Php4, Php5 Programming, Ftp Web Hosting, Subdomain, Cpanel Blog

564 Part IV . Implementing Network Services in SUSE Linux Specifying both options puts a limit on the upper and lower lease time allowed for clients to hold the DHCP configuration. (Again, you add both options to /etc/ dhcpd.conf.) default-lease-time 43200 # 12 hours max-lease-time 86400 # 24 hours This example specifies a lower limit of 12 hours, and an upper limit of 24 hours until a lease is renewed on the client. Other DHCP Options DHCP is an extremely powerful configuration tool when you have many client machines that must be configured. It is not just limited to IP address allocation and can be extended to encompass a large proportion of network configuration, from WINS servers to network time servers. View the dhcp-options man page for more information on what options your DHCP server can present to your network clients. Starting and Stopping DHCP Clients To be able to use DHCP, your client machines must know how to actually send DHCP requests to the network for configuration. In SUSE, you can use the Network Configuration of YaST (Network Devices . Network Card) to configure a network interface to use DHCP. Another useful way to send a DHCP request is with ifup-dhcp and ifdown-dhcp. If you are using a wireless network, or you want to bring up a network interface temporarily using DHCP, then you can use the ifup-dhcp command: bible:~ # ifup-dhcp eth0 Starting DHCP Client Daemon on eth0… . . . This command starts the DHCP client and attaches it to the eth0 interface. In the event that you want to remove the DHCP client from a network interface, thus removing its dynamic network configuration, you need to use the ifdown-dhcp command: bible:~ # ifdown-dhcp eth0 This removes the DHCP client from the network card specified, in this case eth0.
We highly recommend you visit web and email hosting services if you need stable and cheap web hosting platform for your web applications.

Chapter 20 . Configuring and Using DHCP Services 563 Defining Host Groups If you need to specify explicit configurations for a group of machines, you can use a group definition. A group definition enables you to define a group of machines with a specific configuration that also inherits the global configuration. Consider Listing 20-3. Listing 20-3: Defining a Host Group group { option subnet-mask 255.255.255.0; option domain-name-server 192.168.0.2, 192.168.0.3; option domain-name wileybible.com ; host bible { option host-name bible.wiley.com ; hardware ethernet 00:03:FF:69:68:12; fixed-address 192.168.0.8; } host sospan { option host-name sospan.wiley.com ; hardware ethernet 00:03:FF:69:68:13; fixed-address 192.168.0.9; } } Note We now have two machines, bible and sospan, defined as static hosts in dhcpd.conf. Specifically for those machines we have defined only their host name (host-name) and their IP address (fixed-address). As we have defined a group that encompasses the host definitions, these hosts also inherit the subnet mask, DNS servers, and domain name settings. Make sure you do not forget the opening and closing curly brackets when you define a group. Specifying Leases A DHCP client keeps its information for a finite amount of time. You can specify the amount of time (in seconds) a client keeps the DHCP information using the default- lease-time. If the client does not specify a lease expiry time, the server s preference will be used. If a client does specify a lease time, the server can enforce a maximum time, max-lease-time, overriding the client s preference.
Searching for affordable and reliable webhost to host and run your web applications? Go to our java web server services and you will be pleased.

562 Part IV . Implementing Network Services in SUSE Linux Host Specification If you have a specific host that needs explicit settings, you can set this with the host section in dhcpd.conf. For the host specification to work, you need to specify the hardware address of the machine you want to configure. This can be found by issuing the ifconfig command for the interface in question on the client machine. See Listing 20-2 for an example. Listing 20-2: Output of ifconfig bible:~ # ifconfig eth0 Link encap:Ethernet HWaddr 00:03:FF:69:68:12 inet addr:192.168.131.70 Bcast:192.168.131.255 Mask:255.255.255.0 inet6 addr: fe80::203:ffff:fe69:6812/64 Scope:Link UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1 RX packets:30256 errors:0 dropped:0 overruns:0 frame:0 TX packets:35690 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:4048565 (3.8 Mb) TX bytes:34473633 (32.8 Mb) Interrupt:11 Base address:0×1080 You can see that in the preceding output for ifconfig, you have found the hardware address (HWaddr) 00:03:FF:69:68:12 for the eth0 interface. Once you find the hardware address of the machine in question, you can define a host entry in /etc/dhcpd.conf. host bible { option host-name bible.wiley.com ; hardware ethernet 00:03:FF:69:68:12; fixed-address 192.168.0.8; } The important parts of the host configuration are the hardwareethernet and the fixed-address parameters: . The hardwareethernet parameter needs to be the Hwaddr that is specified through the ifconfig command. . The fixed-address parameter is the IP address that will be used for this host specifically.
In case you need affordable webhost to host your website, our recommendation is ecommerce web host services.

