bootpgw(1Mtcp)
bootpgw --
Internet Boot Protocol gateway
Synopsis
in.bootpgw
[ -i ]
[ -s ]
[ -t timeout ]
[ -D debug_level ]
[ -h hop_cnt ]
[ -a gw_addr ]
[ -w wait_tm ]
server
Description
bootpgw implements a simple BOOTP
gateway which can be used to forward requests and responses
between clients on one subnet and a BOOTP or
DHCP server (that is,
bootpd(1Mtcp)
or
dhcpd(1Mtcp)
on another subnet.
While either
bootpd or bootpgw will forward
BOOTREPLY packets, only bootpgw will
forward BOOTREQUEST packets.
One host on each network segment is normally configured to
run bootpgw
from inetd by including the following line in
the file /etc/inetd.conf:
bootps dgram/i udp wait root /usr/sbin/in.bootpgw in.bootpgw server
The /i option to the socket type (sock_type)
``dgram'' is required in order to
identify the interface on which a packet was received (by
activating the IP_RECVIFINDEX option on the socket).
This mode of operation is referred to as ``inetd mode'' and
causes bootpgw to be
started only when a boot request arrives.
If it does not receive another packet within fifteen minutes of the last
one it received, it will exit to conserve system resources.
The -t option controls this timeout (see ``Options'').
It is also possible to run
bootpgw in ``standalone mode'' (without
inetd) by simply invoking it from a shell like
any other regular command. This is not very
useful for bootpgw which has very little start up delay
because it does not read a configuration file.
bootpgw automatically detects whether it was invoked
from inetd or from a shell and automatically
selects the appropriate mode. The -s or
-i option may be used to force standalone or
inetd mode, respectively (see ``Options'').
Options
-a gw_addr-
Specifies what address to fill in for the gateway address.
Since more than one address can be assigned
to an interface, bootpgw will forward packets to
the address specified.
-D debug_level-
Sets the debug_level variable that controls the
amount of debugging messages generated. For example,
-D 1 will set the debugging level to 1.
Recognized values are 0, 1, 2, and 3 or greater. Zero
generates no messages and 1 to 3 generate increasing
amounts of messages. Specifying an integer over 3 has the
same result as specifying 3. For compatibility with older
versions of bootpgw, the option -d
(without an argument) will simply increment the debug level
by one.
-h hop_cnt-
Sets the maximum number of hops allowed for requests;
bootpgw increments the hop count of the
BOOTREQUEST packet. The packet is dropped if the
hop_cnt limit is reached. The default
hop_cnt is 4.
-i-
Force inetd mode. This option is obsolete, but
remains for compatibility with older versions of
bootpgw.
-s-
Force standalone mode. This option is obsolete, but
remains for compatibility with older versions of
bootpgw.
-t timeout-
Specifies the timeout value (in minutes) that a
bootpgw process will wait for
a BOOTP packet before exiting. If no packets are
received for timeout minutes, then the program
will exit. A timeout value of zero means ``run forever''.
In standalone mode, this option is forced to zero.
-w wait_tm-
Sets the minimum number of seconds a client must wait
before bootpgw will forward its
BOOTREQUEST packet. The default
wait_tm value is 3.
server specifies the name of a BOOTP server
to which bootpgw will forward all BOOTREQUEST
packets it receives.
Operation
bootpgw listens for any packets sent to the
bootps port and forwards any
BOOTREPLY packets.
When bootpgw is started, it determines the
address of a BOOTP server whose name is provided
as a command line parameter. When bootpgw
receives a BOOTREQUEST packet, it sets the
``gateway address'' and ``hop count'' fields in the packet
and forwards the packet to the BOOTP server at
the address determined earlier. Requests are forwarded
only if they indicate that the client has been waiting for
at least three seconds.
During initialization, bootpgw determines the
UDP port numbers to be used by calling
getservbyname (see
getservent(3N))
(which normally uses /etc/services).
Two service names (and port numbers) are used:
bootps-
BOOTP server listening port
bootpc-
BOOTP client destination port
If the port numbers cannot be determined using
getservbyname, then the values default to
bootps=67 and bootpc=68.
Files
/etc/services-
internet service numbers
References
bootp(1Mtcp),
bootpd(1Mtcp),
bootpef(1Mtcp),
bootptab(4tcp),
dhcpd(1Mtcp),
inetd(1Mtcp),
inetd.conf(4tcp),
tftpd(1Mtcp)
© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 25 April 2004