Questions tagged [dhcp-server]
Dynamic Host Configuration Protocol (DHCP)
547
questions
4
votes
2
answers
2k
views
Can a DHCP Server detect Windows version?
How can a DHCP server distinguish between Windows 10 and Windows 7 clients?
I want to identify the Windows version of the clients using the vendor class, and assign the specified settings.
I am ...
0
votes
1
answer
91
views
In a network with two DHCP servers, how does one server know about leases that a client obtained from the other
A client broadcasts a DHCP discover message. Two servers received and reply with offers message, but client accepts the 1st reached msg from 1st server.
What happens to the 2nd server offer message?
...
0
votes
0
answers
52
views
Cannot connect to Internet due to DHCP and DNS issue
I have an issue with our AD server DHCP and DNS configuration. Here are 2 situations:
Some devices have multiple different IP address for the same device in DHCP and DNS server. After deleting the ...
0
votes
0
answers
55
views
Vendor-class-based options in KEA DHCP server
I want to send DHCP option 66 with different values, based on vendor class identifier. I've created client classes in config, but I don't know how to tell the server to use them. This is what I have ...
0
votes
1
answer
37
views
script to print dhcpd.leases info to syslog/file
So i'm running dhcpd on a server and to my knowledge the logs from dhcpd are not adjustable, if they are i'm dying to know how...
Anyways, i need something to check the dhcpd.leases-file which is ...
1
vote
0
answers
91
views
Freeradius dhcp relay
I have a freeradius v3 running on my raspberry pi together with pihole.
I have a external NGFW acting as a DHCP Server.
I want the freeradius to "forward" all DHCP requests to the firewall, ...
-1
votes
1
answer
173
views
Linux Bind9 DNS server, configuration throwing errors
I am having problem with DNS configuration in Linux. I am using isc-dhcp-server as DHCP server and bind9 as DNS server, but I it returning me errors.
This is my Setup
Internet <--enp0s3 interface--&...
0
votes
1
answer
140
views
How do I deploy correctly my DHCP Servers with DHCP Option 82?
My Goal is to achieve a seperate DHCP Pool on my switches, how am I able to achieve it on a flat network hosted for a LAN-Party. Which means seperate VLANs should be avoided
We're talking about ...
1
vote
0
answers
489
views
Different gateway for a single host in DHCP server
I am using ISC DHCP Server and I want to assign a different default gateway for one of the devices using that DHCP.
I have the network 192.168.0.0/24, and two redundant ISC DHCP servers assign IP ...
-1
votes
3
answers
806
views
DHCP providing IP but not creating DNS A record
I'm having a problem setting up a virtual machine IP assignment via DHCP.
The virtual machine is a clean installation of Ubuntu Server 22.04 The DHCP server is a Windows Server Domain Controller.
When ...
1
vote
2
answers
309
views
How would you set up a macOS laptop to maintain the same IP address between ethernet and wifi?
I have a situation where I need to maintain the same IP address and/or hostname between two network interfaces on several macOS laptops: the ethernet and wifi.
The topology is such that there is a ...
1
vote
2
answers
1k
views
Devices keep getting IP from previous VLAN
Some devices (printers and laptops) that are moved to another building with a different VLAN will not release the IP address assigned. I noticed this first when a laptop reported no network ...
1
vote
1
answer
322
views
DHCP failover with PXE
I'm trying to set up DHCP failover with PXE booting allowed from one of the DHCP servers. As required by the DHCP specification, I've setup separate pools for "regular" DHCP and for PXE ...
0
votes
0
answers
406
views
Wrong DHCP-Adress when switching VLANs
I have a problem with our fairly new kea-dhcp setup. We have a bunch of different VLANs in use for which we want to give out DHCP-Adresses. For this purpose we use a little APU-box which serves our ...
0
votes
1
answer
81
views
Change DHCP range and tcpip connections
I want to change the dynamic range of my DHCP server for a network e.g. it is at the moment from 192.168.0.2 to 192.168.0.100 I want to move it from 192.168.0.101 to 192.168.0.200 but I don't want to ...
0
votes
0
answers
2k
views
ISC DHCP server web interface
I want to ask what web interface could be used for isc dhcp server on Ubuntu 22.04 server. I want to create dhcp server on ubuntu, I installed and configured isc dhcp but now i want to manage it from ...
-3
votes
1
answer
387
views
Windows Server 2019 DHCP Option 33
Noticed there is an option in DHCP for static routes, looks like it is using a server name and an IP that you assign, is this the same thing as adding an entry into the host record like we used to do ...
