 S0=0 &C1 -- OK
ttyUSB2<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 -- OK
ttyUSB2<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK
ttyUSB2<*1>: Modem Identifier: ATI -- Manufacturer: +GMI: HUAWEI TECHNOLOGIES CO., LTD
ttyUSB2<*1>: Speed 9600: AT -- OK
ttyUSB2<*1>: Max speed is 9600; that should be safe.
ttyUSB2<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK

Found a modem on /dev/ttyUSB0.
Modem configuration written to /etc/wvdial.conf.
ttyUSB0: Speed 9600; init "ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0"
ttyUSB2: Speed 9600; init "ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0"

3. update "/etc/wvdial.conf"

[Dialer Defaults]
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Modem Type = Analog Modem
; Phone = 
ISDN = 0
; Password = 
; Username = 
Phone = #777
Modem = /dev/ttyUSB0
Username = 93XXXXXXXX
Password = 93XXXXXXXX
Baud = 9600

4. run the command "wvdial"

$ sudo wvdial
--> WvDial: Internet dialer version 1.61
--> Cannot get information for serial port.
--> Initializing modem.
--> Sending: ATZ
ATZ
OK
--> Sending: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
OK
--> Modem initialized.
--> Sending: ATDT#777
--> Waiting for carrier.
ATDT#777
CONNECT
--> Carrier detected.  Waiting for prompt.
^DSDORMANT:1
--> Don't know what to do!  Starting pppd and hoping for the best.
--> Starting pppd at Sat Aug 21 14:24:31 2010
--> Pid of pppd: 16220
--> Using interface ppp0
--> pppd: @�:[08]��:[08]
--> pppd: @�:[08]��:[08]
--> pppd: @�:[08]��:[08]
--> local  IP address 115.XXX.XXX.XXX
--> pppd: @�:[08]��:[08]
--> remote IP address 220.XXX.XXX.XXX
--> pppd: @�:[08]��:[08]
--> primary   DNS address 202.XXX.XXX.XXX
--> pppd: @�:[08]��:[08]
--> secondary DNS address 202.XXX.XXX.XXX
--> pppd: @�:[08]��:[08]

5. update "/etc/resolv.con"

nameserver 202.XXX.XXX.XXX

reference:
http://www.gnulinux.in/blog/my-user-experience-reliance-netconnect-broadband-service-and-ubuntu-904

19 March 2010

Radio Resource Management

RRM, Part I
RRM, Part II
RRM, Part III, Dynamic Channel Assignment (DCA)
RRM, Part IV, TPC (Transmit Power Control)
RRM, Part V, Coverage Hole Detection

Reference:
http://wirelessccie.blogspot.com/2009/08/rrm-radio-resource-management-deep-dive.html

22 February 2010

802.11 channels

UNII - Unlicensed National Information Infrastructure
DFS - Dynamic Frequency Selection
TPC - Transmitter Power Control

5GHz radio devices should follow 802.11h specification - DFS and TPC

UNII2 - (52, 56, 60, 64 ==> 5250MHz - 5350MHz)
UNII2 Ext - (100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140 ==> 5470MHz - 5725MHz)

FCC Rule requires that products operating in the UNII-2 and UNII-2 extended bands must support Dynamic Frequency Selection (DFS), to detect and automatically adjusts channels to protect WLAN communications from interfering with military or weather radar systems.