At the moment there is no other way to use this service than getting an invitation code. I will post my opinion here as soon as I understand what to do with Wave. I am interested in Project management using Google Wave, so if you have any ideas, please, share.

Related posts:

1. Free Software: How Did it Appear

Let’s start with such an understandable and well known notion as password. By entering password user authentication, i.e. confirmation that the account will be used by its owner, occurs.

Users should know that operating systems are generally well secured to prevent unauthorized use. That’s why for a violator it’s much easier to get somehow user’s password and login into system pretending to be an authorized user. So instead of cracking security systems that become more and more complicated, violators tend to use methods of social engineering, manipulating users for the only purpose of gathering the information they need.

Kevin Mitnick (former hacker, current security consultant) emphasizes that “it is much easier to trick someone into giving a password for a system than to spend the effort to hack into the system.” He argues that it was the single most effective method in his arsenal.

To prevent such kind of situations follow the below mentioned recommendations:

1. Do not write your password on the display of you PC and do not attach any stickers with passwords to it. Anyone can see them!
2. Do not save your passwords in text files, unless you’re sure that those files cannot be read by someone else.
3. Do not store corporative secret information in the common folders (such as Documents, Pictures and etc.), which can be accessed by anyone
4. Create strong passwords (at least 8 characters, digits and letters, different letter case).Violators use different kind of software that allows them to enumerate all the possible passwords in order to get the right one. Given process is generally known as “brutal force“. Thus the shorter and the more “typical” (violators use special dictionaries that include all the frequently used passwords like “12345″, “password”, “iloveyou” and the combination of users’ last names, first names, and birthdays) your password is, the faster it will be detected. You can check most common passwords and brutal force analytics here.Let’s discuss given point a little bit more.

   You should know that the weakest passwords are short or are words, names, or derivations of words or names. If you simply change an “A” to a “4” or an “s” to a “$”, it won’t significantly increase the security of a password. The password crackers generally have customizable sets of rules that they uses to try various permutations on supplied dictionary words and user information as possible passwords.

   There are three main properties that define the security of a password: length, character set, and randomization. Strength in one of these properties can make up for weaknesses in the others (at least to a certain degree).

   If passwords are not limited to seven or eight characters, length is probably the easiest way to increase the security of a password. No doubt it is easier to choose a very long password than a very random one. Thus, a 40-character password that uses only lowercase letters and spaces will be extremely difficult to break.. However it’s not a great idea to pick a password from a popular text such as one of Shakespeare’s plays or sonnets.

   As for the characters used in a password, they have a major effect on the security of the password, especially when the length of a password is limited. An eight-character password with lowercase letters and punctuation is over 800 times (!!!) harder to break than a password of the same length with just lowercase letters. When considering the characters used in a password it is useful to break the character set into groups: uppercase and lowercase letters each account for 26 characters, numbers account for only 10, and special characters account for 34. Strong passwords should have at least one character from each of three different groups.

   Although truly random passwords are pretty hard to remember, they are very strong as well. It’s more logical to generate a password from a pattern that is meaningful only to you. For example, “NwtfcIuf2y”    is meaningful only for me, because I know that it stands for “Nokia was the first cellphone I used for 2 years”. Remember that adding a number to a random password would make it even better.

   In addition to that we would recommend you to use password managers which help you to generate strong passwords and store them in an encrypted form. As an example, you can check KeePass that is available for various operating system including Linux.

5. Сhange your passwords on a regular basis. Software used to crack passwords tries to discover passwords using the data trapped in the Net or snatched from the system files of your operating system. Remember that violators may try to discover your password for years, in case it’s of great value for them.Though some may say that you need to change your passwords every week, there is no need to do this so often. For a usual user it’s recommended to change passwords once in 90-120 days. As far as Microsoft policy is concerned it’s 42 days by default.
6. Scan you computer for malware software (in particular for the software that can track the sequences of key presses) on a regular basis and take appropriate measures to prevent their appearance (check the post “Choosing an Antivirus for Linux“).
7. Do not open suspicious letters and do not run unknown programs.
8. In case you are really concerned about the security of your data, you should use multifactor authentication, which at the moment is available for all Linux users and represents the most reliable and modern solution. In comparison with the usual authentication that is based on the fact that you know the password, multifactor authentication includes several principles, such as: “you know” (the password or PIN code), “you are” (biometric data – fingerprints and iris scan), and “you have” (hardware keys). Hardware keys, being effective protection devices that are plugged into the serial, parallel or mostly used USB port, ensure that only authorize individuals access your sensitive information. Using them you can significantly strengthen Virtual Private Network security for remote access, protect data on laptops and PCs, improve network access security and simplify password management and protection. They include such devices as smartcards, USB authenticators, hybrid authenticators and etc. Linux users can use a broad spectrum of authentication devices from well-known manufacturers, such as Aladdin, Safenet (Rainbow), Bestoken (the information about other devices can be checked on the website of OpenCT project), there is even a solution that allows you to use a usual USB Flash for authentication.

Of course, all the above mentioned recommendations should be used simultaneously as a system; otherwise they will hardly bring the result you want.

One of the most characteristic features of secret information is a strictly restricted amount of people who have access to it. To prevent the acquisition of secret data by outsiders you need:

• to use capabilities provided by operating system for differentiation of access between users
• not to install and use unrelated services on workstations, where secret information is stored or used. In case of great data importance it’s better to disconnect the workstation form the network and physically not to allow someone to use it, except the intended ones.
• to use data encryption facilities. This is the only way to protect data from administrators who have unlimited access to the system.It should be mentioned that there are a lot of different types of encryption, both for individual files (PGP, GnuPG), and disk partitions (TrueCrypt). All those programs ensure extremely high level of security being at the same time free software.

