Questions tagged [isc-dhcp]

ISC DHCP is open source software that implements the Dynamic Host Configuration Protocols for connection to a local network. It is a reference implementation of those protocols, but it is also production-grade software, suitable for use in high-volume and high-reliability applications. DHCP is available for free download under the terms of the ISC License, a BSD style license.

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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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DHCP DDNS Updates to secondary DNS sever

I am trying to configure DDNS updates from the ISC DHCP server to the zone that is hosted on the windows server, in the dhcpd.conf I have zone section a below zone example.com. { primary 192.168.0.45; ...
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isc-dhcp-server does not push domain-name to client

I have installed the DHCP server (isc-dhcp-server) on my Ubuntu 20.04. The client computer (also a Ubuntu 20.04 Desktop machine) gets assigned IP address, but id doesn't get the assigned domain-name (...
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Server DHCPv6 with Linux Alpine

I want create a server dhcp6 with alpine I'm using Kea-dhcp6. The my file config this is: { # DHCPv6 configuration starts on the next line "Dhcp6": { # First we set up global values &...
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Windows AD not updating Linux DDNS in hybrid integration

I am setting up a Windows AD server, with a Linux DDNS setup. The Linux DDNS runs perfectly fine as expected. However, when I try to add the AD role to the Windows Enterprise 2019 server, the role ...
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How to get custom option on client from ISC DHCP server

Over ISC-DHCP server I wanted to define a custom DHCP Option, for which I am using below config option imagefile code 224 = ip-address; subnet 192.168.29.0 netmask 255.255.255.0 { range 192.168.29.1 ...
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netplan - Network with DHCP configured, but no internet

I am trying to configure my Ubuntu Server 20.04 LTS to use DHCP in its network configuration. Many tutorials on the internet recommend that I create the following file with the following settings... ...
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Unable to add forward map SERVFAIL/REFUSED DDNS

I am using bind9 on a primary dns server with two secondary dns servers in a master/slave relationship. I am attempting to implement DDNS but seem to be running into a problem when it comes to adding ...
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Block the DHCP server from broadcasting into the second ethernet interface

I have setup my DHCP server by following the instructions in https://wiki.debian.org/DHCP_Server. This all works but the issue I am having is the DHCP server is being broadcast in the main company ...
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Isc-dhcpd using includes in subnets

Trying to move some commands to includes. Putting it directly on the config works Is there any way to accomplish this? I have subnets with the same information over and over again. Errors: /opt/dhcpd/...
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Can isc-dhcpd be configured to remove DNS records when leases expire?

I've configured my dhcp server so it can successfully add records to a private DNS zone when it issues a lease for a client. I never see it removing a lease however. Is it supposed to do so or is ...
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How to view IPv6 leases assigned by isc-dhcp-server through dhcpd6.leases?

Is there a command or utility to view IPv6 leases assigned by isc-dhcp-server? I know of several utilities for IPv4 such as dhcp-lease-list or the web-based glass, but none work for IPv6. Any ...
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How to register SLAAC hosts in dnsmasq for host resolution?

On my network, hosts receive IPv6 information through SLAAC (radvd). The RDNSS server is specified as follows, and runs dnsmasq RDNSS fd8a:9ae9:9afc:fa2::1 { }; Is there a way to have hosts ...
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Why is ISC DHCP server ignoring the fixed-address statement?

I want for the devices which belong to different VLANs to have different routers. For instance: The device 10.0.10.84 inside a VLAN 10.0.10.0/24 would have its router set to 10.0.10.1, whereas: The ...
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DHCP Server - Unable to share Internet to clients

note: I will call the server running isc-dhcp-server "DHCP-SERVER", and computer wired to my switch "DHCP-Clients" Hi, I am currently setting-up a network, and i am unable to share ...
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223 views

how does isc-dhcp-server start on debian 10 with systemd

I'm on a beaglebone black running a debian 10 console image. A bit of an odd setup that I have, but I need to make it run that way. The issue: isc-dhcp-server fails to start at boot, but does start ...
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how to setup dhcp relay in maas?

