Dhcpd

Overview

dhcpd 서버 설치 및 설정하기.

dhcp 는 Dynamic Host Configuration Protocol 의 약자로, 네트워크에 새로운 호스트가 추가되었을 때, 할당 가능한 IP 주소를 확인해서 현재 사용중인 IP 주소와의 충돌없이 IP 주소를 사용할 수 있도록 해주는 프로토콜이다. dhcpd 는 이를 관리하는 역할을 하는 데몬(deamon)을 뜻한다.

Installation

• Ubuntu 사용시, 다음명령어로 간편하게 설치가 가능하다

<source lang=bash> $ sudo apt-get install isc-dhcp-server </source>

Configuration

dhcpd 데몬을 관리하는 설정파일의 위치는 다음과 같다.

/etc/dhcp/dhcpd.conf

dhcpd 사용을 하기 위해서는 위의 파일을 열어 몇가지 수정을 해야 한다.

• Example

pchero@mytravel:~$ cat /etc/dhcp/dhcpd.conf
#
# Sample configuration file for ISC dhcpd for Debian
#
# Attention: If /etc/ltsp/dhcpd.conf exists, that will be used as
# configuration file instead of this file.
#
#

# The ddns-updates-style parameter controls whether or not the server will
# attempt to do a DNS update when a lease is confirmed. We default to the
# behavior of the version 2 packages ('none', since DHCP v2 didn't
# have support for DDNS.)
ddns-update-style none;

# option definitions common to all supported networks...
option domain-name "example.org";
option domain-name-servers ns1.example.org, ns2.example.org;

default-lease-time 600;
max-lease-time 7200;

# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;

# Use this to send dhcp log messages to a different log file (you also
# have to hack syslog.conf to complete the redirection).
log-facility local7;

# No service will be given on this subnet, but declaring it helps the 
# DHCP server to understand the network topology.

#subnet 10.152.187.0 netmask 255.255.255.0 {
#}

# This is a very basic subnet declaration.

#subnet 10.254.239.0 netmask 255.255.255.224 {
#  range 10.254.239.10 10.254.239.20;
#  option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
#}

# This declaration allows BOOTP clients to get dynamic addresses,
# which we don't really recommend.

#subnet 10.254.239.32 netmask 255.255.255.224 {
#  range dynamic-bootp 10.254.239.40 10.254.239.60;
#  option broadcast-address 10.254.239.31;
#  option routers rtr-239-32-1.example.org;
#}

# A slightly different configuration for an internal subnet.
#subnet 10.5.5.0 netmask 255.255.255.224 {
#  range 10.5.5.26 10.5.5.30;
#  option domain-name-servers ns1.internal.example.org;
#  option domain-name "internal.example.org";
#  option routers 10.5.5.1;
#  option broadcast-address 10.5.5.31;
#  default-lease-time 600;
#  max-lease-time 7200;
#}

# Hosts which require special configuration options can be listed in
# host statements.   If no address is specified, the address will be
# allocated dynamically (if possible), but the host-specific information
# will still come from the host declaration.

#host passacaglia {
#  hardware ethernet 0:0:c0:5d:bd:95;
#  filename "vmunix.passacaglia";
#  server-name "toccata.fugue.com";
#}

# Fixed IP addresses can also be specified for hosts.   These addresses
# should not also be listed as being available for dynamic assignment.
# Hosts for which fixed IP addresses have been specified can boot using
# BOOTP or DHCP.   Hosts for which no fixed address is specified can only
# be booted with DHCP, unless there is an address range on the subnet
# to which a BOOTP client is connected which has the dynamic-bootp flag
# set.
#host fantasia {
#  hardware ethernet 08:00:07:26:c0:a5;
#  fixed-address fantasia.fugue.com;
#}

# You can declare a class of clients and then do address allocation
# based on that.   The example below shows a case where all clients
# in a certain class get addresses on the 10.17.224/24 subnet, and all
# other clients get addresses on the 10.0.29/24 subnet.

#class "foo" {
#  match if substring (option vendor-class-identifier, 0, 4) = "SUNW";
#}

#shared-network 224-29 {
#  subnet 10.17.224.0 netmask 255.255.255.0 {
#    option routers rtr-224.example.org;
#  }
#  subnet 10.0.29.0 netmask 255.255.255.0 {
#    option routers rtr-29.example.org;
#  }
#  pool {
#    allow members of "foo";
#    range 10.17.224.10 10.17.224.250;
#  }
#  pool {
#    deny members of "foo";
#    range 10.0.29.10 10.0.29.230;
#  }
#}

subnet 192.168.125.0 netmask 255.255.255.0 {
    option subnet-mask	255.255.255.0;

    range 192.168.125.10 192.168.125.100;
    range 192.168.125.150 192.168.125.200;
} 

제일 아래쪽 subnet 192.168.125.0 부분이 dhcp 설정을 하는 부분이다.

• subnet 192.168.125.0 netmask 255.255.255.0

관리하고자 하는 네트워크 대역과 넷마크스를 설정한다. 위의 예제에서는 192.168.125.0/24 대역을 관리하는 것으로 설정했다.

• option subnet-mask

dhcp 서비스를 받는 클라이언트들의 기본 넷마스크를 설정하는 부분이다.

• range 192.168.125.10 192.168.125.100

관리하는 IP 주소를 지정하는 부분이다. 192.168.125.10 ~ 192.168.125.100 까지의 주소를 할당해준다.

• range 192.168.125.150 192.168.125.200

관리하는 IP 주소를 지정하는 부분이다. 192.168.125.150 ~ 192.168.125.200 까지의 주소를 할당해준다.

External links

• https://help.ubuntu.com/community/isc-dhcp-server