Network Notation

Network Notation

There are two parts to “network notation”: the first part contains the first IP address in the network range; the second part contains the subnet mask (i.e. the size of the network). There are two common ways to write the subnet mask. Unfortunately, both ways are something that only computer engineers enjoy.

Let’s go through an example. A mail server will only send out mail coming from a trusted network — you don’t want anyone on the Internet using your mail server and all your bandwidth! In our example, all of the machines on our LAN use IP addresses with 192.168.1.x IP addresses. The subnet mask for these 256 IP addresses can be specified with either /24 or 255.255.255.0. The full network notation ends up looking like:

192.168.1.0/24, or
192.168.1.0/255.255.255.0

By the way, the first and last addresses (192.168.1.0 and 192.168.1.255 in our example) are reserved and cannot be used. We really only have 254 usable IP addresses in our case.

The table below is a list of common netmasks.

Netmasks and Networks

Netmask IPs Sample Usable Range

/8 — 255.0.0.0 16777214 192.168.1.1 - 192.255.255.254
/16 — 255.255.0.0 65534 192.168.1.1 - 192.168.255.254
/24 — 255.255.255.0 254 192.168.1.1 - 192.168.1.254
/25 — 255.255.255.128 126 192.168.1.1 - 192.168.1.126
/26 — 255.255.255.192 62 192.168.1.1 - 192.168.1.62
/27 — 255.255.255.224 30 192.168.1.1 - 192.168.1.30
/28 — 255.255.255.240 14 192.168.1.1 - 192.168.1.14
/29 — 255.255.255.248 6 192.168.1.1 - 192.168.1.6
/30 — 255.255.255.252 2 192.168.1.1 - 192.168.1.2

Source: http://www.clarkconnect.com/wiki/index.php?title=Network_Notation

Aggregation: ParagonHost, LLC http://www.ParagonHost.com “World Class Internet Services”

Windows Key - Features and Shortcut Tips

That Windows Key

I get a lot of questions about what that little Windows key is for. Well, the simple answer is that when you hit it, the start menu pops up but it’s got a LOT more functionality than that.

It’s actually pretty cool what Windows can do with that key. There’s a whole bunch of key combinations that can really speed up starting and running certain programs or functions of Windows.

Winkey Display or hide the Start menu.
Winkey+BREAK Display the System Properties dialog box.
Winkey+M Minimize or restore all windows.
Winkey+E Open My Computer.
Winkey+F Search for a file or folder.
CTRL+Winkey+F Search for computers.
Winkey+F1 Display Windows 2000 Help.
Winkey+R Open the Run dialog box.
Winkey+TAB Switch between open items.
Winkey+U Open Utility Manager
Winkey+D Show Desktop

IE Browser - Keyboard shortcuts

IE is a great web browser. It’s got a whole bunch for very useful tools in it. There’s also a collection of keyboard shortcuts that help you to get at those tools. Below is a fairly complete list of them.

Create a new IE window ctrl-n
Open (a webpage) ctrl-o
Refresh a webpage (to see new content) ctrl-r
Print (works with almost all Windows programs ctrl-p
Find (something on the page) ctrl-f
Add the current page to your favorites ctrl-d
Get help (works with all Windows programs) F1
Previous page (like clicking the back button) Alt-Left arrow
Next page Alt-Right arrow
Scroll up and down through the document Up and Down arrow keys
Stop downloading a page Esc
Open search Window ctrl-e
Open Favorites Window ctrl-i
Open History Window ctrl-h
Add www. to the start and .com to the end of what’s in the address bar (type yourtechonline and then ctrl-enter) ctrl-enter

Temporary Internet Files

Summary: Temporary Internet Files explained. There is also information how to delete temporary internet files and corresponding index.dat files.

What are Temporary Internet Files?

Temporary Internet Files are, in fact, the cache of the Internet Explorer. This means that when you load a web page with Internet Explorer, it is saved on your computer so that if you later decide to open the same page again, it will open a lot faster. Temporary Internet Files improve speed of web browsing and also make possible so called offline browsing, which gives you the ability to open the web pages from cache even when you are not connected to the Internet.

Despite all these positive things about Temporary Internet Files, they have one big drawback: they compromise your privacy. Everyone with access to your computer can look into your Temporary Internet Files folder (location of this folder is discussed here) and see the sites that you have visited in the past. You can manually delete the contents of Temporary Internet Files folder (explained here) but this will not erase all traces of the pages because a special file called Index.dat is placed in this folder and it will still preserve the names and even the dates of your first visits to many pages.

Where is located Temporary Internet Files folder?

The location of the Temporary Internet Files folder depends on the version of Windows and whether or not you are using user profiles.

