Web And Email Hosting, Jsp, Tomcat, J2Ee, Hibernate Programming Blog

Adding other host addresses You can use the Network Configuration window to add host names and IP addresses to the Ethernet LAN for the computers on your network as well. This adds host name and IP address pairs to your /etc/hosts file (which you could also edit manually, if you prefer). Note If you are using a DHCP server to centralize assignments of your IP addresses, you probably want to centralize host name look-ups as well. In this way, you don’t have to change every computer’s /etc/hosts file every time a computer is added or removed from your network. Refer to Chapter 23 for information on how to do this. To add host names and addresses, do the following: 1. Start the Network Configuration. As root user from a Terminal window, type neat. The Network Configuration window appears. 2. Click the Hosts tab. A list of IP addresses, host names, and aliases appears. 3. Click Add. A pop-up window appears asking you to add the IP address, host name, and aliases for a host that you can reach on your network. Figure 15-7 shows the Network Configuration window and the pop-up window for adding a host. Figure 15-7: Add hosts to /etc/hosts using the Network Configuration. 4. Type in the IP address number, host name, and, optionally, the host alias. 5. Click OK. 6. Repeat this process until you have added every computer on your LAN. 7. Click Apply to apply the changes. 8.
Note: In case you are looking for affordable and reliable webhost to host and run your j2ee application check Vision web design programs services

Figure 15-6: Configure your LAN interface using the Network Configuration window. 4. Select Activate device when computer starts to have the network interface start at boot time. 5. Click the Protocols tab. You should at least see TCP/IP. 6. Click TCP/IP and select Edit. On the TCP/IP Settings window that appears, you can enter the following information: Automatically obtain IP address settings with: Make sure that the check box is off next to this box. (If you were getting your IP address from a DHCP server, this box would be on and the rest of the information would be obtained automatically.) Address: Type the IP address of this computer into the Address box. This number must be unique on your network. Subnet Mask: Enter the netmask to indicate what part of the IP address represents the network. (Netmask is described earlier in this chapter.) Default Gateway Address: If there is a computer or router connected to your LAN that is providing routing functions to the Internet or other network, type the IP address of the computer into this box. 7. Click OK in the TCP/IP Settings window to save the current configuration. 8. Click OK in the Ethernet Device window to close that window. 9. Click Apply in the Network Configuration window to apply the changes.
Note: If you are looking for cheap and reliable webhost to host and run your mysql application check Vision mysql hosting services

Class C 192.168.0.0 to 192.168.255.255 256 So, for a small private LAN, the following numbers are examples of IP addresses that could be assigned to the host computers on your network. (You could use any of the network numbers plus host numbers from the table. These are just examples.) 192.168.1.1 192.168.1.2 192.168.1.3 192.168.1.4 192.168.1.5 You could continue that numbering up to 192.168.1.254 on this network, and you could use a network mask of 255.255.255.0. Adding host names and IP addresses When you install Red Hat Linux, you are given the opportunity to add your TCP/IP host name and IP address, as well as some other information, to your computer. You also need to set up a way to reach the computers on your LAN. That s done either by adding all computer names and IP addresses to your /etc/hosts file (described here) or by using a DNS server. Cross-Reference DNS servers are discussed in Chapter 16. If you did not identify your IP address during installation of Red Hat Linux, you can do so at a later time using the Network Configuration window (neat command). This procedure lets you attach a particular IP address to your Ethernet interface, so your computer knows what address to listen for. Note A computer can have more than one IP address because it can have more than one network interface. Each network interface must have an IP address (even if that address is assigned only temporarily). So, if you have two Ethernet cards on your computer (eth0 and eth1), each needs its own IP address. Also, the address 127.0.0.1 represents the local host, so users on the local computer can access services in loopback. To define your IP address for your eth0 interface, follow this procedure: 1. Start the Network Configuration. As root user from a Terminal window, type neat. The Network Configuration window appears. 2. Click the Devices tab. A listing of your existing network interfaces appears. 3. Double-click the eth0 interface. A pop-up window appears, enabling you to configure your eth0 interface. Figure 15-6 shows the Network Configuration window and the pop-up Ethernet Device window configuring eth0.
Note: In case you are looking for affordable and reliable webhost to host and run your business application check Vision php5 hosting services

