How to: Make your Phone number appear to be an empty number or couldn’t be connected

iPhone

Make it empty number

1 Bring up the dial panel

iPhone - Dial panel
iPhone – Dial panel

2 Enter following code then press the green dial button

**21*888888#

iPhone **21*888888#
iPhone **21*888888#

3 After a message following screen will appear

iPhone - Notification screen
iPhone – Notification screen
iPhone - Notification screen
iPhone – Notification screen

4 Now try to call your number from other phone, you will hear message like “Your call could not be connected, please check the number and try again.”

Note: Your phone will not receive any notification until you reverse the change

Reverse the change (Make the number back to normal)

1 Bring up the dial panel again

2 Enter following code, then press green dial button

##21#

##21#
##21#

3 After a message following screen will appear

iPhone - Notification screen
iPhone – Notification screen
iPhone - Notification screen
iPhone – Notification screen

4 Now try to call your number from other phone again, it’s back to normal now

Android

For android, the process is very similar to iPhone.

To Enable this function

Use following code then press dial button

**21+123456# (123456 should be the number you want to forward to)

To revert the change

Use following code then press dial button

#21#


How to: Use curl to submit Google Form

Before crafting the curl command, we need to find the “name” attributes for the text boxes and the value for them, we can use built-in developer tools from different browsers to find that out, record the value of the “name”

Now we can craft the curl command

curl https://docs.google.com/forms/d/e/stringoForTheGoogleForm/formResponse -d ifq -d "entry.1773835858=text1" -d "entry.784619947=text2" -d submit=Submit

Make sure after the string from copied URL we put “/formResponse”, it there is “viewform” at the end of the URL replace that with “formResponse”


“entry.1773835858” and “entry.784619947” are the “name” value for two text boxes

Now we can use the above curl command to submit the Google Form


Linux Command Line/ Terminal Disk Space Usage tool (Find largest folder/file)

For finding largest file/folder or showing disk space usage on Windows, refer to this one: How to: Find Largest file on Windows, Windows 7, Windows 10, Microsoft Windows, Windows Server (Disk Space Usage)

Ncdu (NCurses Disk Usage) is a command line tool to view and analyse disk space usage on Linux.

It can be easily installed on most Linux systems with package management system.

ncdu on Kali Linux 2020
ncdu on Kali Linux 2020

Debian/Kali Linux/Ubuntu etc. Linux installation

sudo apt install ncdu -y
 
OR
 
sudo aptitude ncdu -y

RHEL/CentOS/Fedora etc. Linux installation

If EPEL repo is not installed yet, we have to install EPEL repo first

sudo yum -y install epel-release

Next, we can now install ncdu

sudo yum install ncdu -y

Using ncdu is simple.

Show current working directory info

ncdu

Show info for a folder e.g. “/etc”

ncdu /etc

To show more info about a folder while in ncdu, press “i” key (Press “i” again to dismiss)

ncdu - i
ncdu – i

Press Shift + ? to show help document while in ncdu

ncdu help
ncdu help

Press “q” key to quit menus and the ncdu program


How to Fix: Cisco Aironet, Mobility Express-WMM Policy should to be required, Over the DS has to be disabled

The Error

So we are getting these two complaints from Cisco Aironet Mobility Express – Best Practices

WMM Policy should to be required

Over the DS has to be disabled

Cisco Aironet Mobility Express - Detailed Best Practices
Cisco Aironet Mobility Express – Detailed Best Practices

The Fix

1 Connect to the Mobility Express via console or SSH to the controller

Note: Make sure we have the correct “WLAN ID” ready

2 Use following commands to fix these errors

config wlan security ft over-the-ds disable [wlan id]
config wlan security ft over-the-ds disable [wlan id]
config wlan security ft over-the-ds disable [wlan id]
config wlan wmm require [wlan id]
config wlan wmm require [wlan id]
config wlan wmm require [wlan id]

How to Fix: Microsoft Word Error, can’t save to OneDrive, can’t save…

The Error

Word saving files to onedrive

Sorry we couldn’t find https://……… is it possible it was moved, renamed or deleted?
The file you are merging into is currently in use, Please try again later.

The Fix

We need to repair the Office.

Method 1

1 Use start menu to search “Control” then open control panel or Use Win + R key combination to open “Run window”

Microsoft Windows - Run window
Microsoft Windows – Run window

Then type “appwiz.cpl” then hit Enter key to bring up the “Programs and Features” window

2 Find office, click on “Change -> Repair”

Method 2

If you are using office 365, you can just download the office installation file from Microsoft, then repair install.

Possible Errors during installation/rearing

If the following error appears

Installing office
Something went wrong
Error Code: 30010-4

Close all windows related to the office and office rearing properly.

Restart the Windows Operating System.

Then try to install office again.

When the rearing or installation is done, there should be on problem to save to OneDrive, OneDrive for business, or save to local hard drive.


How to: Keep leading zero in Microsoft Excel

Usually, when entering leading zeros in a number cell or general cell, the leading zeros will not retain and will be removed.

