Many passwords have one or more of these problems:

1) It is based on a word found in a dictionary. This is easily broken as a program can go through the dictionary and try every single possible word.

2) It is based on something personal to you. This is less of an issue if the person trying to break your password does not know who you are, but if you choose a password such as your wedding date or the birthday of you or someone close to you, and the person trying to break your password knows you, it might ease their “job” of breaking your password.

3) It is short. The less characters in a password, the less combinations are possible. Let’s say you only choose lowercase letters from the English alphabet. So you have 26 different letters to choose from. To guess a 1-letter password, you would have to try up to 26 combinations. Let’s add another letter then. Now we have a 2-letter password, which means there are 26 combinations for the first letter and 26 combinations for the second letter, which, with basic math, gives us a total of 676 (26² squared) different combinations. For each letter, we can multiply the amount of combinations with 26. To give you a quick overview, here is the amount of combinations for some various lengths:

1 letter: 26 combinations

2 letters: 676 combinations

3 letters: 17576 combinations

4 letters: 456976 combinations

6 letters: 308915776 combinations

And so on.

As you can see, this number rises quite rapidly. I would still recommend a password of at least 10 characters. But we can do even better than just using letters – and this brings us to the next problem:

4) It lacks numbers and symbols (and either uppercase or lowercase letters). If we add both upper- and lowercase letters, numbers and symbols to the mix, we can further raise the number of combinations. In my head I can think of 26 lowercase letters, 26 uppercase, 10 numbers and at least 25 symbols – that is 87 combinations! If you want, you can try and put into your calculator how many combinations there is for a password with only 5 characters, but 87 combinations.

So, how do we create a strong password, that does not have the problems above, but is easy to remember?

Let’s put up some rules:

- No words.

- We require at least 1 symbol and at least 1 number, and both big and small letters.

- The passwords length should be at least 10 characters.

Sure, we could type a bunch of random numbers, letters and symbols, but this wouldn’t be very easy to remember – and writing it down kind of defeats the purpose. Instead, we will think of a sentence that we are be able to remember and then use letters from this sentence. An option can be a line from a song. Let me give an example:

To be or not to be, that is the question

We pick out the first letter of each word, which gives:

Tbontbtitq

This covers problem 1, 2 and 3. Now we “inject” letters and symbols into the password. For instance, when you pronounce “to” – it sounds like “two”, so we can change the first two T’s into the number 2 (or if the sentence actually had a number spelled out in it, we could also change that into a number). Now we need a symbol. We are in luck however, as the sentence actually contains a symbol – the comma. So let’s see what we got:

2bon2b,titq

Then we only need an uppercase letter. I like to pronounce the sentence above like this: “To be or not to be, THAT is the question”, so we can change that T into uppercase.

Our end product is this:

2bon2b,Titq

A complex password, but quite easy to remember.

Note 1: When choosing a password, you might want to stick to some of the more well-known symbols (though this decreases the amount of combinations you can choose). Some places don’t allow any symbols, and some only allows the rather common ones, such as: – (dash) _ (underscore) and a blank space. Some also do not allow the password’s first character to be a number and/or symbol.

Note 2: I would also suggest to come up with 2 passwords. The first one should only be used when it is being sent over an encrypted connection (see below) AND when you trust the third party (a good example is your web bank). The other can be used for less secure places, but it should also be less damaging if this password was broken.

Encrypted connection: If you are communicating with the web page through an encrypted connection, your web browser will usually display a lock somewhere on the window, and the URL will say https:// in the beginning, rather than http://. If not, your password is sent as clear text and could be grabbed by a third party.

For an example of an unencrypted and encrypted page, see:

http://www.google.com/ (unencrypted)

https://www.google.com/accounts/Login (encrypted)

Remember, if you are using Gmail, you can choose whether to use an encrypted connection or not under settings.

To remove the sound at the login window, simply go to System -> Administration -> Login Window. Choose the Accessibility tab and uncheck the “Login Screen Ready” box.

For the piece of music after logging in, this can be changed at System -> Preferences -> Sound. Choose the Sounds tab, find Login under Desktop and doubleclick the text that says Default, which will bring up a small dropdown menu where you can choose between Default, Custom and the feature we want, Disabled.

The first step in this process is to enable the WoL functionality in the BIOS (it is not supported by all hardware though). In the BIOS, look for a setting either called “Wake on Lan” or perhaps something to the extend of “Power On By PCI Devices”. The exact name and location is unfortunately BIOS dependant.

After editing the BIOS, we need to run the following command: “ethtool ethX” (replace X with the interface you want to set up). If ethtool isn’t installed on the server, it can be done by typing “apt-get install ethtool”.

The command will tell you a bunch of stuff about the specified interface – what we are looking for is the following line:

Supports Wake-on: pg

The “g” in this connection means that the interface supports Wake-on by something called a MagicPacket (we will get to that one in a second).

Now, to enable this behaviour, we run the following command:

ethtool -s ethX wol g

This only lasts until next time we boot the computer however.So in order for this command to run every time we boot the computer, we’ll make a script that does this for us.

Go to “/etc/init.d/” and use the command “touch <filename>.sh” to make a file with the specified filename. Enter the empty file and add the following lines:

#!/bin/bash
ethtool -s ethX wol g

Then make the file executable with “chmod -x <filename>.sh”, and finally add it to the runlevels with this command:

update-rc.d -f <filename>.sh defaults

Now, wake on lan should be enabled.

So how do we actually wake the computer?

First, install the “wakeonlan” program, with “apt-get install wakeonlan”.In order to turn our computer on, we also need to know which hardware address it has. On the server, run “ifconfig” and in the first line of the corresponding interface, it should say “HWaddr” and then a bunch of numbers and letters, two-by-two, seperated with colons. This is the computers physical address (also known as hardware address) and the one we need to use to wake it.

