Unknown client alerts and clients not getting IP addresses

Fleming, Tony t.fleming at tcu.edu
Tue Aug 23 13:08:58 UTC 2016


Thank you.

Please let me know if you would like to see more of the configuration, but for now I am including one subnet and client configuration block.



class "Wired" {

        match hardware;

}

class "Wireless" {

        match hardware;

}



shared-network "STUWIRELESS-XXX" {

        authoritative;

        subnet 10.31.0.0 netmask 255.255.240.0 {

                pool {

                        allow members of "Wireless";

                        default-lease-time 3600; #1 hour

                        max-lease-time 3600;

                        option ntp-servers X.X.X.X, X.X.X.Y;

                        option domain-name-servers X.X.X.X, X.X.X.Y;

                        one-lease-per-client true;

                        option routers 10.31.0.1;

                        deny unknown-clients;

                        range 10.31.0.20 10.31.15.254;

                }

        }

}



subclass "Wireless" 44:85:00:2F:81:86;

host XXXX.STUDENT.XXX.XXX {

hardware ethernet 44:85:00:2F:81:86;

}





Here is the logged output:

Aug 23 07:52:56 srvr04 dhcpd: DHCPDISCOVER from 44:85:00:2f:81:86 via 10.31.0.1: network STUWIRELESS-XXX: no free leases

Aug 23 07:53:00 srvr04 dhcpd: DHCPDISCOVER from 44:85:00:2f:81:86 via 10.31.0.1: network STUWIRELESS-XXX: no free leases

Aug 23 07:53:09 srvr04 dhcpd: DHCPDISCOVER from 44:85:00:2f:81:86 via 10.31.0.1: network STUWIRELESS-XXX: no free leases



Here is the lease status:

Ranges:

shared net name        first ip                   last ip                    max      cur      percent  touch   t+c  t+c perc

STUWIRELESS-XXX    10.31.0.20       - 10.31.15.254      4075   436     10.699   3639  4075   100.000



It appears I have plenty of IP addresses in this pool. It appears the look-up to match a known client is failing for some reason.



BTW,

I did clean-up a lot of dead host entries (cut the file size into 2/3rds of its original size), but still having the trouble.



Any help is appreciated.

Thank you.



-----Original Message-----
From: dhcp-users [mailto:dhcp-users-bounces at lists.isc.org] On Behalf Of Simon Hobson
Sent: Tuesday, August 23, 2016 2:29 AM
To: Users of ISC DHCP <dhcp-users at lists.isc.org>
Subject: Re: Unknown client alerts and clients not getting IP addresses



"Fleming, Tony" <t.fleming at tcu.edu<mailto:t.fleming at tcu.edu>> wrote:



> Background:

>                 We create a host record for each device that connects to our network

>                 Over the years our dhcpd.conf file has grown due to

> little purging (yeah - I know we should be purging the data)

> Symptom:

>                 Suddenly today, we began getting reports users are unable to get an IP address.

>                 The clients vary from iphones, to OS X and PC laptops

>                                 The issue doesn't seem to be OS or hardware dependent

>                 My logs are alerting:

>                                 dhcpd: DHCPDISCOVER FROM

> xx:xx:xx:xx:xx:xx via x.x.x.x: uknown client In my dhcpd file there is a "host" record for each device - so I am scratching my head to why the device isn't getting an IP address.

>                 Not all devices are having trouble getting IP leases

> Workaround:

>                 We have removed the directive in dhcpd.conf to "deny unknown clients"

>                 Now all of our devices are getting IP addresses.



Post your config - not all of it ;-)

But when you trim it, be very very careful that you don't alter the structure at all.

Include a problem client - both it's config and the log entries for it.



_______________________________________________

dhcp-users mailing list

dhcp-users at lists.isc.org<mailto:dhcp-users at lists.isc.org>

https://lists.isc.org/mailman/listinfo/dhcp-users
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/dhcp-users/attachments/20160823/81309c02/attachment.html>


More information about the dhcp-users mailing list