Procedura veloce per installare un server DHCP
1) yum -y install dhcp
2) cp -f /usr/share/doc/dhcp*/dhcpd.conf.sample /etc/dhcpd.conf
3) vi /etc/dhcpd.conf
# line 4: specify your network and subnetmask
subnet
192.168.91.0
netmask
255.255.255.0
{
# line 7 : specify default gateway
option routers
192.168.91.2
;
# line 8: specify subnetmask
option subnet-mask
255.255.255.0
;
# line 10: specify NIS domain name iy you using.
# make it comment if you don not use.
# make it comment if you don not use.
option nis-domain
"instyle.locale"
;
# line 11: specify domain name
option domain-name
"instyle.locale"
;
# line 12: specify IP address of DNS nel caso che il server faccia anche da dns
option domain-name-servers
192.168.91.20
;
# line 14: make it comment
#
option time-offset
-18000;
# line 21: specify the range of IP addresses for clients
range dynamic-bootp
192.168.91.128 192.168.91.254
;
# line 22: default's terms of lease
default-lease-time
21600
;
# line 23: maximun terms of lease
max-lease-time
43200
;
# line 26: make following lines comment
#
host ns {
#
next-server marvin.redhat.com;
#
hardware ethernet 12:34:56:78:AB:CD;
#
fixed-address 207.175.42.254;
#
}
4) /etc/init.d/dhcpd start
Starting dhcpd:
[ OK ]
5) Aprire la porta del firewall, si tratta della porta 67 UDP dopo il daemon DHCP sta in listening.
6) Il DHCP risponde sulla porta 68 UDP
7) chkconfig dhcpd on
12) per vedere se ci sono dei problemi andare a vedere i log creati in /var/log/messages
13) Nel caso in cui abbiamo piu' sottoreti una soluzione è settare un server dhcp per ogni lan oppure abilitare il DHCP Relayng su ogni singolo router
ddns-update-style interim;
subnet 192.168.1.0 netmask 255.255.255.0 { option subnet-mask 255.255.255.0; option broadcast-address 192.168.1.255; option routers 192.168.1.1; default-lease-time 600; max-lease-time 604800; option domain-name "example.com"; option domain-name-servers 192.168.1.1, 192.168.1.2; option time-offset 7200; option ntp-servers 192.168.1.1; range 192.168.1.100 192.168.1.200; }
subnet 192.168.2.0 netmask 255.255.255.0 { option subnet-mask 255.255.255.0; option broadcast-address 192.168.2.255; option routers 192.168.2.1; default-lease-time 600; max-lease-time 604800; option domain-name "example.com"; option domain-name-servers 192.168.2.1, 192.168.2.2; option time-offset 7200; option ntp-servers 192.168.2.1; range 192.168.2.100 192.168.2.200; }
8) Ecco delle opzioni suppletive:
ddns-update-style interim
subnet 192.168.1.0 netmask 255.255.255.0 {
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255; ip di broadcast
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255; ip di broadcast
option routers 192.168.1.1;
default-lease-time 600;
max-lease-time 604800;
option domain-name "example.com"; dominio da passare ai client
option domain-name-servers 192.168.1.1, 192.168.1.2;
option time-offset 7200;
option ntp-servers 192.168.1.1; Time Server
range 192.168.1.100 192.168.1.200;
default-lease-time 600;
max-lease-time 604800;
option domain-name "example.com"; dominio da passare ai client
option domain-name-servers 192.168.1.1, 192.168.1.2;
option time-offset 7200;
option ntp-servers 192.168.1.1; Time Server
range 192.168.1.100 192.168.1.200;
#sezione per definire IP statici
host server1 {
hardware ethernet 00:00:00:12:34:AB;
fixed-address 192.168.1.10;
}
hardware ethernet 00:00:00:12:34:AB;
fixed-address 192.168.1.10;
}
#in questo caso passiamo dei parametri specifici
host server2 {
hardware ethernet 00:00:00:23:45:EF;
fixed-address 192.168.1.11;
option host-name "web1.servers.example.com";
option domain-name "servers.example.com";
}
hardware ethernet 00:00:00:23:45:EF;
fixed-address 192.168.1.11;
option host-name "web1.servers.example.com";
option domain-name "servers.example.com";
}
}
9) si possono definire dei gruppi specifici:
ddns-update-style interim
subnet 192.168.1.0 netmask 255.255.255.0 {
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255; ip di broadcast
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255; ip di broadcast
option routers 192.168.1.1;
default-lease-time 600;
max-lease-time 604800;
option domain-name "example.com"; dominio da passare ai client
option domain-name-servers 192.168.1.1, 192.168.1.2;
option time-offset 7200;
option ntp-servers 192.168.1.1; Time Server
range 192.168.1.100 192.168.1.200;
default-lease-time 600;
max-lease-time 604800;
option domain-name "example.com"; dominio da passare ai client
option domain-name-servers 192.168.1.1, 192.168.1.2;
option time-offset 7200;
option ntp-servers 192.168.1.1; Time Server
range 192.168.1.100 192.168.1.200;
group {
option domain-name "servers.example.com";
option ntp-servers 192.168.1.5;
host server1 {
hardware ethernet 00:00:00:12:34:AB;
fixed-address 192.168.1.10;
option host-name "db1.servers.example.com";
}
host server2 {
hardware ethernet 00:00:00:23:45:EF;
fixed-address 192.168.1.11;
option host-name "web1.servers.example.com";
}
}
option domain-name "servers.example.com";
option ntp-servers 192.168.1.5;
host server1 {
hardware ethernet 00:00:00:12:34:AB;
fixed-address 192.168.1.10;
option host-name "db1.servers.example.com";
}
host server2 {
hardware ethernet 00:00:00:23:45:EF;
fixed-address 192.168.1.11;
option host-name "web1.servers.example.com";
}
}
10) Shared Network:
shared-network internal {
option domain-name "test.example.com";
option domain-name-servers 192.168.0.1;
option routers 192.168.0.1;
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.100 192.168.1.200;
}
subnet 192.168.2.0 netmask 255.255.255.0 {
range 192.168.2.100 192.168.2.200;
}
}
option domain-name "test.example.com";
option domain-name-servers 192.168.0.1;
option routers 192.168.0.1;
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.100 192.168.1.200;
}
subnet 192.168.2.0 netmask 255.255.255.0 {
range 192.168.2.100 192.168.2.200;
}
}
11) per testare che la sintassi del file sia corretta si usa:
service dhcpd configtest
13) Nel caso in cui abbiamo piu' sottoreti una soluzione è settare un server dhcp per ogni lan oppure abilitare il DHCP Relayng su ogni singolo router
ddns-update-style interim;
subnet 192.168.1.0 netmask 255.255.255.0 { option subnet-mask 255.255.255.0; option broadcast-address 192.168.1.255; option routers 192.168.1.1; default-lease-time 600; max-lease-time 604800; option domain-name "example.com"; option domain-name-servers 192.168.1.1, 192.168.1.2; option time-offset 7200; option ntp-servers 192.168.1.1; range 192.168.1.100 192.168.1.200; }
subnet 192.168.2.0 netmask 255.255.255.0 { option subnet-mask 255.255.255.0; option broadcast-address 192.168.2.255; option routers 192.168.2.1; default-lease-time 600; max-lease-time 604800; option domain-name "example.com"; option domain-name-servers 192.168.2.1, 192.168.2.2; option time-offset 7200; option ntp-servers 192.168.2.1; range 192.168.2.100 192.168.2.200; }