I have 5 subnets and I don't know how to set them on MAAS subnet to connect to a one dhcp relay agent. image1 Do I have to add each subnet to specific vlan and fabric or as shown here they all can be ...
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isc-dhcp dhclient request address endless loop

when a Linux Mint 20 virtualbox VM requests the network config to the home LAN router DHCP through isc-dhcp client with the stock /etc/dhcp/dhclient.conf config file everything runs fine: (BTW 192.168....
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isc-dhcp-server (dhcpd) gives old next-server in DHCP offer

I'm running isc-dhcp-server (dhpcd) version 4.4.1 on ubuntu 20.04 with a subnet configured like so, which has been working just fine. # /etc/dhcp/dhcpd.conf subnet 10.0.1.0 netmask 255.255.255.0 { ...
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dhclient is sending host-name for IPv4 but not IPv6

I am setting up a home server running Debian 10 (Buster), but I have been unable to associate the host's name with its IPv6 addresses. I have a router running OpenWRT, which is configured with dnsmasq ...
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ISC DHCP server - append “01” to the end of Option 43

My current Option 43 generates this hex value in DHCP Offer. See my current configuration below. f2080a0a0a0a0a141414 I need to add "01" at its very end and increase length from "08&...
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Automatically update isc-dhcp failover servers configuration files

I have a pair of failover isc-dhcp servers on Ubuntu 16.04 machines. I want a subnet{} part of a config file of one server to be automatically updated when I manually update a config file of another ...
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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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ISC-DHCPd how to assign different DHCP settings even if request originated from different subnet?

Network setup 10.0.1.0/28 (VLAN 1) 10.0.1.32/28 (VLAN 1) ISC-DHCPd setup subnet 10.0.1.0 netmask 255.255.255.240 { option routers 10.0.1.1; } subnet 10.0.1.32 netmask 255.255.255.240 { option ...
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Why does a manually deleted dhcpd lease return?

DHCPD: 4.3.6 OS: CentOS 8 I removed an entry from the dhcpd.leases file by using Webmin. It seemed to work for a time, but then the entry popped back into the file. Thinking it was a Webmin issue I ...
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228 views

Why can't I use IPv6 address for DHCPv4 client option 6 (DNS server)

I am trying to configure options for a DHCP network and the proprietary software (that is layered on top of ISC's DHCP server) that I am using won't allow me to put in an IPv6 address. In other ...
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118 views

One DHCP server assigns IP, but another assigns other options

Is it possible to make isc-dhcp-server send dhcp options like filename, vendor-class-identifier but NOT an IP address for the client? That is, I need dhcpd to send a few options but NOT the client's ...
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Why is my DHCP client w/ reserved address missing the default gateway?

I'm running isc-dhcp-server on Ubuntu 18.04. Clients without a DHCP reservation are able to get an IP address, subnet mask, default gateway and DNS servers from the pool no problem. As soon as I ...
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2k views

isc-dhcp-server fails if interface not connected on reboot

On Ubuntu 18.04 on my gateway server, I've installed and configured isc-dhcp-server, but it doesn't start up (i.e. it fails to start) if there's nothing connected to enp2s0 after a reboot. Note it ...
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63 views

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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Configuring isc-dhcpd server for DHCPv6 with multiple NTP addresses

I'm trying to configure a DHCPv6 server to provide more than one NTP address (option 56) using the isc-dhcpd server. Is there a currently supported way of doing this? My first attempt was defining a ...
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335 views

Clear routes from DHCP option 121

I have 3 subnets 192.168.10.0/24 192.168.103.0/24 192.168.2.0/24 Most of them can route to each other via static routes defined in their respective default gateways. However due to some ...
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140 views

How to add more than 32 routes to isc-dhcp-server and separate them to 2 fields?