If we want to keep the leading zeros, here is how:

1 Right click on the cell which we want to keep leading zeros for, then click on “Format Cells…”

Microsoft Excel
Microsoft Excel

2 Follow the steps, Click on “Custom” then type zeros under the “Type”, if you want to Three digits then enter three zeros, then click on “OK” button to save the changes for this cell

Microsoft Excel - Format Cells
Microsoft Excel – Format Cells

3 Now we can see the leading zero retained for the cell if the value is less than 100.

Microsoft Excel - Format Cells - 000
Microsoft Excel – Format Cells – 000

Extended Reading- Alternatives

We can also format the cell to “Text” format rather than “Number” if we are not doing any calculation with that cell.

There are 2 ways to do this

Method 1

Instead of type 001 in the cell, we can type ‘001, this way it’s stored as text, the leading zeros will be kept as well.

Method 2

Using the “Format Cells” mentioned in the beginning, we can click on “Text” instead of “Custom”, the leading zeros will be retained.

Bottom line/Rule of thumb

If you don’t care what format the data should be stored as, then use whichever method you are happy with.

Generally, we should store data in correct, it might save us huge amount of time in the unknown future, that means, if there is only numbers going to be saved in the cells, then it’s better to format those cells as “Number”


How to: Find Largest file on Windows, Windows 7, Windows 10, Microsoft Windows, Windows Server (Disk Space Usage)

For finding largest file/folder or showing disk space usage on Linux, refer to this one: (Linux Command Line/ Terminal Disk Space Usage tool (Find largest folder/file))

Sometimes, we want to find largest files or folders from our computer, especially when we are running out of space on hard drive. Because spending time to find different small useless files and then delete them can be very time consuming and after all it’s possible that we have only deleted couple MB of files which won’t help much. Remove one or two huge files or folders may help a lot.

Here is a list of software which can be used just for this purpose and for free, even better, some are open source.

WinDirStat

WinDirStat
WinDirStat
  • Easy to use
  • Free, Open Source
  • Can be installed
  • Portable version available (via portableapps)

SpaceSniffer

SpaceSniffer
SpaceSniffer
  • Easy to use
  • Free
  • Portable version available

WizTree

WizTree
WizTree
  • Easy to use
  • Free
  • Can be installed
  • Portable version available

Summary

Out of three, WinDirStat is the only open source one, Space Sniffer and WinTree are both freeware only.

WinDirStat does not provide official portable version, but portable version can be downloaded from portableapps. Both SpaceSniffer and WizTree provide official portable version.

All of them are very easy to use, the user interface of WinDirStat and WizTree are very similar, you click on the tile or block to reveal the file name, while SpaceSniffer displays the file and folder name directly on the tile/block.

Bottom line, choose whichever you like to use or give all of them a try and decide which one to go with, or even keep all of them in your bag, backup plan will not hurt 😉

Download/Resource

  1. WinDirStat
  2. SpaceSniffer
  3. WinTree

How to Fix: Cisco Mobility Express Controller (Access Point) keep disconnecting/excluding users/clients

The issue

Cisco Mobility Express Access Point keep disconnecting/excluding clients/users from time to time, the configuration seems fine on the controller but somehow, it keeps excluding clients.

Sometime we can discover following errors

[Date] [Time] [AP IP address] [AP Name]: *Dot1x_NW_MsgTask_0: [Date] [Time]: %DOT1X-4-MAX_EAP_RETRIES: 1x_auth_pae.c:6710 Max EAP identity request retries (3) exceeded for client [MAC Address]

The above error can be caused by many factors, some of them can be, low signal strength between AP and the client, RF interference etc. which cause the client to keep re-authenticating, eventually caused a behavior seemed with many tries of authentication, this triggers the protection from “Client Exclusion Policy” finally the client gets excluded for a period of time. The results will be the clients keeps getting disconnected. Local EAP parameters can be one of the reason as well.

The Fix

Distribute the access points correctly at right distance, adjust antenna power for access points correctly, configure the RF frequency correctly to minimize interference, eventually improve the RF signal quality, and strength reaching out at clients. That should reduce the error.

Workaround

There are some workaround may or may not work

(Cisco Access Point disconnecting clients from time to time can be caused by signal issue plus following settings, we can use following workaround to get around with it but it’s not recommended to disable them completely for enterprise environment since those are security features.)

1 If you get a lot of excluded clients try to follow this “How to: Check/Enable/Disable Cisco Controller (Access Point) Client Exclusion Policy settings (Mobility Express) via Controller Console” to disable “Client Exclusion Policies”. So that they will not be excluded. (Note: This is a security feature, we really should fix the root cause rather than disabling Client Exclusion Policies, especially within enterprise environment)

2 If you are getting a lot of similar errors in red at the top of this page, try to follow this “How to Check/Change: Cisco Controller/Mobility Express (Access Point) Local EAP settings, commands” to increase value for “EAP-Identity-Request Max Retries” available value is 1 to 20, Recommendations for the Max Retries is 12.

