DHCP Server en GNS3
Escenario en GNS3
Instalamos Appliance Toollkit
Ingresamos a GNS3-Marketplace lo descargamos e instalamos en nuestro GNS3.
En caso no sepan instalar appliances en GNS3 les recomiento buscar tutoriales en YouTube que no es complicado!
Asignamos una IP a nuestro servidor DHCP
root@DHCP:~# ip add add 192.168.20.100/24 dev eth0
root@DHCP:~# ip route add default via 192.168.20.1
root@DHCP:~# ip add
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
7: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000
link/ether c6:c6:f5:bd:ef:08 brd ff:ff:ff:ff:ff:ff
inet 192.168.20.100/24 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::c4c6:f5ff:febd:ef08/64 scope link
valid_lft forever preferred_lft forever
root@DHCP:~# ping -c 1 192.168.20.1
PING 192.168.20.1 (192.168.20.1) 56(84) bytes of data.
64 bytes from 192.168.20.1: icmp_seq=1 ttl=255 time=11.2 ms
--- 192.168.20.1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 11.169/11.169/11.169/0.000 ms
Configuramos nuestro servidor DHCP
1. Vamos a la siguiente ruta y hacemos un backup al archivo dhcpd.conf
root@DHCP:~# cd /etc/dhcp/
root@DHCP:/etc/dhcp# ls -l
total 12
drwxr-x--- 2 root dhcpd 4096 Apr 8 2021 ddns-keys
-rw-r--r-- 1 root root 3646 Mar 9 2021 dhcpd.conf
-rw-r--r-- 1 root root 3331 Mar 9 2021 dhcpd6.conf
root@DHCP:/etc/dhcp# mv dhcpd.conf dhcpd.conf.backup
root@DHCP:/etc/dhcp# ls -l
total 12
drwxr-x--- 2 root dhcpd 4096 Apr 8 2021 ddns-keys
-rw-r--r-- 1 root root 3646 Mar 9 2021 dhcpd.conf.backup
-rw-r--r-- 1 root root 3331 Mar 9 2021 dhcpd6.conf
2. Ahora creamos nuestro archivo dhcpd.conf y lo personalizamos
root@DHCP:/etc/dhcp# touch dhcpd.conf
root@DHCP:/etc/dhcp# nano dhcpd.conf
Copiamos lo siguiente en el archivo dhcpd.conf y lo guardamos:
default-lease-time 600;
max-lease-time 7200;
subnet 192.168.199.0 netmask 255.255.255.0 {
range 192.168.199.101 192.168.199.254;
option domain-name-servers 192.168.199.200;
option routers 192.168.199.1;
}
default-lease-time 600;
max-lease-time 7200;
subnet 192.168.10.0 netmask 255.255.255.0 {
range 192.168.10.10 192.168.10.254;
option domain-name-servers 192.168.199.200;
option routers 192.168.10.1;
}
default-lease-time 600;
max-lease-time 7200;
subnet 192.168.20.0 netmask 255.255.255.0 {
range 192.168.20.10 192.168.20.254;
option domain-name-servers 192.168.199.200;
option routers 192.168.20.1;
}
3. Ahora modificamos el archivo isc-dhcp-server que está en la siguiente ruta y asignamos la interfaz por donde comenzara a responder las solicitudes de DHCP, en nuestro caso la interfaz en la eth0
root@DHCP:/etc/dhcp# nano /etc/default/isc-dhcp-server
# Defaults for isc-dhcp-server (sourced by /etc/init.d/isc-dhcp-server)
# Path to dhcpd's config file (default: /etc/dhcp/dhcpd.conf).
#DHCPDv4_CONF=/etc/dhcp/dhcpd.conf
#DHCPDv6_CONF=/etc/dhcp/dhcpd6.conf
# Path to dhcpd's PID file (default: /var/run/dhcpd.pid).
#DHCPDv4_PID=/var/run/dhcpd.pid
#DHCPDv6_PID=/var/run/dhcpd6.pid
# Additional options to start dhcpd with.
# Don't use options -cf or -pf here; use DHCPD_CONF/ DHCPD_PID instead
#OPTIONS=""
# On what interfaces should the DHCP server (dhcpd) serve DHCP requests?
# Separate multiple interfaces with spaces, e.g. "eth0 eth1".
INTERFACESv4="eth0"
INTERFACESv6=""
Activamos nuestro servidor DHCP
Por defecto el servidor DHCP esta inactivo asi que procedemos a activarlo
root@DHCP:~# service isc-dhcp-server status
Status of ISC DHCPv4 server: dhcpd is not running.
root@DHCP:~# service isc-dhcp-server start
Launching IPv4 server only.
* Starting ISC DHCPv4 server dhcpd [ OK ]
Ahora configuramos DHCP Relay
L3SW1(config)#int vlan 10
L3SW1(config-if)#ip helper-address 192.168.20.100
L3SW1(config-if)#int vlan 20
L3SW1(config-if)#ip helper-address 192.168.20.100
L3SW1(config-if)#exit
Validamos que nuestro servidor DHCP este funcionando
1. En la PC-TAC ingresamos a la ruta /etc/network/interfaces y descomentamos las dos ultimas líneas para configuración por DHCP
root@DHCP:~# nano /etc/network/interfaces
#
# This is a sample network config uncomment lines to configure the network
#
# Static config for eth0
#auto eth0
#iface eth0 inet static
# address 192.168.0.2
# netmask 255.255.255.0
# gateway 192.168.0.1
# up echo nameserver 192.168.0.1 > /etc/resolv.conf
# DHCP config for eth0
auto eth0
iface eth0 inet dhc
2. Apagamos y encendemos la PC-TAC
root@TAC:~# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.10.11 netmask 255.255.255.0 broadcast 0.0.0.0
ether 76:1a:f8:e0:a9:6f txqueuelen 1000 (Ethernet)
RX packets 7 bytes 1284 (1.2 KB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4 bytes 864 (864.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
3. Visualizamos los mensajes DHCP intercambiamos entre el cliente y servidor
root@DHCP:/var/log# tail syslog
Feb 26 15:57:26 DHCP dhcpd[231]: Wrote 0 leases to leases file.
Feb 26 15:57:26 DHCP dhcpd[231]: Server starting service.
Feb 26 16:09:55 DHCP dhcpd[231]: DHCPDISCOVER from 12:9a:eb:09:c8:2c via 192.168.10.1
Feb 26 16:09:56 DHCP dhcpd[231]: DHCPOFFER on 192.168.10.10 to 12:9a:eb:09:c8:2c via 192.168.10.1
Feb 26 16:09:56 DHCP dhcpd[231]: DHCPREQUEST for 192.168.10.10 (192.168.20.100) from 12:9a:eb:09:c8:2c via 192.168.10.1
Feb 26 16:09:56 DHCP dhcpd[231]: DHCPACK on 192.168.10.10 to 12:9a:eb:09:c8:2c via 192.168.10.1
Feb 26 16:10:31 DHCP dhcpd[231]: DHCPDISCOVER from 76:1a:f8:e0:a9:6f via 192.168.10.1
Feb 26 16:10:32 DHCP dhcpd[231]: DHCPOFFER on 192.168.10.11 to 76:1a:f8:e0:a9:6f via 192.168.10.1
Feb 26 16:10:32 DHCP dhcpd[231]: DHCPREQUEST for 192.168.10.11 (192.168.20.100) from 76:1a:f8:e0:a9:6f via 192.168.10.1
Feb 26 16:10:32 DHCP dhcpd[231]: DHCPACK on 192.168.10.11 to 76:1a:f8:e0:a9:6f via 192.168.10.1
Servido