Since 2007

[Rails] Installation on Centos 5.4

admin — Sun, 07 Mar 2010 00:19:26 +0000

//View current gem list
$ gem list

// Install rails
$ gem install rails
// Install sqlite3-ruby
$ gem install sqlite3-ruby

// Move into the directory where you will create the project
$ cd /path/to/yourproject
// Create the project
$ rails [project_name]
// Move into the project directory
$ cd [project_name]
// Start the Ruby Webserver
$ ruby script/server
or
$ ruby script/server –port=xxx

// Open up a web brower
http://[ip_or_domainname]:3000
or

http://[ip_or_domainname]:[your_defined_port]

That’s all!

[Rubygems] Installation on Centos 5.4

admin — Sat, 06 Mar 2010 22:35:15 +0000

[Run this command if it applies to your environment]
$ su -l
[Enter your sudo password]

[Step skipped to get the lastest Rubygem - use either FTP or wget]
[I placed my copy in /usr/local/src/ ]
# tar xzvf rubygems-1.3.x.tgz
# cd rubygems-1.3.x
# ruby setup.rb

[Final check]
[Checking Rubygem Version]
# gem -v
1.3.6
[Checking Rubygem Path]
# which gem
/usr/local/bin/gem

All done!!

[Ruby] Installation on Centos 5.4

admin — Sat, 06 Mar 2010 21:40:39 +0000

If you want to manually install the latest Ruby version:

[Run this command if it applies to your environment]
[apt-get install build-essential for Debian based]
$ su -l
[Enter your sudo password]
[Install the following if missing and needed]
# yum groupinstall ‘Development Tools’
# yum install openssl-devel
# yum install zlib-devel
# yum install ruby-devel sqlite-devel
[Step skipped to get the lastest Ruby - use either FTP or wget]
[I placed my copy in /usr/local/src/ ]
# tar xzvf ruby-1.9.1-pxxx.tar.gz
# cd ruby-1.9.1-pxxx
# ./configure –prefix=/usr/local [or your preferred directory]
# make && make install

[Final check]
[Checking Ruby Version]
# ruby -v
ruby 1.9.1p376 (2009-12-07 revision 26041) [i686-linux]
[Checking Ruby Path]
# which ruby
/usr/local/bin/ruby

All done!!

[IPv6] How to disable Teredo for Windows Vista, 7 and Server 2008

admin — Sat, 06 Mar 2010 02:38:59 +0000

In Windows Vista, 7 and Server 2008, IPv6 is installed and enabled by default. When IPv4 and IPv6 are both enabled, IPv6 connection is preferred.

The IPv6 protocol for Windows Vista, 7 and Server 2008 supports Teredo as a Teredo client.

If you wish to use 6in4 tunneling instead, then you must disable Teredo before configure your machine:

‘netsh interface teredo set state disabled‘

[Ruby] What is Ruby?

admin — Sun, 18 Oct 2009 00:25:40 +0000

Ruby is a dynamic object-oriented programming language.
You can use the language for Web development or system utilities.
It can handle graphics as well – [gruff, scruff, rgl, graphiviz and more].
Ruby uses an interpreter instead of compiler.

Founder of Ruby:
Created by Yukihiro Matsumoto.
In 2005 and 2006, the Ruby on Rails Web development framework became popular.

32bit ASN

admin — Wed, 07 Oct 2009 02:02:35 +0000

Excellent video tutorial on 32bit ASN

IPv6 host address interpretation

admin — Sat, 03 Oct 2009 23:01:39 +0000

Bits	Name	Purpose
1-3	Format Prefix(FP)	Address type(unicast, multicast)
4-16	Top-level aggregation ID(TLA ID)	Highest-level organization(major upstream ISP)
17-24		Reserved
25-48	Next-level aggregation ID(NLA ID)	Regional organization(local ISP)
49-64	Site-level aggregation ID(SLA ID)	Site-specific subdivision(subnet)
65-128	Interface ID	Specific device address:a transformation of the MAC address

[Sys-Admin - Basic]Administrative Commands

admin — Sat, 03 Oct 2009 22:46:22 +0000

Unix Operating Systems or Unix Like Operating Systems include a number of generic TCP/IP user commands as follows:

:~$ hostname
Display the name of the local system

:~$ ifconfig
Display information about network interfaces (also configure them)

:~$ ping
Perform a simple network connectivity test

:~$ arp
Display or modify the IP-to-MAC address-translation tables

:~$ netstat
Display various network usage statistics

:~$ route
Display or modify the static routing tables

:~$ traceroute
Determine the route to a specified target host

:~$ nslookup
Determine IP address-to-hostname and other translations produced by the Domain Name Service

MySQL time-related commands

admin — Sat, 03 Oct 2009 01:19:26 +0000

mysql> SELECT UNIX_TIMESTAMP();

mysql> SELECT NOW();

mysql> SELECT UNIX_TIMESTAMP(timestamp);

mysql> SELECT FROM_UNIXTIME();

mysql> SELECT FROM_UNIXTIME(unixtime);

mysql> SELECT DATE_SUB(NOW(), INTERVAL 1 DAY);

Protocol 41

admin — Sat, 19 Sep 2009 01:05:53 +0000

Tunneling is used when two hosts using IPv6 want to communicate through a region of IPv4.
When a packet enters and passes through the IPv4 region, IPv6 packet is encapsulated in IPv4 packet.
The IPv6 packet leaves the capsule when it exits the region of IPv4.
The source and destination fields are set to IPv4 addresses of tunnel endpoints.
The IPv4 Protocol field within the IPv4 header is set to 41 to indicate an encapsulated IPv6 packet.
When using the tunnel, firewalls and/or routers using packet filtering must be configured to allow IPv4 Protocol 41 packets to be received and forwarded.

Quick Illustration:

[IPv6 Host]                                          [IPv4 Only Region]                                          [IPv6 Host]
                   {Tunneling start ————————————————————Tunneling end}
[IPv6 Header]                                           [IPv4 Header]                                        [IPv6 Header]
[Payload]                                                 [IPv6 Header]                                          [Payload]
                                                                 [Payload]

[IPv6 encapsulated Protocol 41 Packet] ——————————-> [NAT Appliance - "check point"]

If NAT appliance supports Protocol 41 then it allows the packet and forward it
If NAT appliance does not support Protocol 41 then it drops the packet