Installing Nutanix Community Edition above Vmware ESXi without SSD

No detailed write up. Just the points.
I wanted to test Nutanix Community edition. I have Dell poweredge M630 blade server with only two HDDs ( 512 GB) in RAID-1 configuration. Nutanix CE requires minimum 2 SSDs. Inorder to emulate this, I installed VMWare ESXi hypervisor. The steps for this is easily available. Now create a VM in this VMWare ESXi hypervisor, which will be our Nutanix AHV host. So it is a hypervisor over hypervisor.

How to bypass a website ban by DNS over HTTPS?

Recently I found that my default search engine DuckDuckGo (duckduckgo.com) was not opening in any web browser, while all other websites are working fine. In a basic troubleshooting, I found that my ISP ( ACT Fibrenet in Bengaluru, India) is blocking my DNS query to duckduckgo.com. ( See my blog on Domain name service DNS ).

DNS-over-HTTPS (DoH)

What is Domain name service (DNS) ?

When we type a URL address in any internet browser like google chrome or Internet explorer, the browser translates that name to something it understands, a number, called IP Address. In Internet, all the connected devices have an unique IP address. Eg: Google website ( google.com or google.in ) has an unique IP Address, Yahoo has its own address. It is difficult to remember all these addresses, that is when DNS helps us. A server running this DNS service maintains a table to translate the Name to IP Address to make things easy for humans

Extending Multiple VLANs over trunk interface to Windows Server

Physical setup:

A Microsoft windows server with two NICs connected to a Network switch. There is a requirement to extend multiple VLANs to the server.

Steps:

Configure the network switch interfaces connected to the server as trunk ports. Trunk ports allow multiple VLANs to pass-through. Technically, All the packets passing through trunk ports must have an VlanID in the ethernet packet. the receiving switch decides where to forward the packet based on the VlanID tag. If any packet arrives without VlanID, it is considered as packet belonging to the VLAN marked as "Native VLAN". In cisco switches, "Vlan 1" is the default "Native VLAN".
Cisco Switch commands:

IPv6 Internet access from IPv4 (BSNL) DSL Connection

As of now AFAIK BSNL, the largest ISP in India, is not providing IPv6 Internet to DSL home users. So here is a cool way to connect to IPv6 Internet using a IPv4 DSL connection.

Scenario:
I have a BSNL DSL Broadband connection with dynamic IPv4 address with NAT.
Here I will demonstrate a way to access IPv6 Internet using a IPv6-over-IPv4 tunnel from tunnel broker Hurrican Electric. I am running Ubuntu Linux 14.04.

TL DR:

Signup with any IPv6 tunnel brokers in internet like Hurrican Electric or SixxS. Create a regular IPv6 tunnel. Add v4tunnel interface configuration in our computer.

Enabling developer options in Android 4.1+

Developer options like USB debugging are by default disabled in Android 4.1+ ( Android 4.2, Android 4.4.4) and the menu to enable is hidden!.

To Enable Developer Options:

1. Go to "Settings"
   

Extract data from .dbk backup of Sony Xperia

Sometimes it happens that restoring from a .dbk backup fails (especially after flashing a custom ROM). You can extract data like contacts, messages etc from .dbk file as follows:

1. Locate .dbk file. If you took backup using Sony PC Companion, Default backup folder is C:\Users\USERNAME\Documents\Sony\Sony PC Companion\Phone backups .
2. Copy .dbk file to Desktop.
3. Rename .dbk to .zip. Say Original file be XYZ.dbk , Rename to XYZ.zip
4. Extract using any unzip softwares ( Eg: WinRAR, 7zip etc)

5. In Extracted contents, See "Applications" Folder. Inside it, Each data type will have separate folders. To Extract contacts, Go inside "com.sonyericsson.android.contactsimport" folder and copy "fullbackupdata" file to Desktop. This is the compressed archive of all contacts.

