You can therefore use either the w, who, or users command to know who all are logged into the system.

An example output of the w command may be as follows:
$ w
10:33am up 608 day(s), 19:56, 5 users, load average:
0.36, 0.36, 0.37
User tty login@ idle what
jamesf pts/5 8:52am w
maureenm pts/23 20Apr08 28 -bash
henryj pts/18 9:01am 9 pine
peterb pts/19 21Apr08 emacs -nw html/index.html
meganr pts/8 10:12am 3days -csh
andrewf pts/12 16Apr08 5:29 /usr/bin/perl -w
perl/test/program.pl

An example output of the who command:
$ who
jamesf ttyp0 Apr 26 08:11 (66.164.235.73)
maureenm ttyp3 Apr 26 20:26 (66.164.235.73)

An example output of the users command:
$ users
jamesf maureenm henryj peterb meganr andrewf

You can also list all UNIX users, including those who are not logged in; you can use the /etc/passwd file and the finger username or last – l username commands to get specific information about them. A typical entry in the /etc/passwd file looks like this:
root:*:0:0:System Administrator:/var/root:/bin/sh

You can then use the awk or cut utilities to trim this information to exactly what you want.

For example, to just see the Unix user names, use the command $ cat /etc/passwd | cut -d: -f1.
$ cat /etc/passwd | cut -d: -f1
…
jamesf
maureenm
…

Or, to only see their real names:
$ cat /etc/passwd | cut -d: -f5
…
James Forlon
Maureen Major

Downloading FreeBSD UNIX

This is an operating system that is a derivative of BSD. It was developed at UCLA, Berkeley and is mainly for x86 compatible (which also embraces Pentium and Athlon), amd64 compatible, Alpha/AXP, IA-64, PC-98 and Ultras ARC architecture. You can download this operating system by copying and pasting this link to your browser: Freebsd.org

Downloading OpenBSD UNIX

This system offers a free, multi-platform operating system that is 4.4BSD based. Correctness, portability, proactive security, standardization and integrated cryptography are some of the cross-cutting themes that underpin the system. OpenBSD also sustains binary emulation of systems like SVR4 Solaris, Linux, and Sun OS among others. You can easily download OpenBSD from the Internet by going to Openbsd.org and choosing your preferences.

Downloading Solaris UNIX

Sun’s Solaris Operating System is considered by many as one of the top UNIX environment-based systems with a little over 600 features for the latest release, the Solaris 10 OS. Many Open Source disciples will be pleased to know that many applications are ready to run on Solaris platform and this saves time which would have been taken up by deployment. This amazing software can be downloaded from Sun.com

Downloading Fedora Linux

This is a system developed by Redhat which aims to develop a complete, general purpose operating system that is all done in a public platform. This system can be downloaded on Fedoraproject.org

Downloading Debian Linux

This is a free operating system that uses Linux Kernel (which is the core of the OS) but most of it’s tools are from the GNU project, which is why it is also called Debian GNU/Linux. This OS comes with 8710 packages which are precompiled to facilitate easy installation. Debian Linux can be downloaded on this site: Debian.org

Downloading Ubuntu License

Ubuntu is a community-based open source operating system that can be used on desktops, notebooks and servers as well. It can be downloaded for free, and depending upon where you are located , you can apply for a copy of this free software to be shipped to you by Canonical, the company behind the project. You can also download Ubuntu by going to this site: Ubuntu.com

Additional Reading on Downloading Unix

• Download Unix
• Linux Download
• Download Unix

There are those who believe that one can prevent unauthorized access by disabling the broadcast SSID feature. This method is ineffective, because in the process of reconnecting to the network, the user will have to enter the correct SSID in order to access, and an eavesdropper can then use some sniff (using something like Kismet) out the SSID which will be transmitted in clear text, and then access the network himself. Most NETGEAR products with the site survey feature can help you look for networks SSID’s. Actually, the SSID itself is not a very strong feature, and for enhanced security, needs to be used in conjunction with other security measures like Wired Equivalent Privacy (WEP) or Wi-Fi Protected Access (WPA), the latter being the most accepted .

