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 ...

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dhcpd (isc-dhcp-server) not using part of address range

dhcpd (isc-dhcpd-4.3.4 under Debian) ignores part of specified address range. I have the subnet 10.24.32.0/22 assigned to interface: 10.24.32.0/22 dev net0 proto kernel scope link src 10.24.32.1 ...
2
votes
1answer
20 views

Can I prevent Debian from hitting DHCP server twice during installation?

I have a DHCP server used to do unattended installations of Debian: boot from PXE, and then install the operating system with a preseed. The DHCP server (Debian's isc-dhcp-server package) is ...
4
votes
2answers
513 views

Why do I get “No subnet declaration” starting ISC DHCP server on subinterfaces?

I have created two subinterfaces on eth0 : eth0:0 with IP 192.168.10.1/24 eth0:1 with IP 192.168.11.1/24 Configured /etc/dhcp/dhcpd.conf like that: option domain-name-server 194.204.159.1; ...
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0answers
546 views

How to manage gateway assignment in different VLAN's with isc-dhcp-server?

We are managing our network by using DHCP and we sometimes add new subnets (IP Pools) to network through different VLANs. What we want to do is to manage all those IP pools from same DHCP server but ...
2
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3answers
2k views

Fixed dhcp host to automatically expire any lease

I have the following situation: Multiple offices with multiple firewall/dhcp servers. Every time the IT team of some office plugs a new network printer i need to create a fixed-address entry, and ...
0
votes
1answer
11k views

SLES DHCP Dynamic DNS: Unable to add forward map…: not found

I have a SUSE Linux Enterprise Server 11.3 install running on Amazon EC2 based off the official AMI. With DHCP and BIND configured (via yast) I'm having issues with Dynamic DNS. When a client ...
0
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0answers
20 views

DHCPv6 not working when UFW is enabled (Ubuntu 16.04 LTS)

So, as the title says, I setup a isc-dhcp-server for DHCPv6, which is working as long as UFW is disabled. Once enabled, though I have all the necessary rules in place, and UFW is enabled for v6, it ...
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1answer
83 views

Block DHCP server from other network

I have problem on PC's (Windows 7) with two network interfaces, sometimes nic that is supposed to be in network 10.1.19.0 has address from 192.168.0.0 My networks: 192.168.0.0/24 with DHCP running on ...
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0answers
29 views

Linux machine gets different IP through and after installation

we have some automatic building of our building machines using packer (jessie, trusty, xenial, macos, ...) on separate network (VLAN on L3 switch which is used as default GW for the network). Till now,...
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1answer
83 views

Why does a DHCP4 client not respond to the DHCP Offer from a DHCP server?

An extremely simple DHCP server works reliably with Windows 10 PCs and Android devices. It receives DHCP Discover from a client, replies with DHCP Offer, then receives DHCP Request from a client. ...
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0answers
53 views

How to configure isc-dhcpd-server to update reverse zone without client pre configuration?

I'm trying to set up isc-dhcpd-server from ubuntu 16.04 (4.3.3-5ubuntu12) to configuring heterogeneous network with ubuntu, windows, macos, other ip devices. I'm already setuped bind to store ip ...
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0answers
10 views

What data is stored in DHCID RR by rfc 4701 (in lay terms)?

To understand what is going on my dhcp server I need to understand what is stored in this record that idenities my dhcp clients. I have long read this standart. But cannot understand. In lay terms I ...
1
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0answers
20 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 "...
0
votes
2answers
62 views

Don't write “no free leases” messages from ISC DHCP server to systemd log

I have a DHCP server that provides TFTP server IP, NBP (Network Bootstrp Program) and IP addresses to PXE clients. When a machine boots normally (not PXE boot) it gets an IP address from another DHCP ...
0
votes
1answer
40 views

DHCP renew fails with multiple subnets on same link

Our network currently consists of 3 subnets on the same link: 1.2.3.0/24 is the global subnet 10.1.0.0/16 is used for NAT (because there are far more than 200 clients) 192.168.0.0/16 is the "guest ...
1
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1answer
74 views

Multiple interface Red Hat 6 ISC DHCP Server sending Incorrect PXE next-server

My setup: Red Hat 6.7 isd dhcp server 2x networks connected (A and B) One DHCP pool configured on Network A When I had this server set up on a single network ("A") it worked fine, now that I added a ...
2
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2answers
3k views

ISC DHCP server: how many IPs are in use?