So, having that, we can now use the command “wakeonlan <hardware address>” to wake the computer.

A single note: This only works when you are on the same LAN as the server.

net.ipv4.conf.icmp_echo_ignore_all=1

in the “/etc/sysctl.conf” file.

Now I just need to figure out how to set up a machine to only respond to ping from a certain IP range.. Any suggestions?

The motd will look something like this:

The programs included with the Ubuntu system are free software;

the exact distribution terms for each program are described in the

individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by

applicable law.

To access official Ubuntu documentation, please visit:

http://help.ubuntu.com/

System information as of Sat Mar  7 20:50:01 CET 2009

System load:  0.83              Swap usage:  0%     Users logged in: 1

Usage of /:   37.4% of 9.02GB   Temperature: 45 C

Memory usage: 30%               Processes:   147

Graph this data and manage this system at https://landscape.canonical.com/

In order to change the message of the day, we first want to edit the file “/etc/motd.tail”. You might have noticed that this file does not contain all the information you was presented with when you logged in, and you might also have noticed the “motd” file in the same folder. The “/etc/motd” file is where all this information is gathered and the actual file presented to you. So if you want a one-time change to your motd that will be reverted on reboot, you can edit the “/etc/motd” file.

I am not sure if I changed something, but after I had edited the motd.tail file, the system information was no longer being updated. In order to turn it back on, I had to enable the motd updates with the following command: “update-motd –enable” (this means you can’t update the “/etc/motd” file though, as it will be overwritten fairly recently). There is a cronjob attached to this updating, which updates every 10 minutes. If you do not want the system information, you might want to remove this (it is installed at: “/etc/cron.d/update-motd”).

If you do want the system information, you might not want to display the last line of text saying:

“Graph this data and manage this system at https://landscape.canonical.com/”

This is fairly easy to remove. Open the file “/usr/lib/python2.5/site-packages/landscape/sysinfo/landscapelink.py” and find the following three lines:

self._sysinfo.add_footnote(
“Graph this data and manage this system at “
“https://landscape.canonical.com/”)

And comment them out like this:

#        self._sysinfo.add_footnote(
#            “Graph this data and manage this system at “
#            “https://landscape.canonical.com/”)

This looks pretty good, but you might notice that if you boot the server and log in right away, there are no system information. This is because the cron job haven’t had a chance to run yet. Luckily, it is something we can solve.

Go to the folder “/etc/rcS.d/” and find the file called “Sxxbootmisc.sh”. The x’s in bold are a value, but the exact number varies – for instance, on two of my computers it is S80bootmisc.sh and S55bootmisc.sh. This file is run when the computer boots. When you located it, open it. Scroll through it until you find a line saying “# Update motd”. Here you can add the following line: “/etc/update-motd.d/50-landscape-sysinfo >> /var/run/motd”. This will make the system information be updated and added to the motd file when the computer boots.

The file mentioned above (50-landscape-sysinfo) might also be worth to look into, though it does not give many options for editing, but it would be possible to add a command such as “uptime” to what is shown.

Note: If you want to add some space between the various information, you can use an empty “echo” command.

When you log in through SSH, besides showing the motd, it will also tell you the last login to the server. Should you want to turn this line off, this is done in the file “/etc/ssh/sshd_config” where you change the line:

“PrintLastLog yes”

to

“PrintLastLog no”

Simple as that.

On the server, open “/etc/ssh/sshd_config” in your favorite editor and change where it says “Port 22″ to whichever number you’d like. Let’s say you choose 122. Save the config file and restart the ssh service with the command “/etc/init.d/ssh restart”. Next time you want to SSH into the machine, simply type “ssh <IP adress> -p 122″.

From what I read, it is a problem with gparted though, as formatting through the terminal shouldn’t be a problem. I am not secure enough in my commandline skills to do that though.

There was no issue with using the “Create a USB startup disk” in System -> Administration. However, when I put my 4 GB USB key in the Shuttle and booted, I only got the message:”Verifying DMI Pool” and a few garbled character after that.

After looking around at Google for a bit, it seemed like others had the same issue. Instead, I took my trusty Microdrive, put it in a CF card reader and after fighting with gparted for a few minutes again, got the USB startup disk installed on that.

I put it in the Shuttle and it ran just fine.

I chose not to install anything but Ubuntu Server itself and OpenSSH, as I am not exactly sure of which services I want this server to run.

The plan is to add a firewall between the router and the Internet, and add a low-power server for services, such as backup, file storage, (FTP?), etc.
I have already bought an Alix (a small embedded PC using only 3 Watts) from the company PC Engines, their new model 6b2, which I want to act as the firewall and to control the network behind it (for instance starting computers with WOL (Wake On Lan) when they are needed). I also purchased a 8 GB Microdrive on Ebay to plug into it (the Alix normally takes Compact Flash (CF) cards, but a Microdrive fits into a CF type II slot). My reason for getting a Microdrive instead of a CF card is because I did not want to worry about my CF card getting “worn out”. See the following quote from Wikipedia:

“Flash memory, regardless of format, can take only a limited number of erase/write cycles to a particular “sector” before that sector can no longer be written.”

This means I can write to the disk often, instead of having to go through hoops to make sure that the file system only writes to the disk when necessary (not something I want to go through, as I am not a very experienced Linux guy yet).

I have also purchased a Shuttle (model K45) for running the service-server, together with a 1TB harddisk from WD (Western Digital).

I am planning on running Ubuntu Server on both computers, as I don’t have much knowledge about Linux yet. This is where I am right now, having only worked slightly on the Shuttle and Alix so far. I plan on writing some guides and/or tutorials about the services I set up and tweaks I do, so others might benefit from my trials.