To indicate the network identifier, a CIDR IP address is followed by a slash (/) and then a number from 13 to 27. A smaller number indicates a network containing more hosts. Here is an example of an IP address that uses the CIDR notation: 128.8.27.18/16 In this example, the first 16 bits (128.8) represent the network number and the remainder (27.18) represent the specific host number. This network number can contain up to 65,536 hosts (the same as a class B address). The following list shows how many hosts can be represented in networks using different numbers to identify the network: /13 524,288 hosts /14 262,144 hosts /15 131,072 hosts /16 65,536 hosts /17 32,768 hosts /18 16,382 hosts /19 8,192 hosts /20 4,096 hosts /21 2,048 hosts /22 1,024 hosts /23 512 hosts /24 256 hosts /25 128 hosts /26 64 hosts /27 32 hosts The CIDR addressing scheme also helps reduce the routing overload problem by having a single, high-level route represent many lower level routes. For example, an Internet service provider could be assigned a single /13 IP network and assign the 500,000-plus addresses to its customers. Routers outside the ISP would only need to know how to reach the ISP for those half-million addresses. The ISP would then be responsible for maintaining routing information for all of the host routes with that network address. Getting IP addresses So, what is the impact of assigning IP addresses for the computers on your LAN? How you choose which IP addresses to use depends on your situation. If you are part of a large organization, you should get addresses from the network administrator of your organization. Even if you don t connect to other LANs in your organization, having unique addresses can make it easier to connect to other LANs in the future. If you are setting up a network for yourself (with no other networks to consider in your organization), use private addresses or (if you need the network to be part of the Internet) apply for your own domain name and IP addresses. (You can get unique IP addresses and domain names from Network Solutions at http://www.networksolutions.com/ or, more likely, from your Internet Service Provider.) If you don t need to have your LAN accessible from the Internet, choose IP addresses from the set of available general-purpose IP addresses. (Using these private IP addresses, you can still access the Internet from your LAN for such things as Web browsing and accessing e-mail by using a feature described in Chapter 16 called IP masquerading.) Table 15-1 lists the private IP addresses not used on any public part of the Internet. Table 15-1: Private IP Addresses Network Class Network Numbers Addresses per Network Number Class A 10.0.0.0 167,777,216 Class B 172.16.0.0 to 172.31.0.0 65,536
Note: If you are looking for high quality webhost to host and run your jsp application check Vision florida web design services

0 and 254 can t be assigned to hosts). Here is an example of a Class C network number: 194.122.56 When IP addresses were created, nobody expected that, even though this numbering scheme represented millions of potential addresses, there wouldn t be enough to go around. Now, if you get an official pool of addresses assigned to you for the Internet, you will get either a Class C address or part of a Class A or Class B address. The question becomes: How can a network number be divided among several networks? The answer is: by using a netmask. Understanding netmasks Let s say that you are assigned the Class B address 135.84, but you are only given the pool of numbers available to the address 135.84.118. How do you tell your network that every address beginning with 135.84.118 represents a host on your network, but that other addresses beginning with 135.84 should be routed to another network? The answer is with the netmask. The netmask essentially identifies the network number for a network. When you assign the IP address that is associated with your computer’s interface to the LAN (eth0), you are asked for a netmask. By default, your computer will fill in a number that masks the part of your IP address that represents the Class of your network. For example, the default netmasks for Class A, B, and C networks are the following: Class A netmask: 255.0.0.0 Class B netmask: 255.255.0.0 Class C netmask: 255.255.255.0 Now, if your network was assigned the network number 135.84.118, to tell your computer that 135.84.118 is the network number and not 135.84 (as it normally would be for a Class B address), add a netmask of 255.255.255.0. Thus, your network has available host numbers of 1 to 254 (which would go into the fourth part of the number). To further confuse the issue, you could mask only one or more bits that are part of the IP address. Instead of using the number 255, you could use any other number from 1 to 254 to mask only part of the numbers in that part of the address. (The numbers that you can use for each network get rather strange when you do this.) Classless Inter-Domain Routing The class method of allocating IP addresses had several major drawbacks. First, few organizations fell neatly into one class or another. For most organizations, a Class C address (up to 256 IP addresses) was too small, and a Class B address (up to 65,534 IP addresses) was too big. The result was a lot of wasted numbers in a world where IP addresses were running short. Second, IP classes resulted in too many routing table entries. As a result, routers were becoming overloaded with information. The Classless Inter-Domain Routing addressing scheme set out to deal with these problems. The scheme is similar to IP address classes, but offers much more flexibility in assigning how much of the 32-bit IP address is the network identifer. Instead of the first 8, 16, or 32 bits identifying the network, 13 to 27 bits could identify the network. As a result, groups of assigned IP addresses could contain from 32 to about 524,000 host addresses.
Note: In case you are looking for affordable and reliable webhost to host and run your j2ee application check Vision web and email hosting services

