Sample dhclient.conf

add unknown-99 and unknown-123

# Configuration file for /sbin/dhclient, which is included in Debian's
#	dhcp3-client package.
#
# This is a sample configuration file for dhclient. See dhclient.conf's
#	man page for more information about the syntax of this file
#	and a more comprehensive list of the parameters understood by
#	dhclient.
#
# Normally, if the DHCP server provides reasonable information and does
#	not leave anything out (like the domain name, for example), then
#	few changes must be made to this file, if any.
#

#send host-name "andare.fugue.com";
#send dhcp-client-identifier 1:0:a0:24:ab:fb:9c;
#send dhcp-lease-time 3600;
#supersede domain-name "fugue.com home.vix.com";
#prepend domain-name-servers 127.0.0.1;
request subnet-mask, broadcast-address, time-offset, routers,
	domain-name, domain-name-servers, host-name,
	netbios-name-servers, netbios-scope, interface-mtu, nwip-suboptions, unknown-99, unknown-123;
#require subnet-mask, domain-name-servers;
#timeout 60;
#retry 60;
#reboot 10;
#select-timeout 5;
#initial-interval 2;
#script "/etc/dhcp3/dhclient-script";
#media "-link0 -link1 -link2", "link0 link1";
#reject 192.33.137.209;

#alias {
#  interface "eth0";
#  fixed-address 192.5.5.213;
#  option subnet-mask 255.255.255.255;
#}

#lease {
#  interface "eth0";
#  fixed-address 192.33.137.200;
#  medium "link0 link1";
#  option host-name "andare.swiftmedia.com";
#  option subnet-mask 255.255.255.0;
#  option broadcast-address 192.33.137.255;
#  option routers 192.33.137.250;
#  option domain-name-servers 127.0.0.1;
#  renew 2 2000/1/12 00:00:01;
#  rebind 2 2000/1/12 00:00:01;
#  expire 2 2000/1/12 00:00:01;
#}

Sample dhclient-enter-hooks script

#
# The purpose of this script is just to save the DHCP-vairables used for
# location determination (99 and 123) in the file /tmp/dhcp_loc.txt.

# To enable this script set the following variable to "yes"
RUN="yes"

if [ "$RUN" = "yes" ]; then
	echo 99=$new_unknown_99 > /tmp/dhcp_loc.txt
	echo 123=$new_unknown_123 >> /tmp/dhcp_loc.txt
fi

Sample /tmp/dhcploc.txt

(dummy location)

99=
123=48:60:49:8:1c:48:21:e6:59:4b:13:c0:0:21:b3:1