Grow Wifi

How To Debug WLAN Client connectivity Issues: Debugging is a Skill which every Test engineer should have and everyone has there own style of doing it. A same approach might not be the best approach for every problem. Also, it is very much dependent on the resources available at that moment. Lot of beginners have this question as "How to Debug". Well, you learn the answer based on your own experience and if you have a great team, they will share their experience. As they say, " A smart person learns from his mistakes, but a smarter learns from others". A good team is one which shares their learning with their peers and create that culture of sharing knowledge. As part of this Blog I will share some pointers that I have learnt with my experience and I am open to any sort of comments. Since most of my career till now has been with testing WLAN clients, I will restrict this to debugging WLAN Clients and not AP/Infra. Scenario 1 - Device not connecting: ...

802.11w Protected Management Frames Why? As you are aware that Management Frames are not encrypted in WLAN networks and this causes WLAN networks to be vulnerable to Denial of Service Attacks (DoS). Let us see a few of the Denial of Service attacks which Attackers can use to disrupt few or all of the users in a WLAN network. DoS Attacks Following frames can break the existing wireless connection (without PMF support) and will lead to Denial of Service attack. Sending Deauth or Disassoc notification to AP Sending (Re) Association request to AP. Sending Auth frame to AP. Sending Deauth or Disassoc notification to Station Sending Channel switch announcement to Station. How to solve the problem? Once the 4 way Handshake is done, the AP and the STA have the PTK and GTK to encrypt data. The same keys can now be used to encrypt Management frames to provide a certain level of Protection against DoS Attacks. Access Point and the Station both needs to have s...

Kick Start PYTHON... So you want to start learning automation/scripting, but don't know how? Believe me, everyone's been there. I started learning python while I was commuting from Home to Office and other way, just by watching videos. I started with this great series by Google, Google Python quick class .  I would also recommend you to practice what he shows in his videos. One more thing where most people go wrong after watching such videos is that, you stop after watching a video series. You have to "apply" in your day to day work to learn a language. You really don't need anything to practice python, other than python. If you are a manual tester, and want to get in to automation or learn scripting, this is the best thing to start of with. As a manual tester, you will be having Logs to analyse, or analyse WLAN sniffer capture, or create reports using logs. For all of this you can use python and increase your efficiency. (This is also a kind...

Overview: Few of the 5Ghz channels is shared with Radars Systems. The channels that are used for Radar Systems depend on the Regulatory rules of that country and may differ from country to country and these channels are called DFS channels (Dynamic Frequency Selection). When a 5Ghz channel is used by a Radar system, any wlan device cannot operate on that 5Ghz channel. This is becuase we do not want to interfere the operation of a miltary Radar System. So who takes care of not operating on the DFS channel? Well its usually the AP who has the capability of detecting Radar Signals and switching away from that channel and also, announcing to the clients that there is a Radar Signal detected and the AP would be switching to a new channel. How is it informed to the clients? Answer is a new IE, called 'Channel Switch Announcement IE'. Length :  Set to 3 bytes Channel Switch Mode : Indicates any restrictions on transmission until a channel switch. An AP in a ...

The default Colouring Rule that Wireshark provides for WLAN packets is not the best one. People who are used to use Omnipeek, often find it difficult to use Wireshark to check WLAN packets. There are coloring rules in Wireshark that we can define to make WLAN captures look similar to Omnipeek. After applying the Rules, this is what WLAN capture looks like in Wireshark: If you are interested to have this look then follow the below procedure to have Omnipeek Look in Wireshark: Save the below text in a file in your computer: # DO NOT EDIT THIS FILE!  It was created by Wireshark @wlan.ba_req@wlan.fc.type_subtype == 0x18@[65535,65535,65535][50372,41120,0] @wlan.ps_poll@wlan.fc.type_subtype == 0x1a@[65535,65535,65535][36281,18871,45656] @wlan.qos_null@wlan.fc.type_subtype == 0x2c@[65535,65535,65535][36281,18871,45656] @wlan.null_data@wlan.fc.type_subtype == 0x24@[65535,65535,65535][36281,18871,45656] @EAPOL@eapol@[65535,65535,65535][8611,29490,4718] ...

AIFS Arbitration Inter-Frame Spacing (AIFS) defines different inter-frame gaps for traffic from each of the 4 priority queues. This replaces the original DCF Inter-Frame Spacing (DIFS) which defined only a single inter-frame gap value for all data frames. Using AIFS, each frame awaiting transmission must wait until the medium is declared to be available through Clear Channel Assessment (CCA) and the Network Allocation Vector (NAV). Once the medium is available, each logical station (one for each priority queue) must wait the defined inter-frame space time based on the queue to which the traffic is assigned. Each of the 4 priority queues has a defined inter-frame space value corresponding to the priority assigned to the queue. For example, the Voice queue is the highest priority and as such has the lowest inter-frame space timer. The AIFS timers assigned by IEEE 802.11e are all defined as 1 Short Inter-Frame Spacing (SIFS) value plus a variable number of slots times (AIFSN) wh...