Questions tagged [dhcpd]

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Configure a DHCP server with isc that gives the clients IPs depending on the OS

The problem is that I cannot put a static IP or filter by mac because some clients have dual boot and use both Windows and Ubuntu, I need to be able to somehow distinguish between both OS and both ...
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Multiple name matching statements in dhcpd.conf

Can a class have multiple match hostname statements, e.g. match if substring (option host-name,0,2) = "foo"; match if substring (option host-name,0,3) = "DESK" ?
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ISC DHCP server assigns reserved IP addresses incorrectly via reuse for the wrong MAC

DHCP clients that want to renew their lease with a reserved IP get a DHCPACK although the MAC address does not match. It made no difference where the host definition was located. outside the " ...
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ISC DHCP for relay agents

I would like to configure DHCP server for my networks, but in the same time, i don't want to setup dhcp server on the network where the server itself is. DHCPD insist to configure subnet declaration ...
1 vote
1 answer
510 views

DHCPv6 fixed assigment

Trying to assign fixed ipv6 addresses to my coreos master and worker nodes from my Centos in order to have dual stack running on the cluster. However I am having a hard time getting it to assign the ...
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ISC-DHCP and BIND 9 DNS: DDNS update fails for /27 subnet

I have a problem with DDNS update with ISC-DHCP server. My /etc/dhcp/dhcpd.conf subnet section that doesn't work is: subnet 193.198.186.192 netmask 255.255.255.224 { range 193.198.186.200 193.198....
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dhcpd server invalid mac detection

On my dhcp configuration, i have on commit hook to save device information. My problem is some of the mac addresses becomes invalid: 8:7c:39:cf:b6:3f - this should start with zero 8:d0:b7:52:f9:68 - ...
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1 vote
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What is the exact meaning of "On Commit" in ISC DHCP server configuration?

I know there are three kinds of events we can use for scripting in ISC dhcpd -- commit, expire and lease. My problem is, I am having a little problem in understanding the "commit" event. I ...
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Cannot ping anything on intranet or internet when connected to second subnet in isc-dhcp-server

On my local network, I've got Ubuntu Server running isc-dhcp-server and named. I have a lot of devices that I've assigned static addresses to, and up until now have assigned a small range of IP ...
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What is the difference between a 'host' entry and a 'lease' entry in dhcpd.leases?

In the managed file dhcpd.leases, our lifecycle management application adds a host h1.example.com { ... } entry when building a virtual-machine from the application. However, already built machines ...
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No free leases error with a Static CentOS SolusVM KVM slave

I have a KVM SolusVM VPS slave with CentOS 7 that posts this message every couple seconds: dhcpd: DHCPDISCOVER from 00:25:90:cd:xx:xx via viifbr0: network 0.0.0.0/0: no free leases I use a static IP ...
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How to set up dynamic DNS for 'host' in isc dhcpd

I have set up a couple of subnets in my network, and in one of these subnets I'm setting up hosts like this: subnet 10.0.0.0 netmask 255.255.255.0 { option ntp-servers 10.0.0.1; option time-...
1 vote
3 answers
4k views

isc-dhcp-server: Using option dhcp-client-identifier in host declaration to identify a client

I'm using isc-dhcp-server version 4.3 (isc-dhcpd-4.3.5) as a DHCP server for my local IPv4 LAN and I'm trying to configure it to use the option dhcp-client-identifier (DHCP option 61) in a host ...
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dhcpd unexpectedly destributes a useless route for another subnet as a default gateway

Our dhcpd.conf defines two subnets such like, subnet 192.168.0.0 netmask 255.255.255.0 { option routers 192.168.0.1; # internet gateway } subnet 192.168.1.0 netmask 255.255.255.0 { option ...
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DHCPd IP dispatch

For my tests, the following was done with 2 virtual machines. The server is under CentOS7 and the client under Windows 10 (MAC : 08:00:27:bd:3d:ab). After every modification on the server side, I ...
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Replay DHCPDECLINE to host by edit ethernet address in dhcpd

I known in dhcpd.conf, I can use following config to assigned a fixed ipv4 address to a client. host h1{ hardware ethernet 11:22:33:44:55:66; fixed-address 192.0.2.2; } range 192.0.2....
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Dhcpd won't start due to selinux

have searched tirelessly and can't find an answer to this thats not confusing. I have a clean install of centos 6.2 32bit on a machine I use as a router. with selinux enabled dhcpd refuses to start ...
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Force dhclient to always provide a unique IP from the available pool

I'm running RHEL 7.4 and the dhcpd is controlled by DD-WRT off my router. Tried to use: dhclient -r; dhclient -x; rm -f /var/lib/dhclient.leases; ip a; dhclient -v but it either returns the same ...
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CentOS 7 DHCP server, get IP but cannot ping server or client

I'm trying to create a nat, however, before I can get that far I need to network two PCs via ethernet. The server looks like this: 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state ...
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Exclude subnets from distribution?

