The Default Linux File Systems (Filesystems)

The default filesystems that are recognized by Linux are specified in the text file named filesystems in the /proc directory.

Four of the filesystems that are commonly found on a Linux system are: ext2 (old and less common), ext3 (very common), iso9660 and swap.

Some Linux distributions also use other filesystems.

For example, instead of the ext3 filesystem, the SUSE and openSUSE distributions use the reiserfs filesystem by default.

In addition to the above linux filesystems, by default Linux can also recognize a partition that is a “swap” partition.

Depending on the documentation that you are reading and the command or utility that you are using, “swap” is not typically considered to be a filesystem type. It is a type of partition that is treated by the OS as virtual memory (where hard disk storage space works as though it is RAM memory).

The following is a description of some of the commonly used Linux filesystems.

ext2 (second extended filesystem) supports UNIX/Linux files and directories and allows for long file names (up to 255 characters).

ext3 (third extended filesystem) is the current default filesystem for Red Hat, Fedora and many other Linux distributions. The ext3 filesystem is on the way to becoming the de facto standard for Linux.

ext3 is based on the previous ext2 filesystem. It is basically the same as ext2, with the main difference being that ext3 supports a feature called “journalling”. The greatest benefit of this feature is that it provides a quicker recovery when a filesystem “crash” occurs and a system goes “down” (and stops working).

If files are corrupted on a partition using ext2, then the Linux fsck (filesystem check) utility is run to check the filesystem and repair it and this can take a very long time.

When the files on an ext3 filesystem become corrupted, then the fsck utility is still run to check and repair the filesystem, but this takes much less time due to the journalling feature of ext3.

vfat is the Linux filesystem that is compatible with DOS file names and Windows long file names. In some Linux utilities, “vfat” appears as “fat” or “fat32″.

iso9660 is the filesystem used on a CD-ROM.

swap (a.k.a. Linux swap partition, swap drive, swap space) is a disk partition that is used by the Linux OS as “virtual memory”. Linux uses the disk space that you have specified for the swap drive as though it were RAM (memory chips in your system).

The Linux filesystem type concepts and definitions covered here apply to: Ubuntu, Debian, Red Hat, Fedora, SUSE, Slackware, openSUSE – and ALL other Linux distributions.

If you are want to become Linux administrator then you like to know more about linux mount as well.

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The Linux mount command is used to mount a filesystem by assigning a mount point (such as a directory below the /mnt directory) to a hard disk partition or other disk device, such as a CD-ROM drive.

After the partition or device has been mounted, it can be accessed by application Linux software programs, utilities and commands.

Example of Using the Linux mount Command

For example, the following command:

$ mount /dev/cdrom /mnt/cdrom causes the device file named cdrom in the /dev directory to be mounted “onto” the cdrom directory below /mnt.

The cdrom directory becomes the “mount point” for the CD and this allows you to access the filesystem of the CD.

The files in the / (root) directory of the CD become accessible below the full path of /mnt/cdrom.

Listing the Contents of the Linux /dev System Directory Below The / (Root) Directory

Many of the important Linux system directories, such as the /dev directory, are located directly below the / (root) directory.

Now look at the contents of the /dev directory and find out what Linux uses it for.

Examples of Using the Linux ls Command to the List System Directories and the /dev Directory

The following command lists the contents of the / directory – from any directory. The “-l” option of the ls command is not required here.

$ ls / Notice the dev directory, which is below the / (root) directory in the full path of /dev.

Viewing the Contents (Directories and Files) in the /dev Directory Path

Now run the following command to see the contents of the /dev directory, without having to change directory.

$ ls /dev Example of Using the Linux nl Command To Number Lines of Output

The Linux nl (number line) command can be used to count and display the number of lines in a file or the output of a command.

In the folloinwg example, the output of the ls command is “piped” (with the vertical bar symbol) to the nl command to display a count of the output of the command.

$ ls -l /dev | nl This shows the device driver files for many different types of Linux hardware devices that are located in /dev and a count of the number of them.

Linux Commands Training Tips: On more current Linux systems, the mount command may not be required and your devices may automatically mount below the /media directory. For example, if you put a CD in your drive and it automatically appears on your Linux desktop, you do not need to use the mount command to do the steps in the command example above. The Linux ls command and dev system directory concepts covered here apply to ALL Linux distributions and versions, including Ubuntu, openSUSE, Debian, SUSE, Fedora, Slackware and Red Hat Linux.

