Chapter 8: DHCP

Chapter 8: DHCP

1. Introduction to DHCPv4

   • The DHCPv4 server dynamically allocates, or leases, an IPv4 address

2. Operation of DHCPv4

   • Origin of the lease
     • DHCPDISCOVER
   • DHCP detection (DHCPDISCOVER)
     • uses layer 2 and layer 3 broadcast addresses to communicate
   • DHCP offer (DHCPOFFER)
     • reserves an available IPv4 address to lease to the client
   • DHCP request (DHCPREQUEST)
     • serves as notification of binding acceptance to the selected server
   • DHCP acknowledgment (DHCPACK)
     • verify the lease information with an ICMP ping
   • Renovation of the lease
     • DHCP request (DHCPREQUEST)
       • You can extend the lease.
     • Acuse de recibo de DHCP (DHCPACK)
       • the server verifies the lease information when returning a DHCPACK

3. DHCPv4 message format

   • Operation code (OP)
     • specifies the type of message generated
   • Type of hardware
     • Ethernet, 15
     • 20 is a serial line
   • Hardware address length
   • Jumps
     • controls message forwarding
   • Transaction identifier
     • to match the request
   • Seconds
   • Indicators
     • you use a client that does not know your IPv4 address
   • Client's IP address
     • is used by a client during the lease renewal
   • Your IP address
   • IP address of the server
   • IP address of the gateway
     • routes DHCPv4 messages
   • Customer hardware address
   • Customer hardware address
   • DHCP options

4. Configuring a basic DHCPv4 server

   • Step 1: Exclude IPv4 addresses
   • Step 2: Configure a DHCPv4 pool
   • Step 3: Configure specific tasks

5. Verification of DHCPv4

6. Relay of DHCPv4

   • Port 37: Weather
   • Port 49: TACACS
   • Port 67: DHCP / BOOTP client
   • Port 53: DNS
   • Port 68: DHCP / BOOTP server
   • Port 69: TFTP
   • Port 137: NetBIOS name service
   • Port 138: NetBIOS datagram service

7. Configuring a router as a DHCPv4 client

8. Configuring a wireless router as a DHCPv4 client