Dynamic Addresses With dynamic addresses, a client computer gets its IP address assigned from a server on the network when the client boots. The most popular protocol for providing dynamic addresses is called Dynamic Host Configuration Protocol. With this method, a client computer wouldn’t necessarily have the same IP address each time it boots. For this first example, let s assume that you are setting up a LAN with no outside connections. So, in this section I describe how to use static IP addresses. This is where each computer has a hard IP address and maintains its own list of host names and IP addresses for the computers it communicates with. This will work fine for communicating with a few computers on a LAN. Tip If you expect to add and remove computers regularly from your LAN or if you have a limited number of IP addresses, you should use DHCP to assign IP addresses. Chapter 23 describes how to set up a DHCP server. Understanding IP addresses An IP address is a four-part number, with each part represented by a number from 0 to 255 (256 numbers total). Part of that IP address represents the network the computer exists on, whereas the remainder identifies the specific host on that network. Here is an example of an IP address: 192.168.35.121 Originally, IP addresses were grouped together and assigned to an organization that needed IP addresses, based on IP address classes. Later, a more efficient method, referred to as Classless Inter-Domain Routing (CIDR), was created to improve routing and waste fewer IP addresses. These two IP address methods are described in the following sections. IP address classes Unfortunately, it s not so easy to understand which part of an IP address represents the network and which represents the host without some explanation of how IP addresses are structured. The way IP addresses are assigned is that a network administrator is given a pool of addresses. The administrator can assign specific host addresses within that pool as new computers are added to the organization s local network. There are three basic classes of IP addresses, each representing a different size network: Class A Each Class A address has a number between 0 and 127 as its first part. Host numbers within a Class A network are represented by any combination of numbers in the next three parts. A class A network therefore contains millions of host numbers (approximately 256 X 256 X 256, with a few special numbers being invalid). Whole Class A networks were once assigned only to the largest organizations but, I have been told, are no longer assigned. A valid Class A network number is: 24. Class B A Class B IP address has a number between 128 and 191 in its first part. With a Class B network, however, the second part also represents the network. This enables a Class B network to have more than 64,000 host addresses (256 X 256). A whole Class B network is also rarely assigned. A valid Class B network number is: 135.84 Class C A Class C IP address begins with a number between 192 and 223 in its first part. With a Class C network, the first three parts of an IP address represent the network, whereas only the last part represents a specific host. This makes it so each Class C network can have 254 numbers (the numbers
Note: If you are looking for best quality webspace to host and run your tomcat application check Vision personal web hosting services

