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From Bugzilla Helper: User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.5) Gecko/20031007 Netscape/7.1 Firebird/0.7 Description of problem: I just upgraded DHCP-client-3.0pl1-1cra.i386.rpm on a clients Red Hat 9 server. eth1 is operating as a client from an Internet provider. eth0 uses dhcp-server-3.0pl1-1cra.i386.rpm as a DHCP server to all workstations on eth0. The server also ruins its own named (DNS) server. Problem: this version ignores my supersede commands in /etc/dhclient.conf and consequently overwrites my /etc/resolv.conf with my ISP's informations. This really, really freaks out my Samba file server, which is set to resolve (/etc/resolv.conf) host names with my local name server. As a temporary solution, I commented out the commands in /sbin/dhclinet-script: "function make_resolv_conf" and hand corrected /etc/resolv.conf. Many thanks, --Tony aewell@gbis.com My /etc/dhclient.conf (local domain name changed): reject 192.168.255.10; prepend domain-name-servers 192.168.255.10; supersede domain-name "iamnottellingyou.com"; supersede domain-name-servers 192.168.255.10; Version-Release number of selected component (if applicable): DHCP-client-3.0pl1-1cra.i386.rpm How reproducible: Always Steps to Reproduce: 1. write a local DNS server into /etc/resolv.conf 2. up and down your ethernet port connected to the internet ifdown eth1; ifup eth1 or similar 3. check your /etc/resolv.conf, it will contain your ISP's DNS server Additional info:
For situations like this it is better to set the PEERDNS=no flag in your ifcfg files. This will prevent the dhclient code from trying to update the resolv.conf. The client code is only built for the simple case so handling complicated cases where there are multiple network devices does not always work. Dan
Hi Dan, This is a portion of a letter Ted Lemon sent me. He is the original author of dhclient. (Unfortunately, he is no longer its maintainer. I have no clue who the current maintainer is.) To: dhcp-client@isc.org Subject: Re: Need DNS help In-Reply-To: Message from Anthony Ewell <aewell@gbis.com> Date: Fri, 24 Aug 2001 19:39:16 -0400 From: Ted Lemon <mellon@nominum.com> > Is there a way to over ride this (my local DNS resolves names > from the Internet faster than my ISP's anyway -- has a much > smaller cache to deal with)? in your dhclient.conf: supersede domain-name-servers 10.0.0.1; Ted also wrote me recently that "supersede" was suppose to work, that the problem was a recent bug added to the code, and, unfortunately, he was no longer in a position to help. (I did not save his letter.) So, this really is a bug and really does need fixing. The error is in whatever calls dhclinet-script's "function make_resolv_conf". Please do not close or defer this bug until it is actually corrected. Thank you for the work around. --Tony aewell@gbis.com
well, not from RH, but from Slackware - I discovered (man dhcpcd - duh) that using the -R flag when calling dhcpcd will prevent it from overwriting the resolv.conf file - and that should solve your problems. Just add the -R flag wherever your system is calling dhcpcd (/etc/rc.d/rc.inet1 in slack) and you are all set.
dhclient-3.0.1-x (current version) now fully supports and honours the supersede, prepend and append options when placed in /etc/dhclient-${interface}.conf (eg. /etc/dhclient-eth0.conf if eth0 is the interface being configured with DHCP - NOT /etc/dhclient.conf - this file is never used).