A NEW DYNAMIC-AUTO-STATIC TECHNIQUE FOR DHCPv4 IP ADDRESS ALLOCATION

One feature of Dynamic Host Configuration Protocol (DHCP) servers is the ability to assign static (fixed) IP Addresses for well-known clients in the Local Area Network (LAN) based on their Medium Access Control (MAC) addresses. This typically involves manual intervention by the network administrator to enter the correct MAC address and IP address information into the DHCP server configuration file, and to restart the DHCP server to apply the changes. Obviously this process tends to be time consuming and error prone, due to mistyping the MAC address or assigning duplicate IP addresses to multiple clients. This paper describes an automated technique called the Dynamic-Auto-Static (DAS) technique to automate the static (fixed) IP assignment process and minimize manual intervention by network administrators. The proposed technique automatically white-lists dynamically assigned IP addresses allocated to new clients joining the LAN for conversion into static or fixed IP address assignments after the client has exceeded a network administrator specified threshold for DHCP lease renewals. The network administrator can review the whitelist to make changes where necessary. The DAS technique comprises the following tasks: (1) Analysis of all MAC addresses and associated IP addresses within the DHCP leases file, (2) Update of the DHCP server configuration file with new whitelisted static IP address assignments, and (3) Restart of the DHCP service to implement the new IP address assignment policy. These tasks were automated using the Linux cron facility.