Chapter 20 . Configuring and Using DHCP Services 561 To put this all together, you need to specify a subnet class that defines the address scheme and the options discussed previously (see Listing 20-1). Listing 20-1: /etc/dhcpd.conf Configuration for a Test Network authoritative; ddns-update-style none; subnet 192.168.0.0 netmask 255.255.255.0 { range 192.168.0.10 192.168.0.250; option routers 192.168.0.8; option domain-name-server 192.168.0.2, 192.168.0.3; option domain-name wileybible.com ; option time-servers 192.168.0.2; } Putting all of this together, we have specified that this DHCP server is authoritative for the local network and that we are not using dynamic DNS. Next, we specify a subnet on the network (192.168.0.0/24). In this subnet we are allocating IP addresses from a pool between 192.168.0.10 and 192.168.0.250, with a default gateway of 192.168.0.8, and the DNS servers are located at 192.168.0.2 and 192.168.0.3 with a search domain of wileybible.com. We have also told the client machine that it should synchronize its time with the server 192.168.0.2 (optiontime-servers). When configured, you need to specify which network interface DHCP will listen on to provide its service. To do this, edit the /etc/sysconfig/dhcpd file and edit the DHCPD_INTERFACE parameter. If you have multiple Ethernet adapters in your system, it is important to set this explicitly; otherwise, you will probably find your DHCP server running on the wrong network portion. For example, to tell DHCPD to work with the eth0 network interface, use the following: DHCPD_INTERFACE= eth0 When set, start (or restart if currently running) the DHCP server with rcdhcpd start. Tip To make sure dhcpd starts when your system boots up, use chkconfig -a dhcpd.
From our experience, we can recommend PHP5 Web Hosting services, if you need affordable webhost to host and run your web application.

560 Part IV . Implementing Network Services in SUSE Linux IP Address Ranges It is common that you will use DHCP in a small network segment that contains permanent IP assignments for your servers. In this case, you need to exclude some IP addresses from being assigned to your DHCP clients so that duplicate addresses are not created. Assuming that your servers are between 192.168.0.1 and 192.168.0.9, you can create a range of available IP addresses using the range parameter: range 192.168.0.10 192.168.0.250; This distributes the defined range across your network when a request comes in for DHCP. Assigning a Default Gateway Another common network configuration option is to set the default router for your network clients. To do this, you need to specify the optionrouters parameter. option routers 192.168.0.8; In this example, you have a gateway on your network with the IP address of 192.168.0.8. Configuring Name Services To resolve hosts, you need to configure your nameserver addresses and also a domain for the host. This is accomplished by using the domain-name-servers and domain-name options. option domain-name-servers 192.168.0.2, 192.168.0.3; option domain-name wileybible.com ; ddns-update-style When using dynamic DNS (updating a DNS server with the name and IP address of an assigned host), you need to specify an update style. There are two on the table at the moment, awaiting standardization. Previous versions of DHCP used an ad hoc mode, and the interim solution until standardization is the interim keyword. Regardless of whether you are using dynamic DNS, you must specify a ddns-update-style in the configuration file. The ad hoc version of dynamic DNS has been deprecated, so the standard is to use interim. As we are not using dynamic DNS in this implementation, we specify none, as we did in Listing 20-1. For more information on using Dynamic DNS with DHCP, take a look at www.mattfoster.clara.co.uk/ddns.htm.
Please visit Domain Name Hosting services for high quality webhost to host and run your jsp applications.

Chapter 20 . Configuring and Using DHCP Services 559 Figure 20-8: The DHCP Server configuration editor s Dynamic DHCP screen Manually Configuring a DHCP Server While YaST provides a convenient interface for configuring standard DHCP servers, you can achieve much finer-grained configuration if you configure a DHCP server manually by editing its configuration file. Configuration options for the DHCP server are stored in /etc/dhcpd.conf. The default file is heavily commented, so standard configuration is quite easy. In this section, we will configure a standard server, giving out IP addresses on a range of 192.168.0.10 192.168.0.250 inclusive. We add the relevant configuration options to the /etc/dhcpd.conf configuration file throughout the rest of this section. When configuring your DHCP server, one of the first things you need to think about is whether this server is to be an authoritative DHCP server. When you say that a DHCP server is authoritative, you are telling it that it controls DHCP service for the local network. This helps to stop rogue servers from confusing your clients. Note
From our experience, we are can tell you that you can find a reliable and cheap webhost service at Java Web Hosting services.

