DHCP
DHCP. DHCP. Dynamic Host Configuration Protocol (DHCP) From 1993 An extension of BOOTP, very similar to DHCP Same port numbers as BOOTP DHCP is the preferred mechanism for dynamic assignment of IP addresses DHCP can interoperate with BOOTP clients. DHCP.
DHCP
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Presentation Transcript
DHCP • Dynamic Host Configuration Protocol (DHCP) • From 1993 • An extension of BOOTP, very similar to DHCP • Same port numbers as BOOTP • DHCP is the preferred mechanism for dynamic assignment of IP addresses • DHCP can interoperate with BOOTP clients.
DHCP • Dynamic Host Configuration Protocol • It is a method for assigning Internet Protocol (IP) addresses permanently or to individual computers in an organization’s network • DHCP lets a network administrator supervise and distribute IP addresses from a central point and automatically sends a new IP address when a computer is plugged into a different place in the network
Motivation for DHCP • Static Vs Dynamic IP • Configuration parameters for network hosts • IP address • Router • Subnet Mask • Others..
Dynamic Host Configuration Protocol (DHCP) • Four Key benefits to DHCP: • Centralized administration of IP configuration. • Dynamic host configuration. • Seamless IP host configuration. • Flexibility and scalability.
Disadvantages of DHCP • When DHCP server is unavailable, client is unable to access enterprises network • Your machine name does not change when you get a new IP address • Uses UDP, an unreliable and insecure protocol. • DNS cannot be used for DHCP configured hosts.
Security problem • DHCP is an unauthenticated protocol • When connecting to a network, the user is not required to provide credentials in order to obtain a lease • Malicious users with physical access to the DHCP-enabled network can instigate a denial-of-service attack on DHCP servers by requesting many leases from the server, thereby depleting the number of leases that are available to other DHCP clients
Limitations • Some machines on your network need to be at fixed addresses, for example servers and routers • You need to be able to assign a machine to run the DHCP server continually as it must be available at all times when clients need IP access
DHCP Operation • DCHP DISCOVER • DCHP OFFER
DHCP Operation • DCHP DISCOVER At this time, the DHCP client can start to use the IP address • Renewing a Lease (sent when 50% of lease has expired) If DHCP server sends DHCPNACK, then address is released.
DHCP Operation • DCHP RELEASE At this time, the DHCP client has released the IP address
BOOTP/DHCP Message Format (There are >100 different options)
DHCP Message Type • Message type is sent as an option.