One of the free software features consists in the fact that its source code is generally free to access. Some security experts consider that the opportunity for violators to scrutiny the algorithms of your OS represents potential threat. However more often free access of the algorithms is considered to be an advantage, because security experts have the opportunity to analyze code and satisfy with it if it’s enough secure, or to inform developers if there are any mistakes.

You should know that at the moment all the widespread encryption algorithms, including the ones presenting state standards, are published to be studied and examined by experts and the ones who are interested in them.

Another great thing about the open software is that users do not depend on vendors as far as security policy, updates, support and security patches are concerned. Given fact allows them to prolong the life of software for ever and ever. Moreover having the full access to the specifications and the source code of the software even a small company can improve and change it according to their certain needs.

That’s why we strongly recommend you to use software with open source code for data security; because it’s well examined by experts and does not have any loopholes to be used by violators. In addition to that you should always check if there are any vulnerabilities found in the OS and install updates.

Related posts:

1. Password Manager Usage in Linux
2. Working with MS Office Word documents in Linux OS

Unlike the original antivirus programs that were based solely on the treatment of computer viruses, a modern antivirus program is designed to protect the system from a great number of different possible malicious programs (worms, viruses, Trojan horses, rootkits, spyware , adware), phishing attack etc.

It is known that the first antivirus programs have appeared in 1983.

Antivirus programs have independent and proactive way of functioning. Most antivirus programs with proactive mode can not work simultaneously on a single computer. Some antivirus programs come with built-in firewall, spyware detection tools and related security tools.

Recently, on various forums there have been a lot of discussions whether to install antivirus software on Linux or not. Many people do not understood what exactly do these antivirus programs and whether they have ever needed them.

Well, here is the list of most popular antivirus softwares you can use on your Linux.

Avast! Antivirus

Avast! Antivirus is a freeware antivirus software, produced by Czech company ALWIL Software, operating since 1991. The first version was published in 1988. It is currently available in 27 languages. Its effectiveness has been confirmed by ICSA certified and it was awarded with many prizes like Virus Bulletin 100% Award. The program is available in two versions: Home Edition and Professional.

Simple user interface is available when you run scans on demand. It allows you to easily define the basic parameters and functions to access files in quarantine, preview, and the event log to update virus signatures. Extended interface is available only in Professional version.

The program integrates with the operating system layer, allowing access to critical system functions from the context menu.

The Linux version of the user interface requires GTK + 2.x. If  it’s not present in the system, it will be added during installation.

The last stable version is 4.8.1356, released 2009-09-25.

Main features:

Antivirus kernel:
- Almost 100% detection
- Outstanding performance
- Reasonable memory requirements
- ICSA certified

User Interface:
- Intuitive Simple User Interface
- Independent on installed graphic libraries
- Testing of whole disks or just selected folders
- Defining and running of antivirus tests
- Working with the scan results
- Actions with infected files
- Storing the scan results (history)
- Virus encyclopedia
- Command-line scanner with STDIN/STDOUT mode

Updates:
- Non-incremental updates
- Updates can be completely automatic
- Standard updates are provided 2 times a week

Related posts:

1. Choosing a Linux Live CD
2. Password Manager Usage in Linux
3. Using RAR in Linux: Guide and Samples

• User account binding to the physical line, for example, using MAC-address of the network interface. Linux user has to configure network interfaces to establish such a connection;
• VPN-technologies allowing user authentication and secure connection. For example, PPTP, L2TP or IpSec;
• PPPoE (Point-to-Point Protocol over Ethernet) which this article is about.

PPPoE represents a network protocol for encapsulating Point-to-Point Protocol (PPP) frames inside Ethernet frames. PPPoE expands the capability of PPP allowing a virtual Point-to-Point connection over a multipoint Ethernet network architecture. Given protocol was published by IETF in 1999 and its specification is RFC 2516.

In fact PPPoE does not have important advantages in comparison to the above mentioned alternatives. However the following ones can be emphasized:

• It’s significantly more secure than MAC-binding and allows user to change network interfaces connected to the provider without appealing to provider’s customer support; still it slightly reduces the bandwidth of the network interface;
• Its configuration is simpler that the one of VPN-connection and requires less parameters to be introduced by user. In particular there is no need to configure IP-address or to specify the address of VPN-server.

Thus, most likely you will encounter PPPoE just because you ISP will provide the Internet via this technology. Although provider’s technical support generally can help you just with Windows, you can easily connect your PC with Linux operating system following our instructions.

The best way to use PPPoE on Linux is to do it with the help of pppd (Point-to-Point Protocol daemon) package, which supports PPPoE since version 2.4.2, and is usually pre-installed (in case it’s not, you can easily get and install it). PPPD is used to manage network connections between two nodes on Unix-like operating systems. The role of pppd is to manage PPP session establishment and session termination.

In addition to that there must be in-kernel PPPoE support. Most likely you already have it because it’s included in all modern distributions by default. However if you don’t, we will discuss how to add it a little bit later.

For now let’s see how you can set up a PPPoE connection using graphical interface (in this certain case we will use Ubuntu 9.04, though Ubuntu 9.10 beta is already available). Open: System – Preferences – Network Connection. Choose DSL tab and press “Add”:

Fill in the “Connection name” (anything you want), “Username” and “Password” fields, check or leave uncheck “Connect automatically”, “Show password” and “Available to all users” boxes:

NOTE: In case you are going to use this connection just for the Internet, you can leave “Service” field empty.

Choose Ipv4 Settings tab and make sure that the Method is Automatic (PPPoE):

That’s it! Now you can connect to the Internet without any problems.

However if you don’t really like using graphical interface or simply haven’t it (for example, on the server), there is another way to configure it.

