Mick Genie ever posted iptables Handy Guide earlier. However there do not have clear guide on which function and it’s description.

Most of the Linux Operating System do come with iptables and it is used to control the packet traffic of a PC.

Iptables used to manage through chains and there are three type of chains
– INPUT : Control Incoming packet
– OUTPUT : Control Outgoing packet
– FORWARD : Control packet that are forward

In order to control the chain, you need some action,
– ACCEPT : To allow a packet
– DROP : To disallow the packet
– REJECT : The target packet will be stopped.
– RETURN : Go to another chain of table.


iptables handy guide

iptables used to setup, maintain and inspect the tables of IP packet filter rules through Linux Kernel. You can modify or manage the rules through the command from console or SSH.

To list the IPs that is being blocked, you may run the command as below.

iptables -L -n

You will get the list of the IP that is being listed from the Iptables Kernel rules as command above.

To block an IP using iptables,

iptables -D INPUT -s xxx.xxx.xxx.xxx -j DROP

where xxx.xxx.xxx.xxx is the actual IP

Continue reading iptables handy guide

Ruby on Rails Handy Guide

Some Useful command
To install ruby Gem,
gem install [gem_name]
eg, gem install rails

To install ruby Gem with certain version,
gem install [gem_name] –version=x.x.x
eg, gem install rails –version=2.3.5
eg, gem install rails -v=2.3.5

To update ruby Gem,
gem update [gem_name]
eg, gem update mysql

To update ruby Gem with latest version(for all)
gem update –system

To check missing gem
rake gems:install (must run from rails apps folder)

To install gem with lesser space
gem install –no-rdoc –no-ri [gem_name]
eg. gem install –no-rdoc –no-ri rails

To check RoR log,
Path: /home/[cpanel_username]/etc/rails_apps/[apps_name]/log

Continue reading Ruby on Rails Handy Guide