Use WebDAV to create a simple document portal

It is my experience that email is frequently used (or rather abused) to exchange documents of business sensitive nature.

As all should know email is an insecure way of communicating, and unless documents are fully encrypted, it should not be used to exchange/share documents of any sensitive nature.

A much sensible alternative is to build and to use a secure document exchange portal to facilitate exchange of files between business partners. Such portal can be created with commercial software packages. However, I recommend that you take a serious look at WebDAV protocol. WebDAV can be utilized to build a simple but secure and highly usable file portal, and if you create it with Apache and mod_dav open-source packages, such portal will also be very inexpensive. Read the rest of this entry »

On the Subject of Passwords

Today’s entry explains a few things about computer passwords: how the passwords are cracked, and how to prevent it by choosing strong passwords that are, at the same time, rather easy to remember.

Passwords are stored as hashes

Passwords are stored on computers in the form of hashes. Hash does not equal encrypted text. Encryption can be reversed – it is almost as easy to convert from a plain text to an encrypted text as it is to convert back from an encrypted text to a plain text. With hashes, it is a completely different story. it is easy to convert a plain text to a hash, but the opposite process of converting a hash to a plain text that it encodes is almost impossible to perform. Not completely impossible but almost impossible – it may take a millisecond to convert a plain text to a hash, but the opposite process may require years of computing time. Read the rest of this entry »

Network Monitoring on a Budget

In this post, I want to discuss how to monitor a small network without spending big money. The goal of such monitoring is primarily security. We want to look for signs of presence of attackers and malware on our network. It is quite a daunting task, especially if there is no dedicated budget and no dedicated personnel (which is what one usually finds in small, and sometimes even not so small institutions). Below, there are some of the things that I have tried. If you have other ideas, please share them (send a comment). Read the rest of this entry »

To secure your MS Windows computer

This post is intended primarily for home users of Microsoft Windows based PCs. It describes a simple and quite basic approach that should make your computer significantly more secure. While the target of this post are Microsoft Windows installations (and especially Windows XP), many of presented here ideas are valid for other operating systems, too.

Note, that steps in securing Windows installations that are listed below are based on personal experience rather than on any “scientific” study. Approach described here has worked very well for me, and I see no reason why it should not work for you. The first three steps are actually the most important ones – this is where most of security is realized. Read the rest of this entry »

Antivirus programs: how much protection do they really offer?

A large majority of users of PCs with Microsoft Windows operating system have some antivirus software installed on their systems by now. While most would agree that this is a good thing, what is very unsettling to me is that many (most?) of users have a false sense of security. They believe that their systems are secure from computer malware. This is especially true if they have a paid subscription to an antivirus program. I have heard more than once someone saying: “I pay for \main antivirus vendor name here\ software and updates, and I do not have to worry about viruses and security.” Somehow paying for protection is supposed to guarantee its effectiveness.

Unfortunately, antivirus programs offer modest protection, at best. In independent tests performed by NSS Labs, best anti-virus programs are able to detect only about 70% of computer malware. There are many forms of malware that often all antivirus programs fail to detect and, thus, do not protect from them. To give a recent example, Brian Kreb posted on 07.22.2009 on his Security Watch blog at Washington Post Read the rest of this entry »

IFSTAT network data visualized

I have many computer systems on my network that stay powered on 24/7 (these are mostly servers but also many desktops systems stay on for a variety of reasons). Monitoring network bandwidth usage on such systems can be quite desirable. It can help to detect, let’s call them, “unofficial” activities by users. It can also help to detect presence of a network active malware. Whatever your reasons are, if you are interested in network monitoring, IFSTAT program is your friend.

IFSTAT – http://gael.roualland.free.fr/ifstat/ – is a great tool written by Gaël Roualland for network usage monitoring on individual computer hosts . IFSTAT runs on most computer platforms, it is very easy to install, and very easy to use.

IFSTAT generates large volumes of of data that is not easy to analyze especially when one has to deal with data coming from tens of hosts. A graphical presentation of IFSTAT data should substantially facilitate analysis. I developed a simple tool to collect and to visualize data collected by IFSTAT.

My tool is intended for networks of computers. It is not intended (and probably not very useful) for a home computer user with a couple of systems on the network.

Approach

IFSTAT is executed on individual computer hosts in a continuous or a semi-continuous manner. IFSTAT data is sent periodically to a Web server host via HTTP POST method. Perl scripts on the server process submitted data and make it available for presentation. Data is collected and presented per host and per calendar month. Color is used for presentation of network bandwidth values (in addition to numerical values). You can see an example of IFSTAT presentation page generated on the web server here.
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Backup each Samba share to a separate archive

The backup script that I use on my Samba file servers, stores each Samba share in a separate cpio archive (i.e. in a separate backup file). I find such share-based backup arrangements very convenient.

My script – see below – extracts share names and paths from Samba configuration file. When a new share is configured in Samba, it is automatically added to backups.

The script runs full backup followed by 30 incremental backups. After 30 incrementals, the cycle repeats itself – full + 30 incrementals. The script keeps track of the count for each share (their counts do not have to be in sync).
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