Monday, April 15, 2013

What is a Glue Record?

Category: — SkyHi @ Monday, April 15, 2013

Glue Records

This article offers a definition of a Glue Record, a description of why a Glue Record is need and how they are resolved through DNS, and how to create a Glue Record through the CloudAccess.net Client Area.

What is a Glue Record?

Why are Glue Records needed?

How to create a Glue Record

What is a Glue Record?

A Glue Record is the IP Address of a name server at a domain name registry. Glue Records are fundamental parts of DNS records because they help to resove DNS servers at a core level. If you would like to change the name servers for a site, you ll have to provide the Glue Records for the new name serves. Without them, a domain name will not work because anyone requiring the DNS information will be stuck in a loop. There is a cyclic dependency of circular referencing. Circular references exist where the name servers for a domain can t be resolved without resolving the domain they re responsible for. Glue Records are additional A records that allow the DNS client to locate name servers. 

When are Glue Records needed?

For example, let s say your domain (yourdomain.com) is using ns1.nameserver.com and ns2.nameserver.com as name servers, but gridfast.net also uses ns1.nameserver.com and ns2.nameserver.com as name servers. This is how the cyclic dependency is created. To break the cycle, DNS systems use Glue Records. 
You can also understand Glue Records by understanding A Records. An A record (an A address) is a DNS record that can be used to point your domain name and host names to a static IP address. For example, the A record for gridfast.net includes ns1.gridfast.net and ns2.gridfast.net and their IP addresses. These servers can be reached directly without any further resolution. For a domain name like CloudAccess.net, however, the root DNS servers pass the ns1.gridfast.net and ns2.gridfast.net nameservers, and a further chain of resolution is needed to resolve the DNS. This is when a Glue Record is needed.


REFERENCES
http://www.cloudaccess.net/infrastructure-networking/66-servers-dns/318-glue-records.html

MySQL 4.1+ using old authentication

Category: — SkyHi @ Monday, April 15, 2013

When I was working with XAMPP in Ubuntu and asked write PHP script to connect to remote MySQL server which is using PASSWORD hash function to save the password for user, and I found following error.

Warning: mysql_connect() [function.mysql-connect]: Premature end of data (mysqlnd_wireprotocol.c:554) in path/to/the/file/where/connection/script/is/written/

Warning: mysql_connect() [function.mysql-connect]: OK packet 1 bytes shorter than expected in path/to/the/file/where/connection/script/is/written/

Warning: mysql_connect() [function.mysql-connect]: mysqlnd cannot connect to MySQL 4.1+ using the old insecure authentication. Please use an administration tool to reset your password with the command SET PASSWORD = PASSWORD('your_existing_password'). This will store a new, and more secure, hash value in mysql.user. If this user is used in other scripts executed by PHP 5.2 or earlier you might need to remove the old-passwords flag from your my.cnf file in path/to/the/file/where/connection/script/is/written/

As you will see, the core issue here is that MySQL can have passwords with hashes stored in the old 16-character format, which is not supported by PHP 5.3′s new mysqlnd library.
Since I couldn’t find a good solution with a quick Google, here is how I solved this without having to downgrade PHP or MySQL (as some of the solutions suggested):

1. Change MySQL to NOT to use old_passwords
It seems that even MySQL 5.x versions still default to the old password hashes. You need to change this in “my.cnf” (e.g. /etc/my.cnf): remove or comment out the line that says
old_passwords = 1
Restart MySQL. If you don’t, MySQL will keep using the old password format, which will mean that you cannot upgrade the passwords using the builtin PASSWORD() hashing function. You can test this by running:
 
mysql> SELECT Length(PASSWORD('xyz'));
+-------------------------+
| Length(PASSWORD('xyz')) |
+-------------------------+
|                      16 |
+-------------------------+
1 row in set (0.00 sec)
The old password hashes are 16 characters, the new ones are 41 characters.
2. Change the format of all the passwords in the database to the new format
Connect to the database, and run the following query:
mysql> SELECT user,  Length(`Password`) FROM `mysql`.`user`;

This will show you which passwords are in the old format, ex:
+----------+--------------------+
| user     | Length(`Password`) |
+----------+--------------------+
| root     |                 41 |
| root     |                 16 |
| user2    |                 16 |
| user2    |                 16 |
+----------+--------------------+
Notice here that each user can have multiple rows (one for each different host specification).
To update the password for each user, run the following:
UPDATE mysql.user SET Password = PASSWORD('password') WHERE user = 'username';
Finally, flush privileges:
FLUSH PRIVILEGES;