Is there any way to add long list routes to server? Actually now I can add only 32 routes because we have only 1 octet for them. After adding more than 32 routes I received "Malformed packet" by ...
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1answer
150 views

Isc Dhcp-allow only 1 lease from opt82 tag

I'm implementing an isc dhcp server that will be utilizing option 82 tags from our switches to hand out dhcp information/addresses I'd like to deny multiple requests with the same tag (if someone ...
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1answer
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ISC-DHCPD & BIND9: Adjust hostname for BIND ddns registration

I am running isc-dhcpd-4.4.1 and BIND 9.11.6 daemons on FreeBSD 11.2 server for a small company. dhcpd serves a number of Windows stations (assigning them mostly static IP addresses), several special-...
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ISC-DHCPD & BIND9: Dynamic DNS interaction

I am running isc-dhcpd-4.4.1 and BIND 9.11.6 daemons on FreeBSD 11.2 server for a small company. dhcpd serves a number of Windows stations (assigning them mostly static IP addresses), several special-...
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622 views

Proxmox KVM IPv6 Routed not working

I got a /48 v6 assigned by my Provider with a dedicated server, on which I did install Proxmox 5. My Issue is, that the dhcpdv6 should assign the VM a fixed ip, but it does not get the IP assigned. I ...
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1answer
276 views

isc-dhcp host using files

I configured ise-dhcp-server, which works fine, but my dhcpd.conf is starting to become very big. I'm trying to find information (without results), on whether it's possible to use something like ...
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2answers
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How do I purge dhcpd.leases? [duplicate]

I'm running DHCPD (isc-dhcp-4.2.4) on an Ubuntu 14.04 system. The var/lib/dhcp/dhcpd.leases file is getting pretty huge (350MB). Looking in it, there's historical data going back many months about ...
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DHCP client doesn't get address

I'm trying to use a Phytron MCC-1 motor controller which gets its IP only via DHCP (no manual setting). I setup isc-dhcp-server on ubuntu as such: # /etc/dhcp/dhcpd.conf option domain-name "example....
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How to use omshell with ICS DHCP?

In /etc/dhcp/dhcpd.conf have added omapi-port 7911; omapi-key testkey; key testkey { algorithm hmac-sha256; secret QUt1z1O3fxqgSDKILAMXFA==; } but it won't let me connect when I do # systemctl ...
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186 views

windows machine gets assigned wrong netmask

I have a Debian based DHCP server. It assigns correct netmask 225.225.225.0 for all devices (WiFi router, voip, scanner) except for the windows machines. They all get assigned 224.0.0.0 for some ...
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227 views

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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1answer
654 views

DHCP: Advertise DNS Server with port (not 53)

In my network I have a small docker swarm running several apps. Latest I tried to setup two new services offering DHCP with ispcpd and DNS with unbound to the network. Master of the swarm is a new ...
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1k views

ISC-DHCP-SERVER adding incorrect reverse zone entry

I have ISC-DCHP-Server and BIND9 running on Debian Stretch. I am trying to setup Dynamic DNS for my client computers, but I'm struggling with the reverse zone. Currently, when computers request an ...
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1answer
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Multi router network and IPv6 DHCP/RA issues - How to assign default routers?

I've again got problems with our LAN. There are 4 WAN gateways all on the same subnet, all with 100M uplink. On IPv4 I advertise default routers using a ISC DHCP Server. On IPv6 there doesn't seem to ...
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429 views

Why would ISC dhcpd ignore vendor options?

I'm trying to use an existing dhcpd to autoconfigure Raritan networked PDUs. This works roughly like PXE booting: there are additional DHCP options that direct the device to fetch a config file via ...
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1answer
4k views

ISC DHCP assign pool/subnet to certain MAC addresses

Hej, desperate here! I'm running isc-dhcp-server 4.1 here (with webmin but that's another topic) and want to give some options (tftp-server and bootfile) to network-components that I can identify by ...
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2answers
627 views

Disabled dhcp-server on router prevents clients from getting an address

I have a weird issue on my local network which prevents some clients, sometimes acquiring an ip address from the real dhcp-server (x.x.x.3). The dhcp-server is a CentOS VM running isc-dhcp-server for ...

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