joind - BOOTP and DHCP server daemon
/usr/sbin/joind [-f] [-dn] [-ln] [-t minutes]
Sets foreground mode. In this mode, joind will not run as
a daemon. All messages are written to standard out (stdout)
and standard error (stderr), although warnings and
errors are still sent to syslog(3) as well. Sets debug
level to n. If debug is turned on, log messages are also
enabled. Enables warning (n > 0) and log (n > 1) messages.
If n is not explicitly given, the value one (1) is
assumed (warnings are turned on). Terminates if minutes
have passed and no packets have been received. This
option is valid only if joind was started from inetd.
The joind server is the server that provides configurations
to clients on the network using the DHCP or BOOTP
protocols; it normally runs as a daemon process, and may
be started either from the shell command line interface or
by the inetd daemon.
In default mode of operation, joind reads configuration
and policy information from files created by xjoin, the
graphical user interface tool for administering these
databases. It then listens on a well-known port for
client hosts requesting configuration either by the DHCP
protocol or by the BOOTP protocol.
The joind daemon looks in the /etc/services file to find
the port numbers it should use. Two entries are
extracted: The BOOTP server listening port. The destination
port used to reply to clients.
If the port numbers cannot be determined in this manner,
they are assumed to be port 67 for the server and port 68
for the client.
When a request is received from a client on a network that
is administered by a joind daemon, it responds with an
Internet address that the client can use, and sufficient
information to permit the client to boot and configure its
TCP/IP stack according to either the DHCP or BOOTP protocols
as described in RFC1541 and RFC1497, respectively.
The joind daemon rereads its configuration file when it
receives a hangup signal (SIGHUP) or when it receives a
BOOTP request packet and detects that the file has been
updated. Hosts can be added, deleted, or modified when
the configuration file is reread.
The joind server writes informational and error messages
in four categories: errors, warnings, information, and
debug. Errors are severe, usually unrecoverable events
within the server due to resource exhaustion and other
unexpected failure of system calls. Warnings are less
severe, do not terminate the server, and in most cases
describe unusual or incorrect datagrams received from
clients, or requests for service that cannot be provided.
Informational messages provide a human readable transcription
of (correct) actions performed by the server on
behalf of client hosts. Debug messages may be generated at
various levels of verbosity from zero (not at all) through
nine, as controlled by the -d option.
The disposition of messages is (by default) as follows:
warning, information, and debug messages are discarded:
errors are written to /var/join/log and are sent to the
system logger syslog(3) at priority LOG_ERR and with a
facility identifier LOG_DAEMON. If warnings were enabled,
they are also sent to syslog with the same facility, but
at priority LOG_WARNING. The creation and disposition of
messages is controlled by the -f, -d, and -l command line
options, and the environment variable JOINLOG.
BOOTP Information [Toc] [Back]
If you plan to use the joind daemon to support BOOTP
requests only, you might want the inetd daemon start joind
automatically. To do this, uncomment the following line
in the /etc/inetd.conf file:
bootps dgram udp wait root /usr/sbin/joind joind
This causes joind to be started only when a boot request
arrives. If joind does not receive another boot request
within fifteen minutes of the last one it received, it
exits to conserve system resources.
To run the joind daemon, you must also run the tftpd daemon.
Upon startup, joind first reads its configuration file,
/etc/bootptab, and then begins listening for BOOTREQUEST
packets.
A cluster member should never be a DHCP client. It should
always use static addressing.
If a cluster is to support a DHCP server, there can be
only one DHCP server for all the cluster members using a
common database with failover.
Do not terminate the server with SIGKILL. Doing so leads
to data loss, and frequently results in a corrupted
database. Use SIGTERM, SIGINT or SIGQUIT instead.
Nonstandard subnet masks for all networks administered by
the server must be available either through /etc/join/netmasks
or NIS.
The database used by the server does not support multiuser
write concurrency. When the server is in operation the
entire database is locked against other applications.
This means that you cannot use jdbmod or xjdbmod to modify
records in the database while the server is running. The
converse is also true.
If the naming policy is to be changed (for example, from
assigning names by MAC address to assigning names by IP
address) you must first, before changing the server policy
database, stop the server, dump the name data (using jdbdump),
and then reload after the policy file has changed.
SIGTERM, SIGINT, SIGQUIT and SIGUSR2 terminate the server
in a controlled manner. SIGHUP tells the server to reread
its configuration databases. SIGUSR1 dumps database
internals.
Never stop the server with SIGKILL. This leads to data
loss and corruption of the lease and names databases.
By default, joind reads its configuration and policy
databases from files in the /etc/join directory. The
environment variable JOINCONFIG may be used to select a
different directory. These databases may be stored as text
or binary. The text files are: Parameters and configuration
data for individual clients, client classes, and networks.
Networks joind controls, and a pool of IP
addresses which are available for the server to assign to
clients. A collection of names available on a per-joinserver,
per domain-name that the server can assign to
clients. Parameters governing the behavior of joind, and
general policies concerning network administration and
their binary counterparts: bootptab.hsh, nets.hsh, namepool.hsh,
and server.hsh.
During operation, the server creates dynamic database
bindings of IP addresses and names to MAC addresses. The
following files are stored under the /var/join directory,
unless overridden by the environment variable JOINSPOOL.
B-trees Hash indexes.
The joind daemon writes a startup message and other messages
previously described in the $JOINSPOOL/log file
unless the environment variable JOINLOG is set, in which
case the file named by that variable is used (NOTE: this
must be an absolute filename, not a directory, nor a path
relative filename). The (human readable) log.
Commands: inetd(8), joinc(8), xjoin(8)
System calls: syslog(3)
Files: bootptab(4), namepool(4), nets(4), server.pcy(4)
Information: DHCP(7)
RFC1497, RFC1541, RFC1542, RFC1533, RFC1534
joind(8)
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