REFERENCE
http://lampsailesh.blogspot.com/2011_05_01_archive.html#5294498109303285481

Monday, March 25, 2013

CentOs - make time zone chagne permanent

Category: — SkyHi @ Monday, March 25, 2013 



 1.  Edit /etc/sysconfig/clock
          * ZONE="US/Central" <-this br="" change="" is="" the="" to="" value="">          * UTC=false
          * ARC=false 
   2. run tzdata-update
   3. run /etc/init.d/ntpd restart


REFERENCES

Friday, March 22, 2013

Change Default Editor for visudo in Ubuntu

Category: — SkyHi @ Friday, March 22, 2013

Ubuntu and Debian use the alternatives system to maintain the symbolic links for programs. When you first run visudo, it will prompt a list of editors for you to choose from. Unfortunately, it doesn’t tell you how to change that setting again. The mostly happend situation is: you set it to “nano” at first, and can’t change it to “vi” at a later time.
Here is the command to bring up that list again:
sudo update-alternatives --config editor
Some people suggest using command EDITOR=vi visudo, or export EDITOR=vi; visudo, but it’s really annoying if you have to remember and type so many letters everytime you run this command.



REFERENCES

Tuesday, March 12, 2013

How to enable multiple remote connection for windows server 2012

Category: — SkyHi @ Tuesday, March 12, 2013

By default Windows 2008 only allows a user one single session over RDP. While in some instances this can be quite handy, if like me, you have multiple developers working on a single server, your frustration from being randomly logged out by a colleague can come to the boil. Quick and easy solution.
Log in to your Windows 2008/Windows 2008 R2 machine (it can be via RDP if you wish)
Open up Remote Desktop Session host Configuration
(this is under Start > Administrative Tools > Remote Desktop Services)
Double click on the centre section marked Edit Settings (note that the setting marked Restrict each user to a single session will be marked as Yes)
image
Now uncheck the checkbox marked Restrict each user to a single session and click OK
image
Close the window and you’re done! Now you’ll note the the same screen says No
image 


Answer:
1. Open command propmt
2.write gpedit.msc and open it
3.Go to computer configuration -> Administrative Tempalates -> Wondows Components
->Remote Desktop services -> Remote Desktop Session Host -> Connections.
4. Here Disble the below mentioned.

Restrict Remote Desktop Services user to a single remote.....

NOw goto command propmt and update the group ploicy using below mentioned command.

Goto command propmt and type -> gpupdate and enter it. it should be successfully applied.



Thursday, February 28, 2013

How do I change the DRAC root password?

Category: — SkyHi @ Thursday, February 28, 2013

Step by step for iDRAC6:
  • Log in as root
  • Select Remote Access from the left-hand menu
  • Select the Network/Security tab
  • Select the Users tab
  • Click the number “2” hyperlink in the User ID column
  • Select Configure User and click Next
  • Select Change Password and fill out the following password fields
  • Click Apply


REFERENCES
http://kb.eclipseinc.com/kb/how-do-i-change-the-drac-root-password/

Wednesday, February 27, 2013

Using the Local Default Gateway with a Windows VPN Connection

Category: — SkyHi @ Wednesday, February 27, 2013

To stay connected while I’m out of the office or travelling, I use a VPN connection from my laptop to a Windows Server. And while the benefit of being able to quickly and securely access my documents and other files on the server over any Internet connection is nice, the drawback is that all Internet traffic gets routed through the default gateway on the remote network – meaning that surfing the Web or accessing other Internet resources outside of the VPN is usually slower than just using the local connection.
In cases where I know that the local connection is secure (at home or at a remote office), I still want to be able to use mapped drives and securely access the files on my server via the VPN, but I want to use the local connection to do all other Internet surfing.
The secret lies in the default gateway. If you use the local default gateway, Internet traffic will be routed via the local connection. If you use the remote default gateway, Internet traffic goes through the remote connection. By default, Windows VPN connections use the remote gateway – but changing the default is very easy.
Open your local network connections (on Vista or Windows 7, just click the network icon in the tray), find your VPN connection, right-click it, and select Properties. Click the Networking tab, select Internet Protocol Version 4 (TCP/IPv4), clickProperties, click Advanced, then uncheck Use default gateway on remote network. Press OK until all the dialog boxes are closed. That’s it!
Connect to your VPN, and verify that you’re using the local connection to access the Web by using the IP Address Lookup Tool at WhatIsMyIp.com.
In situations where you aren’t sure of the local network’s security, you can re-enable the remote default gateway and surf using the gateway connected to your VPN server. It may be slower, but it could be worth it in scenarios where security is more important than speed.

REFERENCES
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