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ISC-DHCP server

Overview

Zone Manager can provision ISC-DHCP servers. The whole provisioning process is based on Server Farmer ssh/scp-passwordless connections, so you first need to install Server Farmer:

  • on all DHCP server hosts that you want to provision
  • on Zone Manager central instance (it has to be farm manager for DHCP server hosts)

You can find more instructions about Server Farmer here.

Provisioning process

Once you completed creating an initial database for Zone Manager, you can add such scripts to your /etc/crontab file (one entry per DHCP server):

*/30 * * * * root /opt/zonemanager/scripts/dhcpd/cron.sh your-dhcp-server.local yourzone 192.168.8.0 255.255.255.0 authoritative

Arguments 192.168.8.0 and 255.255.255.0 are the local network address and mask, that are configured in DHCP pool. Zone Manager will filter out all database entries, that don't match given network - so you can safely mix entries for different physical networks and DHCP servers within a single database.

How the provisioning process works:

  • dhcpd.conf file is created locally and saved into ~/.zonemanager/cache directory
  • dhcpd.conf file is copied using scp to /etc/dhcp directory on DHCP server
  • isc-dhcp-server service is restarted

Configuration structure

Zone Manager is primarily focused on DNS management. It keeps configuration for internal (eg. home, office) zones divided into 3 files:

~/.zonemanager/dns/zone.all - common for all configured zones, holds all static entries (updated manually)

~/.zonemanager/dns/zone.yourzone - separate for each configured zone, holds all zone-specific static entries (you can eg. have multiple offices, and in each office set hostname printer.office to have different IP address, specific to the local network)

~/.zonemanager/dns/zone.yourzone-dynamic - separate for each configured zone, holds all zone-specific dynamic entries (these files are meant to be generated automatically by some external tool, at your disposal - otherwise they should be empty)

Example entries:

server.dc1                               A          192.168.8.3       75:2c:35:23:54:94
printer.dc1                              A          192.168.8.4       75:2c:3f:45:43:23

The last, 4th column is optional and contains MAC address. Only entries with MAC address are used for DHCP configuration.

Configuration templates

Each physical network (zone) has its own configuration template. This is the example template named ~/.zonemanager/dns/dhcpd.yourzone:

ddns-update-style none;
default-lease-time 1800;
max-lease-time 3600;
@@authoritative@@

log-facility local7;

option domain-name "office";
option domain-name-servers 192.168.8.1, 192.168.8.2;
option routers 192.168.8.1;
option broadcast-address 192.168.8.255;

subnet 192.168.8.0 netmask 255.255.255.0 {
    range 192.168.8.3 192.168.8.249;
}

@@entries@@

Such template should contain 2 keywords, which are expanded by Zone Manager:

  • @@entries@@ - expanded to generated list of DHCP records
  • @@authoritative@@ - expanded to either authoritative; configuration directive, or to empty string (depending on the last argument in crontab invocation, see above)