More information about EAP-* parameters can be found in “How to Check/Change: Cisco Controller/Mobility Express (Access Point) Local EAP settings, commands


How to Check/Change: Cisco Controller/Mobility Express (Access Point) Local EAP settings, commands

EAP-Identity-Request Timeout (seconds)
EAP-Identity-Request Max Retries
EAP Key-Index for Dynamic WEP
EAP Max-Login Ignore Identity Response
EAP-Request Timeout (seconds)
EAP-Request Max Retries
EAPOL-Key Timeout (milliseconds)
EAPOL-Key Max Retries
EAP-Broadcast Key Interval
RSN Capability Validation

Show current Local EAP settings

1 Login to Cisco Controller (Mobility Express) via console or SSH

2 Type following command

show advanced eap
show advanced eap
show advanced eap

Change Local EAP settings

config advanced eap [name] [value]
config advanced eap ?
config advanced eap ?

Bonus

Increase value for “EAP-Identity-Request Max Retries” may fix or reduce following error

[Date] [Time] [AP IP address] [AP Name]: *Dot1x_NW_MsgTask_0: [Date] [Time]: %DOT1X-4-MAX_EAP_RETRIES: 1x_auth_pae.c:6710 Max EAP identity request retries (3) exceeded for client [Client MAC Address]

More information about EAP-* (non-Cisco official)

EAP-Identity-Request Timeout:

This timer affects how long we wait between EAP Identity  Requests.  By default this is one second (4.1 and lower) and 30 seconds  (4.2 and greater.  The reason for this change was, we found that some  clients, hand helds, phones, scanners etc, had a hard time responding  fast enough.  Devices like laptops, usually do not require a  manipulation of these values.  Available value is from 1 to 120.

So, what happens with this attribute set to a value of 30?  When  the client first connects, it sends and EAPOL Start to the network, the  WLC sends down an EAP packet, requesting the user or machines Identity.   If the WLC does not receive the Identity Response, it sends another  Identity Request 30 seconds after the first.  This happens on initial  connection, and when the client roams.

What happens when we increase this timer?  If everything is good,  there is no impact.  However, if there is an issue in the network  (including client issues, AP issues, RF issues), this can cause delays  in network connectivity.  For example, if you set the timer to the  maximum value of 120 seconds, the WLC waits 2 minutes between Identity  Requests.  If the client is roaming, and the Response is not received by  the WLC, we have created, at minimum, a two minute outage for this  client.

Recommendations for this timer is to set it at 5.  There is no  current reason, to place this timer at it’s maximum value.

EAP-Identity-Request Max Retries

So, for max retries, what does this value do?  In short, this is  the number of times the WLC will send the Identity Request to the  client, before removing it’s entry from the MSCB.  Once the Max Retries  is reached, the WLC sends a de-authentication frame to the client,  forcing them to restart the EAP process.  Available value is 1 to 20.   So let’s look at this for a moment.

The Max Retries is going to work with the Identity Timeout.  If  you have your Identity Timeout set to 120, and your Max Retries to 20  how long does it take for the client to be removed?  120 * 20 = 2400.   So it would take 40 minutes for the client to be removed, and to start  the EAP process over again.  If instead you set the Identity timeout to  5, with the Max Retires of 12, 5 * 12 = 60.  So there is one minute  until the client is removed, and it has to start EAP over.

Recommendations for the Max Retries is 12.

EAPOL-Key Timeout

For the EAPOL-Key Timeout value, the default is 1 second or 1000  milliseconds.  What this means is when it comes time to exchange the  EAPOL keys between the AP and client, the AP will send the key and wait  up to 1 second by default for the client to respond.  After waiting the  defined time value, the AP will re-transmit the key again.  You can use  the command “config advanced eap eapol-key-timeout <time>” to alter this setting.  The available values in 6.0 are between 200 and  5000 milliseconds, while codes prior to 6.0 allow for values between 1  and 5 seconds.  Keep in mind that if you have a client which isn’t  responding to a key attempt, extending the timers out can give them a  little more time to respond….however, this could also prolong the time  it takes for the WLC/AP to deauthenticate the client in order for the  whole 802.1x process to start fresh.

EAPOL-Key Max Retries

For the EAPOL-Key Max Retries value, the default is 2.  What this  means is that we will retry the original key attempt to the client 2  times.  This setting can be altered using the command “config  advanced eap eapol-key-retries <retries>”.  The available  values are between 0 and 4 retries.  Using the default value for the  eapol key timeout (1 sec) and the default value for the eapol key retry  (2) the process would go as follows if a client doesn’t respond to the  initial key attempt:

1 – AP sends key attempt to the client
2 – Wait 1 second for a reply
3 – If no reply, then send eapol key retry attempt #1
4 – Wait 1 second for a reply
5 – If no reply, then send eapol key retry attempt #2
6 – If there is still not a response from the client and the retry value  is met, then deauthenticate the client.

Again, as with the EAPOL-Key Timeout, extending the EAPOL-Key  retry value could in some circumstances be beneficial, however setting  it to the max may again be harmful as the deauthenticate message would  be prolonged. [2]

Resources

[1] Information About Local EAP
[2] EAP Timers on Wireless Lan Controllers