Linux DHCP Clients On a Linux client you can type ifconfig ethO

(changing ethO to another interface name, if appropriate). This command produces information on the network interface, including the hardware address (labeled HWaddr) on the first line of the output. This command requires that the interface be activated, although it need not be assigned an IP address.

Windows 9x/Me DHCP Clients Windows 9x/Me provides a network configuration and information tool that you can access by typing

WINIPCFG in a DOS prompt window. The result resembles Figure 27.2. Be sure you select the correct adapter in the selection box (with the highlighted label of ISA Ethernet Adapter in Figure 27.2). The Adapter Address field shows the MAC address.

Figure 27.2: Windows 9x/Me provides a GUI tool for displaying the MAC address and other network information.

Windows NT/2000/XP DHCP Clients Windows NT, 2000, and XP provide a tool similar to Linux's ifconfig for displaying information about the network interface. Type IPCONFIG /ALL in a DOS prompt window to learn about your interfaces. A line labeled Physical Address should reveal the MAC address.

Mac OS DHCP Clients Both Mac OS Classic and Mac OS X reveal the MAC address in their GUI network configuration tools. In Mac OS Classic, open the TCP/IP Control Panel and click the Info Button. The Hardware Address line shows the MAC address. In Mac OS X, open the System Preferences tool and click the Network option. Be sure you select the correct network device in the Show list button. The display should resemble Figure 27.3. The MAC address is called the Ethernet Address in this tool.

Figure 27.3: Mac OS X calls the MAC address the Ethernet Address in its GUI configuration tool.

Locating the Address from the DHCP Server No matter what OS the client uses, there are several ways you can locate the MAC address from the DHCP server. One method is to configure the DHCP client to use DHCP and then activate its network interface. Assuming the server is configured to deliver addresses as described in the earlier section, "Configuring Delivery of Dynamic Addresses," the DHCP client should pick up an address. You can then examine the DHCP server's logs for evidence of a lease granted for that address. The DHCP leases file (typically /var/lib/dhcp/dhcpd.leases) should include a multiline entry identifying the IP address and MAC address. Typing grep dhcpd /var/log/messages | tail -n 1 as root should also reveal an entry with the IP address and MAC address in question. (If some other DHCP activity occurs between the target system's lease being granted and your typing this command, though, that activity will show up instead. Increase the number from 1 to 2 or higher to reveal earlier entries.) Finally, you can type ping -c 1 /'p.addr; /sbin/arp ip.addr, where ip.addr is the IP address, to learn the MAC address of the computer. This last approach will also work if you temporarily configure the future

This document was created by an unregistered ChmMagic, please go to to.regist* DHCP client with a static IP address.

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