First of all you need to check if there is in-kernel PPPoE support:

modprobe pppoe

In case the module wasn’t found, we need to create a kernel module. Make sure that you have kernel sources by going to the source directory – /usr/src/linux-x.x.x and run the following command:

make menuconfig

In the configuration window that will appear after the previous command open Network device support -> PPP over Ethernet (Experimental) and set “M” value there;

Or you can directly change .config (that can be found in the source directory - /usr/src/linux-x.x.x/):

CONFIG_PPPOE=m

Now we need to compile modules:

make modules

In case you get some compile errors like “field pppox have not defined in union…”, just as I did, try to make some changes in the following two files:

/usr/src/linux-x.x.x/drivers/net/pppoe.c

/usr/src/linux-x.x.x/drivers/net/pppox.c

- Add just after the comments (before any of #include directives) the following line:

#define CONFIG_PPPOE_MODULE

- Save the above mentioned files and retry compiling with

make modules

After successful compiling copy files

/usr/src/linux-x.x.x/drivers/net/pppoe.o

/usr/src/linux-x.x.x/drivers/net/pppox.o

(pay attention to “.o” extention!) to /lib/modules/x.x.x/kernel/drivers/net

Refresh the file with dependencies:

depmod -a

Now check one more time if the following command is working:

modprobe pppoe

In case it’s ok, we can go ahead with pppd configuration.

1) We need to add to /etc/ppp/chap-secrets our login and password.

If you plan to use pppd for more than one connection, than there is a necessity to introduce a unique ID along with login and password. For example, “PROV”:

ourlogin PROV ourpassword *

(of course, instead of “ourlogin” and “ourpassword” we need to write true values)

2) We have to create a file (let it be “myprov”) in /etc/ppp/peers.

Here are the things we need to write in this file:

user ourlogin (ourlogin – the same login as we introduced in chap-secrets)

plugin rp-pppoe.so

eth0 (your interface via which you want to receive pppoe)

noipdefault (in case your ISP provides dynamic IP)

usepeerdns (to receive DNS from provider)

defaultroute (while connecting to the Internet the provider’s router will be used as a gateway by default)

persist (fixed connection)

remotename PROV (PROV – an ID we introduced in chap-secrets)

3) Finally we need to save everything. To call the connection we use the command:

pppd call myprov

If pppd displays that it can’t load, for example, /usr/lib/pppd/2.4.3/rp-pppoe.so, we need to check where pppd is:

whereis pppd

-  After that we should make a link in /usr/lib/pppd/2.4.3 to our rp-pppoe.so:

ln –s [our rp-pppoe.so] [/usr/lib/pppd/2.4.3/rp-pppoe.so]

If pppd loads, but fails to create PPPoE socket, check log, maybe there are some messages like:

modprobe: can’t locate module net-pf-24

-  If there are, we need to write in /etc/modules.conf:

alias net-pf-24 pppoe

No doubt using PPPoE in Linux is as simple as it is in other operating systems. Graphical interface allows you to connect it in a very fast and intuitive way. However if you want be able to solve different kind of problems that may appear, it’s a great idea to make use of command line. Anyway it won’t take you more than 5-10 minutes to setup the connection, so check it out right now in order to see how easy it is.

Related posts:

1. Setting Up Network Interfaces in Linux
2. Setting Up SSH clients on Windows Mobile Devices
3. IPv6 advantages and its configuration in OS Linux

There are multiple compression algorithms available to compress data. You should remember that some kinds of data can be highly compressed and some kinds of data do not benefit from compression. At the moment archive formats are also used to package software files for distribution, installation, and execution.

Let’s see what the most popular archive formats are and what they are used for. All of them are divided into 5 different types:

1. Archiving only formats (only combine files):

- ar, cpio, tar and etc.

2. Compression only formats (only compress files):

- gzip, bzip2, LZMA, compress and etc.

3. Multi-function formats can combine, compress, encrypt, create error detection and recovery information, and repackage the archive into self-extracting/self-expanding files:

- 7z, ACE, ARC, cpt, dmg, GCA, kgb, LZX, RAR, qda, ZIP and etc.

4. Software Packaging formats are used to create software packages that may be self-installing files:

- deb, pkg, RPM, MSI, JAR and etc.

5. Disk Image formats are used to create disk images or optical disk images of mass storage volumes:

- OEB Package Format, OEBPS Container Format, Open Packaging Conventions and etc.

If you would like to learn more about archive formats, please visit this page.

Most likely you’ve already understood that in the given post we are not going to review all the archive formats, but the most popular one – RAR.
As it was mentioned before RAR is a multi-function archive file format that supports data compression, error recovery, file spanning and etc. Though at the moment it’s licensed by Win.rar GmbH, it was originally developed by Russian software engineer – Eugene Roshal (RAR comes from Roshal ARchive).

You should know that RAR files can be created only using commercial software and the one that has permission from the author. In fact the only freeware that can be used to create RAR files is RAR for Pocket PC.

The most popular software for creating RAR files is WinRAR, which you probably are familiar with. Of course, it’s available only for Windows, so we won’t discuss it in detail. However there is WinRAR’s command line counterpart – RAR. It’s also commercial software but is available for WIndows, Linux, Mac OS X, MS-DOS, OS/2 and FreeBSD. In addition to that there is a multi-platform unrar tool from the same distributor that is used just to extract RAR files but not to write them.

