Private and Public IP Addresses: What’s the Difference ?

Internet Protocol (IP) addresses is usually of two types: Public and Private. If you have ever wondered to know what is the difference between a public and a private IP address, then you are at the right place.

In this post I will try to explain the difference between a public and a private IP address in layman’s terms so that it becomes simple and easy to understand.

What are Public IP Addresses?

A public IP address is assigned to every computer that connects to the Internet where each IP is unique. In this case, there cannot exist two computers with the same public IP address all over the Internet. This addressing scheme makes it possible for the computers to “find each other” online and exchange information. User has no control over the IP address (public) that is assigned to the computer. The public IP address is assigned to the computer by the Internet Service Provider as soon as the computer is connected to the Internet gateway.

A public IP address can be either static or dynamic. A static public IP address does not change and is used primarily for hosting web pages or services on the Internet. On the other hand, a dynamic public IP address is chosen from a pool of available addresses and changes each time one connects to the Internet.

Most Internet users will only have a dynamic IP assigned to their computer which goes off when the computer is disconnected from the Internet. Thus when it is re-connected it gets a new IP.

What are Private IP Addresses?

An IP address is considered private if the IP number falls within one of the IP address ranges reserved for private networks such as a Local Area Network (LAN). The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private networks (local networks):

10.0.0.0 – 10.255.255.255 (Total Addresses: 16,777,216)
172.16.0.0 – 172.31.255.255 (Total Addresses: 1,048,576)
192.168.0.0 – 192.168.255.255 (Total Addresses: 65,536)

Private IP addresses are used for numbering the computers in a private network including home, school and business LANs in airports and hotels which makes it possible for the computers in the network to communicate with each other.

Say for example, if a network X consists of 10 computers, each of them can be given an IP starting from 192.168.1.1 to 192.168.1.10. Unlike the public IP, the administrator of the private network is free to assign an IP address of his own choice (provided the IP number falls in the private IP address range as mentioned above).

Devices with private IP addresses cannot connect directly to the Internet. Likewise, computers outside the local network cannot connect directly to a device with a private IP. It is possible to interconnect two private networks with the help of a router or a similar device that supports Network Address Translation.

If the private network is connected to the Internet (through an Internet connection via ISP), then each computer will have a private IP as well as a public IP. Private IP is used for communication within the network where as the public IP is used for communication over the Internet. Most Internet users with a DSL/ADSL connection will have both a private as well as a public IP.

You can know your private IP by typing ipconfig command in the command prompt. The number that you see against “IPV4 Address:” is your private IP which in most cases will be 192.168.1.1 or 192.168.1.2. Unlike the public IP, private IP addresses are always static in nature.

Common Myth about Private IP Address:

Most people assume that a private IP is the one used for stealth Internet activities and hence cannot be detected. But this is NOT TRUE!.

Unlike what most people think, a private IP address (unlike the private telephone number) is just like any other IP address that belongs to a private network. In reality, there is no public IP address that is impossible to trace as the protocol itself is designed for transparency.

 

Change the MAC address in Windows 7

To spoof your MAC address in Windows 7 there are a few facts you need to know. If your network adapter has newer updated drivers, then you can only spoof your mac address to an address that begins with 12. For example 12197ECD414A. You should enter the MAC address without the dashes.

If you would like to spoof your mac address to an address that begins with 00 (for example 00197ECD414A) you must downgrade your network adapter's drivers to an early version.

Go to Start and then click Run. In the text box type CMD (enter). In the command prompt type ipconfig /all. This command gives you all the information for any network card in your system including the wired network adapter, bluetooth adapter, and the wireless adapter. So you’ll have to look under the specific heading you need because each adapter will have it’s own MAC address. The MAC address is called Phyical Address.  Now you know your MAC address.

Go to Start -> Control Panel -> Network and Internet -> Network and Sharing Center -> Change Adapter Settings -> Properties -> Configure -> Network Address -> Value (type your new MAC address). Enter the MAC address without the dashes.

To verify the change of MAC address. Go to Start and then click Run. In the text box type CMD (enter). In the command prompt type ipconfig /all.

Connect Your DVR to Your LAN

we will assign your surveillance DVR an IP address.  Make sure that your DVR is connected to your network by attaching an ethernet cable to the back of your DVR and attaching the other end to your router.

1. Login to your DVR by pressing the menu button on the DVR or on the wireless remote control.

2.  When you are prompt to enter a password, just press the OK button on the DVR or remote.  The default admin password for the DVR is blank.  If you have already setup an admin password for your DVR, then enter this, then press OK.

3.   From your DVRs System menu, select External Device.

4.   On the External Device menu, select TCP/IP Setup.

5.   On the TCP/IP Setup screen, select DHCP setup and press enter.

6.  On the DHCP setup screen, confirm that the DHCP mode is set to automatic.  If it is not, adjust it so that it is by pressing the OK button. 

7. Select Detect IP and press enter.  The screen should refresh and populate values below.  Note the IP address.  This is the internal IP address that your router has assigned to your DVR.  This is the IP address that you will setup port forwarding for.

8.   After you have noted this IP address, select DHCP Mode and press OK.  The mode will be changed Manual.  This will ensure that your DVR will always be assigned the same IP address from your router. THIS IS IMPORTANT because if you loose power to your router, your router may assign your DVR a difference IP address and you will no longer be able to access the DVR remotely.

9.   Press the menu button once to return to the TCP/IP setup screen.

10. On the TCP/IP setup screen, select IP config setup and press enter.  On the IP config setup screen, confirm the port number of your DVR as seen below.  The default port is 8000.  If your DVR is not set to port 8000, please edit this value to set to 8000.  NOTE: please ignore that the below screen shot shows port 50000.  Port 50000 was used for the last version of the JPEG DVR.

