Forward Network Traffic With Iptables

From time to time I come across something truly amazing that I just must share no matter how tired I am. Even though they are typically very simple it helps me remember in the future and I hope it also helps others out wfhen they have the same problems that I do. I recently migrated a server from Slicehost to Linode and I wanted to find a quick and easy way to forward web traffic on various ports to the new server while DNS caught up. The answer was simple… iptables. I found this in an article here.

echo "1" > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination 1.2.3.4:80
iptables -t nat -A PREROUTING -p tcp --dport 3306 -j DNAT --to-destination 1.2.3.4:3306
iptables -t nat -A POSTROUTING -j MASQUERADE

Linux Disk Imaging with Clonezilla and PXE

Now that I finally have a file server at home I got curious again with disk imaging solutions. After doing some research I found a pretty awesome tool called Clonezilla. After downloading the live CD and playing around for a while the first thing I wanted to do was test it out in a PXE boot fashion. Here was my quick and hackish approach. My test run was on a VirtualBox VM in Xubuntu 10.04 with a bridged adapter.

1. Install TFTP server

sudo apt-get install tftpd-hpa
sudo start tftpd-hpa

Ensure /var/lib/tftpboot exists. If it does not:

mkdir -p /var/lib/tftpboot

Ensure that the values in /etc/defaults/tftpd-hpa match.

2. Install DHCP server

sudo apt-get install dhcp3-server
sudo vim /etc/dhcp3/dhcpd.conf

Add something similar to the following…

default-lease-time 86400;
max-lease-time 604800;
authoritative;

subnet 192.168.1.0 netmask 255.255.255.0 {
        range 192.168.1.10 192.168.1.15;
        filename "pxelinux.0";
        next-server 192.168.1.121;
        option subnet-mask 255.255.255.0;
        option broadcast-address 192.168.1.255;
        option routers 192.168.1.1;
}

sudo service dhcp3-server start

The next-server option needs to be the IP of the TFTP server. Everything else should be self explanatory.

Before proceeding verify both services are listening.

sudo netstat -upan | awk  '{print $6}'
2008/dhcpd3
582/dhclient
3627/in.tftpd

3. Install syslinux if it is not already (it should be). Copy over pxelinux.0 into the appropriate location.

sudo apt-get install syslinux
sudo cp /usr/lib/syslinux/pxelinux.0 /var/lib/tftpboot

4. Download latest clonezilla zip from SourceForge.

sudo unzip clonezilla-live-*.zip
sudo cp live/vmlinuz /var/lib/tftpboot/
sudo cp live/initrd.img /var/lib/tftpboot/
sudo cp live/filesystem.squashfs /var/lib/tftpboot/
cd /var/lib/tftpboot
sudo touch boot.txt
sudo mkdir pxelinux.cfg
sudo touch pxelinux.cfg/default

Your tree should end up looking something like this in the end:

├── boot.txt
├── filesystem.squashfs
├── initrd.img
├── pxelinux.0
├── pxelinux.cfg
│   └── default
└── vmlinuz

5. Create configs

sudo vim boot.txt

I made my menu look something like the following…

========================================================================

 .d8888b.  888                                    d8b 888 888
d88P  Y88b 888                                    Y8P 888 888
888    888 888                                        888 888
888        888  .d88b.  88888b.   .d88b. 88888888 888 888 888  8888b.
888        888 d88""88b 888 "88b d8P  Y8b   d88P  888 888 888     "88b
888    888 888 888  888 888  888 88888888  d88P   888 888 888 .d888888
Y88b  d88P 888 Y88..88P 888  888 Y8b.     d88P    888 888 888 888  888
 "Y8888P"  888  "Y88P"  888  888  "Y8888 88888888 888 888 888 "Y888888 

======== Boot Options: ================================================

>> clonezilla ......... Regular Boot
>> clonezilla_safe .... Failsafe Mode

=======================================================================

And finally the pxe config…

sudo vim pxelinux.cfg/default

Looked something like this:

DISPLAY boot.txt

LABEL clonezilla
	kernel vmlinuz
	append initrd=initrd.img boot=live union=aufs noswap noprompt vga=788 fetch=tftp://192.168.1.121/filesystem.squashfs

LABEL clonezilla_safe
	kernel vmlinuz
	append initrd=initrd.img boot=live union=aufs noswap noprompt vga=normal nomodeset nosplash fetch=tftp://192.168.1.121/filesystem.squashfs

PROMPT 1
TIMEOUT 0

Please note that the IP address should be the IP of the TFTP server!

Now testing with a Dell Latitude E6410 I hit F12 on the BIOS screen, Select Network Adapter, and SUCCESS! You should see your boot.txt with a “boot:” prompt. Please share your experiences and alternative implementations on how you solved this issue. I would love to hear them!

My Test results:
250 GB (239.9 GB after formatting)
67.7 GB in use
175.2 GB free
Transfer Rate: Started at 900 MB/min at first, peaked at 1.91 GB/min, ended at 1.72GB/min, average 1.7 GB/min
Time elapsed: 37 minutes, 41 seconds

Possible Migration from Ubuntu to Gentoo Linux (Nope, Arch!)

I have been giving it a lot of thought recently. I have been using Ubuntu for a couple years now and I think I am ready to move on. I haven’t tried Gentoo since college and I thought that tonight was a good night to check in on it. I was worried that it may be somewhat dead and that no one used it anymore so I decided to see if they had a chat room on irc.freenode.net – boy was I suprised! The channel was booming! I am currently installing a test drive VM right now. The installation process is so refreshing. Tonight made me realize that I have really let myself go since college. I am sick of Ubuntu and how it constantly wipes my ass for me, but fails sometimes anyway. I currently am running Ubuntu 9.10 with Gnome and the plan is to migrate to Gentoo and Xfce. The following information illustrates my reasons for wanting to switch. Ones that weigh more for me are in bold.