In Windows' DHCP server it is possible to exclude an entire subnet from being given out to clients which doesn't have a reservation. They call this "IP addresses excluded from distribution". Now I ...
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3 votes
1 answer
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Edgerouter DNSmasq send updates to BIND

TL;DR: How do I configure the Ubiquiti EdgeRouter, running DNSmasq or DHCPd, and NSupdate, to send its DHCP leases to a central BIND server? I have a system comprised of a few Ubiquiti EdgeRouter X's ...
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2 votes
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538 views

Weird answer of linux DHCP server to gratitious ARP causes DHCP failure

This is a problem, that I ran into recently on a quite heavily configured linux server. This machine runs Samba as an Active Directory Domain Controller, a mail server, a web server, two virtual ...
2 votes
2 answers
3k views

Multiple IPv6 routers on the same network

I have two ISPs for my home network. They are connected to two separate routers. If I run radvd and dhcpd on both routers at the same time, I get no IPv6 connectivity. My IPv6 connectivity only works ...
1 vote
1 answer
2k views

DHCP and logging fixed address "leases"

I have been tooling with a dhcpd server that i have been setting up for, well, for the general excitement of it i guess. I have a bunch of different configurations. I have noticed that fixed-address ...
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1k views

How can I configure DHCP server to issue the same fixed-address by matching with the client identifier in the discover message

I am able to config fixed ip address with hardware ethernet options, but i am trying to assign fixed ip based on client id(option 61) from DISCOVER message. I tried with below configs , but it doesn't ...
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dhcpd hostgroup in a single file

Is it possible to set dhcpd to read MAC addresses from file, and then to set IP and hostname for those particular hosts? To be more clear - everything is supposed to be in that file: mac, ip and ...
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1 answer
3k views

Option 81 in DHCP

Just curious about this. When we enable option 81 on a DHCP network, the DHCP server will start updating the zone that comes along with the client's FQDN. Now, how would client will ever know its ...
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1 answer
4k views

how to block incoming DHCP DISCOVERY messages

I'm running ISC DHCP deamon on centOS and want to block unwanted(by clients MAC address) discovery messages before they reach dhcpd. how can I do this with iptables or anything else?
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dhcpd daemon taking huge amount of memory and restarting with out of memory error

I have to configure isc-dhcp-server for 1 million clients which listens on 4094 vlan tagged interfaces, where each vlan interface is mapped to a subnet declaration. Therefore in total 4094 subnet ...
2 votes
1 answer
5k views

Unable to add forward map ...: SERVFAIL

DHCPD[4.3.5] error: Unable to add forward map from nvhenz710.hen.mentats.us to 172.24.1.31: SERVFAIL no errs in BIND 9.11.1-P2-RedHat-9.11.1-2.P2.fc26 $ groups named dhcpd named : named dhcpd ...
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103 views

How To Use host tag In dhcp.conf

My question is simple. I tried to assign a fixed IP address to wlan0 connected users using dhcp.conf. From configuration file: host clientA{ hardware ethernet 00:80:c6:f6:72:00; fixed-address 192....
2 votes
1 answer
2k views

Isc-Dhcpserver static DHCP missing client-hostname

I got a strange problem with my isc-dhcpserver (Ubuntu 16.04). When clients are requesting from the server, I can see the following output in /var/log/syslog : Jun 21 21:41:25 drake dhcpd[265]: ...
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1 answer
3k views

DHCP Client starts sending DHCP Discover messages upon receiving a NAK from another DHCP server

I am trying to set up a DHCP client that is supposed to get its IP address via DHCP. I have configured two DHCP servers (one in 192.168.X.X pool and the other in 162.16.X.X pool). Then, the client ...
1 vote
0 answers
79 views