By the way…do you want to learn exactly how to use Linux and run Linux commands for Linux System Administration and get real, practical Linux training experience by running hundreds of examples of Linux commands? Stay tune as I add more about Linux.

Linux DHCP is Dynamic Host Configuration Protocol. It is used to control vital networking parameters of hosts (running clients)with the help of a server. DHCP is backward compatible with BOOTP. For more information see RFC 2131 (old RFC 1541) and other. (See Internet Resources section at the end of the document).

This mini-tutorial covers both the DHCP _SERVER_ daemon as well as DHCP_CLIENT_ daemon. Most people need the client daemon which is used byworkstations to obtain network information from a remote server. The serverdaemon is used by system administrators to distribute network informationto clients so if you are just a regular user you need the _CLIENT_ daemon.

Downloading the client daemon (dhcpcd)

Depending on your distribution you might have to download the DHCP client daemon. If you want to compile it from the source youpackage you need is called dhcpcd and the current version is 1.3.18. It is maintained by Sergei Viznyuk <sergei@phystech.com> andtoday it comes as a binary package with most distributions.

dhcpcd source can be downloaded from following locations

• ftp://ftp.phystech.com/pub/ (Primary site)
• http://www.cps.msu.edu/~dunham/out/

Then follow the instructions below. They should be the same.

Tying it all together

After your machine reboots your network interface should be configured.Type: ifconfig.

You should get something like this:

          lo        Link encap:Local Loopback            inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0          UP BROADCAST LOOPBACK RUNNING  MTU:3584  Metric:1          RX packets:302 errors:0 dropped:0 overruns:0 frame:0          TX packets:302 errors:0 dropped:0 overruns:0 carrier:0 coll:0eth0      Link encap:Ethernet  HWaddr 00:20:AF:EE:05:45          inet addr:24.128.53.102  Bcast:24.128.53.255  Mask:255.255.254.0          ^^^^^^^^^^^^^^^^^^^^^^^          UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:24783 errors:1 dropped:1 overruns:0 frame:1          TX packets:11598 errors:0 dropped:0 overruns:0 carrier:0 coll:96          Interrupt:10 Base address:0x300

If you have some normal number under inet addr you are set. If you see0.0.0.0 don’t despair, it is a temporary setting beforedhcpcd acquiresthe IP address. If even after few minutes you are seeing 0.0.0.0 pleasecheck out Troubleshooting. DHCPcd is a daemon and willstay running as long as you have your machine on. Every three hours itwill contact the DHCP server and try to renew the IP address lease. Itwill log all the messages in the syslog (on Slackware/var/adm/syslog, RedHat/OpenLinux/var/log/syslog).

One final thing. You need to specify your nameservers. There are two ways to doit, you can either ask your provider to provide you with the addresses of yourname server and then put those in the/etc/resolv.conf or DHCPcd will obtainthe list from the linux DHCP server and will build aresolv.conf in /etc/dhcpc.

I decided to use linux DHCPcd’s resolv.conf by doing the following:

Back up your old /etc/resolv.conf: mv /etc/resolv.conf/etc/resolv.conf.OLD

If directory /etc/dhcpc doesn’texist create it: mkdir /etc/dhcpc

Make a link from /etc/dhcpc/resolv.conf to/etc/resolv.conf: ln -s/etc/dhcpc/resolv.conf /etc/resolv.conf

If that doesn’t work try this (fix suggested by<nothing@cc.gatech.edu> with a little amendment by HenrikStoerner):

This last step I had to perform only because my dhcpcd doesn’tcreate an /etc/dhcpc/resolv.conf. In /etc/sysconfig/network-scripts/ifup Imade the following changes (which are a very poor hack, but they workfor me):

elif [ "$BOOTPROTO" = dhcp -a "$ISALIAS" = no ]; then    echo -n "Using DHCP for ${DEVICE}... "    /sbin/dhcpcd -c /etc/sysconfig/network-scripts/ifdhcpc-done ${DEVICE}    echo "echo \$$ > /var/run/dhcp-wait-${DEVICE}.pid; exec sleep 30" | sh    if [ -f /var/run/dhcp-wait-${DEVICE}.pid ]; then^^^^        echo "failed."        exit 1