Let’s try to figure out the advantages of RAR in comparison to other file archivers. Here are the most important ones:

• RAR uses 128-bit AES (Advanced Encryption Standard) algorithm that is significantly better than the cryptographic algorithm used in Zip 2.0. This means that RAR encryption is much safer.
• RAR has a better rate of compression than early compression algorithms like ZIP and gzip (still it generally compresses the data a little bit slower)
• RAR has a recovery record function: archive formats contain redundant data embedded in the files in order to detect data storage or transmission errors, and the software used to read the archive files contain logic to detect and correct errors. Thus it allows you to restore a damaged file.
• Multi-volume archive support: ability to break a RAR-archive into many smaller files
• RAR allows you to work with any files as far as their size is concerned (till 8 EB = 8,000,000,000,000,000,000 B = 8 x 10¹⁸ bytes or 8 billion gigabytes), while popular ZIP format is limited to 2 GB.
• RAR offers an optional compression algorithm highly optimized for multimedia data.

Now we are going to discuss how you can use RAR in Linux. First of all let’s see what should you do to open RAR-archives.

Due to the fact that there is no RAR support in Linux by default, we will need to install unrar command:

a) If you use Debian Linux, you need to type apt-get as follows to install unrar program:

# apt-get install unrar

b) In case of Fedora use yum command:

# yum install unrar

c) If you none of the above mentioned works for you, please do the following:

- download binary package from official rarlab site:

$ cd /tmp
$ wget http://www.rarlab.com/rar/rarlinux-3.6.0.tar.gz

- untar file:

$ tar -zxvf rarlinux-3.6.0.tar.gz

- go to rar directory (both unrar and rar commands are located in rar sub-directory):

$ cd rar
$ ./unrar

- copy rar and unrar to /bin directory:

# cp rar unrar /bin

In case you get glibc error, you need to use rar_static (you can find it in the same installation package) instead of rar and copy it to /bin under rar name.

d) You can also install it using Synaptic: System – Administration – Synapric Package Manager – find both rar and unrar – install them

For now everything should work fine. Here are some of the examples how you can use unrar command:

1) Suppose we want to open music.rar in the current directory:

$ unrar e music.rar

2) If you want to extract files with the full path, type the following command:

$ unrar x music.rar

3) In case you need to check the integrity of the file, use the command:

$ unrar t music.rar

4) To list the file inside RAR archive, use command:

$ unrar l music.rar

If you are searching for a GUI utility to extract and handle rar files with, there is PeaZip for Linux which may be very useful.

Let’s check how we can create archives using rar command. The list of rar options for Linux is pretty impressive, so we will mention just the most important ones:

-  Add files to archive (add all *.mp3 files from the current directory to the archive.rar):

rar a archive *.mp3

In this case the .rar extension will automatically append to the archive (the full name will be             archive_file.rar). If archive.rar already exists in the present working directory, then the         file you are trying to add to archive.rar will be simply added to the existing archive.           Just in case archive.rar already contains a file with the same name the old file will be replaced with the new one. Other files stored inside the archive will be unaffected. Please remember that this action is blind, meaning that RAR does not check the time stamps of files.

- Add files and check time stamps (denoted by «-u») using the command:

rar a -u archive *.mp3

- Archiving all files and directories in current directory:

rar a archive

- Archiving the content of a particular directory:

rar a archive  /music/korn

- Archiving groups of files (according to the type):

rar a archive '*.jpg'

- Deleting files from archive (all .png files in from the current directory):

rar d archive '*.png'

- Locking archive so that any command which intends to change the archive will be ignored:

rar k final.rar

- Renaming archived files. Here is the command syntax:

rar rn <arcname> <srcname1> <destname1> … <srcnameN> <destnameN>

rar rn data.rar readme.txt readme.bak info.txt info.bak

Thus it will rename readme.txt to readme.bak and info.txt to info.bak in the archive data.rar

-  Creating recovery volumes – .rev files.

They can be later used to reconstruct missing and damaged files in a volume set. This command makes sense only for multivolume archives and you need to specify the name of the first volume in the set as the archive name. For example:

rar rv3 data.part01.rar

This feature may be useful for backups or, for example, when you posted a multivolume archive to a newsgroup and a part of subscribers did not receive some of the files. Reposting recovery volumes instead of usual volumes may reduce the total number of files to repost.

Each recovery volume is able to reconstruct one missing or damaged RAR volume. For example, if you have 30 volumes and 3 recovery volumes, you are able to reconstruct any 3 missing volumes. If the number of .rev files is less than the number of missing      volumes, reconstructing is impossible. The total number of usual and recovery volumes must not exceed 255.

«N» parameter specifies a number of recovery volumes to create and must be less than the total number of RAR volumes in the set.

- Encrypting files with the password (using «-p») while archiving. The password is case-sensitive. If you omit the password on the command line, you will be prompted with message “Enter password”.

rar a -pfcfcfc archive '*.txt'

This command adds files *.txt and encrypt them with password «fcfcfc»

- Creating SFX – Self-Extracting archives:

If you use this switch when creating a new archive, a Self-Extracting archive (using a module in filedefault.sfx or specified in the switch) would be created. In the Windows version default.sfx should be placed in the same directory as the rar.exe, in Unix – in the user’s home directory, in /usr/lib or /usr/local/lib.

rar a -sfxwincon.sfx myinst

Create SelF-eXtracting (SFX) archive using wincon.sfx SFX-module.

Of course all the above mentioned options represent just some of the available ones. If you would like to learn more, please check «rar.txt» file from the installation package (User’s manual).

Conclusion

As you can see RAR for Linux is an extremely powerful tool that represents very decent replacement for WinRAR. As far as the functionality is concerned you get absolutely the same software. The only thing that may be a little bit difficult in the very beginning is the necessity to use command line. However it’s not as hard to use, so in some time you will find yourself using it without any problem.

Related posts:

1. Searching files in Linux
2. System and File Backup on Windows and Linux
3. Choosing an Antivirus for Linux

Most likely the great majority of you are familiar with Windows Search Function that is pretty easy to use. In fact all Linux distributions have such an option (a graphical one) as well, so you won’t lack any functionality. However if you want to be able to find absolutely everything you need, it’s better to choose command line that has some really powerful tools to use.

