dhclient starts on startup, but no IP is configured

Isaac Grover isaac.grover at gmail.com
Tue Aug 15 01:14:23 UTC 2006

On 8/14/06, Glenn Satchell <Glenn.Satchell at uniq.com.au> wrote:
> >Date: Mon, 14 Aug 2006 08:13:45 -0500
> >From: "Isaac Grover" <isaac.grover at gmail.com>
> >To: dhcp-users at isc.org
> >Subject: dhclient starts on startup, but no IP is configured
> >
> >Good morning from Wisconsin,
> >
> >I am running FreeBSD 6.1-RELEASE with four NICs: rl0, rl1, dc0 and
> >sis0.  All the *0 NICs are static IPs, and rl1 is the only NIC that
> >gets its IP through DHCP.  At the moment, there is nothing else
> >running on this box except ssh and no firewall is configured yet.
> >
> >On boot, dhclient starts up to get an IP for rl1 via DHCP, but there's
> >an error and I see the dump of what looks like a README, but it
> >scrolls by too quick to catch it all.  After logging in, doing an
> >'ifconfig rl1' never shows an IP for rl1.  Minutes can go by; still no
> >IP.  So I do a 'killall dhclient; /sbin/dhclient rl1' and I have an IP
> >for rl1 within seconds.
> >
> >Has anyone here seen this behavior before?
> >
> >Thank you in advance,
> >--
> >Isaac Grover, Owner
> Hi Isaac,
> Some switches take a while for a port to be active after the link is
> detected. In the meantime dhclient times out. So when you manually run
> dhclient after the system has booted, the switch port is now active and
> communication happens.
> If you search to archives for terms such as "portfast" I think you'll
> find how to disable this on, at least, Cisco switches. Alternatively
> you may be able to bump up the timeout in dhclient.conf.
> regards,
> -glenn

Thank you for the info about portfast, but I'm not running Cisco
switches.  The "switch" is a stock Linksys WRT54GS acting as a DHCP
server for this client only as a test.  I also configured it as a
switch so this client would get an IP from the upstream DHCP server,
still the same results.  After boot, ten minutes went by before I got
impatient and did a "killall dhclient ; /sbin/dhclient rl1" to force
the client to request an IP.

It almost seems as if two instances of dhclient are starting up
simultaneously on boot, and the second instance is causing the first
instance to get confused and not actually accomplish anything.

Isaac Grover, Owner
Quality Computer Services of River Falls, Wisconsin
Affordable I. T. Consulting, Web Design, and Web Hosting.
Commercial and Residential Inquiries Welcomed.
Web: http://www.qcs-rf.com

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