558 Part IV . Implementing Network Services in SUSE Linux Figure 20-7: The DHCP Server configuration editor s Global Settings screen 5. To modify the range of addresses that your DHCP server can provide in response to DHCP client requests or the duration of the IP address leases given to clients, click the Dynamic DHCP item from the tree view at left in the YaST DHCP Server configuration editor. This displays a screen like the one shown in Figure 20-8. To update any of these entries or add a new value, select the appropriate field and enter the new information. 6. To exit the YaST DHCP Server configuration editor, click Finish. If you have made changes to your DHCP server s configuration, you may first want to go to the DHCP Server Start-Up screen shown in Figure 20-5 and click the Save Settings and Restart DHCP Server Now button to make those changes take effect immediately. Otherwise, those changes will take effect the next time you restart your DHCP server or the next time you reboot your system if you have configured the DHCP server to start automatically at boot time.
From our experience, we can recommend PHP5 Web Hosting services, if you need affordable webhost to host and run your web application.

Chapter 20 . Configuring and Using DHCP Services 557 2. To modify whether the DHCP server starts automatically, click either the Start DHCP Server When Booting or Start DHCP Server Manually radio buttons. This screen also enables you to start the DHCP server if it is not already running or to save any configuration changes that you have made on other DHCP Server configuration screens and to restart the DHCP server with those settings. 3. To change the Ethernet interface on which your DHCP server is listening for DHCP client requests, click the Card Selection item from the tree view at left in the YaST DHCP Server configuration editor. A screen like the one shown in Figure 20-6 is displayed, in which all available Ethernet interfaces on your system are listed. To specify that the DHCP server listens on another Ethernet interface, simply select the name of that interface from the choices listed on this screen. Figure 20-6: The DHCP Server configuration editor s Card Selection screen 4. To change any of the basic network information provided to DHCP clients by your DHCP server, click the Global Settings item from the tree view on the left in the YaST DHCP Server configuration editor. This displays a screen like the one shown in Figure 20-7. To update any of these entries or add a new value, select the appropriate field and enter the new information.
We recommend you use shared web hosting services, because many users agree that it is cheap, reliable and customer-satisfying webhost.

556 Part IV . Implementing Network Services in SUSE Linux Reconfiguring an Existing DHCP Server in YaST As explained in the previous section, YaST provides an easy-to-use and intuitive interface for DHCP server configuration. If you use YaST to configure an existing DHCP server, you will see the YaST screens and dialog discussed in this section. If you have not already configured a DHCP server on your system, YaST walks you through the configuration process using the YaST DHCP Server Configuration Wizard, which was explained in the previous section. The YaST screens for configuring an existing DHCP server are very similar to those in its DHCP Server Configuration Wizard, except that they do not walk you through a specific sequence of screens. You can select any of the YaST DHCP Server configuration screens at any time by selecting the same of that screen from the tree view in the DHCP Server configuration screen show in Figure 20-5. To reconfigure an existing DHCP server using YaST, do the following: 1. Start YaST and select the Network Services item from the left pane, and choose DHCP Server. You will see the screen shown in Figure 20-5. Figure 20-5: The DHCP Server configuration editor s Start-Up screen
We recommend you use shared web hosting services, because many users agree that it is cheap, reliable and customer-satisfying webhost.

Chapter 20 . Configuring and Using DHCP Services 555 Figure 20-4: The final screen in the YaST DHCP Server Wizard 5. To configure your DHCP server to start automatically whenever you boot your system, click Start DHCP Server When Booting. At this point, you can click Finish to close the DHCP Server Wizard, or click the DHCP Server Expert Configuration button to further modify your configuration information and enter the existing YaST DHCP Server configuration interface that is discussed in the next section. 6. If you selected Finish in the previous step, the DHCP Server Configuration Wizard exits, but your DHCP Server is not actually running yet. To start your DHCP server manually, start or go to a Konsole or other X terminal window, use the su command to become the root user, and execute the following command to start your DHCP server: /etc/init.d/dhcpd start Tip As previously mentioned, the DHCP Server Wizard displays only the first time you configure a DHCP Server on your system. Subsequent administration is done using the very similar YaST screens discussed in the next section. If you want to re-run the DHCP Server Configuration wizard at any time, you can do so by removing the DHCP server configuration file, /etc/dhcpd.conf.
In case you need quality webspace to host and run your web applications, try our personal web hosting services.