6. This "fullbackupdata" can be extracted using restoreData.jar . Download jar file from https://docs.google.com/file/d/0B4IK3kVRTwmtQkROa2s4aGx1VWc/edit. Keep jar file in same folder as "fullbackupdata". NOTE: If you cannot find restoreData.jar file at this link, Just Google it.
7. Now run jar file. It will output a restore.tar file. Note: To run .jar file you should be having JAVA installed.
8. This tar file can be extracted using any Unzip programs ( WinRAR, 7zip etc) . Inside you can find the full_backup_vcard.vcf VCard File which can be imported into phone contacts. Note: For importing to Phone, Copy this file to your sdcard. In phone, Go to Contacts -> import/export -> Import from storage

Credits

Johannes Deml and Nikolay Elenkov

Enabling SSH and block Telnet in Cisco Routers/Switches

SSH protocol encrypts the traffic between client and server in a remote session. So for network security purpose, we should enable only SSH access to networking devices.

Before enabling SSH, make sure we configured hostname and domain name properly. This will be used to store the name of the RSA key pair generated.  All the configurations are to be done in Global config mode.

hostname Router1
ip domain name ds.myorganization.in

Change hostname and 'ds.myorganization.in' domain name to your organization domain name. Now generate the RSA keys for SSH

crypto key generate rsa

This will ask the number of bits required for modulus function. Default is 512 bits but if we want to enable SSH version 2, bits should be more than 768. So, better keep 1024 bits.

Setting up a Syslog server in Ubuntu for Cisco routers/switches

Configuration to be done in Ubuntu server

RSYSLOG is the default logging utility in Ubuntu. Main configuration file for rsyslog is /etc/rsyslog.conf. Make sure that there is a line as follows in the rsyslog.conf file.

$IncludeConfig /etc/rsyslog.d/*.conf

Now make a new file (say cisco.conf) in /etc/rsyslog.d directory.
Add these line to cisco.conf

local7.*    /var/log/cisco/cisco.log

This means that all syslog messages with facility (or tag) as local7 (Local7 is the default tag on all syslog messages from cisco devices) should be logged to cisco.log file at /var/log/cisco directory. So create a folder named cisco at /var/log and a blank document cisco.log inside that folder.
Now just restart rsyslog daemon using the command

sudo service rsyslog restart

Configuration to be done in Cisco device

In the Cisco router/switch whose logs are to be logged in the syslog server, configure the following :

logging Ubuntu_Server_IP

For example,

logging 192.168.2.1

Now all the logs from Cisco device will be logged to Syslog server in the Ubuntu machine. You can see the logs at System Log viewer by opening /var/log/cisco/cisco.log

Show running-config as read-only in Cisco routers without using AAA with TACACS+ and RADIUS

Sometimes it happens that we have to provide read only access to the running configuration of routers to someone who has a lower privilege. Cisco defines privilege level 15 as full access privileged EXEC mode and privilege level 1 as the normal user exec mode. In between levels are not defined by default. We can use privilege command to move commands from one privilege level to another.


commands:

privilege exec all level 10 show running-config

alias exec shrun show running-config view full

username hdesk privilege 10 secret hdesk@1234

Explanation:

1. Move show running-config command to a privilege level 10
2. But to view the running configuration, instead of show running-config, we have to type complete show running-config view full. So let's create a alias named shrun. This is optional.
3. Now create a user with the privilege level 10. This user will be now able to see running configuration using the alias command shrun .

Linking Outlook.com or Windows Live Hotmail with Microsoft Outlook 2010

Say you have to link your Outlook.com mail lisa@contoso.com ( See more about Contoso ) with Microsoft Outlook 2010 64 bit.

First of all, Download the hotmail connector for Outlook at http://www.microsoft.com/en-in/download/details.aspx?id=21305 (for 32 bit) Or  http://www.microsoft.com/en-in/download/details.aspx?id=24677 (for 64 bit).

Now double click the downloaded exe file ( named as OutlookConnector.exe ) to install it.

Now configure Outlook.com mail in outlook as you configure any other mails. See the steps below:

Setting up wireless ad-hoc computer to computer network in Windows 8

 In earlier versions of Windows, It was easy to create ad-hoc network to share your internet connection with another computer or mobile through WiFi. In Windows 8 , there is no direct way to make ad-hoc network.