There are two kinds of SSID. These are Extended Service Set Identifier (ESSID) and Basic Service Set Identification (BSSID). The difference between the two is that ESSID requires an access point whereas, BSSID, which is really an ad hoc SSID, doesn’t. When considering which SSID is best for you, consider the following:

1. Many companies like having their names as the SSID for their public WLAN’s. It would be ill advised to do that for a private WLAN though, as malicious elements may relish launching a denial of service attach against the owners of the network.
2. A scrambled SSID (that is, one using characters such as d*&%$#G?!!) may again prompt a presumptuous hacker to do something unpleasant to your network, if he decides that you could be hiding something. In addition, such characters make network administration unwieldy. Not many people can remember an SSID which looks like d*&%$#G?!! off the top of their heads.
3. Perhaps the best solution is to use a pseudo name. It makes it difficult for others to guess your SSID, and in addition, your network doesn’t give away your identity.

Choosing SSID calls for careful consideration on how it will affect the effectiveness of your WLAN in terms of manageability, security and functionality.

Additional Reading on SSID’s

• SSID
• SSID

Skype.

Skype is one of the pioneers of VoIP calls. Skype provides unlimited free calls if you make them from one computer or device to another. These are known in the industry as PC-to-PC calls. Both the caller and the recipient have to have the Skype software installed, which can be downloaded for free. Its status as the most popular VoIP platform means there are many users out there, making it possible to reach millions of people. However, remember most VoIP providers allow free calls only within their platforms. If you are interested in calling a landline through Skype, you will have to buy Skype credit. Users in North America can make unlimited calls to landlines for about $30 a year, which is not exactly an arm and a leg.

Raketu.

Apart from the $9.95 “deposit” that will be required when registering, Raketu is otherwise an impressive VoIP provider. One can make not just free PC-to-PC calls, but also free calls to landlines and mobile phones to around 42 countries. The deposit you made when you registered will probably be spent if you call a destination that is not included in the free calls package.

VoiceCheap.

This service allows users to make free calls, and unlike Skype, one can make free calls to landlines and unlike Raketu, the free calls package includes many more countries. Their software is also free to download. The downside for this service is that the free calls are limited to 300 minutes per week, making it slightly unattractive for the most loquacious of us.

Gizmo.

If you are a Gizmo user, you might benefit from their “All Calls Free” plan, where free calls can be made to the PC’s, mobiles and landlines of other Gizmo users. The software for the service is free and can be downloaded, installed and used with ease. However, the laborious procedure one has to undergo to enjoy free calls to mobile/landlines really raises questions about the genuineness of this service. The rules are absent when making PC-to-PC calls, and anyone who tries to cut corners when calling mobile/landline even slightly, is likely to be slapped with some bill for calls that, on the face of it, are supposed to be free.

There are many more VoIP providers than can be discussed here in a resources-friendly manner (time and space) but it is evident from that all of these services have their quirks, so you need to examine each carefully before deciding which one of them is your best choice.

Additional Reading on Free VoIP

• Free VoIP

Different platforms have different ways of changing Internet protocol addresses. If you are using Microsoft’s Windows Operating system, you may follow the instructions outlined below. The procedure for different versions of Windows OS may differ, but retain major similarities. This is how you would change an IP address for your own Local Area Network (LAN):

1. Go to the desktop and click on “Start”, and then go to “My Network Places”.
2. Alternately, after clicking on “Start”, you can go to “Network Neighborhood”, and in either case, go to “Properties”.
3. Right-lick on LAN and select “Properties”.
4. Click on the Internet Protocol (TCP/IP) and then select “Properties”.
5. On the Internet Protocol (TCP/IP) properties section, Choose, “use the following IP address”.
6. Write down the old IP address before removing it (you might need it if you have problems with the new one), and then insert the new IP address.
7. Specify the suitable subnet mask for your network. Remember here that the leftmost bits have to be set to ’1′ and the ones on the rightmost have to be set to ’0′.
8. Specify the “Default Gateway” in the appropriate box. This amounts to adding the IP address of the computer or device that connects other computers to the Internet, including the one that you are about to change.
9. You will also need to specify the IP address of the computer that distributes host names to IP addresses on the “Preferred DNS Server” box.
10. Finish the process by clicking Ok on all dialogue boxes.

Linux Users

You will need a root access to change IP address for this platform. And if you already have it, then go to the command prompt and move to the /etc/sysconfig/network directory. Make the appropriate changes to the interfaces file, including adjusting your network settings.

Additional Reading on Changing Your IP Address

• Change IP Address
• Change Your IP Address

Boot up the computer, log-in as root, go to the # prompt, and then type the cat /etc/resolv.conf

The results will turn up the domain suffix on the first row and the DNS IP on the second.