1
vote
0
answers
615
views
deploying pfSense in OVH public cloud as a DHCP server in HA
I am trying to deploy two pfSense in the OVH public cloud (OpenStack).
Each has its own public IPs and public connectivity works without any problem.
Things become more complicated on the vRack part (...
0
votes
2
answers
662
views
Getting IP address from another subnet's DHCP
As in the diagram below I have two routers on two different subnets.
I connected them together but have not set static routes yet.
Network Diagram
However, when connecting from Access Point A's SSID, ...
0
votes
1
answer
291
views
DHCP renewal can't go through because DHCP server is down
To my experience, if a DHCP client tries to renew its lease, but the DHCP server is down, and after the lease time is over, there are two possible scenarios:
The client keeps the IP
The client goes ...
0
votes
0
answers
741
views
How to manually purge dhcpd.lease?
How do I manually purge ALL dhcpd.lease ?
Can I just sudo echo /dev/null > /var/lab/dhcpd/dhcpd.lease ?
It's a special use case of testing ground; we have an isolated LAN for developers to do test ...
1
vote
1
answer
533
views
DHCP server does not provide correct filename for PXE
I'm trying to configure PXE server for both Legacy/UEFI support. So I need to provide different bootloaders based on architecture of machine.
Here's part of dhcpd.conf:
option architecture-type code ...
0
votes
1
answer
68
views
Windows DHCP IOT retain same IP
I am trying to address a problem.
We have a windows DHCP server and some devices, which we need to replace on needs. The device has a custom DHCP client which sends DHCP-DISCOVERY Packet with ...
0
votes
1
answer
730
views
Centos 7 dhcp server not responding to UEFI PXE DISCOVER
I'm trying to set up a Centos 7 server as a dhcp server for PXE (UEFI). I'be tried several changes to the dhcpd.conf file, but nothing seems to make a difference.
dhcpd.conf:
allow booting;
allow ...
0
votes
1
answer
162
views
Migration strategy to migrate a DHCP scope from old DHCP server to new DHCP server as smooth as possible
My current homeLab and entire home is currently running on a single subnet 192.168.0.0/24 with my ISP provided router running a DHCP scope handing out addresses in the 192.168.0.20-192.168.0.254 range,...
0
votes
1
answer
95
views
Force sending DHCP options
I have a lab spectrometer that boots using PXE from boot files stored on a computer. They exist inside a local network with the computer acting as both the DHCP and TFTP server.
The spectrometer ...
0
votes
1
answer
362
views
Setting up LAN gateway for school club network - "No subnet declaration for enp3s0"
I am a computing teacher, I am trying to setup a "sandbox" network with internet access for an after school computing club.
I have an old PC (Debian 11 installation) with 2 ethernet ...
0
votes
1
answer
996
views
DHCP logs showing (no free leases)
I have setup new isc-dhcp-server in ubuntu 20.04. all client getting connect but showing there logs (no free leases)
client connected only 25 machine.
sudo tail -f /var/log/syslog
Sep 9 09:43:57 ggn-...
1
vote
1
answer
405
views
How to send custom DHCP option on all Offer and Ack packets in kea?
I'm using the Kea dhcp server, and I want to use the DHCP options to send data to the server's clients. Following the instructions here, I listed the option with the "always-send": true ...
0
votes
1
answer
1k
views
Decode UID from dhcpd.leases
I have am testing a device on my network which has this lease assigned:
lease 192.168.110.85 {
starts 3 2022/07/20 16:12:37;
ends 3 2022/07/20 16:22:37;
cltt 3 2022/07/20 16:12:37;
binding ...
0
votes
0
answers
3k
views
dhcp: lease expiration vs. infinite lease
As per RFC2131, when the lease expires the client has to stop using the IP address. So do I understand right that if the lease lifetime is set to infinite on the server, then the client does not need ...
1
vote
0
answers
147
views
libvirt and dnsmasq does not allow to start Kea DHCP server
I have libvirt installed which instantiates dnsmasq process per each virtual bridge interface, e.g. virbr0, however for some reason I can't start kea-dhcp server on other interfaces in the system, ...
1
vote
1
answer
598
views
Freeradius with dhcp server: Calls to perl module returns error
This is a continuation of my previous question in sending static routes from Freeradius DHCP server implementation in combination with Strongswan VPN server.
When debugging Freeradius using tcpdump ...
0
votes
1
answer
619
views
isc-dhcp-server ip-range speicifc domain-name-server
I'm trying to get an isc-dhcp-server configuration to use different DNS-Servers based on the ip-address assigned.
