Debian DHCP server設定

• 安裝dhcp server套件
  
  debian:~# apt-get install dhcpd
  
  
• 基本設定
  
  指定listen的介面
  
  debian:~# vi /etc/default/dhcp
  INTERFACES="eth0"
  
  debian:~# vi /etc/init.d/dhcp
  # Defaults
  INTERFACES="eth0"
  
  
• DHCP模式
  
  
  1. 單純DHCP：同一區網內，一電腦為DHCP Server，並單純做IP的指派，介面設定為eth0即可
     
     debian:~# vi /etc/dhcpd.conf
     
     add/fix
     
     option domain-name-servers 140.134.4.1; #設定dns
     default-lease-time 600; #設定租約
     max-lease-time 7200;
     
     #network/netmask 這邊是用子網路切割140.134.210.128/25
     
     subnet 140.134.210.128 netmask 255.255.255.128 {
     range 140.134.210.240 140.134.210.245; #ip範圍
     option routers 140.134.210.254; #GATEWAY
     option subnet-mask 255.255.255.128; # netmask
     option broadcast-address 140.134.210.255; #broadcast
     }
     
     "option routers 140.134.210.254;"的設定如果將ip改成DHCP Server的電腦，就會變成DHCP/NAT的模式
     
     
  2. DHCP/NAT：eth0為外網設定eth1為內網，並需將listen的介面改成eth1，並利用iptables做nat的轉換
     
     network--eth0 eth1-- local
     
     debian:~# vi /etc/dhcpd.conf
     
     add/fix
     
     option domain-name-servers 140.134.4.1; #設定dns
     default-lease-time 600; #設定租約
     max-lease-time 7200;
     
     subnet 192.168.20.0 netmask 255.255.255.0 {
     range 192.168.20.101 192.168.20.200; #ip範圍
     option routers 192.168.20.1; #GATEWAY，eth1的ip
     option subnet-mask 255.255.255.0; # netmask
     option broadcast-address 192.168.20.255; #broadcast
     host inside {
     hardware ethernet 08:00:27:C9:D0:47; #靜態DHCP設定
     fixed-address 192.168.20.100;#指定ip
     }
     }
     
     設定iptables nat，如不做此設定local網路會無法上網
     
     debian:~# echo "1" > /proc/sys/net/ipv4/ip_forward
     debian:~# iptables -t nat -A POSTROUTING -s 192.168.20.0/24 -j MASQUERADE