I changed to:

elif [ "$BOOTPROTO" = dhcp -a "$ISALIAS" = no ]; then    echo -n "Using DHCP for ${DEVICE}... "    /sbin/dhcpcd    echo "echo \$$ > /var/run/dhcp-wait-${DEVICE}.pid; exec sleep 30" | sh    if [ ! -f /var/run/dhcp-wait-${DEVICE}.pid ]; then^^^^^^       echo "failed."       exit 1

Now sit back and enjoy .

eth0      Link encap:10Mbps Ethernet  HWaddr 00:C0:4F:D3:C4:62          inet addr:183.217.19.43  Bcast:183.217.19.255  Mask:255.255.255.0          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:2875542 errors:0 dropped:0 overruns:0          TX packets:218647 errors:0 dropped:0 overruns:0          Interrupt:11 Base address:0x210

255.255.255.255 all-ones

route add -host all-ones dev eth0

route add 255.255.255.0 dev eth0

# Sample /etc/dhcpd.conf# (add your comments here) default-lease-time 600;max-lease-time 7200;option subnet-mask 255.255.255.0;option broadcast-address 192.168.1.255;option routers 192.168.1.254;option domain-name-servers 192.168.1.1, 192.168.1.2;option domain-name "mydomain.org";subnet 192.168.1.0 netmask 255.255.255.0 {   range 192.168.1.10 192.168.1.100;   range 192.168.1.150 192.168.1.200;}

option netbios-name-servers 192.168.1.1;

host haagen {   hardware ethernet 08:00:2b:4c:59:23;   fixed-address 192.168.1.222;}

touch /var/state/dhcp/dhcpd.leases

/usr/sbin/dhcpd

/usr/sbin/dhcpd eth1

/usr/sbin/dhcpd -d -f

/etc/rc.d/rc.local

Now you can maintain your network systems by using Linux DHCP Server and you must not worry about giving DHCP manually to each client computer.

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This chapter will show you how to convert your Linux box into an FTP server using the VSFTP package. The RedHat software download site runs on VSFTP. By using Linux FTP Server users can easily share files in your network systems.

FTP Overview

File Transfer Protocol (FTP) is a common method of copying files between computer systems. Two TCP ports are used to do this:

FTP Control Channel – TCP Port 21

All commands you send and the ftp server’s responses to those commands will go over the control connection, but any data sent back (such as”ls” directory lists or actual file data in either direction)will go over the data connection.

FTP Data Channel – TCP Port 20

Used for all data sent between the client and server.

Active FTP

Active FTP works as follows:

o Your client connects to the FTP server by establishing an FTPcontrol connection to port 21 of the server. Your commands such as ‘ls’ and ‘get’ are sent over this connection.

o Whenever the client requests data over the control connection,the server initiates data transfer connections back to the client. The source port of these data transfer connections is always port 20 on the server,and the destination port is a high port on the client.

o Thus the ‘ls’ listing that you asked for comes back overthe “port 20 to high port connection”, not the port 21 control connection.

o FTP active mode data transfer therefore does this in a counter intuitive way to the TCP standard as it selects port 20 as it’s source port(not a random high port > 1024) and connects back to the client on a random high port that has been pre-negotiated on the port 21 control connection.

o Active FTP may fail in cases where the client is protected from the Internet via many to one NAT (masquerading). This is because the firewall will not know which of the many servers behind it should receive the return connection.

Passive FTP

Passive FTP works as follows:

o Your client connects to the FTP server by establishing a FTP control connection to port 21 of the server. Your commands such as ‘ls’ and ‘get’ are sent over that connection.

o Whenever the client requests data over the control connection,the client initiates the data transfer connections to the server. The source port of these data transfer connections is always a high port on the client with a destination port of a high port on the server.

o Passive FTP should be viewed as the server never making an active attempt to connect to the client for FTP data transfers.

o Passive FTP works better for clients protected by a firewall as the client always initiates the required connections.

Problems With FTP And Firewalls

FTP frequently fails when the data has to pass through a firewall as FTP uses a wide range of unpredictable TCP ports and firewalls are designed to limit data flows to predictable TCP ports. There are ways to overcome this as explained in the following sections.

