10. DHCP
Dynamic Host Configuration Protocol (DHCPv4)
Allocate IP address to end devices
automatic (fix)
dynamic
DHCPDISCOVER (broadcast)
DHCPOFFER (unicast)
DHCPREQUEST (broadcast)
DHCPACK (unicast)
Lease Renewal
DHCPREQUEST (unicast)
DHCPACK (unicast)
Configuration
Excluding IPv4 Addresses
Configuring a DHCPv4 Pool
Configuring network address, subnet mask, default gateway, dns, domain-name
show ip dhcp binding
Router as client
interface
ip address dhcp
DHCP Relay
Forward DHCPv4 broadcasts to the DHCPv4 server
interface
ip helper-address destination-ip-of-dhcp-server
IPv6
SLAAC
DHCPv6
DHCPv6
Stateless
ipv6 nd other-config-flag
Stateful
ipv6 nd managed-config-flag
DHCPv6 Message
DHCPv6 SOLICIT (FF02::1:2) - multicast
DHCPv6 ADVERTISE
DHCPv6 INFORMATION-REQUEST (Stateless)
DHCPv6 REQUEST (Stateful)
DHCPv6 REPLY
DHCPv6 Stateless Configuration
Configuring a DHCPv6 Pool
Configuring dns, domain-name
interface
ipv6 dhcp server dhcpv6-pool-name
ipv6 nd other-config-flag
Router as client
interface
ipv6 enable
ipv6 address autoconfig
DHCPv6 Stateful Configuration
Configuring a DHCPv6 Pool
Configuring address prefix, dns, domain-name
interface
ipv6 dhcp server dhcpv6-pool-name
ipv6 nd managed-config-flag
Router as client
interface
ipv6 enable
ipv6 address dhcp
DHCPv6 Relay
interface
ipv6 dhcp relay destination destination-ip-of-dhcpv6-server
DHCP starvation attacks
An attacker floods the DHCP server with DHCP requests
DHCP spoofing attacks
An attacker configures a fake DHCP server
DHCP Snooping
Configure trusted source
ip dhcp snooping
interface
ip dhcp snooping trust
ip dhcp snooping limit rate
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