If for some reason the LRP box is malfunctioning and you are running Windows (95 or 98) which is using a cable/modem or DSL, follow the following steps:

1. Go to the “Start” button, and then go to “Run”, and type “winipcfg”.
2. Choose the appropriate “Network Adapter”.
3. Then click on “More Info” button and there you shall find your primary DNS.

The following instructions may be used to find DNS server by those who are using Windows NT/2000/XP operating systems, and who are using a cable, modem or a DSL:

1. Go to the “Start” button, click on the “Run” button, and then go to the command prompt by typing in there “cmd”.
2. After c black screen opens, type in there “ipconfig /all”.
3. And there you shall have your DNS servers for your location.

If on the other hand, if you are on Windows ME that is already using a cable, Modem or on DLS, this is how to find your DNS server location:

1. Go to the “Start” button, go to “Run” and go to the command prompt once again.
2. Type the following; “ipconfig /all”
3. Press the space bar to move forward and your problem will have been solved.

Alternately, you may still locate your DNS server by this procedure.

1. Go to the Control Panel and click on the domain Icon.
2. If you have more than one domain, select the appropriate one from the domain list.
3. The resulting window will show both the primary and secondary Domain Name Servers.

It has to be said though that, although you don’t have to be a nerd to follow the steps outlined above, some people would find the exercise of finding the DNS server to be a little complicated and even for them, there is still an alternative. If for some reason or out of curiosity they would just like to know, they need to call their ISP, who in most cases will be glad to help. That has to be the easiest way to find the DNS Server.

Additional Reading on Finding Your DNS Servers

• Find DNS Servers
• Find DNS Servers

If for some reason the device using a private address such as 192.168.1.1, wishes to communicate with other networks, an interceding gateway is required so that the external network will be presented with a “reachable” IP address and that the routers will allow the traffic between the two networks to be transmitted. This “intercessor gateway” usually turns out to be the NAT or a proxy server. There is a caveat though. If two private networks were to contact each other, there is a possibility of network conflict if the private IP’s turn out to be identical, and in this case not even NAT would help.

Sometimes it becomes impossible to access the router through 192.168.1.1. This can be caused by invalid browser settings or an invalid IP address from the router. This can be dealt with by clearing the browser settings and disabling all the antivirus and firewall software. Linksys routers use 192.168.1.1 as their default IP address. Care should be taken not to have identical IP addresses in a network that has such devices as network conflict is most likely to occur. One thing should be clear about private IP addresses 192.168.1.1; whereas two different networks may use IP addresses that can be found in another network, no two identical private IP’s should be in any given network. When adding a new device to your network, be certain that its default IP address is not already in use on your network.

Additional Reading on 192.168.1.1

• 192.168.1.1
• 192.168.1.1
• 192.168.1.1
• 192.168.1.1
• 192.168.1.1

Why use VLANs?

VLANs avoid some of the problems encountered while using the traditional LANs of requiring additional bandwidth. This is because the packets are required to pass through multiple levels of network connections as the network is usually fragmented. Secondly the traditional LAN’s have tended to focus too much on the physical location on the equipment and personnel. And this has its drawbacks. When it comes to VLAN’s, someone in New York can access and make a computer printout using a printer in London! Further, a properly designed VLAN can ensure that only devices on the network can send o0r receive packets intended as a source or destination.

Types of VLAN’s.

There are several types of VLAN’s as defined. These include; Port Based VLANs, MAC Based VLANs, Protocol Based VLANs and IP Subnet Based VLANs.

Port Based VLANs.

Here, all the Internet traffic that arrives at a certain port of a switch is linked to a particular VLAN. In this way, several VLAN’s can be connected through a single switch and run concurrently without any hitches. This would work optimally in a static environment, where member of different VLAN’s remain the same over a prolonged period of time and seldom change.

MAC Based VLANs.

In this case, the incoming traffic is inspected for the source and destination MAC addresses and the respective VLAN’s are determined. By working like that, the VLAN connects to all computers to all the ports and a switch will then associate the respective computers with the appropriate VLAN as configured.

Protocol Based VLANs.

As the name suggests, the VLAN is protocol that is used to transmit data, and the each protocol is assigned on a different port. This method allows for the logical segmentation of a network.

IP Subnet Based VLANs.

All the traffic in this type of VLAN is split, depending on the Internet Protocol (IP) subnet of each source or destination. In this type of VLAN, users can physically move the computers from one place to another and still retain the same VLAN settings intact.