Client Protected By A Firewall Problem

Typically firewalls don’t let any incoming connections at all,this will frequently cause active FTP not to function. This type of FTP failure has the following symptoms:

o The active ftp connection appears to work when the client initiates an outbound connection to the server on port 21. The connection appears to hang as soon as you do an “ls” or a “dir” or a”get”. This is because the firewall is blocking the return connection from the server to the client. (From port 20 on the server to a high port on the client)

Solutions

Here are the general firewall rules you’ll need to allow FTP clients through a firewall:

Client Protectedby Firewall – Required Rules for FTP

*Many home based firewall/routers automatically allow traffic for already established connections. This rule may not be necessary in all cases.

** in some cases, you may want to allow all Internet users to have access, not just a specific client server or network.

Server Protected By A Firewall Problem

o Typically firewalls don’t let any connections come in at all. FTP server failure due to firewalls in which the active ftp connection from the client doesn’t appear to work at all

Solutions

Here are the general firewall rules you’ll need to allow FTP severs through a firewall

Server Protectedby Firewall – Required Rules for FTP

*Many home based firewall/routers automatically allow trafficfor already established connections. This rule may not be necessary in all cases.

** in some cases, you may want to allow all Internet users to have access, not just a specific client server or network.

How ToDownload And Install The VSFTP Package

· As explained previously, RedHatsoftware is installed using RPM packages. In version 8.0 of the operatingsystem, the VSFTP RPM file is named:

vsftpd-1.1.0-1.i386.rpm

Downloading and installing RPMs isn’t hard. If you need are fresher, the RPM chapter covers how to do this in detail.

· Now download the file to a directory such as /tmp and install it using the “rpm” command:

[root@bigboy tmp]# rpm -Uvh vsftpd-1.1.0-1.i386.rpm
Preparing… ########################################### [100%]
1:vsftpd     ###########################################[100%]

[root@bigboy tmp]#

How To Get VSFTP Started

The starting and stopping of VSFTP is controlled by xinetd via the /etc/xinetd.d/vsftpd file. VSFTP is deactivated by default, so you’ll have to edit this file to start the program. Make sure the contents look like this. The disable feature must be set to “no” to accept connections.

service ftp
{

disable = no
socket_type = stream
wait = no
user = root
server = /usr/sbin/vsftpd
nice = 10

}

You will then have to restart xinetd for these changes to take effect using the startup script in the /etc/init.d directory.

[root@aqua tmp]#  /etc/init.d/xinetd restart

Stopping xinetd: [  OK  ]

Starting xinetd: [  OK  ]

[root@aqua tmp]#

Naturally, to disable VSFTP once again, you’ll have to edit /etc/xinetd.d/vsftpd,set “disable” to “yes” and restart xinetd.

Testing To See If VSFTP Is Running

You can always test whether the VSFTP process is running byusing the netstat –a command which lists all the TCP and UDP ports on which the server is listening for traffic. The example below shows the expected output, there would be no output at all if VSFTP wasn’t running.

[root@bigboy root]# netstat -a | grep ftp
tcp       0       0       *:ftp        *:*        LISTEN
[root@bigboy root]#

What Is Anonymous FTP?

Anonymous FTP is used by web sites that need to exchange fileswith numerous unknown remote users. Common uses include downloading software updates and MP3s to uploading diagnostic information for a technical support engineer’s attention. Unlike regular FTP where you login with a user-specific username, anonymous FTP only requires a username of “anonymous” and your email address for the password. Once logged in to a VSFTP server, you’ll automatically have access to only the default anonymous FTP directory /var/ftpand all its subdirectories.

As seen in the chapter on RPMs, using anonymous FTP as a remote user is fairly straight forward. VSFTP can be configured to support user based and or anonymous FTP in its configuration  file.

The /etc/vsftpd.conf File

VSFTP only reads the contents of its /etc/vsftpd.conf configurationfile when it starts, so you’ll have to restart xinetd each time you edit the file in order for the changes to take effect.

This file uses a number of default settings you need to know.By default, VSFTP runs as an anonymous FTP server. Unless you want any remote user to log into to your default FTP directory using a username of “anonymous”and a password that’s the same as their email address, I would suggest turning this off. The configuration file’s anonymous_enable instruction can becommented out by using a “#” to disable this feature. You’ll also want to simultaneously enable local users to be able to log in by uncommenting the local_enable instruction.