If you have Windows XP or Windows 2000 then Temporary Internet Files are in this location (note that on your PC they can be on other drive instead of drive C):

C:\Documents and Settings\\Local Settings\Temporary Internet Files\

If you have Windows Me, Windows 98, Windows NT or Windows 95 then index.dat files are in these locations:

C:\Windows\Temporary Internet Files\

C:\Windows\Profiles\\Temporary Internet Files\

Note that on your computer the Windows directory may not be C:\Windows but some other directory. If you don’t have Profiles directory in you Windows directory don’t worry - this just means that you are not using user profiles.

How to delete Temporary Internet Files?

To delete Temporary Internet Files manually, do the following things:

1. Start Internet Explorer and click Tools menu, then select Internet Options… from this menu. This will open the Internet Options window.

2. Click General tab and then find in the section Temporary Internet Files the button Delete Files… and click it. A new dialog box opens.

3. In the Delete Files dialog box, click to select the Delete all offline content check box if you want to delete all Web page content that you have made available offline.

4. Click OK to delete the files. Note that if you are doing this for the first time, the deleting can take a large amount of time, so be patient.

WARNING! This will most probably delete all visible items in the Temporary Internet Files folder (except cookies) but a number of invisible traces may remain in the index.dat files. The only way to be sure that you are getting rid of all traces for good is the usage of specialized privacy protection program like Mil Shield - a powerful privacy protection program that was designed specifically to clean and shred the Temporary Internet Files. Additional benefit is the ability to preserve the tracks from some chosen by you sites (selective cleaning), which makes your browsing more comfortable and safe (it is rather suspicious to always have empty history, cookies and Temporary Internet Files - it is better to leave some tracks from “innocent” sites). Mil Shield also cleans all other tracks as index.dat files, cookies, history, cache, AutoComplete records, UserData records, history of recently used folders and documents and many more.

More information about the article: http://www.milincorporated.com/a-temporary-internet-files.html

About The Author

Mil Incorporated was founded with an ambitious objective to be a trusted software partner for individuals and enterprises around the world. Mil Incorporated provides software security and privacy solutions that incorporate state of the art technology, security expertise, and substantial resources.

Web address: http://www.milincorporated.com/

RSA Attack Efficiency Improves

August 2006 saw the disclosure of a fairly interesting attack against the RSA encryption algorithm (most famously being used in SSL - protecting online transactions). While it didn’t target the actual algorithm, which still has not been broken, it is a so-called side channel attack, targeting the peculiarities associated with implementing the algorithm on various computing hardware.

The team behind the initial disclosure have recently submitted a modified approach to the attack, resulting in almost-astronomical improvements in attack efficiency.

In basic terms, the attacks rely upon a phenomenon known as ‘Branch Prediction Analysis’, where a program / attacker is able to predict what other software is doing as it passes through the CPU of a system.

In the first iteration of the described attack, the method required snooping on what was happening with the CPU for a relatively long period (or number of cycles), and certain software that implemented SSL protection (OpenSSL) quickly introduced patches to protect against this listening attack.

While many hardware manufacturers and Operating System developers have introduced defensive mechanisms to try and prevent this sort of attack taking place, it has been discovered that Pentium-IV (PIV) chips with Hyper-Threading enabled still have two caches that are not adequately protected. The new iteration of the attack, using a technique dubbed ‘Simple Branch Prediction Analysis’ (SBPA) targets both of these caches and can extract almost the complete secret SSL key in just one cycle. Running as an unprivileged user, this method can also target and extract data from any other software processes running on the system (SSL is an example in this case).

The technical black magic of how a branch predictor attack works can be explained as follows. Although modern CPUs are very quick, they still can’t process absolutely every bit of information that they need to without a queue building up. This queue of instructions / data waiting for processing sits in a cache next to the CPU and they are executed in order of priority / time spent in the queue (various tuning settings come into play). By attempting to monopolise the CPU’s attention, and filling the cache, the miniscule timing differences between when instructions from the same process are executed can give hints about what other instructions and data are moving through the CPU. Being able to interpret what this data is exactly, is key to branch prediction.

Mitigating the issue is the requirement to be running secure and insecure processes on the same processor at the same time, and for the attacker being able to run their process as a local user. Due the spying process capturing almost 100% CPU continuously while it is running, normal system monitoring software should be alerting administrators to something out of the ordinary running on the system.

What real-world threat exists for this relatively esoteric attack? Shared-server installations. It would be possible for a lesser-privileged account holder on a shared server to run the spying process while other account holders are negotiating SSL connections. A well timed attack will allow them to run their spying process once (and thus minimise the attention drawn to it), and then be able to effectively intercept SSL communications directed at the target.

About The Author

Carl Jongsma is the founder and lead researcher for Sûnnet Beskerming (http://www.beskerming.com), an Information Security company that services the world and still maintains the local touch.

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