Ubuntu 9.10 Pros:
Just works
Apt package management is speedy
Well supported
Attractive
I know it

Ubuntu 9.10 Cons:
Does too much
Gnome is bloated
Deb package dependencies are crazy sometimes
Can be slow at times

Gentoo Pros:
Very trim and lightweight
Forces you to learn and maintain general linux knowledge
Very flexible

Gentoo Cons:
Takes FOREVER to compile packages and dependencies
Emerge can have issues
Not for lazy people (and im pretty lazy)

As I write this post I am on step 9/10 of the install. I will provide updates as time goes on.

Update 1:
I encountered three problems and got them all resolved. I am currently installing Xfce and xdm right now. The problems I faced:
1. Changed password for root user for install, not chrooted gentoo environment.
2. The install CD loads out of date drivers so hard drives show up as hda during install but sda during initial boot. This screwed up both GRUB and /etc/fstab.
3. I forgot to compile my network card drivers into the kernel so my eth0 device didn’t exist.

I also found this quite interesting and hilarious (click on it to read):

Update 2:
Gentoo compiles are taking WAY too long and the installation takes 4+ hours to complete. This is just not an option these days, especially for my work laptop. I decided to give Arch + Xfce a shot and it was a breeze. I still feel like I get way more control than I did in Ubuntu without all of the bloat. I am going to try this out for a while and see how I like it. If for whatever reason I dislike it, I will be switching to Xubuntu and call it a day.

Selling points on Arch:
The Arch Build System – Amazing!
The Arch User Repositories, for must haves like my beloved google-chrome!
Minimalistic approach

Kris I hope you are happy…

Integrating Ruby On Rails with Apache2 in Ubuntu 9.10

This is a quick and dirty walkthrough on how to integrate Rails with Apache2 in Ubuntu via Phusion Passenger. This guide provides setup instructions for a solution that includes:

• Apache2
• MySQL 5
• Phusion Passenger
• Ruby 1.8.7
• RubyGems + gems

Install All Required Packages from Apt

sudo apt-get install apache2 ruby irb ruby1.8-dev rdoc build-essential libopenssl-ruby apache2-prefork-dev libapr1-dev libaprutil1-dev mysql-server libmysql-ruby libmysqlclient-dev

Install RubyGems

wget http://production.cf.rubygems.org/rubygems/rubygems-1.3.6.tgz
tar xvzf rubygems-1.3.6.tgz
cd rubygems-1.3.6.tgz
sudo ruby setup.rb
sudo ln -s /usr/bin/gem1.8 /usr/bin/gem

Install Required Gems

sudo gem install rails passenger mysql

Compile Passenger Apache2 Module

sudo /usr/bin/passenger-install-apache2-module

Configure Apache2

sudo vim /etc/apache2/mods-enabled/phusion.load

Add the following:

LoadModule passenger_module /usr/lib/ruby/gems/1.8/gems/passenger-2.2.11/ext/apache2/mod_passenger.so
PassengerRoot /usr/lib/ruby/gems/1.8/gems/passenger-2.2.11
PassengerRuby /usr/bin/ruby1.8
RailsEnv development

Setup Test Virtual Host

sudo rm /etc/apache2/sites-enabled/000-default
sudo vim /etc/apache2/sites-enabled/railstest

Add the following:

<VirtualHost *:80>
    ServerName localhost
    DocumentRoot /var/www/testapp/public
</VirtualHost>

Restart Apache2

sudo /etc/init.d/apache2 restart

Setup Default MySQL Database

mysqladmin create testapp_development -u root -p

Setup Test Rails Application

cd /var/www
sudo rm index.html
rails testapp -d mysql
cd testapp
sudo vim config/database.yml

Put in your root MySQL username and password.

Test!

1. Open browser: http://localhost
2. Click link: About your application’s environment

If you see something like the following then you were successful!

Syncing Tomboy Notes Over SSH

Over the past couple of months I have started to really get into the habit of quickly dumping useful information or code snippets into Tomboy notes to save it for future use. I now use Tomboy for the majority of my note taking needs. I am very happy to get away from the notepad / gedit crutch. One issue that I faced is that I had some notes at home on my PC and other notes at work on my laptop. Thankfully, Tomboy notes has a nifty syncing feature that enables us to sync notes over SSH.

1. Create a directory on a server with SSH to host the notes

ssh tgeek@myserver.example
mkdir tomboy

2. Create an SSH key on each machine that you want to sync with and do necessary prep

ssh-keygen -t rsa
ssh-copy-id -i /path/to/keys/mynewkey tgeek@myserver.example

3. Download sshfs on each machine that you want to sync with

sudo apt-get install sshfs

4. Setup Tomboy to sync

4.1 In Tomboy, goto Preferences.
4.2 Click on the Add-ins tab and ensure that Synchronization -> SSH Sync Service Add-in is Enabled (if it is grayed out then it is disabled).
4.3 Click on the Syncronization tab.
4.4 For Service, choose SSH (sshfs FUSE)
4.5 Enter the credentials for your server that you setup in step 1.
ex. Server: myserver.example
Username: tgeek
Folder Path: /home/tgeek/tomboy
4.6 Click Save

I have this working in Ubuntu 9.10 and it is beautiful!