By default VSFTP only allows anonymous FTP downloads to remote users, not uploads from them. Also by default, VSFTP doesn’t allow remote usersto create directories on your FTP server and it logs FTP access to the /var/log/vsftpd.loglog file.

The configuration file is fairly straight forward as you cansee in the snippet below. Remove/add the “#” at the beginning of theline to “activate/deactivate” the feature on each line.

# Allow anonymous FTP?
anonymous_enable=YES
…

…

# Uncomment this to allow local users to log in.
local_enable=YES
…

…

# Uncomment this to enable any form of FTP write command.

# (Needed even if you want local users to be able to uploadfiles)
write_enable=YES
…

…

# Uncomment to allow the anonymous FTP user to upload files. Thisonly
# has an effect if global write enable is activated. Also, you will
# obviously need to create a directory writable by the FTP user.
#anon_upload_enable=YES
…

…

# Uncomment this if you want the anonymous FTP user to be ableto create
# new directories.
#anon_mkdir_write_enable=YES
…

…

# Activate logging of uploads/downloads.
xferlog_enable=YES
…

…

# You may override where the log file goes if you like.

# The default is shown# below.
#xferlog_file=/var/log/vsftpd.log

FTP Security Issues

The /etc/vsftpd.ftpusersFile

For added security you may restrict FTP access to certain usersby adding them to the list of users in this file. Do not delete entries from the default list, it is best to add.

Anonymous Upload

If you want remote users to write data to your FTP server then it is recommended you create a write-only directory within /var/ftp/pub.This will allow your users to upload, but not access other files uploaded by other users. Here are the commands to do this:

[root@bigboy tmp]# mkdir /var/ftp/pub/upload
[root@bigboy tmp]# chmod 733 /var/ftp/pub/upload

FTP Greeting Banner

Change the default greeting banner in /etc/vsftpd.confto make it harder for malicious users to determine the type of system you have.

ftpd_banner= New Banner Here

Using SCP As SecureAlternative To FTP

One of the disadvantages of FTP is that it does not encryptyour username and password. This could make your user account vulnerable to an unauthorized attack from a person eavesdropping on the network connection.Secure Copy (SCP) provides encryption and could be considered as an alternative to FTP for trusted users. SCP however does not support anonymous services, a feature that FTP does.

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Having the ability to go wireless in your home or at the office is a great feature to have. Not only is it the freedom to be mobile, but also leaving your house wired free, and not having to route cables through drilled walls, shows another area where wireless is too good to miss out on. The freedom to roam your house from room to room, or even sit under the palm tree of your garden on a hot sunny day, proves there’s no going back from wireless network. However, because of the nature of the technology, wireless has a number of security issues we must be aware of And you will learn how to secure wireless network.

A neighbor, hacker or someone just by your home can easily detect your wireless network signals and attempt to connect to your wireless access point. This is because wireless network systems uses radio frequency and data travels through the air, though they do not need physical access to your router. This is where the security concern comes from.

So let’s get to the point. How bad could it be not secure wireless network?

The common stressing points we hear everyday regarding wireless security is the ability that an evil doer can easily sniff data, coming and going to your wireless access point. Also they will have the ability to use your router to browse the web just as you do… using your bandwidth.

It doesn’t really sound that bad… Does it?

Well how about if your neighbors or anyone on the street outside your home were using your wireless access point and taking part in illegal downloads, visiting illegal websites and generally using the web for criminal activity. Who do you think would get the blame? When you have the FBI busting through your door, and you’re quick to think your children are not as innocent as they claim to be, it may be a mountain for you to climb out of at this point.

The illegal downloads and criminal activity that was occurring from the next house on, was all under your ID. They were using your accesspoint which from the ISP point of view was coming from your home. Thisis what happened when you are not securing your wireless network.

To add to this, in a couple of months time when your bank statement arrives through the door showing you spent £3000 on a new TV, as well as purchasing a set of Golf clubs, it may just all be too late by then. A hacker could have easily sat outside your home and sniffed your bank details or any other confidential details you may have used when online, all from the comfort of their car or home.  All they need is a wireless laptop to do this, and sit within a range of your wireless network router, in other words somewhere outside your house!