Adding Ethernet after Red Hat is installed If Red Hat Linux is already installed when you want to add your Ethernet card, simply power down the system, install the card, and reboot the computer. If the card is supported, it is likely that the proper driver will be found and assigned to the board using the eth0 interface. At this point, you simply need to do a bit of configuration (mostly to assign an IP address to the interface) using the Network Configuration window (described in the Adding host names and IP addresses section later in this chapter). Adding two Ethernet cards If your computer is acting as a router between two LANs (or if it simply is connected to two LANs), you may need to do some special setup to get two LAN cards to work on your computer. If both cards are PCI or EISA LAN cards, they will probably be autodetected so no further configuration will be needed to add the cards. However, if at least one card is an ISA cards, you will need to add some information to your /etc/modules.conf file. To add two ISA cards to your computer, you need to identify the Ethernet interface associated with each card (eth0, eth1, etc.), then identify the I/O base addresses for each card. Then you must add this information to the /etc/modules.conf file. The following is an example: alias eth0 3c501 alias eth1 3c503 options 3c501 io=0×280 options 3c503 io=0×300 In this example, there is a 3Com 3c501 assigned to the eth0 interface and a 3c503 card assigned to eth1. The base addresses are 0×280 for the 3c501 card and 0×300 for the 3c503 card. The modules are loaded after your computer boots. If both cards you are adding are of the same type, you may be able to use a single options line (for example, options wd io=0×280,0×300) or, if the module supports only one card at a time, you may need two options lines (which results in the module being loaded twice). The best reference for supported Ethernet cards and modules is Appendix A of the Red Hat Linux Reference Guide. This guide contains a listing of Ethernet cards, the modules needed to use them, and the options you need with each module. For more information on adding multiple Ethernet cards, refer to the Ethernet-HOWTO document. You can also check out the Multiple Ethercards document at www.scyld.com/expert/multicard.html. Cross-Reference Chances are that if you are adding two or more LAN cards to one computer, you may want that computer to act as a router between the two networks. Setting up routing functions is described in Chapter 16. Configuring Host Computers Each computer you communicate with (including your computer) must have a unique address on the network. In TCP/IP, each computer needs to be assigned an IP address and (usually) a host name. When a user runs a program to communicate with another computer, the user typically enters the computer name (or IP address) that it wants to communicate with. There are two basic ways to assign a host name and IP address to the network interfaces: Static Addresses With static IP addresses, each computer has its IP address entered in manually. This can be done at Red Hat Linux installation time or later using the Network Configuration window. With this method, the computer has the same IP address each time it boots.
Note: If you are looking for cheap and reliable webhost to host and run your web application check Vision coldfusion web hosting services

Intel EtherExpressPro 100 In addition to these cards, there are many, many cards that work well. You need to gauge the demands on your network to decide if you can get by with a 10 Mbps network or if you need 100 Mbps. Of course, if you are used to a 28.8 Kbps modem connection to the Internet, any working LAN will look fast to you. Even an old 8-bit Ethernet card can provide about 20 times the speed of that old modem. Caution Eight-bit Ethernet cards aren t being made any more. You can, however, find them anywhere that used computer parts are sold. For light performance, you can use wd8003, 3c503, and ne1000 cards. Avoid 3c501 cards because they are said to provide poor performance. Laptop (PCMCIA) Ethernet cards There are a large number of Ethernet drivers available for laptop computers (typically using PCMCIA cards). PCMCIA stands for Personal Computer Memory Card International Association. Essentially, it is a standard that enables small, removable cards to be used to connect devices to a laptop computer. I have a Netgear 10/100 Mbps PCMCIA card (model FA 410Txc) in my laptop. Red Hat Linux detected my card automatically. I simply configured the eth0 interface using the Network Configuration as described in the discussion on adding your host information after installation later in this chapter. (Basically, what you still need to do is assign an IP address to the interface and decide if you want your LAN connection to start automatically at boot time.) PCMCIA cards that are supported in Red Hat Linux are defined in the file /etc/pcmcia/config. There are more than 100 PCMCIA Ethernet cards listed, a handful of wireless PCMCIA LAN drivers, and a couple of Token Ring PCMCIA cards. The Ethernet-HOWTO is not up to date with all the PCMCIA Ethernet cards that are now supported. Be sure to check this file before buying a card (or giving up on the one that you have). Note Linux probes for PCMCIA cards by launching the /etc/init.d/pcmcia script. Options required for your PCMCIA cards are contained in the /etc/sysconfig/pcmcia file. Adding Ethernet during Red Hat installation When you install Red Hat Linux, if your Ethernet card is already installed, the installation procedure will let you set up Ethernet using that card. Figure 15-5 shows the Ethernet setup screen you see during installation. Figure 15-5: Configure your Ethernet card for TCP/IP during installation. The information you enter into the Network Configuration screen is described in Chapter 2. If you didn’t set up your network at that point, you can do it now as described in the next section.
Note: In case you are looking for affordable and reliable webhost to host and run your j2ee application check Vision j2ee hosting services