1. Geeky way:
   Use netsh wlan commands to setup a new network, and share your internet using Internet Connection Sharing (ICS)
• Go to cmd . Right click and Run as administrator.

• Type the following command
  netsh wlan set hostednetwork mode=allow ssid=network_name key=password_here
  For example:
  netsh wlan set hostednetwork mode=allow ssid=HOMEWIFI key=password1234
  (Note: Password should be minimum of 8 characters. )

Installing MK Livestatus and Adding to Nagios 3 in Ubuntu

Livestatus is a new approach for accessing Nagios data. It has a lot of advantages over the classical NDO approach. Livestatus make use of Nagios Event Broker API. It loads a binary module into Nagios Process. Livestatus creates a socket from which data can be read whenever required.
Many Nagios addons use Livestatus as the backend like NagVis, Check_MK etc.

Installing Livestatus

• Download stable version livestatus zipped file from http://mathias-kettner.de/check_mk_download.html. Eg: mk-livestatus-1.2.2p3.tar.gz

How to screen capture in Sony Xperia U with ICS

To take screenshot in Xperia U, press Power button and Volume down button simultaneously till it captures with a sound. The image will be stored in /mnt/sdcard/Pictures/Screenshots.

Automatic back up of Cisco routers - Kron scheduler

If your are a network engineer, it is a monthly or weekly job to take back up of the router configurations . If it is a small network with a few routers or switches, it is easy to manage. But if it is a large network , It is a hectic job. So I rely on Cisco Kron command.

Configuring Mozilla Thunderbird for Microsoft Exchange mail

Microsoft Exchange is the widely used mail solution in buisiness world. Microsoft Outlook is the email client used with this . But if we have to configure mail in our Linux machine, we have to go for some alternative email clients . Mozilla Thunderbird is a good alternative for Outlook. It is also pre-installed in many distros (like Ubuntu 13.10 )To configure Mozilla Thunderbird for Exchange mail , we can use an addon - ExQuilla. This addon is able to connect to Exchange 2007, 2010 and latest 2013 also.

Monitoring BGP using NAGIOS

We can use check_bgp NAGIOS plugin for monitoring BGP. Visit  http://exchange.nagios.org/directory/Plugins/Network-Protocols/BGP-2D4/check_bgp/details for more details.

How to install and configure check_bgp plugin?

In the demonstration, I will be using NAGIOS server installed in Ubuntu Linux, and i want to monitor BGP in a Cisco ASR 1006 router. Since this plugin uses BGP4-MIB and SNMP, It can be used to monitor any router with SNMP.

1. Download check_bgp.pl perl script from the link given above. 0.4 is the recent version.

How to find which application is using a TCP port in Windows

If a port is already in use by some unknown program and when you try to use the same port , you get a lot of errors like "Port already in use" , "Bind Exception" , "Port 80 already in use" etc. So in such case, You have to find out which process is already using this port and you can kill that process.

Steps to find which application is using a TCP port in Windows

1. Type the command to find the Process ID
Go to Run -> cmd and Type


 netstat -ano | more 

Installing TFTP Server on Ubuntu

TFTP Server is usefull for PXE booting or configuring automatic back up of Cisco routers and Switches etc. Installing TFTP Server can be done in a few steps :

We are going install TFTP Server on a machine running Ubuntu ( version 10.04 32 bit Desktop Edition).

Steps to Install and Configure TFTP Server on Ubuntu

1. Step 1: Install TFTP Server
Either you can install using command line or Go to Ubuntu Software center. In command line type"sudo apt-get install tftpd-hpa" Or Search for tftpd-hpa in Software Center and click install

Active Directory Authentication for APACHE Web Server

For authenticating users against their Active Directory account in APACHE Web Server, you have to edit the /etc/apache2/httpd.conf .

Notes

1. You should bind some other common AD account with LDAP
2. Provide LDAP URL of you Domain Controller . Here I assume the Domain is DC.EXAMPLE.COM and IP of the Domain Controller is 192.168.40.1 .
3. I am binding with another account guest@example.com . So give FQDN of this acount .
4. You should enable the authnz_ldap module for apache.