Since most businesses and many households have local area networks (LANs), you will find the task of connecting a security DVR to a LAN is a common procedure. While it is a relatively simple thing for most security equipment installers, it is complex enough to confuse many users, especially users who have never worked with IP numbers before or have never worked with LAN topology.

Let's begin by identifying your LAN topology. To do this, locate your

1) security DVR,

2) the router attached to your security DVR and

3) a computer/workstation that is attached to the same router. It can also help if you locate

4) the modem  (or router AND modem)  that connects to the internet outside your home or facility - it is usually the first piece of hardware attached to the internet cable the comes through the wall. If you don't have #3 (computer attached to the same router shared by your security DVR), create one now and verify that the PC/workstation has a working connection. If you can't find or locate #4 (modem that provides connection to the internet) don't worry about it at this point since locating it may not be necessary.

Some typical network topologies are shown below. Figure #1 represents a simple network topology you might find in small business, while figure #2 represents a very simple network you would find in many homes. (Figure #2 actually represents the bare minimum hardware & connections you need for remote DVR monitoring/programming.).

Make sure (verify) your network connection is active and your PC can connect to the internet without any problems. Start at your PC and do the following:

1. Go to the COMMAND PROMPT. Different Windows versions have different ways of getting a COMMAND PROMPT. Most Windows versions let you reach a command prompt by going to START, then RUN, then type CMD into the window and hit ENTER. If successful you'll see a screen similar to Figure 3.

2.  Figure 3 shows a computer screen with the command prompt, and the PROGRAM FILES folder is open. That location should be fine. Type IPCONFIG/ALL and hit ENTER.  You should see a display screen similar to Figure 4.

( If you DON'T see Figure 4, they you are probably getting an error message. You'll need to find the person who installed your OS and find out why it doesn't have essential DOS files - you won't be able to continue this procedure without them.)

IPCONFIG is a standard Microsoft DOS command. You can read all about it at the official Microsoft website (http://technet.microsoft.com/en-us/library/bb490921.aspx), if you want. When you use this command as described here, it will report the computer's IP numbers so you can record them for your records. It does NOT change any settings or perform any kind of configuration process.

3. Write down the IP numbers shown under

IP ADDRESS (192.168.1.100),

SUBNET MASK (255.255.255.0),

GATEWAY (192.168.1.1) and

DNS SERVERS (206.222.98.82, 216.199.46.11, 206.222.98.82 - this particular computer has 3 DNS SERVER connections) and label them.

NOTE: Some versions of MS Windows will display IPv4 ADDRESS and an IPv6 ADDRESS - you want to use the IPv4 ADDRESS numbers.

4. Now get the IP Address of the security DVR. Got to the VRR andaccesssthe programing menu and get to the NETWORK settings area. Find the option that says DHCP (Dynamic Host Configuration Protocol) and ENABLE it..

5. Still at the DVR, write down the IP addresses it shows in the DHCP screen. Now turn OFF DHCP (or DISABLE it). If the IP addresses shown did not change, go to the next step. IF THEY DID CHANGE, re-enter them in the fields shown (DO NOT enable, or turn on, DHCP again).). If the IP addresses shown did not change, go to the next step. IF THEY DID CHANGE, re-enter them in the fields shown (DO NOT enable, or turn on, DHCP again).

6. Note the PORT NUMBERS shown in the DVR NETWORK screen. Write them down.

7. Test your configuration. Do the following at the PC/workstation that shares the same router as your DVR:

·   Get to the COMMAND PROMPT.

·   Type PING [IP Address], hit ENTER. (In our example the IP address is 192.168.1.100)

·   If you get a REPLY message, it communicated. If not, and you got a TIME OUT message of any kind then check your settings.

8. Your DVR has CLIENT SOFTWARE or REMOTE VIEWING SOFTWARE that was included in the box. Locate it and install it on the PC/workstation.

·   If your DVR has a webserver you can use IE Browser to communicate with the DVR - just type in the DVR IP Address in the URL bar of the browser.

Port Forwarding & Accessing Your DVR from Outside Your Network

To set up external (remote) viewing of your DVR and attached cameras, you will need to access your router. Refer to the router's User Manual to learn how to set port forwarding. If you can't find it, look here http://www.portforward.com/english/routers/port_forwarding/routerindex.htm. All routers have a different method of setting up port forwarding so it's impossible to instruct you here.

Program the router so that when it gets an internet request for the IP ADDRESS of the DVR it will refer (or activate) to the PORT NUMBER of the DVR (you wrote these numbers down earlier, right?). Normally most routers have a field for each physical connection and it will be obvious where to place the IP and PORT NUMBER information. If you can't find how to access your router, look at the router closely and make sure it is indeed a router and NOT a switcher. It should be ok if it's labeled ROUTER/SWITCHER but if it is an older piece of hardware and just says SWITCHER, discard it and get a true ROUTER.

Test the connection from an network external location. If the IP numbers and Port Forwarding numbers are set correctly you should be able to receive streaming video.

Using IE Browser VS Client/Remote Viewing Software

If the DVR has a webserver, then you can use IE Browser to connect to the DVR. Put the DVR IP address in the URL bar of the browser (like http://192.168.100.200, etc).

If the DVR does NOT have a webserver, then you will need to install the client/remote viewing software (that came with the DVR) on the PC/workstation you are using to view your security installation. The Client Software (or Remote Viewing Software) gives you additional features, such as ability to program motion detection, etc., that the IE Browser can not provide. Since each surveillance DVR has it's own client software, you'll have to refer to the software manual for help using their software.

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