In the given post we are going to review some of these tools in detail. Nevertheless it should be emphasized that there is no need to worry even if you don’t really like using command line, because no scripts or complex expressions will be discussed – just easy and understandable methods.

First of all we need to define common types of search requests. Here are the most important ones:

• Search by file name or mask (this type also includes file searching according to a certain path and exclusion of a particular path from the search)
• Search by file type (extension)
• Search by file access/creation/modification date/time
• Search by file size
• Search by file owner and access permissions
• Search of system and executable files

As far as the commands used to find files are concerned there are four of them to be reviewed:

1) find

This command is considered to be the most powerful one. It checks the file system in real time based on certain criteria. That means you will always get the most up-to-date results without the necessity to update a database. Of course, you can perform all sorts of operations on the files that were found. In addition to that is should be emphasized that file command allows you to check temp folders as well (in comparison with locate command).

However due to the fact that file command does search through the file system hierarchy, it’s considerably slower than other commands. That’s why it’s recommended to narrow your search (of course, if there is such a possibility) by searching in certain directories.

2) locate

The locate command uses a database (instead of file system itself) for searching, so it’s significantly faster than file command. However using database means that the database has to be updated in order to ensure proper search results (all new files have to be included and deleted ones mustn’t be considered). Once your database is updated you are ready to search. To update the database the only thing you should do is to run the following command:

updatedb

Taking into consideration the fact that many users may forget to update the database each and every time, it’s recommended to set up a cron job for that purpose. Here you can learn more about the cron.

3) whereis

Given command is useful in case you need to find source, binary and/or executable files which are associated with manual pages. As a return of this command you get the path.

Let’s check an example. Suppose that you need to find out where Firefox is installed. Here is what you enter and what you get:

whereis firefox

firefox: /usr/bin/firefox /etc/firefox.cfg

4) which

The which command being pretty simple is very similar to the previous one (whereis command) but it shows you the full path of shell commands instead.

It’s very useful for finding out “which” binary the system would execute if you typed the command out. Since some programs have multiple versions installed the which command comes in handy to tell you which version it is using and where it is located.

For now let’s take a closer look at each of the above mentioned commands as far as their usage is concerned.

Command Line – find

As it was mentioned before the find command is one of the best ways to search files in Linux because it has a great deal of parameters, which make it extremely easy to find the files you need. Still it should be mentioned that in most cases the usage of this powerful command is limited to the basic parameters. Of course, you can find almost everything using just those basic parameters, but you should understand that you lose much more if you don’t learn all about find tool.

Nevertheless it’s not an easy task because the syntax of this command is pretty difficult. Thus in this case you should choose between power and simplicity. If you really need the power of find tool, let’s check its potential.

In fact the best way to learn how you can use find command is to go through a lot of different examples. We will start from the easiest till more complicated ones.

File name

1. find -name 'form.html'

- name: means that the attribute is the file name
- ‘form.html’: entered text must be found.
(!) Always enclose the filename in single quotes (!)

Thus this case the system would search for a file named form.html in the current directory and any subdirectory.

In fact Current directory can be denoted in two different ways:

find 
find .

2. find / -name 'form.jpg'

Here the system would search for any file named form.jpg on the root and all subdirectories from the root.

(!) If you root as the starting point for a find command, your system can be slowed down significantly. However in case you really must run such a command, it would be better run it during low-use time or overnight. In order to make it easier for you to get familiar with the results you can redirect the output to a file using the following syntax:

find / -name '*.jpg' > allimages.out

3. find /home/fred -name 'index*'

The system would search for files having the letters index as the beginning of the file name in the directory /home/fred and its subdirectories as well.

(!) If you have some doubts about the case of the filename, there is a way not to consider it – use –iname instead of –name. So all files starting with any combination of letters in upper and lower case such as INDEX or indEX or index would be found. However in this case it will be slower, because case insensitive search takes more time (!)

4. find /usr /home /tmp -name "*.png"

As you can see in this example there is a possibility to specify more than one starting directory in a search string. Thus the system would search for a png file in user, home, temp directories and their subdirectories.

5. find . -path '/files' -prune -o -name "*.jpg"

-path: means that the attribute is the directory (path)
-prune -o: used to exclude files or directories from search

In this case the system would search for jpg files in the current directory and its subdirectories excluding files directory.

6. find /usr /home -name "*.jar" 2>/dev/null

If you need to search files in a certain directory, there is a possibility that you will get some errors due to the lack of permissions. Such errors can make it hard to find the line (search result) you need. To prevent them (errors) from appearing you need to use the above mentioned parameter.

- 2>/dev/null: given parameter is not related to find tool as such. “2″ indicates the error stream in Linux, and /dev/null is the device where anything you send simply disappears. So 2>/dev/null sends all error messages to the null file, thereby providing cleaner output.

(!) There is one more thing you can do – replace 2>/dev/null with 2>error.txt. If you use the last parameter after the search you would have a file named error.txt in a proper directory with all the error messages in it (!)

File size

7. find /music -name '*.mp3' -size +3000k

The system would search for any mp3 files that have a size more than 3000 Kilobytes (>3MB) within music directory and its subdirectories.

(!) If you would like to search for files that are, for example, less than 3000 Kilobytes, just use “-3000″ instead of “+3000″ (!)

File type

8. find /music –type d

In this case the system searches for file type. The command would find all the subdirectories in music directory.

Here are some other file type that find command can locate:

- b – block (buffered) special
- c – character (unbuffered) special
- l – symbolic link
- p – named pipe (FIFO)
- s – socket

Finding time

9. find . -mtime -1

The system would find all the files modified within the last hour in current director.

