Moving a UNIX box to DHCP on the gigabit network

Note: While it is certainly possible to operate a server using a dynamically assigned address, we suggest statically assigning addresses to critical systems to reduce the possibility of conflict or confusion.

For those who wish to use DHCP (for workstations perhaps), we present the following guidelines for the UNIX variants currently supported by UCNS. Please note that these changes will impact users, and possibly require system reboot, so schedule accordingly.

Note: this document assumes you are migrating from a class B network setup with a 16-bit network mask (255.255.0.0) to a class C network with a 24-bit network mask (255.255.255.0). Our usual setup with a 24-bit network mask is a network with a base address of 128.192.subnet.0 and a gateway of 128.192.subnet.1. In some cases (such as a building with very few clients) we may assign a network with different parameters. In such a case, substitute the network parameters the NOC gives you for the netmask, base address and gateway when making your changes.

Irix:

    The following applies to 6.5x.
  1. Open a winterm and su to root. Make sure autoconfig_ipaddress is on by running:
    /etc/chkconfig autoconfig_ipaddress on .
    This will ensure that the DHCP client (Proclaim) is run at startup.
  2. Open the Toolchest and launch the System Manager
  3. In the System Manager, choose Networking and Connectivity, then Set Up and Start Networking and click Next.
  4. Select the network interface you wish to configure (probably "ec0"). Click Next.
  5. For the hostname and address screen, ensure that "Use DHCP Client" is NOT checked (we'll let the Proclaim DHCP client handle that). Enter the fully qualified hostname (ie. some_machine.example.exampledomain.edu). Enter an arbitrary IP address and netmask (Proclaim will get this from the DHCP server, but the setup tool requires something in these fields). Click Next.
  6. Confirm your settings and click OK if they're all correct.
  7. Don't restart your system yet.
  8. In the System Manager window (still open) click Modify Network Settings and Next.
  9. Make sure the primary network interface is enabled and click Next.
  10. Add the default route to your network routing table by selecting add default route and entering the IP address of your default gateway (probably 128.192.subnet.1), where subnet=the third number in your machine's IP address. Proclaim (the DHCP client program) can determine the appropriate IP and subnet mask for your machine, but cannot set the default route or the nameservers (next step). Sorry!
  11. Disable IP forwarding (unless you want this box to be a router--probably not), and click Next.
  12. Enter (or verify) the name server entries:
    	128.192.1.9
	128.192.1.193
	168.24.242.249
    and click Next.
  13. Specify your host resolution order, which should probably be "Files", "DNS", "None", unless you're using NIS. Click Next.
  14. Doublecheck all these settings and click Next if they're correct.
  15. Reboot the system. When it comes back up you should be able to resume all your regular network activities.
  16. If you haven't already done so, create an /etc/ntp.conf file with the following contents: 
    	server time1.uga.edu
	server time2.uga.edu
	fudge 127.127.1.0 stratum 100
    If this file exists and contains any lines refering to "broadcastclient" delete them or comment them out. Changing the stratum for localhost to 100 means the local hardware clock will only be used as a backup.

Solaris

  1. If you haven't already done so, edit the file /etc/ntp.conf to include the following:


    2. server time1.uga.edu
    server time2.uga.edu
    fudge 127.127.1.0 stratum 100
     If this file exists and contains any lines refering to "broadcastclient" delete them or comment them out. Changing the stratum for localhost to 100 means the local hardware clock will only be used as a backup.

  2. Su to root and run sys-unconfig and then enter to confirm your action. This will undo the network configuration of your box, and also shutdown the system.
  3. At the ok prompt type boot. When the system comes up you will be asked to supply system configuration as though you were performing a fresh install. The only change is that you will answer "yes" to DHCP. NOTE: Although the campus DHCP server is configured to provide name server info, the current Solaris client can't accept it, so you'll still have to specify the IPs of the name servers as follows:
            128.192.1.9
        128.192.1.193
        168.24.242.249
    Also note that DHCP will work only if you specify the OS as "Solaris" in the DHCP database. Since the web front end does not currently provide this option, you'll need to send mail to dhcptf@listserv.uga.edu specifying which machines in your range run Solaris and use DHCP. Note also that although the DHCP is configured to provide the FQDN, our experience indicates that Solaris clients will receive only the short hostname (mybox instead of mybox.mydomain.uga.edu). You may have software or scripts that expect the FQDN. If this is the case, you will need to edit /etc/hosts and add the FQDN after the short name. The line will be flagged with the comment "Added by DHCP".
  4. Reboot the system.

Linux

  1. If you haven't already done so, edit the file /etc/ntp.conf to include the following:


    2. server time1.uga.edu
    server time2.uga.edu
    fudge 127.127.1.0 stratum 100
     If this file exists and contains any lines refering to "broadcastclient" delete them or comment them out. Changing the stratum for localhost to 100 means the local hardware clock will only be used as a backup.

  2. Edit the file /etc/sysconfig/network-scripts/ifcfg-eth0 and make sure it has the following lines:


    3. DEVICE=eth0
    BOOTPROTO=dhcp
    ONBOOT=yes

  3. There is no need to worry about the contents of /etc/resolv.conf; these are obtained from the DHCP server.

  4. Stop and restart the network by running:


    5. /etc/rc.d/init.d/network restart

    You can check on network settings by running:

    /sbin/ifconfig -a

Last modified: Wednesday, 05-Dec-2001 17:43:21 EST
URL: http://www.uga.edu/~ucns/wsg/gigdhcp.html