isc dhclient not appling alias to interface

paranoid.schizophrenic.2 paranoid.schizophrenic.2 at gmail.com
Thu Sep 22 13:41:01 UTC 2016


Not to ask stupid questions, but are you sure that you are actually
executing the right program? It actually takes a bit of work to get
the isc-dhcp-client package to work.

OpenBSD's network start up script (netstart) actually invokes
'dhclient' which is selected based on the PATH.. In my configuration
/sbin is listed before /usr/local/sbin. This means that Theo's version
is automatically selected and the the isc-dhcp-client package version.

If you have handled that little issue, is ir possible that you
actually have both versions running? You can get some very interesting
and unpredictable results by having two separate dhclients attempting
to manage a single interface.

Regards,
The Paranoid Schizophrenic

On 9/21/16, Theodore Wynnychenko <tmw at uchicago.edu> wrote:
> Hello
> I am looking at replacing the base dhclient in OpenBSD with the
> isc-dhcp-client
> available in OpenBSD's packages.
>
> The primary reason for this is to take advantage of having an alias ip
> address
> assigned to the interface.
>
> But, I can't seem to figure out how to get this done.
>
> I don't know why, but I can't get the isc-dhcp-client to assign an alias to
> the
> interface, despite the documentation that states it should.
>
> This is being run on OpenBSD current.
>
> The isc dhclient available is 4.3.4
>
> # /usr/local/sbin/dhclient --version
> isc-dhclient-4.3.4
>
>
> I have created an /etc/isc-dhclient.conf file:
> ---
> timeout 60;
> retry 60;
> reboot 10;
> select-timeout 5;
> initial-interval 2;
> script "/usr/local/sbin/dhclient-script";
>
> supersede domain-name "domain.com";
> supersede domain-name-servers d.n.s.1,d.n.s.2;
>
> request subnet-mask, broadcast-address, time-offset, routers;
>
> alias {
>   interface "em0";
>   fixed-address fi.xed.ip.addr;
>   option subnet-mask 255.255.255.0;
> }
> ---
>
> But, after killing the running dhclient process (included with OpenBSD's
> base
> installation), removing the leases at /var/db/dhclient.leases* and starting
> isc-dhcp-client with:
>
> # /usr/local/sbin/dhclient -cf /etc/isc-dhclient.conf em0
>
> The isc client is able to get an offer from the dhcp server:
>
> Sep 21 16:18:05 xxx dhclient: DHCPDISCOVER on em0 to 255.255.255.255 port
> 67
> interval 2
> Sep 21 16:18:05 xxx dhclient: DHCPOFFER from xx.xxx.xx.x
> Sep 21 16:18:10 xxx dhclient: DHCPREQUEST on em0 to 255.255.255.255 port 67
> Sep 21 16:18:10 xxx dhclient: DHCPACK from xx.xxx.xx.x
> Sep 21 16:18:10 xxx dhclient: bound to xx.xxx.xx.xxx -- renewal in 111100
> seconds.
>
> However, the alias does _not_ get assigned to the interface.  The only
> address
> is the dynamically assigned one.
>
> According to the dhclient.conf man page, "the dhcp client can be set up to
> configure an IP alias using the alias declaration."
>
> I understand this to mean that the alias declaration above should result in
> the
> interface being configured with both the dynamically assigned ip address,
> and
> the fi.xed.ip.addr given in the alias declaration of my isc-dhclient.conf
> file.
>
> But this is not happening.  I can find no guidance on what I am doing wrong,
> and
> why the isc-dhcp-client is not assigning the alias.
>
> Thanks for any advice.
>
> Ted
>
>


-- 


paranoid sysadmin


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