I'm wondering what is the correct way to count how many IPs are in use in my network according to the dhcpd process. Is it just a matter of counting "binding state active" lines in dhcpd.leases file? ...
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2answers
39 views

DHCP issue with Cumulus and ESXi

So my switch has Cumulus Linux running on it and I have ESXi running in my network. So my main network is on 172.22.0.0/24 which has my my esxi. The networks I want esxi vms to run on is 172.22.20.0/...
1
vote
1answer
47 views

Traffic control. Prevent unauthorised clients to use IPs outside dhcp range and connect to network. Ubuntu server

I'm new here. I'm looking for a way to prevent my network users to connect to internet using static IPs on their devices outside DHCP range (dhcp range: 10.5.0.1-10.9.254.254). It's like denying ...
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0answers
22 views

Linux clients get DHCP, Mac and Windows clients does not

I'm a sysadmin for a smaller computer lab (~40 clients and ~2000 users). We are, since this fall, seeing some weird issues with DHCP within our network. The server receives a DHCP discovery from the ...
1
vote
4answers
578 views

why would dhcp listen port 80

I have a CentOS server with isc dhcpd and apache 2 webserver running. A couple of minutes ago I have tried to restart apache: /etc/init.d/httpd restart Restart has failed with: Starting httpd: (98)...
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0answers
54 views

dhclient bound to recorded lease even if no DHCP server is availabe

My Ubuntu machine is connected to switch and switch is connected to DHCP server(router).Now whenever DHCP server is down but link is available through switch it tries DISCOVER multiple times. But ...
0
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0answers
36 views

isc-dhcp-server set same ip to eth0 and wlan0

On my network I've several notebook with eth0 and wlan0. I'd like fixed with the same IP. I testing it with the example below. host notebook_a { hardware ethernet ab:ab:ab:ab:ab:ab; fixed-...
3
votes
1answer
122 views

How to generate DHCP Decline scenario / packets

I have a dhcp packets sniffer, which needs to log if it sees dhcp decline response coming from client.I need to know the scenario where client can send dhcp decline response to dhcp server. I tried to ...
0
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0answers
137 views

Force isc-dhcpd to disregard client hostname in ddns updates

I have the following configuration of isc-dhcpd-4.3.1: ignore client-updates; ddns-update-style interim; subnet 192.168.128.0 netmask 255.255.255.0 { use-host-decl-names on; update-static-...
0
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0answers
23 views

Can I use isc-dhcpd to provide an IP address based upon the request parameters?

I've got a dhcp request to be served with ISC-DHCPD: Gateway-IP 10.128.1.9 Client-Ethernet-Address 00:01:23:45:67:89 Vendor-rfc1048 Extensions Magic Cookie 0x63825363 DHCP-Message ...
0
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0answers
58 views

Configuring ISC DHCP server to not serve IP's on the local network

Is it possible to have a DHCP server serve subnets for multiple network segments, but not its own local subnet? I have a DHCP server on a subnet 10.x.x.x. It serves approximately 125 subnets on ...
1
vote
1answer
142 views

Assign more than one IP Address to the same MAC Address on Linux ISC-DHCP Server

I have the following question: One Linux DHCP server in pool mode, because of the step of fabrication, all the products have the same MAC Address that is changed at end of line, the boards use ...
0
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0answers
61 views

dhcpd.conf — one-lease-per-client statement having no effect

I have read on this and this man page that the one-lease-per-client true statement in my dhcpd.conf will stop duplicate leases to a single client. However, I am still able to sustain multiple leases ...
0
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1answer
155 views

ISC DHCP Server “Dynamic and static leases present”

i have a problem similar to Fixed and dynamic IPs in ISC DHPD lead to double lease In my DHCP-Log I often receive warnings like Jan 21 10:20:56 dc2 dhcpd: Dynamic and static leases present for 192....
0
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2answers
70 views

Create smaller subnets from large subnet

My network is 10.10.0.0/16. I would like to break this up into /24s. My environment: I use /etc/hosts with dnsmasq for DNS and isc-dhcp-server for DHCP on an Ubuntu 14.04 server (gateway, router) ...
1
vote
1answer
152 views

Unknown network segment - isc-dhcp-server

My network is operated by Cisco Catalyst with several VLANs and one DHCP server. On the Catalyst, for each vlan is set ip address-helper with the IP of DHCP server. isc-dhcp-server on ubuntu 14.04 is ...
0
votes
1answer
105 views

classes declaration inside of subnets in isc dhcp

I would like to use class declarations based on a subnet scope, is that allowed? Or are all classes global scope? here is my dhcp.conf snippet: subnet 10.200.147.0 netmask 255.255.255.224 { ...
1
vote
3answers
1k views

dhcpd not pushing ddns updates to bind

BIND and DHCPD are configured but as far as I can tell DHCPD makes no attempt to even send Dynamic DNS update to BIND. I can manually add records using nsupdate with the same key I have configured ...
1
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0answers
25 views

