DHCPC(8)

NAME
dhcpc - DHCP client (finite state machine version)

SYNOPSIS
dhcpc [ -d ] interface

DESCRIPTION
dhcpc is a client of DHCP (Dynamic Host Configuration Protocol). dhcpc requests the DHCP server to allocate an IP address for the specified interface. And usually there is an expire date, which is called a lease, with the allocated address. But dhcpc automatically tries to extend the lease before an expiration date comes.

On the basis of RFC, when dhcpc is invoked after rebooting, dhcpc requests server to assign the same address as before. To get the same address, dhcpc creates file named "/var/db/dhcp_cache". This file name could be configured when it is compiled. But it is required that the file must remains after the host reboot. For example, the /tmp directory is not appropriate for this purpose.

If the -d option is specified, dhcpc runs in foreground and debugging mode.

The DHCP client can verify whether its assigned information is still valid at any time. dhcpc verifies when it receives SIGUSR1. If the client needs to get a new address as a result of verification, dhcpc will do so automatically.

On the basis of RFC, the DHCP client may release its assigned address to the server before shutdown. So if dhcpc receives SIGUSR2, it tries to send DHCPRELEASE to the server once and does necessary process to finish its operation.

dhcpc will finish after the resetting network interface when it receives SIGTERM or SIGINT.

FILES
/var/db/dhcp_cache
    The file to record previously assigned informations

SEE ALSO
R. Droms, Dynamic Host Configuration Protocol, RFC2131.

W. Wimer, Clarifications and Extensions for the Bootstrap Protocol, RFC1542.

S. Alexander, R. Droms, DHCP Options and BOOTP Vendor Extensions, RFC2132.

R. Droms, Interoperation Between DHCP and BOOTP, RFC1534.