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Date:      Fri, 15 Jun 2012 23:02:41 +0530
From:      Varuna <varuna@eudaemonicsystems.net>
To:        freebsd-hackers@freebsd.org
Subject:   Re: /etc/resolv.conf getting over written with dhcp
Message-ID:  <4FDB71B9.9070804@eudaemonicsystems.net>
In-Reply-To: <4FDB3BAA.6090906@fluffy.khv.ru>
References:  <4FDB25E0.2070705@eudaemonicsystems.net> <4FDB3BAA.6090906@fluffy.khv.ru>

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Thanks for the pointers.

Dima Panov wrote:
>  From my /etc/dhclient.conf:
> 
> interface "lagg0" {
>     send dhcp-lease-time 3600;
>     prepend domain-name-servers 127.0.0.1, 4.4.4.4, 8.8.8.8;
>     request subnet-mask, broadcast-address, time-offset, routers,
>             domain-name, domain-name-servers;
>     require subnet-mask, domain-name-servers;
> }
> 
> And result is /etc/resolv.conf:
> # Generated by resolvconf
> nameserver 127.0.0.1
> nameserver 4.4.4.4
> nameserver 8.8.8.8
> nameserver 192.168.1.1
True indeed this will work and I did have a look at dhclient.conf(5) to setup 
the freebsd8:/etc/dhclient.conf.  This will still call /sbin/dhclient-script 
which will overwrite the configuration done to the /etc/resolv.conf each time 
the system power is recycled.  As per /usr/src/include/resolv.h, the MAXNS is by 
default set to 3; which the default configuration user will not be aware of as 
the entire focus will be on the ifconfig related flags in /etc/rc.conf.  BTW, 
the example indicated in dhclient.conf(5) has a typo which says 
/etc/dhclient-script instead of /sbin/dhclient-script, indeed the system does 
not fail if the typo exists in dhclient.conf.


Eugene Grosbein wrote:
> There is simple solution: create file /etc/dhclient-enter-hooks
> and override add_new_resolv_conf() there to do nothing:
>
> add_new_resolv_conf() {
>   return 0
> }
>
> Works just fine for my systems.
Indeed this is a good suggestion, and this is if the user is aware of what to 
look for and where in /sbin/dhclient-script it is documented.

A general sysadmin would be aware of /etc/nsswitch.conf and /etc/resolv.conf for 
name resolution issues and I do not think they will be aware of so many possible 
ways to handle the issue of resolv.conf getting overwritten by the usage of dhcp.

What would be the way out? Do you think it would be a good idea to push the 
nameserver configuration information into /etc/rc.conf which happens to be the 
single file that would handle the system configuration?

With regards,
Varuna
Eudaemonic Systems
Simple, Specific & Insightful

IT Consultants, Continued Education & Systems Distribution
+91-88-92-47-62-63
http://www.eudaemonicsystems.net
http://enquiry.eudaemonicsystems.net

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