Weird behavior with multiple pool inside shared networks on isc-dhcp-server

I have a weird behavior on my dhcp-server, I am using a load balance configuration and using multiple pool inside that shared-network, I have this configuration: shared-network "my-shared-network" { ...
0
votes
0answers
83 views

ISC DHCPv6 reservation

I've set up ISC DHCPv6 server on a CentOS 7. Here is the /etc/dhcp/dhcpd6.conf: authoritative; option dhcp6.domain-search "example.com"; default-lease-time 3600; max-lease-time 7200; log-facility ...
0
votes
1answer
3k views

configure a dhcp server to serve two different scope on the same subnet with multiple interfaces

Ok, so here I am with a pretty complicated problem on a Debian Wheezy server I have three interfaces : eth0, eth1 and wlan0 on a single server, eth0 will act as a gateway for eth1 and wlan0, I have a ...
0
votes
3answers
3k views

dhcpd won't let go of old leases

We have DHCP setup to hand out leases in the following range: 192.168.10.190 - 192.168.10.254 (roughly 65 leases) Our small business network only has about 30 computers that use DHCP. We noticed ...
0
votes
1answer
254 views

ISC DHCPD class is not assigned

I'm trying to setup a boot server which only answers to devices which want to boot over the network. Depending on the boot rom, I need to deliver different boot images, the other settings are common. ...
1
vote
0answers
97 views

Can I configure ISC DHCP to issue the same fixed-address to every client?

I have a handful of devices which are normally in separate networks (or perhaps not even connected to a network), and they use DHCP to get their IP addresses. Now I would like to run some script on ...
2
votes
1answer
85 views

Is it possible to set a dhcp option 77 value in vsphere as a config parameter so vNIC ROM (e1000/vmxnet3) uses it during PXE?

I'd like to set a dhcp option 77 string value in vsphere as a config parameter on a vm or vm template so that the vNIC ROM (e1000/vmxnet3) uses it during the DHCP part of PXE. My goal is to have PXE ...
1
vote
1answer
228 views

Symmetric DHCP failover configuration

I have set up a DHCP server on CentOS 7. It runs beautifully, however due to business demands, we are expanding to another site far away. This gives us the opportunity to host a failover DHCP server ...
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votes
2answers
506 views

Can ping server one from client 1, but can't ping client 1 from server

I set up a router on my linux machine as described here. Now I can ping the server/router from my windows client. I can also ping my linux client from my windows client. But I can not ping the windows ...
1
vote
2answers
3k views

Iptables - Allowing only a single dhcp (relay) client

I am trying to create a firewall rule on an Ubuntu 10.04 server running isc-dhcpd. I only want dhcp to be accessible by a single relay host (172.1.1.1). I have iptables set up like so: # iptables -...
1
vote
1answer
374 views

Remotely monitoring ISC DHCP Server with Nagios

I have a WAN and I'm trying to use Nagios to check that a DHCP server in a subnet not directly visible to the Nagios box is up and handing out IP addresses, and I've been unable to make this work. I ...
0
votes
1answer
285 views

How do i keep ISC-DHCPD from offering different IPs when there is two requests from the same MAC

I have a set of Nodes which get their addresses from ISC-DHCPD. Since they boot using PXE, there will be two rounds of DHCP (one from the PXE, one from the OS) and for some reason, ISC-DHCPD will ...
0
votes
4answers
3k views

Blacklisting MAC addresses, but they still take a DHCP lease

At my workplace, we have a Public Wifi network, as well as our Private Wifi network. The Private side has access to see other computers, the printers, servers, and access to the Internet. On the ...
4
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0answers
261 views

Samba4 internal DNS and isc-dhcp zone update

Could anybody explain, how to solve this problem with internal samba4 DNS and dynamic zone updates from isc-dhcp? In the logs I have: dhcpd: Unable to add reverse map from 170.5.168.192.in-addr....
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0answers
241 views

How to configure DHCPv6 and DNSv6 configuration in Ubuntu 12.04?

I'm planning to configure DHCPv6 and DNS server in my network. I would like to understand whether both DHCPv4 and DHCPv6 can be configured using isc-dhcp-server service? When i tried nslookup ...
3
votes
0answers
150 views

Can ISC-DHCP bind to Option 82 rather than Mac Addresses?

We use option 82 information to limit leases presently in ISC-DHCP using a spawn with statement for our billing subclass. This keeps a single household/business from obtaining more leases than they ...