Additional Reading on VLAN’s

• VLAN

1. There could be a firewall that is obstructing VPN traffic by blocking the ports UDP 4500/500 and/or ESP
2. A sloppy connection which may precipitate packet not reaching the VPN concentrator or server. It could also be that the replies from the server are not reaching the client, making the client assume that the service is unavailable.
3. It could also be that the VPN client is behind a NAT device but that the VPN server is not NAT-T enabled, in which case the user will neither send nor receive any data. If this persists for a while, the software client will erase the VPN tunnel.
4. Another possibility could be that the VPN client is used to connect through TCP which now is blocked.

Once you establish that the reason for the error message is a firewall which is blocking the VPN traffic (and this usually happens when one is using Windows XP firewall), you can try to resolve this by configuring the firewall to permit UDP ports 500 and ESP which are required for Cisco VPN client. Alternately, you could try disabling any firewall that is installed on the PC, and once you have done that, try again and see if it works. Besides that, you could also try to confirm that the device that you are using is actually transmitting packets. To do this, start a cmd windows and key in the following command: ( netstat -s -p ip 60)

From there, you shall see the packets sent and received from the IP. In case your device is behind a NAT device as described in (3) above, try to resolve that by using an NAT-friendly VPN scheme. The default setting of IP/ESP does not work with many NAT devices. You can also use the following commands to have a glimpse of what is going on. You could try to ‘ping’ the remote peer and check on why they are not responding to the client.

C:Program FilesCisco SystemsVPN Clientvpnclient stat traffic

C:Program FilesCisco SystemsVPN Clientvpnclient stat tunnel

The problem can also be dealt with by removing and reapplying the crypto map on the interface to connect to the VPN. Also try setting the speed at around 100Mbps/Full duplex on the private interface. Also by setting your MTU to up to 1300 helps to prevent packets from being fragmented, this goes a long way toward increasing performance. Always ensure that the group name is identical to the VPN server group name. This can be done by going to “Start”, then to “All Programs” then to “Cisco Systems VPN Client”, and then to ” Set MTU’.

Additional Reading on Cisco VPN Error 412

• Cisco VPN Error 412
• Cisco VPN Error 412

In the United States during the good old days, the telephone company used to not connect your house to their network and they also did the wiring for you. Well those days are long gone, and most people do the wiring part for themselves after the phone company puts the Network Interface Device (NID) in your basement. Unlike the dreaded power lines, telephone lines are safer to install by a non-expert because of the low voltages they carry. That does not mean that you may do telephone wiring while barefooted on a wet floor. If you are a stickler for rules and standards, you might find it a bit harder to comply with many industry standards for installing telephone wires in your home. First, those standards are too many and it’s a bit confusing to keep up with the current ones. But if are moving into a new facility, the most current standards you may want to use are EIA/TIA T586A.

The work begins at the Network Interface Device, and it has a customer access compartment which one may open and check the lines for a dial tone. You can use a previously-tested corded phone to test the phone lines; as this is the only way you can be certain you are testing the lines, and not the phone. Any phone head that gives a dial tone can be used to test the lines. If on testing no dial tone can be detected, it is likely you have a phone problem. The phone company may be willing to help you with this though they may charge you for the repairs. On the customer compartment on the NID, you will see a line of phone jacks lined up vertically. After testing the lines and finding out that they are fine, the next thing you should do is to label the NID lid so that you can tell which jack is associated with which phone line.

To guard yourself against a possible electrical jolt that you may get from a telephone line, especially when there is an incoming call, it may be a good idea to disconnect your house from the NID before you start wiring (this is particularly important for those with pacemakers which can be interfered with even by a minor shock). And it is not advisable to do your wiring during thunderstorms. For new telephone wiring, use a Cat-5 cable and when attaching this on the NID, you will need to make the appropriate color conversions. This means you will swap black for green, and yellow for red. Note that although it would still work perfectly if you consistently swap the wires the other way around, that is black for red and yellow for green, that this is not considered to be the standard. The four strand wire supports up to two lines and if you want to install more than three or four lines, you will need to buy the eight strand wire, or six strand wire, which is similar to eight strand wire but without the brown wires.

If every thing is hooked up and you still have problems such as one or more phone lines that have no dial tone, there are several possibilities. The fault could be yours or the phone company’s. Just make sure the problem is not yours before calling the company, for you may be asked to pay for their trouble should it be found to be your fault.

Additional Reading on Telephone Wiring

• Telephone Wiring
• Telephone Wiring