# The purpose of this script is just to try and ensure that we don't
# overwrite nameserver information from another source. Specifically,
# it's a fairly common occurance for dhclient to overwrite the
# nameservers which have been configured by vpnc. In many cases, this
# causes DNS to break for the user.
#
# This is a fairly tricky edge case to handle. It's not obvious what
# the proper behavior is in all cases. The root of the problem is just
# that resolv.conf is a pretty simplistic configuration file, with no
# standard system for handling updates from multiple sources.
#
# As a fairly general solution which will hopefully work in most cases,
# we only attempt to update resolv.conf if the nameserver has changed
# since we got the lease. If the nameserver has not changed since the
# lease was BOUND, then presumably resolv.conf either contains what dhclient
# originally put there or some more up-to-date information provided by
# somebody else (such as vpnc).
#
# The only case I know of where this script fails is if you are using
# the nameserver specified by your VPN server and the local DHCP server
# provides a new nameserver in a RENEW request. In that case, resolv.conf
# will be overwritten. However, this case should be pretty rare and it's
# important to preserve correct behavior in the more common case of getting 
# new nameservers in a RENEW request and not using vpnc.


if [ "$old_domain_name_servers" = "$new_domain_name_servers" -a "$reason" = "RENEW" ]; then
	unset new_domain_name_servers
	echo "Removing new name server" >> /tmp/dhclient-script.debug

fi