(!) It should be mentioned that there are three time stamps:

• mtime – the time that the contents of a file were last modified
• atime – the time that a file was read or accessed
• ctime – the time that a file’s status was changed

Each of these time options is used with a value n, which is specified as -n, n, or +n.

• -n returns less than n
• +n returns greater than n
• n returns exactly n matches (!)

10. find . -mtime 1

In this case the system has to find all the files that were modified exactly one hour ago in the current directory. As you understand such a command may not return any results.

11. find . -mtime +1

The system will search for files that were modified more than an hour ago in the current directory.

12. find . -amin -5

The system would find all the files modified within the last 5 minutes in current director.

Executing files

13. find / - name 'screenshot*' -exec ls -l {\}\ \;

- exec: a very important feature that allows you to execute a particular command on the results of the find command.
- ls –l: the command you want to execute
- {\}\: an indicator that the filenames returned by the search should be substituted here
- \: is the terminating string, and is required at the end of the command

Using Boolean operators

14. find /music -name 'Nirvana*' -and -size +5000k

In this case system would search within music directory for files that have their names beginning with ‘Nirvana’ AND whose size is greater than 5000 Kilobytes.

(!) In fact AND operator is used by default, even if you don’t specify it (!)

15. find /music -size +5000k ! -name 'Nirvana*'

Here the command searches in music directory only for files that are greater than 5MB, but they should NOT have ‘Nirvana’ as the starting of their filenames.

16. find /music -name 'Nirvana*' -or -size +5000k

The system would search within music directory for files that have their names beginning with ‘Nirvana’ OR  all the files that are greater than 5000 Kilobytes.

Of course, there are much more things to say about find command, but the above mentioned examples will help you become more familiar with it in order to understand how powerful it is. Here you can check more parameters for find command.

Command Line – locate

As you probably remember given command is significantly faster than the previous one. In addition to that is much simpler. However you may encounter an error while running this command for the first time.  The problem is that Linux requires a database of all the files, so you need to update your database.

Here are some of the examples that will help you get familiar with locate command.

1. locate form.html

The system would produce a list of the locations where you could find files that are named as ‘form.html’. The result may look like that:

/usr/documents/site/form.html

2. locate '*.jpg' -q

The –q option is used to suppress any error messages, such as permission to access files and etc.

3. locate '*.pdf' -n 10

The system would limit the number of returned results to 10.

4. locate Polly.mp3 -i

The system would perform a case insensitive search, i.e. the case of the filenames wouldn’t be considered.

5. locate form.html -l 0

-l: means security level. “0″ turns security checks off. This will make search faster. “1″ turns security checks  on.

Such a command would make your search faster. If you replace –l 0 with –l 1, the process would take more time but the result will be more secure. Moreover it should be mentioned that –l 1 is the default action, if you don’t specify something else.

These were the most commonly used parameters.

Command Line – whereis

Due to the fact that we already know what this command is use for, we are going to go ahead with the parameters for the whereis command. Here they are:

-b – Search only for binaries.

-m – Search only for manual sections.
-s – Search only for sources.

-u – Search for unusual entries. A file is said to be unusual if it does not have one entry of each requested type. Thus `whereis -m -u *’ asks for those files in the current directory which have no documentation.

-B – Change or otherwise limit the places where whereis searches for binaries.

-M – Change or otherwise limit the places where whereis searches for manual sections.

-S – Change or otherwise limit the places where whereis searches for sources.

-f – Terminate the last directory list and signals the start of file names, and must be used when any of the -B, -M, or -S options are used.

1. whereis songbird

The system locates the directories where Songbird is stored

2. whereis -u -M /usr/man/man1 -S /usr/src -f *

In this case the system would search for any manual for any file in the current directory.

Command Line – which

No doubt the which command is the simplest one. There are no parameters to mention, so the only thing we would should do is to take a look at the following example:

which perl

The system would locate the executable location of the perl command. You get:

/usr/bin/perl

What to choose?

As you can see using command line to locate files is not as hard as it seemed to be. At the same time it’s significantly more powerful than the standard search options (graphical ones). Of course, if you are the one who is afraid of command line and don’t want to learn some really “cool stuff”, you can just add this post to your bookmarks and wait till “your time” comes. But in case you have an endless amount of files on your PC and from time to time need to find some of them really quickly, you probably know what to choose, don’t you?

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3. Setting Up PPPoE Connection in Linux

In fact Evolution represents a very functional application which in addition to mail integrates calendar, address book, to-do list, memo tools and etc. One of the nice things about this software consists in the fact that it’s a part of GNOME desktop environment, thus there is no need to install it.

Taking into account that Gmail configuration has some distinctive features, we decided to review it in detail to help you avoid different problems, which may appear.

Configuration of Gmail using POP3

Here are the steps to follow:

1) Open the browser, login to your Gmail account and click “Settings”:

2) Choose “Forwarding and POP/IMAP” panel, make sure that POP is enabled and choose “keep Gmail’s copy in the Inbox” option (2nd point of POP Download section):

3) Click on the Evolution icon (upper panel) or go to: Applications > Internet > Evolution Mail:

4) Click “Forward” button on the Welcome window:

5) Due to the fact that we configure mail for the first time, skip this option and click “Forward”:

6) Write your name, email address and Reply-to:

7) Choose “POP” from the drop-down menu, write everything as you see on the screenshot, of course, you have to type your email address (Username field):

8 ) Check “Leave messages on server” and change the update interval (“Check for new messages every … minutes”), by default it’s 10 minutes:

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The idea of secure passwords has appeared a bunch of years ago when the number of passwords has increased. As it is insecure to use the same password for multiple accounts, you need to either remember all your passwords or write them down anywhere. Luckily, there are some solutions that allow us to maintain security and use secure passwords at the same time. This kind of software is called password managers and we’re going to include a brief review of them.

