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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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 ...
0
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0answers
2k views

ISC DHCPD MAC address matching classes confusion

I'm having trouble successfully matching a mix of different mac address classes to their appropriate subnet declarations. These classes are meant to differentiate IP phones, kvm guests and desktops ...
2
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1answer
2k views

isc-dhcp leases file never cleaned

When running isc-dhcp the leases file seems to grow indefinitely (several hundred MB). If I restart the isc-dhcp service, the file shrinks to 1.5MB. How can I have isc-dhcp flush expired records ...
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1answer
153 views

Linux router share internet between eth2 to eth3 [closed]

I am not a networking guy, so apologies in advance. I have a small Linux (Ubuntu) box with 2 ethernet ports. eth2 is connected to a cable modem that gives it a 192.168.1.x address + internet ...
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0answers
282 views

“ifup eth0” causes dhclient to bring up more than one interface

Can someone tell me why dhclient is not respecting to only handle the one interface it has been passed? I've seen this multiple times over the years; never figured it out - it's not related to ...
1
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0answers
161 views

Binding ISC DHCPD to a virtual (heartbeat) interface

I had a DHCP server that acted as a relay endpoint and worked fine. let's say this is a solo machine with eth0 with an ip of 192.168.0.10 I needed to bring this server down and join it to a cluster, ...
1
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0answers
536 views

Advanced DHCP configuration (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 ...
1
vote
1answer
328 views

Ubuntu server dhcp reservation not working

I need some suggestion, if possible, about a dhcp server and ip address reservation. The system is a Ubuntu server 12.04 LTS. The DHCP is ISC DHCPd version 4.1. This is the /etc/dhcp/dhcpd.conf file:...
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votes
2answers
448 views

DHCPD assigning wrong DNS server

I just installed two Ubuntu 14.04LTS servers. The first one I installed bind9 and isc-dhcp-server on. The second one was left as installed to use DHCP. I created a new private network using VMware ...
2
votes
0answers
873 views

DHCP offer is unicast but DHCPACK is broadcast

My DHCP server broadcast DHCPACK 0xffffffff . it is not working on layer 3 dhcp relay agent . as it can not forward this broadcast message to my client. can any one help me from exactly the broadcast ...
1
vote
1answer
233 views

Multi-homed forward zone DDNS updates always sent out the same network interface

I have a multi-homed server 'dhcp1' with network interfaces '192.168.10.151' (eth0) and '192.168.0.151' (eth1). The machine is attempting to use DDNS with a name server 'ns1' having network interfaces ...
2
votes
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 ...
2
votes
1answer
3k views

ISC DHCP server not dynamically updating DNS

I have an Ubuntu 14.04 server, running an isc_dhcp_server and the bind9 DNS server. Bind acts as a cache, and it maintains the .m domain (and zone) on my local network. The server's address is 10.0.0....
0
votes
1answer
738 views

ISC DHCP Server scope error

Why am I getting the following error after modifying my dhcpd server config? option space definitions may not be scoped
0
votes
1answer
433 views

ISC DHCP - different subnet for specific mac addresses

I'm attempting to create a different subnet for a few specific mac addresses, and have my DHCP config set up as follows: authoritative; shared-network local { subnet 192.168.2.0 netmask 255.255....
4
votes
2answers
2k views

DHCPv6: passing delegated prefix to local RA

I currently have an Airport Extreme as my home office firewall. In addition to handling IPv4 NAT, my ISP (Comcast) delegates an IPv6 prefix to the Airport, which in turn assigns the delegated prefix ...
1
vote
1answer
532 views

How can I configure dhcpd to only update the reverse zone in bind?

I've got dhcpd pushing updates to bind, and it seems to be working fine: named[24161]: client 192.168.10.1#59141: signer "dhcp_updater" approved named[24161]: client 192.168.10.1#59141: updating zone ...
0
votes
1answer
569 views

Using isc-dhcp-server to allocate addresses from subnet different from server subnet

I'm trying to break my network into different subnets. Server is located into 192.168.15.0/24 subnet. I have the following declaration in my dhcp.conf: subnet 192.168.15.0 netmask 255.255.255.0 ...
2
votes
0answers
212 views

DHCP fault tolerant servers: Split pool or failover?