Todays many wireless network router using linux as a tamper proof network security. Why? because linux is widely known as a stable operating system that can be configure to secure network also. by using linux you can have a better network security that you can control and monitor with ease.

Now this also goes for businesses with wireless access points as well and not just for home users. In fact it is so much more crucial for businesses because a hacker can break into their network via the access point, hacking into company confidential data!

Therefore secure wireless network today is crucial for all the reasons above. Identity theft today is on the rise, and hackers will go the distance looking for insecure wireless access points. For this reason you should take the time and ensure you have a secure wirelessnetwork.

Network Security

Secure network is vitally important for most network systems.Whilst email viruses and denial-of-service attacks (DoS attack) maycause us headaches on our home systems, for businesses, these sorts of attacks can cripple a network for days – costing businesses hundreds of millions each year in lost revenue. Not to mention corporate legitimate to clients.

Creating secure network to prevent this type ofmalicious attack is usually of paramount importance for network administrators, and while most invest heavily in some forms of security measures there is often vulnerabilities inadvertently left exposed. Aswe always heards that security is as secure as the weakest link.

Firewalls are the best place to begin when you are trying to develop a secure network. A firewall can be implemented in either hardware or software, or most commonly a combination of both. Firewalls are used to prevent unauthorized users from accessing private networks connected to the Internet, especially local intranets. All traffic entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified criteria. If the packet do not meet security criteria then the system will not allowed those packets entering network system.

Anti-virus software works in two ways. Firstly it acts similarly to a firewall by blocking anything that is identified in its database as possibly malicious (viruses, Trojans, spyware etc). Secondly Anti-virus software is used to detect, and remove existing malware on a network systems or workstation.

You can build your own firewall by using linux, there is a lot of tutorial and white papers on how to build your simple yet powerful firewall by using open source programs. Many company start their simple security by using linux server as their first line of defense.

One of the most over-looked aspects of secure network is time synchronization. Network administrators either fail to realise the importance of synchronization between all devices on a network or the system simply don’t work. Failing to synchronize a network is often a common security issue. Not only can malicious users take advantage of computers running at different times but if a network is struck by an attack, identifying and rectifying the problem can be near impossible if every device is running on a different time.

Even when a network administrator is aware of the importance of time synchronization they often make a common security mistake when attempting to synchronize their network. Instead of investing in a dedicated time server that receives a secure source of UTC (Coordinated Universal Time) externally from their network using atomic clock sources like GPS, some network administrators opt to use a shortcut and use a source of Internet time.

There are two major security issues in using the Internet as a timeserver. Firstly, to allow the time code through the network a UDP port(123) has to be left open in the firewall. This can be taken advantage of by malicious users who can use this open port as an entrance to the network system. Secondly, the inbuilt security measure used by the time protocol NTP, known as authentication, doesn’t work across the Internet which means that NTP has no guarantee the time signal is coming from where it is supposed to.

To ensure that you have a secure network, isn’t it time you invested in an external dedicated NTP time server?

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Do You Need a Home Network Systems

Wireless gear is about the same price as is cabled network equipment; and a length of Cat 5 Ethernet cable costs no more than doesan audio cable. Both wireless and cabled networks have gotten better.The equipment now available has better documentation which makes iteasy even for the less than technically skilled to set up a home network. Everybody uses email now and is aware of a few networking terms (HTTP, ping, etc.).

Thousands of pages have been written about fraud and identity theft due to poor computer security, making people better informed about the issue. The biggest problem for many people is simply familiarizing themselves with the technical terms involved in networking; NICs,protocols and so on. So if you’re interested in building a home network, then get going and start connecting all of those computers in your home together. Learn more tips and information about ecommerce webhosting software here.

How to Build a Simple Home Network Systems

Many people have relatively uncomplicated needs for their home networks. You’re going to need Cat-5 (or Ethernet) cables for a wired network. If you plan to build a wireless network, you can skip the cables.

You’ll also need a switch or a router for all of these cables (or radio waves if it’s a wireless network) to connect to. A router is better and can handle internet connection sharing; it is almost a must for a home network. You’re also going to need Network Interface Cards(or NICs) in each computer, printer or any other device you want to be on the network. If you are building a wired network, you can use Ethernet equipment with 10MB or 100MB speeds. There is also Gigabit Ethernet, but this is prohibitively expensive for many building a home network.