What is a password manager? A password manager software helps a user to organize his passwords. Password manager uses a local database, where the encrypted data is stored. It may also have additional features such as automatically filling in forms or generating random secure passwords.

Password managers are available for many platforms such as for Windows, Linux, MacOS X, Pocket PC, Smart Device, Palm OS and U3. We have taken most popular 3 password managers for linux and are going to describe them below:

Password Gorilla

The Password Gorilla helps you manage your logins. It stores all your user names and passwords, along with login information and other notes, in a securely encrypted file. A single “master password” is used to protect the file. This way, you only need to remember the single master password, instead of the many logins that you use. The latest version 1.4 was released in July 3, 2006. Password Gorilla is platform-independent software, runs on most operating systems has been tested on Windows, Linux and Solaris.

Features:
- Password Safe 3 file format is supported.
- Search Password option.
- Hide main window when coming up and asking to open a file.
- Improved seed for initializing the pseudo-random number generator.
- Allow closing a locked database using the “X” button.

KeePass Password Safe

KeePass Password Safe is a tool for managing user’s passwords, released under the GNU GPL. The program stores logins, passwords and addresses of the URLs in an encrypted database. Access to the database is obtained by providing your password or a file-key. KeePass uses strong and secure encryption algorithms such as AES and Twofish, and hash SHA-256. KeePass keeps encrypted passwords in his memory even after starting and opening a database. There are Linux, Windows and Pocket PC editions of this software and it is highly recommended if you are planning to use them on multiple devices.

GPass

GPass is a password management software for GNOME desktop. GPass encrypts the file that keeps the password collection by using Blowfish security algorithm, one of the most secure on the market. The latest version of GPass is 0.5.1 and was released in March 25, 2006. Requirements are: GNOME2 libraries, OpenSSL cryptographic library.

There are some password managers that are integrated in browsers. An example could be Lastpass. It can be integrated with Firefox to store all your passwords. The only thing that doesn’t seems to be good is that your passwords are stored at a remote server and the possibility of data leek is much higher. Though I don’t think they have any reason to steal your data, it is much more pleasant to have the password database stored at a hard drive or a removable media, just like flash drive. Modern Password managers can be run from a USB Flash so that’s another good feature: your password database becomes portable and you don’t need to keep in mind all your passwords.

We recommend you to use password managers for everyday needs. Never share your password files to anyone and do not write your passwords to a text file. Let password manager do its job!

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1. Enabling all the repositories

Repositories represent software archives were thousands of programs for Ubuntu are stored. Repositories make it very easy to install new software onto Ubuntu using an Internet connection. In addition to that they provide a high level of security, as each program available in the repositories is thoroughly tested and built specifically for each version of Ubuntu. Thus enabling all the repositories you ensure the access to the bigger amount of applications.

It should be mentioned that Ubuntu software repositories are organized into 4 separate components, according to the level of support offered by Ubuntu. Here is the list of those components:

• Main – Officially supported software.

• Restricted – Supported software that is not available under a completely free license.

• Universe – Community maintained software, i.e. not officially supported software.

• Multiverse – Software that is not free.

There are two ways to enable/disable repositories:

a) System > Administration > Software Sources

b) System > Administration > Synaptic >> Settings >> Repositories

Here is the window you get, which gives you the opportunity to choose the repositories you need:

As soon as you’ve done which choosing enabling/disabling of repositories (we suggest you to enable all of them), click “Close” button to save your changes. A dialog box should appear, asking whether you’d like to update the list of repositories. Select “Reload” to update the list. Make sure that you click “Reload” button, because repository information will not be updated until the “Reload” is selected.

IMPORTANT: In case you use Ubuntu 9.04 (Jaunty) all the repositories are enabled by default, so you can skip this step.

The last thing to mention about repositories is that you can use command line instead of graphical interface to manage them. Here you get more info about this method.

2. Installing the system components

a) Adding the fonts

When you first start Ubuntu there are no decent fonts to work with, but this problem can be easily solved. Open the Terminal (Applications > Accessories > Terminal) and enter the following command:

sudo apt-get install msttcorefonts ttf-larabie-straight ttf-larabie-deco mplayer-fonts xfonts-terminus xfonts-terminus-oblique xfonts-mona tv-fonts ttf-tuffy ttf-sjfonts ttf-sil-padauk ttf-sil-ezra ttf-paktype ttf-georgewilliams ttf-fifthhorseman-dkg-handwriting ttf-farsiweb ttf-nafees ttf-mgopen ttf-freefont ttf-dustin ttf-devanagari-fonts ttf-dejavu-extra ttf-dejavu-core ttf-dejavu ttf-bpg-georgian-fonts ttf-bitstream-vera ttf-alee

b) Installing different archivers

sudo aptitude install rar unrar zip unzip p7zip-full p7zip-rar cabextract

c) Installing themes

If you don’t like the default look of the system, you can easily install a lot of different themes. First of all you should run the following command in the Terminal:

sudo apt-get install gnome-themes-extras metacity-themes ubuntume-themes community-themes gnome-art

Of course those themes are not the only ones you can get. Probably you saw a great deal of cool themes on the screenshots of Ubuntu. Here are the things you should do to get much more themes.