I need to replace an aging DHCP server by a fault tolerant solution. I consider using the ISC dhcp server solution which can be setup either as split servers serving non-overlapping ip ranges or as a ...
1
vote
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 ...
1
vote
1answer
609 views

Is it possible to send different-per-subnet DNSes from the single ISC DHCP server?

The case I want to cover is to send different DNS server for one, isolated VLAN, which purpose is to give internet-only access - for our guests. It has no access to our internal network, so it shouldn'...
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votes
1answer
427 views

Enterprise DHCP server solution? [closed]

I have a network of about 1000 assorted devices, all of witch are running by static IP addressing. Given the size of the network and the lapse of technical advice, the addressing scheme is in chaos ...
1
vote
1answer
626 views

ddns correct setting for dhcpd.conf and ifcfg file with regards to hostname

I have recently set up dynamic dns with ISC dhcpd 4 and bind 9. Everything is working as it should except for a handful of hosts on the network which don't resolve. Upon investigating I found they had ...
0
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0answers
163 views

How do I stop a Linux computer from sending a DHCP hostname?

I need to set up a Linux computer so that it uses DHCP but doesn't send any hostname at all. I'm using isc-dhclient-4.2.4 /etc/dhcp/dhclient.conf contains the line send host-name = gethostname(); ...
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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 ...
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votes
2answers
2k views

Multiple subnets on isc-dhcp-server using ddns with bind9

On my network I have two subnets: 10.100.1.0/24 -> Wired/wireless 10.100.7.0/24 -> VPN Both subnets are served by isc-dhcp-server running on a Debian VM. This same VM runs bind9 for my DNS. ISC-...
0
votes
0answers
88 views

DHCP server with ability to update mac address dynamically

Is there a better way to maintain MAC to IP specification in dhcp with out restarting dhcp service each time when there is an update. is it possible to use DHCP with database in Linux to save all ...
2
votes
1answer
5k views

Aliased network interfaces and isc dhcp server

I have been banging my head on this for a long time now. There are many discussions on the net about this and similar problems, but none of the solutions seems to work for me. I have a Debian server ...
1
vote
1answer
4k views

Assign two static IP addresses to one mac address

Can Isc-dhcp-server give two static ip addresses to one mac address? I have several Genexis terminals in my network. Each terminal have two interfaces, one for public traffic and one for a management ...
2
votes
0answers
322 views

ISC DHCPD IPv6 for multiple interfaces

I want to assign multiple IPv6 to a server with multiple NIC. As IPv6 RFC defines, each server has a unique DUID that can have one of the 3 formats (LL, LLT or enterprise). And each NIC has an IAID. ...
1
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0answers
260 views

How to send several instances of the vendor-specific options to a DHCP server using dhclient?

I need to send vendor-options to DHCP server using dhclient (ISC). I've added following lines in the dhclient.conf: option dhcp6.vendor-class code 16 = {integer 32, integer 16, string}; send dhcp6....
2
votes
1answer
2k views

DHCP failover with isc-dhcp-server using two secondary servers

I'm rearranging our network and putting some DHCP failover since we have a lot of machines, and even servers, getting IP addresses with DHCP. Today we have a nice DNS topology with one master server ...
4
votes
2answers
674 views

Prefix Delegation and route creation

I'm using the ISC dhcp server version 4.1 for DHCPv6 prefix delegation on a network. When the server allocates a prefix to a client, the server does not create a route for that prefix to the client ...
1
vote
4answers
8k views

Computer gets IP from DHCP server but has no internet connection

I've installed an isc-dhcp-server on Ubuntu 12.10 and I'm trying to setup a DHCP server on a head node for six worker computers in the local network. The head node itself is a DHCP client receiving ...
1
vote
1answer
244 views

DHCP IPv6 and vendor-encapsulated-options

I was using this option on ipv4 to send some information to the host. On my host lease I have something like: supersede vendor-encapsulated-options = "MY INFORMATION"; On the DHCP client host I can ...
2
votes
1answer
308 views