On a home network, your IP addresses will look like 192.168.0.1 or 10.121.0.1.

If the router has the number 192.168.0.1, then computers and other device should be numbered 192.168.0.2, 192.168.0.3. Don’t assign the same address to two devices. You can also use linux to build a secure router for your home network.

Save Money by Setting Up a Home Network System

A Network Interface Card (NIC) will help you accomplish this.

Installing a network card is as easy as using it. If you are using a wireless system, your network card and router must also be wireless. Today most new computers are equipped with network cards already. There are several manufactures of network card. *3 Com: Producing network cards for the enterprise market. They provide secure type network cards with encryption, remote management, and server features.

*Broadcom: This company’s network cards are usually not visible on retailers shelves because they are already installed in other companies products.

Vital Office Network System Backup Data Recovery

Today’s companies rely almost entirely on their office network system to retain important and irreplaceable data. What happens in the case of a system failure, virus or weather disaster, after which critical data is lost permanently? If the unthinkable happens,companies who have trusted their office network installation company to perform the necessary backup measures can rest assured that their files are able to be recovered after a disaster.

How Common Is System Failure?

The best way to make sure that your company does not have to deal with lost data after an employee, office network or natural disaster is to perform regular file backups.

Office network installation companies recommend backing up data at the end of every workday, as well as performing a full system restore at least once a month to make sure the backup system is working.

Priyo Wibowo | IT Consultant

Introduction to Linux

Linux is an Open source operating system that widely use by many user. Linux known as open source operating system that means you can download all the source code and write your own. By using open source technic or copy left, linux by itself becoming more and more famous.Many people around the world helping each other to make linux a better operating system.

Until now linux development is still going on. We can see so many linux variant each one has their own power to their users. For example many student rely their PC on linux since the cost of operating system license is too expensive. Many company start migrating their systems toLinux environment as it is more stable and cheaper.

Organization use Linux as Server operating systems, desktop and many more. For network systems we use to protect network by using it as firewall and proxy server, and we also use it for bandwidth management so we can manage users bandwidth while accessing internet.

Linux is also been use as email server and database server, it’s cheap and reliable. Many major company rely their business on Linux system as it fast and cheap. Organization gain more benefit while moving their system to linux. For office productivity there is open office application that can be used to boost users productivity so they can keep productive as while they are using other Operating system.

Priyo Wibowo | IT Consultant

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Introduction

Domain Name System (DNS) converts the name of a Web site (www.sekolahlinux.com) to an IP address. This step is important, because the IP address of a Web site’s server, not the Web site’s name, is used in routing traffic over the Internet. This blog will explain how to configure your own DNS server to help guide Web surfers to your site.

Introduction to DNS

Before you dig too deep in DNS, you need to understand a few foundation concepts on which the rest of the chapter will be built.

DNS Domains

Everyone in the world has a first name and a last, or family, name. The same thing is true in the DNS world: A family of Web sites can be loosely described a domain. For example, the domain sekolahlinux.com has a number of children, such as www.sekolahlinux.com and mail.sekolahlinux.com for the Web and mail servers, respectively.

BIND

BIND is an acronym for the Berkeley Internet Name Domain project, which is a group that maintains the DNS-related software suite that runs under Linux. The most well known program in BIND is named, the daemon that responds to DNS queries from remote machines.

DNS Clients

A DNS client doesn’t store DNS information; it must always refer to a DNS server to get it. The only DNS configuration file for a DNS client is the /etc/resolv.conf file, which defines the IP address of the DNS server it should use. You shouldn’t need to configure any other files. You’ll become well acquainted with the /etc/resolv.conf file soon.

Authoritative DNS Servers

Authoritative servers provide the definitive information for your DNS domain, such as the names of servers and Web sites in it. They are the last word in information related to your domain.

How DNS Servers Find Out Your Site Information

There are 13 root authoritative DNS servers (super duper authorities) that all DNS servers query first. These root servers know all the authoritative DNS servers for all the main domains – .com, .net, and the rest. This layer of servers keep track of all the DNS servers that Web site systems administrators have assigned for their sub domains.

For example, when you register your domain my-site.com, you are actually inserting a record on the .com DNS servers that point to the authoritative DNS servers you assigned for your domain. (You can also read more basic networking in network systems).

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