Power up your system. 5. If Red Hat Linux is not installed yet, install the software and reboot (as instructed.) See the discussion on adding Ethernet during Red Hat installation for information on how to answer Ethernet-related questions and the section on configuring host computers for information on adding TCP/IP host names and IP addresses. When the system comes up, your Ethernet card and interface (eth0) should be ready to use. See the section Checking Your Ethernet Connection later in this chapter to learn how to check if your Ethernet connection is working. Choosing an Ethernet card Support for many Ethernet cards is available in Red Hat Linux. If you are adding Red Hat Linux to a computer that already has an Ethernet card installed, you can check the list of supported cards or you can just go ahead and install Red Hat. Red Hat Linux may detect the board automatically. If you have a laptop computer that uses a PCMCIA Ethernet card, the card will probably be detected when you boot your computer. To find out what Ethernet cards are supported, refer to the descriptions of supported networking hardware in the /usr/src/linux*/Documentation/networking directory. To see these descriptions, you need to have the kernel-source package installed. Recommended Ethernet cards The Ethernet-HOWTO recommends the following Ethernet cards as being mature and well-tested in Red Hat Linux. If you want to use one of the cards, you just have to make sure that you have the type of card slot in your computer that the card requires. Here are cards for 16-bit ISA and PCI slots: Recommended 16-Bit ISA Cards: SMC-Ultra/EtherEZ SMC-Elite (WD80×3) 3c509 Lance NE2000 Recommended PCI Cards: 3Com Vortex/Boomerang (3c59x/3c9xx) DEC Tulip (21xxx)
Note: In case you are looking for affordable webhost to host and run your servlet application check Vision ecommerce web hosting services

Red Hat Linux can act as any of the server types described above. However, with a growing number of productivity applications becoming available for Linux and friendly X-based desktops (such as KDE and GNOME), Red Hat Linux is beginning to make a better case for becoming a client system as well. Because Red Hat Linux can run applications as well as offer services, a purer example of a network server is NetWare (from Novell, Inc.). A NetWare server has no way of running applications. It is tuned to store and secure files efficiently, as well as manage groups of printers. With the addition of ZENworks and NDS, NetWare can manage databases of information on all the components on a network. Cross-Reference Chapters 17 through 23 describe how to set up different kinds of servers in Red Hat Linux. Peer-to-peer model In a peer-to-peer network, computers generally behave as equals. Each computer has most of what it needs to operate on its own. Any computer on the network may offer services to other computers. One computer may share the contents of a CD-ROM, whereas another may offer its printer for use by others. A typical peer-to-peer network is one where several employees in a business each have a computer at their desk. A shared printer may be connected to one person s computer, whereas a tape backup system may be connected to another. The drawback with peer-to-peer networks is that if there is a big demand for your printer or other device, your computer s performance may suffer (and so may your work). That s why larger networks tend to offload shared services to a server. After you have made a choice about the typology and computing model you are going to use, the following sections tell you how to actually configure your computers so that they can communicate together. Setting Up an Ethernet LAN After you physically install your Ethernet card, it is possible that Red Hat Linux will automatically detect your card and assign it to the first Ethernet interface on your system (eth0). If Red Hat Linux does find your card, after you connect your hardware you don’t need to do much more than assign addresses. Follow this procedure to set up your LAN and install your LAN cards: 1. Choose a network topology. Earlier in this chapter, I described several different network topologies. This procedure assumes that you are using either a star or a bus Ethernet topology. 2. Choose your LAN hardware. You need an Ethernet NIC for each computer on your network, as well as cables that reach from each computer to the hub. Also, you need to purchase a hub. (See the description of these components earlier in this chapter.) Before you purchase a new NIC, read the following discussion on choosing an Ethernet card. Red Hat Linux does not support all NICs. Choosing one that has already been tested with Red Hat Linux can save you some headaches. 3. Install your NIC cards. Power down your computer and physically install the NIC card (following the manufacturer s instructions). 4.
Note: In case you are looking for affordable and reliable webhost to host and run your business application check Vision ftp web hosting services