Solved

dhcp3 reserved addresses aren't completely reserved

Posted on 2011-03-25
2
569 Views
Last Modified: 2012-05-11
I've reserved a handful of IP addresses in the dhcp3 config of a network.

If a machine with a reserved address connects, it gets its address attributed to it with no problems.

However, There are *other* machines that have connected between  the time I configured dhcp3 and the time the reserved machine connects. Oddly, dhcp3 has attributed some of these reserved addresses to other machines.

Then, when a machine with a reservation connects whose address has already been attributed, it gets the reserved address attributed to it all the same, resulting in a conflict.

I include dhcpd.conf and dhcpd.conf.local, below. Please note that I have left only one reservation in the dhcpd.conf.local for the sake of brevity.

Thanks.


# dhcpd.conf:

ddns-update-style interim;
ddns-domainname "somenet.ch";
ddns-rev-domainname "in-addr.arpa.";
ddns-updates on;
update-static-leases on;

option ntp-servers 192.168.16.21;
option netbios-name-servers 192.168.16.21;
option netbios-node-type 8;

include "/etc/dhcp3/rndc.key";
include "/etc/dhcp3/dhcpd.conf.local";

one-lease-per-client on;
option domain-name "somenet.ch";
option domain-name-servers 192.168.16.21, 195.186.4.109;
default-lease-time 14400;
max-lease-time 22000;
authoritative;
log-facility local7;

zone somenet.ch {
        primary 127.0.0.1;
        key rndc-key;
}

zone 16.168.192.in-addr.arpa. {
        primary 127.0.0.1;
        key rndc-key;
}

subnet 192.168.16.0 netmask 255.255.255.0 {
        range dynamic-bootp 192.168.16.101 192.168.16.199;
        option subnet-mask 255.255.255.0;
        option broadcast-address 192.168.16.255;
        # default-lease-time 14400;
        # max-lease-time 14401;
        option routers 192.168.16.1;
        option domain-name-servers 192.168.16.21, 193.246.63.10;
        allow unknown-clients;
}



# dhcpd.conf.local:

    host montpc02 {
        hardware ethernet b8:ac:6f:3f:94:f0;
        fixed-address 192.168.16.102;
    }

Open in new window

0
Comment
Question by:colliek1
2 Comments
 
LVL 34

Accepted Solution

by:
Duncan Roe earned 500 total points
ID: 35222018
You have defined a range that includes the "reserved" addresses. You must not do that. You need

range dynamic-bootp 192.168.16.103 192.168.16.199;

(this wastes 192.168.16.101 - you could also have if you want range dynamic-bootp 192.168.16.101 192.168.16.101;)

The point is, defining IP addresses that always go to particular MAC addresses does not of itself reserve them - you can only reserve addresses by excluding them from ranges. It then matters little whether you configure a "static" IP address via the MAC or instead you configure the system to have a real static address (i.e. it doesn't used dhcp).
0
 

Author Closing Comment

by:colliek1
ID: 35223261
Of course. It should have been obvious to me. Thanks for the clear and concise explanation.
0

Featured Post

Highfive + Dolby Voice = No More Audio Complaints!

Poor audio quality is one of the top reasons people don’t use video conferencing. Get the crispest, clearest audio powered by Dolby Voice in every meeting. Highfive and Dolby Voice deliver the best video conferencing and audio experience for every meeting and every room.

Join & Write a Comment

I have seen several blogs and forum entries elsewhere state that because NTFS volumes do not support linux ownership or permissions, they cannot be used for anonymous ftp upload through the vsftpd program.   IT can be done and here's how to get i…
Configuring network clients can be a chore, especially if there are a large number of them or a lot of itinerant users.  DHCP dynamically manages this process, much to the relief of users and administrators alike!
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.
This demo shows you how to set up the containerized NetScaler CPX with NetScaler Management and Analytics System in a non-routable Mesos/Marathon environment for use with Micro-Services applications.

746 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

12 Experts available now in Live!

Get 1:1 Help Now