Visit Gnome Look and download from GTK 2.x the themes you want. After that go to System > Preferences > Appearance > Theme and simply drag and drop the theme file you downloaded.

d) Installing CompizConfig Settings Manager to add effects

Given application brings 3D desktop visual effects that improve usability of the system and provide increased productivity. To install run the following command:

sudo apt-get install compiz compizconfig-settings-manager compiz-fusion-plugins-main compiz-fusion-plugins-extra emerald librsvg2-common

e) Installing file managers

In fact standard file manager is pretty decent and the majority of the users, at least at the beginning, will hardly feel the necessity to use another application instead. However you can try to install default file managers for Xfce and KDE desktop environments, just to check if they are more convenient for you. Here are the commands you need to run in order to install them:

sudo apt-get install dolphin

After installation you can find this file manager by going Applications > System Tools > Dolphin

sudo apt-get install thunar

To find this program go to Applications > Accessories > Thunar File Manager

If you like two pane design you can install EmelFM2:

sudo apt-get install emelfm2

This application as Dolphin can be found in System Tools.

Of course there are much more file manager to choose from. So check Synaptic Package Manager and install the ones you like.

f) Installing VirtualBox

VirtualBox is a free x86 virtualization solution allowing a wide range of x86 operating systems such as Windows, DOS, BSD or Linux to run on a Linux system. What for do you need it? It’s up to you. Maybe just to install Ubuntu for testing purposes. Here is the command you need to run:

sudo apt-get install virtualbox-ose virtualbox-ose-source

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Each PDF document contains a complete description of the document, including images, text, vector graphics, raster images, and may contain the necessary fonts to display text. To view PDF documents you need to have certain computer programs, which are free and can be found via the Internet.

PDF files can be used on most platforms, Linux is also included. The free Adobe Reader is the PDF-leader and allows Linux users to read any PDF files, but we have reviewed some alternative viewers you can use to open PDF files in Linux. Here’s the list of 5 most used:

1. Adobe Reader – freeware for Linux.
2. Evince – the default PDF viewer for GNOME.
3. Xpdf for the X Window System.
4. KPDF for the K Desktop Environment.
5. Foxit Reader by Foxit Software.

Adobe Reader

The Adobe Reader (aka Acrobat Reader) is available as a no-charge download from Adobe’s web site, and allows viewing & printing any PDF files. The new Adobe Reader 9.1.3 (for Linux) doesn’t have any critical security vulnerabilities while providing more stability. The update is available as a full Adobe Reader 9.1.3 installer and can be downloaded from the Adobe FTP server. This multilingual update is available in the following language versions: English, French, German, and Japanese.

System requirements:
-32-bit Intel Pentium processor or equivalent
-Red Hat® Linux WS 5, SUSE® Linux Enterprise Desktop (SLED) 10 SP2 or Ubuntu 7.10
-GNOME or KDE Desktop Environment
-512MB of RAM (1GB recommended)
-150MB of available hard-disk space (additional 75MB required for all supported font packs)
-GTK+ (GIMP Toolkit) user interface library, version 2.6 or later
-Firefox 2.0 or later
-OpenLDAP and CUPS libraries

This is the most popular PDF viewer, but there are some alternative viewers and you are welcome to try them too.

Evince

Evince is a document viewer for multiple document formats as pdf, postscript, djvu, tiff and dvi. The goal of evince is to replace the multiple document viewers that exist on the GNOME Desktop with a single simple application. Evince has ben included by GNOME since GNOME 2.12 was released. It is written mainly in C and C++. It has been released under the GNU General Public License, so Evince is free software. It’s not just a PDF viewer, and it’s doing the job very well.

Features:
-Search – Integrated search displaying the number of results found and highlights the results on the page.
-Page Thumbnails – Thumbnails of pages show quick reference for where you’d like to go in a document.
-Document Printing – Using the GNOME/GTK printing framework Evince can print any document it can open.
-Encrypted Document Viewing – Evince can open PDF documents that have been encrypted.

Xpdf

Xpdf is an open source PDF viewer for the X Window System and runs on UNIX, VMS, and OS/2. The non-X components (pdftops, pdftotext, etc.) also run on Win32 systems. Xpdf includes programs which extract images from PDF files or convert PDF to PostScript or text, so it’s not a somple PDF viewer. These programs run on DOS, Windows, Linux and Unix.

It also has been licensed under the GNU General Public License. You can see the Xpdf web page for download  links. Source code, precompiled binaries and language support packages of the current version Xpdf 3.02pl3 are available for Linux, Spartac and DOS/Win32.

KPDF

KPDF is a PDF viewer, based on xpdf for KDE (K Desktop Environment). Same as original Acrobat Reader, it provides side panel with thumbnails, allows double page mode. The TTS (text-to-speech) of PDF documents is also included.

The latest version KPDF 0.5.10. was released on August 26, 2008 and has some interesting features like: three different ways of searching, put fonts used by the document on the properties dialog, support for images with alpha channel, Google-like search on thumbnails, cursor wrapping over screen for continous scrolling, save zoom setting on exit and many others.

Foxit Reader

Foxit Reader is a multilingual PDF reader created by Foxit Software. It is available as freeware but has also a full version with enhanced functionality. As a small and fast PDF viewer, Foxit Reader currently has over 50 million users all around the world. After keeping users waiting for almost two months, Foxit Reader 3.1 has been released and it introduces many fascinating new features including internet search and favorite toolbar settings.

Foxit Reader 3.1 supports internet keyword search. You can select the text and click the pop-up search icon or press and drag the mouse directly to search for the related information in Internet. It also supports customization of toolsappearing in the Favorite Toolbar area, so that users can choose the tools that are used most often easily and quickly. You are welcome to look at the official website for more features.

So you shouldn’t have any problems viewing PDF files in Linux; we have recently reviewed the possibility of viewing doc files in linux and there were no problems too. We are going to check some other popular file formats in the near future, so if you would like to see any specific formats, please, let us know. You are welcome to add comments to this article so we could know what are your areas of interest.

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