Basically, I want some of my client marked as not-trusted, which then may not access ...
0
votes
1
answer
476
views
Migrating Old Active directory Forest with two domains
We have single AD forest with two domains as follows:
Domain A:
Contains nearly 30 servers (7 physicals and 23 VMs) all hosted on Microsoft Hyper-V server
Nearly 500 Active user accounts
A huge file ...
2
votes
0
answers
1k
views
Obtaining two DHCP addresses on Linux
There have been various questions asked a long time ago about obtaining two IP addresses via DHCP on Linux. Most of those are still relating to old 'alias interfaces', like eth0:0, which has been ...
0
votes
1
answer
100
views
ScreenOS SSG-320M Source Interface Based Routing
quick question. Couldn't figure this out with even the ScreenOS Bible.
Juniper SSG-320M Firewall, Just added an 8port PIM Module(ETH1/0 to 1/7):
ETH0/0(Trust) 172.16.1.1/16
ETH0/2(UnTrust) 192.168.0.5/...
0
votes
1
answer
276
views
DHCP server IP reservation during the "offer" step
How long is the IP reserved by the DHCP server, when it sends the offer message? Imagine the client does not send back the request message, after how much time is the IP available again?
Thanks for ...
-1
votes
2
answers
410
views
Our cable modem is acting as a rogue DHCP server, even though its DHCP function is supposedly disabled [closed]
We have, for quite some time, had problems with systems on our LAN coming up "bottled," i.e., with non-functional connections. I recently noticed that the assigned IP addresses looked like ...
0
votes
1
answer
1k
views
Using DHCP reservations instead of static IP address configuration for servers
I was wondering if it is better to use DHCP reservations for servers and computers that must have static IP address, excluding DHCP servers themselves, Domain Controllers, and DNS servers of course, ...
0
votes
1
answer
254
views
static bindings in DHCP server
I'd like to enable static binding in the DHCP server (I'm using KEA Dhcp https://www.isc.org/kea) but I think it is applicable to other implementations as well.
What exactly I want to achieve is to ...
0
votes
0
answers
2k
views
dnsmasq DHCP not working, not replying to DHCP requests
I have setup dnsmasq as DHCP server on a CentOS VM, however it is not replying to DHCP requests. What could be the issue? Following is the configuration and tcpdump logs.
interface=ens224
listen-...
0
votes
0
answers
1k
views
Can't start isc-dhcp-server due to error " AgentInitCheck: agent comms failure"
I have a Raspberry Pi 4 - Model B, and I'm trying to create an adapter from Wi-Fi to Ethernet using the Pi. I'm currently using this gist as a guide for how to create it, but I keep running into an ...
0
votes
2
answers
631
views
ISC DHCP/DDNS setup: Static entries for non-dhcp clients
I have set up a local network with ISC BIND9 and DHCP service. New leases trigger the DHCP to add an A and PTR record which works perfectly.
I also added lots of static host entries in the dhcpd.conf. ...
2
votes
1
answer
3k
views
Identifying current main DHCP server
There are two DHCP server of the same IP address example.(10.100.9.12 and 10.100.9.13).
The gateway, subnet mask, and DNS is the same.
The current DHCP are running on Vlan9.
Is there any possible way ...
1
vote
1
answer
4k
views
Windows DHCP not showing the accurate leases
In Windows System Event log, there are DHCP server warnings that IP address range of a scope (10.40.0.0) that available is low.
Windows Event Log
But in the DHCP program, the Address Leases is only ...
1
vote
1
answer
4k
views
DHCP NTP Server Option 042 not propagated by Windows Server 2016
I am trying to make NTP server settings available to our non-Microsoft devices on local wired and wireless network. Obviously, they don't know how to use MS AD time info from domain controller.
Our ...
0
votes
0
answers
1k
views
Problems with WDS on different subnets
I'm setting up a WDS (Windows Deployment Service), the WDS server is in a different subnet than the clients that need PXE.
These subnets are connected through a VPN tunnel.
Routers are pfsense.
But on ...
0
votes
1
answer
463
views
isc dhcp multiple option 240 in same subnet
I'm fairly new to isc dhcp.
I'm working at an ISP and need to provide our STB's with an option 240, and it has worked fine for years, the problem now is that we are getting a newer model, that needs a ...
0
votes
2
answers
2k
views
Query IP/hostnames in local network (Windows)
I have a Windows Server based network, running a Windows DHCP and DNS server. How can I list all the computers in the local network known to the server? That would mean querying either the DHCP or the ...