DHCPS - single mac whitelist, multiple subnets

I am trying to reduce the size of my broadcast domain and, in order to do this, I need to permit hosts from being able to move from one subnet to another at will. We use a mac whitelist for our dhcp ...
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1 answer
246 views

dhcpd.conf DNS order is being reset after each cobbler sync

I'm trying to switch the order of DNS servers that my clients machines use by editing the /etc/dhcp/dhcpd.conf file in cobbler. This was the settings before I attempted the change: subnet 10.100.48.0 ...
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2 votes
2 answers
40k views

CentOS 7 DHCP server fails to start (won't enable on specified port)

I have a Cent0S 7 miniPC with a wireless and wired network ports. The wireless port (wlp3s0) is connected as a DHCP client with 192.168.10.X addressing and has DNS resolution. I'm trying to setup the ...
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dhcp server not starting on CentOS 5 (XenServer 6.5)

I have a host with XenServer 6.5 (based on CentOS 5) that is currently set up using a static IP by following the procedure here. I have been provided with an IP address, netmask and gateway - I ...
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1 answer
322 views

DHCP leases file has 200+ instances of the same lease?

I'm not sure what's going on here. I have a CentOS 7 DHCP server, and the leases file is growing at a linear but steady rate - it's re-issuing the same lease to the same MAC over and over again, and ...
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1 vote
1 answer
3k views

"match hardware" in dhcpd.conf not working

I've been trying to get mac addresses with a certain OUI into a certain address pool. I haven't been able to get it to work at all. Here is a snippet of my dhcpd.conf and how it's applied. class "...
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1 vote
1 answer
2k views

How can I clear the DHCP GUI in OSX Server? Ghost clients in the building

I have a few client machines showing up in the network (not only in Server.app but also in various logs), which have "Computer Names" (Bonjour names in Apple-speak) which I don't recognize, but ...
2 votes
2 answers
8k views

dhcpd not offering reserved static IP returns unknown lease

typically when I reserve an IP for a MAC addr the device when booting up and requesting a dhcp address, will pick up the address I reserved. However recently the request looks like it comes in but ...
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fedora dhcpd name server configuration

I'm having a hard time configuring a more modern release of a Fedora DHCP service to replace an older one and the problem is that clients aren't getting the appropriate DNS server information. I had ...
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4 votes
2 answers
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WiFi access point without internet access - iOS devices disconnect

I'm trying to configure a WiFi access point to offer a web service on the local network, without offering clients internet access. The web server has a fixed IP address (let's say 192.168.2.2) and for ...
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1 answer
2k views

Client getting wrong option from DHCP server

I'm setting up a machine to load a Debian intallation with PXEBoot, following the guide on the Debian Wiki. I have the boot image sitting on a server, pxe.example.com, at /var/lib/tftpboot/debian-...
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dhcpd.conf for PXE/BOOTP boot not working

I'm trying to configure the dhcpd.conf file so that when I boot through the network using PXE / BOOTP, a bare metal server or a virtual machine (KVM) would get an IP address in the 10.0.2.100 to 10.0....
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1 answer
945 views

Cobbler/TFTP: No filename or root path specified, but why?

I've installed a new Cobbler server and configured it as a DHCP /TFTP server. I've configured the /etc/dhcp/dhcpd.conf like so: [root@centolel ~]# cat /etc/dhcp/dhcpd.conf ddns-update-style interim; ...
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2 votes
2 answers
1k views

Release dhcp lease after forcing client to disconnect

I configured a wifi access point based on OpenWRT to limit the number of clients to 4 at the same time. For that purpose I gave a limited number (4) IP addresses leaseable by DHCP. After a period of ...
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1 vote
1 answer
407 views

Obtaining the running config for dhcpd

Is it possible to obtain the current running config for dhcpd? I inadvertently wiped dhcpd.conf but have not yet restarted the service. It is currently assigning the correct IPs to my test ...
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How to block DHCP traffic using iptables

First let me describe my environment: There is a VM (CentOS) acting as a gateway The gateway VM has to NICs, eth0 connects to public network, eth1 connects to private network eth0 get IP from public ...
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1 vote
1 answer
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DHCP with fixed IP hosts (Ubuntu)

I'm managing an office system that assigns IPs based on the MAC address. The fixed hosts are added in a dhcpd-hosts.conf file which is included in dhcpd.conf. There are some PCs that are not in the ...
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