How Do I Change the DHCP Pool Address on a Cisco ASA 5505

The Cisco ASA 5505 is a high performance firewall appliance with a large number of features. Included in the feature list is DHCP service for hosts on the private network behind the ASA 5505. Occasionally, the DHCP pool addressing may need to be changed in response to modifications on the network.

• Plug a Cisco serial cable from a computer to the ASA 5505. Open a terminal console program such as Hyperterminal or Putty (Microsoft Windows), or Minicom (Linux) and select the com port in use by the Cisco serial cable. Press the Enter key to receive a prompt response from the ASA 5505. Type in an account name and password if required to log in.
• Type "config t" on the ASA 5505 command line. Press Enter to access configuration mode. The command prompt should now look similar to the following:
  ASA5505 (config) #
  where (config) indicates that the context has changed to configuration mode.
• Type "no dhcpd address ip_address_start-ip_address_end name_of_interface" where "ip_address_start" is the first IP address in the current DHCP address pool, "ip_address_end" is the last IP address in the current DHCP address pool, and "name_of_interface" is the network interface to which the current DHCP pool is attached. For example:
  ASA5505(config)# no dhcpd address 172.16.0.17-172.16.0.31 inside
• Type "dhcpd address ip_address_start-ip_address_end name_of_interface" where "ip_address_start" is the first IP address in the new DHCP address pool, "ip_address_end" is the last IP address in the new DHCP address pool, and "name_of_interface" is the network interface to which the new DHCP pool is associated. For example:
  ASA5505(config)# dhcpd address 172.16.0.34-172.16.0.63 inside
• Type "exit" and press the Enter key and then type "copy run start" and press the Enter key again. Follow the example below to save the configuration to NVRAM:
  ASA5505 (config) #exit
  ASA5505 #copy run start