---
name: "gendhcp"
section: "1"
platform: "linux"
package: "bind"
version: "1:8.4.7-1"
release: "Debian 4.0 (Etch)"
platforms: ["linux"]
url: "https://new.carta.tech/gendhcp"
---

# gendhcp(1)

generate a DHCP bootstrap file from flat relational tables

## NAME

gendhcp - generate a DHCP bootstrap file from flat relational tables

## SYNOPSIS

**gendhcp** \[ **-d dbdirectory** \] \[ **-k** \] \[ **-v** \]

## DESCRIPTION

**gendhcp** is a back end to the **updatehosts** command. It should normally only be invoked from the **updatehosts** command.

**gendhcp** converts a set of flat (relational) files into a DHCP server bootstrap file. All input files are kept in the **dbdirectory** which can be specified by the -d command line option. The output file which is named dhcpd.conf is placed in the current directory. When run under **updatehosts** the current directory is normally **/var/named** and the input directory is normally **/var/named/db.** However, these defaults may be different depending upon the updatehosts configuration. See the **[updatehosts(1)](/updatehosts/1.md)** manual page for details.

The -k option generates a bootstrap file so only known hosts (e.g. those with registered MAC layer addresses can bootstrap. This option is off by default which allows any host to boot. The -v option generates additional output on the progress of the bootstrap file generation.

## Input File Formats

**gendhcp** uses **readinfo** to preprocess the input files. The format of each file consists of a set of records separated into fields. Care should be taken to insure the field names are not altered.  Otherwise **gendhcp** will complain. Each fields attributes should be examined carefully when editing the input files. Each file used by gendhcp is described as follows:

- main:

  Contains information about each host.  The fields from this file used by **gendhcp** are as follows:

  - host:

    The domain name of the host.

  - ip:

    The IP address of the host. This field may be set to "dynamic" to indicate this host will be given a dynamic IP address when it boots.  If the IP address is a normal IP address then the DHCP configuration will use the static IP address indicated.

  - ether:

    The hardware MAC address of the host. This must be present for statically configured hosts or for dynamic hosts when the -k flag is set.

subnet: Contains information about subnets used to generate the DHCP configuration files

- subnet:

  The subnet prefix in dotted decimal notation

- mask:

  The mask of the subnet in dotted-decimal

- gateway:

  The IP address of the default gateway for the subnet dns: The IP address of one or more DNS servers separated with commas.

- domain:

  The default domain.

- time:

  The IP address of one or more NTP timeserver separated with commas.

- hardware:

  The hardware type of the clients (defaults to ether).

- dhcprange:

  Range of IP addresses used for dynamic allocation of IP addresses.

- maxdhcplease:

  Maximum time in seconds before a DHCP lease expires.

- dynamicbootp:

  Allows dynamic BOOTP (defaults to no).

## See also

**[gendns(1)](/gendns/1.md)** **[poke\_dhcp(1)](/poke_dhcp/1.md)** **[poke\_ns(1)](/poke_ns/1.md)** **[updatehosts(1)](/updatehosts/1.md)**