After research, discussion in this thread, some more research, and finally just working through the configs on my own network, I have solved the problem of properly configuring a single NIC LMCE to properly serve a LAN by DHCP, switched over from an existing DHCP server. AFAICT, this technique doesn't leave any wrong configurations anywhere inside either LMCE's complex interdependencies or the remnants of the previously existing DHCP system.
* In existing router/gateway
- Disable DHCPd
- Assign LAN IP# on desired subnet (eg 192.168.0.1 )
- Ensure router/gateway is configured to route properly between the newly specified subnet and the other network
* In LMCE Admin site:
- Homepage -> Advanced -> Network -> Network Settings
- Change all 192.168.80.x IP#s to desired subnet (eg. 192.168.0.x )
- Set both NICs to the same IP# (and proper subnet info)
- Reload DCERouter
- Check Homepage -> Advanced -> Network -> Network Settings to be sure settings were properly retained
* /etc/dhcp3/dhcpd.conf :
- Exclude router/gateway IP# from allocatable ranges
- Change "host px[1,2]" lines from 192.168.80.x IP#s to desired subnet IP#s (eg. 192.168.0.253 )
- /etc/init.d/dhcp3-server restart
- Force a LAN host to reset its network configs by DHCP, then test pinging across the router
* Force each host on the LAN to reread its network configs by DHCP (eg. run its DHCP client or reboot if its DHCP client runs at startup).
Note that the dhcpd.conf file regenerated by the LMCE Admin site's Network Settings form has a bug (#3469
) which doesn't change all the IP#s properly. There might be other bugs, so check the whole file to be sure it's correct.
This technique leaves a problem in that any configs of your original router/gateway DHCPd are not available to the LMCE DHCPd, unless you manually recreate them in the LMCE's dhcpd.conf file. Also, the router/gateway LAN IP# must be manually discovered/set, and then the LMCE LAN subnet must be manually configured to accommodate it. There is no way to fix that problem, unless the router/gateway allows its LAN IP# to be set by DHCP (ie. a DHCP client running on the router/gateway that is set by the LMCE DHCPd). Conversely, there is no way for LMCE to insert into the router/gateway DHCPd configs the configs that LMCE needs clients for its own services (like IP phones) to automatically get from a DHCPd when they're plugged into a network. The only way to make DHCP fully automatic for LMCE is to use the recommended network architecture of a pair of ethernet ports on the LMCE server (or use a router/gateway DHCPd that can be remotely configured by the LMCE, and a script to glue them together).
I will now attempt to update the wiki...
I updated the wiki article DHCP Plug and Play: Single NIC & Existing DHCPd
and have updated it again, so it is more current than the discussion in this forum topic.