This HOW-TO of the is a supplement to the Rembo Server's documentation, The Rembo Wizard plug-in module's documentation and to the Internet Software Consortium's documentation for the DHCP 3.0 software. The example platform below is RedHat Linux 7.1 server where both DHCP and Rembo Services are running on the same machine. The explained procedure has following objectives:
In this example, host's MAC address changes from 00:02:b3:1a:5f:16 to 00:02:b3:1a:5f:32.
NB: You must do a telnet, ssh, rlogin or similar on the target server machine, login as <you>. Being root and using su-command will not work!
Below we log on a Rembo/DHCP server with telnet.
telnet <myremboserver>
Verify that the DHCP configuration file dhcpd.conf is not locked for somebody else (if it is, you must either have to contact the person who forgot the lock on, or to have the super-user privileges to unlock the file)
cd /etc/dhcpdir ls -l
Lock the DHCP configuration file for modifications in the rcs(1) version control system
co -l dhcpd.conf
Using vi, emacs or what ever editor you prefer, edit the configuration file. Find first occurrence of the old MAC address in the configuration file, from the PXE option space. The following line explains from which Rembo server the system should be boot from. Below the line has been modified for the new MAC address
subclass "pxeremboclient_freak" 1:00:02:b3:1a:5f:32; # pckimmo
Find now the second occurrence of the old MAC address. It will be on the DHCP option space. Below the MAC address has already been changed
group {
# Kimmo's PC CS network
host pckimmo {
hardware ethernet 00:02:b3:1a:5f:32;
Save the modified dhcpd.conf file. Restart the DHCP services with following command to make modifications public
/etc/init.d/dhcpd restart
Verify that the DHCP services have really started. With a command
ps -ef | grep dhcpd
You should see a process such as
root 13592 1 0 15:31 ? 00:00:00 /usr/sbin/dhcpd -cf /etc/dhcpdir/dhcpd.conf
If you do not see the process it is likely that you have a syntax error in the dhcpd.conf file. Typically this is a missing semi-colon ";" that you have accidentally deleted. Don't panic, instructions will follow.
If you can see the dhcpd process as illustrated above, continue here. Check-in your work to unlock the dhcpd.conf file.
ci -u dhcpd.conf <On one line, explain what you have done, give a name of the machine at least> <Terminate with a ".">
If you cannot figure out what went wrong with the configuration file and why the DHCP service will not start, this is how you can recover the original configuration.
cp dhcpd.conf /tmp/dhcpd.conf_can_not_understand rcs -u dhcpd.conf co dhcpd.conf (if asked is it OK to overwrite, answer Y) /etc/init.d/dhcpd start ps -ef | grep dhcpd
Verify that the Rembo Server configuration file rembo.conf is not locked for somebody else (if it is, you must either have to contact the person who forgot the lock on, or to have the super-user privileges to unlock the file)
cd /rembo ls -l
Lock the Rembo Server configuration file for modifications in the rcs(1) version control system
co -l rembo.conf
Using vi, emacs or what ever editor you prefer, edit the configuration file. Find the occurrence of the old MAC address in the configuration file. Below the line has been modified for the new MAC address
# pckimmo
Host 00:02:b3:1a:5f:32 {
StartPage "net://global/rembowiz.shtml"
Save the modified rembo.conf file. Restart the Rembo Server with following command to make modifications public
/etc/init.d/rembo restart
The ESRF Rembo Server restart script makes a test to see if the server starts correctly. If you see an error message, it is likely that you have a syntax error in the rembo.conf file. Typically this is a missing semi-colon ";" or such.
Check-in your work to unlock the rembo.conf file.
ci -u rembo.conf <On one line, explain what you have done, give a name of the machine at least> <Terminate with a ".">
Host's MAC-address should be changed also on the Rembo Server's file system. This is best done with the Rembo Server Management Console. But since it is a Windows program and may not be always available the following explains how to rename the directory using netclnt-tool on the Rembo Server.
/opt/rembo/misc/netclnt Netclnt 1.1 (c) Rembo Technology Sarl NETFS> connect 127.0.0.1 Password: rembo NETFS> cd hosts Current directory is /hosts NETFS> move 0002b31a5f16 0002b31a5f32 NETFS> exit
18 Nov 2002