NAME

client.pcy − BOOTP and DHCP client policy

DESCRIPTION

client.pcy is a text database, read by joinc on startup, which governs the behavior of BOOTP and DHCP clients.  If the variable JOINCONFIG is present in joinc’s environment, it is taken to be the directory where client.pcy is housed; otherwise /etc/join is searched.  Defaults exist for all parameters and switches, so it is not an error if the file does not exist. 

FORMAT

Blank lines are ignored.  The character ’#’ introduces a comment which continue to the next newline. Each new policy option must begin and end on a separate line.  Policy options are introduced by a keyword, and may be boolean, or may take a value separated from the keyword by whitespace (but not a newline). If an option is present more than once, only the value attached to the last occurrence will be take effect − earlier value(s) will be forgotten. 

KEYWORDS AND VALUES

accept_bootp If no DHCP responses are heard, and this flag is set, the client will use any BOOTP response in configuration.  In this scenario, the client will not renew, rebind expire or release its IP address lease.  In other words the client is given what is effectively an infinite lease.  Although the client will accept BOOTP responses, it will only send DHCP packets. There is no guarantee that BOOTP servers which hear these packets will respond, since they may become confused by the presence of DHCP data within the packet.  This option is not yet implemented. 

arp_timeout seconds
When the client receives an IP address from the server it will perform an ARP on the local network to verify than no other client is in fact using the address. If it receives no reply after seconds expires it assumes that it may use the address. 
Default: 2 seconds.

class_id The client’s class ID. Consult RFC1541 for details. 

client_id Use a client identifier other than the MAC address.  Currently setting client_id tells the DHCP client daemon to use a concatenation of the MAC addr and the interface name as the client ID.  The MAC addr is in internal form, not the human readable colon separated string.  Note that you must use this option when configuring a client with multiple interfaces and where the client’s MAC address is the same on each interface (SUN hardware for example). 

lease_desired seconds The DHCP server grants the client permission to use a an IP address for a fixed period of time (which may be infinite). In the language of DHCP the client is granted a "lease" on the IP address.  With this parameter, the client may request a lease of a particular duration, although servers are not bound to honor the request. If the client doesn’t care seconds should be set to zero; if an infinite lease is required to minus one, -1.  Otherwise specify in seconds the lease duration required. 
Default: 0

retry_broadcast integer This parameter is subtly different from the number of retries a client will make as part of an exponential broadcast retry backoff.  Rather it is the number of separate attempts the client will make to contact a server, assuming that replies are received, but that the client, for one reason or another, rejected those replies. 
Default: 2

timeouts value,value,value....  Clients are required by the DHCP protocol to implement an exponential retransmission and backoff when broadcasting discover or request packets.  The array of values specifies how long the client should wait for replies before timing out and retrying the broadcast. 

Each time the client sends a DHCP protocol packet it waits for a response until a timeout occurs after an given by a member of this array (in seconds).  If a timeout has occurred the packet is re-transmitted with the same XID (see RFC 1541) and the timeout is set to the next positive number in the comma separated list.  The last element in the list is negative or zero.  At this the next action depends on options to the dhcpconf program.  One option is to fail.  Another is to retry forever. If the last value is negative DHCP suspends configuration of the interface for an amount of time given by the negative number terminating the array.  During this time the interface is considered "idle" -- the client is not expecting repsonses destined for the interface and will ignore any that arrive.  When the idle time is over the client begins re-transmitting with a timeout given by the first element in the array and a new XID.  If the last value is zero the client continues to use the same XID and timeout of the last positive value in the array. 
Default: 4,8,16,32,0

use_saved_config If there is no reply to DHCP, and "use_saved_config" is set, then use the configuration stored in <interface>.cf from a previous inocation of the protocol providing the lease is still valid. 

wait_before_broadcast seconds The DHCP protocol requires clients to delay a random time interval on booting, and after each timeout, before broadcasting to the net. This is to prevent network "flooding" in the event of many clients all trying to configure simultaneously (say after a sitewide power-up). This parameter is the maximum delay that the client will tolerate. The actual delay is randomised from zero up to seconds.  Note that on each timeout the client will also delay, and that the second and subsequent delays are also random, and need not be the same as the first. 
Default: 10 seconds.

request parameter_name There may be many instances of the request keyword, each with a different parameter_name.  Each parameter that is configurable through DHCP and the server extensions is identified by a unique parameter Limited size of DHCP packets dictates that a client should not request data which it cannot use. However, different DHCP servers, or different server policies may dictate that a server return more configuration that a client requested.  For a descrtiption of the meaning of the various parameters, consult RFC1542 and others to which it refers.  Valid options follow. The first group are DHCP generic: all_subnets_are_local
arp_cache_timeout
boot_file
boot_file_server
boot_size
broadcast_address
cookie_server
default_ip_time-to-live
dns_domain_name
dns_servers
ethernet_encapsulation
extensions_path
home_directory
host_name
impress_server
interface_mtu
ip_forwarding
keepalive_garbage
lease_time
log_server
lpr_server
mask_supplier
maximum_datagram_reassembly_size
merit_dump_file
name_server
netbios_datagram_distribution_server
netbios_name_server
netbios_node_type
netbios_scope
nis_domain_name
nis_server
non-local_source_routing
ntp_server
path_mtu_aging_timeout
path_mtu_plateau_table
perform_mask_discovery
perform_router_discovery
policy_filter
rebinding_time_value
renewal_time_value
resource_location_server
root_path
router
router_solicitation_address
static_routes
subnet_mask
swap_server
tcp_default_time_to_live
tcp_keepalive_interval
time_offset
time_server_(rfc_868)
trailer_encapsulation
x_window_display_manager
x_windows_font_server

The next are specific to the DHCP server:

nfs_mounted_file_systems
svr4_printer_setup
printers

RELATED INFORMATION

joinc(8),
DARPA Internet Request For Comments RFC1541, RFC1542.