DHCP and BOOTP Service
The Dynamic Host Configuration Protocol (DHCP) server and client are integrated in Cisco IOS. DHCP is based on BOOTP and
shares the well-known UDP server port 67 (per RFC 951, RFC 1534, and RFC 2131). When the BOOTP server and DHCP servers
are disabled, all incoming packets on UDP port 67 are discarded, and ICMP port-unreachable messages are sent out in response.
The no ip bootp server and no service dhcp commands can be used to disable BOOTP and DHCP, respectively, from the global
configuration mode.
Trivial File Transfer Protocol (TFTP) Server
Cisco routers or the flash memory device on the router can act as a TFTP server. The system sends a copy of the system image
contained in ROM or one of the system images contained in flash memory to any client that issues a TFTP Read Request with filename. This service must be disabled to prevent unauthorized reading and writing from the router flash memory.
By default, TFTP support is disabled on all IOS versions. If this service has been enabled, it can be disabled using the no tftp-
server flash:[filename] command from the global configuration mode.
File Transfer Protocol (FTP) Server
Similarly, Cisco routers can act as FTP servers.
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