The following is an extract from a very concise example of how to secure your Linux Computer using IPTables while allowing inbound SSH connections from only trusted hosts.

Okay, so this post will be brief but to the point. Today I needed to lock down a machine I administer so the only inbound connections which were allowed were SSH connections from trusted hosts. I’m using Debian so this will obviously work for other Debian based distros such as Ubuntu, Linux Mint etc.

Assuming you’re running a current version of Debian or a derivative then iptables will already be present on your system. One of the first things to take note is that iptables won’t hold its ruleset during a reboot so to start off this tutorial the first thing I ensured was that the ruleset will be restored when the machine is rebooted. So, as root I edited /etc/rc.local and before the exit line i added /etc/iptables-init.

The full article can be read on Jerry Walsh’s Blog located here:  http://jerrywalsh.org/2012/howto-secure-your-linux-box-with-iptables-0112.html

Do you find it hard to keep track of all the passwords you use for different websites such as facebook, twitter, gmail etc. If so then you should check out PWDHash. With this nifty little addon for firefox you’ll just need to remember one password for all the different websites, not only that but it also makes your passwords more secure and theft proof. Below you can find a tutorial on how to use it.

Stanford PWDHash

People generally use the same password for lots of different websites which is not a very good idea.

PwdHash is a browser addon that transparently converts a user’s password into a domain-specific password.

What does this mean?

Say for example you login to Gmail using the password “password123″ and you also use this same password on your Facebook account. By using PWDHash the password123 is hashed with the domain, gmail.com to give the password “oDWsVkXNO1GpD”. When hashed with facebook.com it gives a completely different password, “2oHZykUiHmA3H”.

You might be wondering at this point, right how am I going to remember a password like “2oHZykUiHmA3H”. With PWDHash installed, you don’t need to remember either of the two long passwords. By hitting F2 (place the cursor in the password field and press the F2 key) and then typing “password123″ PWDHash automatically replaces what you have typed to “oDWsVkXNO1GpD” if you are using gmail.com and “oDWsVkXNO1GpD” if you are using facebook.com.

To start using PWDHash follow these simple steps:

Go here and install the add-on for Firefox or here for Google Chrome

Once you have the addon installed you can then go to the settings page of your Gmail, Facebook, Hotmail or whatever and request a password change.
When you are typing your new password make sure you press F2 before typing it, or alternatively precede it with “@@”.
Once you have entered your new password (usually twice for verification purposes) you should now be able to start using PWDHash, Just make sure to hit F2 before you type your password when logging in

If you are using a different browser or you’re at a computer where PWDHash is not installed simply go to http://www.pwdhash.com and enter the details there. Then just copy and paste your password from the PWDHash website to the password field of where you’re trying to login.