Cannot assign IP address according to an option parameter

I have this DHCP conf file: authoritative; option domain-name "XXX.XXX.XX"; allow bootp; ddns-update-style ad-hoc; class "karpuz-kabugu" { match if (substring (option user-class, 0, 6) = "karpuz")...
4
votes
1answer
914 views

DHCP scope for a user class option

In Linux how can I set a DHCP server configuration which will lease IP addresses from scopes which are defined according to user classes. For example the following configuration leases IP addresses ...
5
votes
2answers
7k views

ISC DHCP infinite lease time

How can i configure ISC DHCP server to infinite lease time for all clients? man dhcpd: Lease Lengths DHCP leases can be assigned almost any length from zero seconds to infinity. ...
4
votes
1answer
355 views

How does broadcasting work on a server with multiple IPs?

Say you have two dhcp servers, A and B. Server A has two IP addresses, 10.0.0.1 and 10.0.0.2. Server B has one IP address, 10.0.0.3. Server A has two instances of isc-dhcp running, one specifying a ...
4
votes
1answer
1k views

DHCPREQUEST and DHCPACK spam in logs

I've recently noticed that my android phone (droid dna, although the thunderbolt that I had before did the same exact thing) is rapidly requesting dhcp info my dhcp server (isc-dhcp-server on debian ...
0
votes
1answer
162 views

How to forward gateway requests for a subnet through another connection under Linux

I have a Debian machine acting as a DHCP server/NAT, connected via PPTP to another machine,connected to a subnet 10.0.0.0. How do I configure it so requests from clients on this machine for the 10.0....
2
votes
1answer
63 views

Changing DHCPv6 server

I have a DHCPv6 daemon that is answering for requests of some machines and everything is working fine. So I decided to remove this DHCPv6 daemon e start another daemon on another server, but the ...
8
votes
4answers
20k views

DHCPDISCOVER/DHCPOFFER, but no DHCPACK

I have a remote client machine that is sending out DHCPDISCOVER's. The server is responding with a DHCPOFFER, but there is no DHCPACK. This repeats about every 30 seconds from the same host. Is ...
4
votes
1answer
10k views

How do I assign hosts to classes in ISC DHCPD?

Suppose I have a bunch of hosts set up like this: host host2 { hardware ethernet 10:bf:48:xx:xx:xx; fixed-address 192.168.1.2; } host host3 { hardware ethernet 10:bf:48:xx:xx:xx; fixed-address 192....
1
vote
1answer
158 views

Can I run 2 dhcp servers when I use predefined host entries?

I have a very specific setup of servers which netboot off a san. All of them provide identical functionality. There are no other machines in this netblock. Each machine boots from an iscsi image ...
1
vote
1answer
5k views

PXE boot linux. PXE-E51: No DHCP or proxyDHCP offers were received

I am trying to have an ubuntu box (192.168.10.9) acting as a PXE server, but i have trouble getting DHCP to work. The PXE server is connected to a SOHO router (192.168.10.1) acting as a switch. I have ...
2
votes
1answer
1k views

When does ISC dhcpd expire leases

When exactly does ISC dhcpd forget a lease that is not explicitly freed by the client? Context: I am running an installation with many small pools (3 address) and it does not seem to cope well when ...
2
votes
1answer
895 views

isc-dhcpd static ip within range

I have a isc-dhcpd server with dhcp-range 10.0.0.10 - 10.0.0.20. There is also a device connected with static ip 10.0.0.10. What would happen when a client with dynamic ip connects to the network? ...
1
vote
0answers
144 views

How to make ISC dhcpd not log a specific hardware ethernet address (mac)

I have isc dhcpd v3 serving a local subnet. I have installed a rogue dhcp server detector (dhcp_probe) which constantly sends dhcp requests. These requests are logged by the legit dhcp server, filling ...
0
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1answer
4k views

Replies to request coming over a relay goes to relay's internal IP, not to original request's source IP

Dhcpd running on Linux gets a dhcp request over dhcrelay which is running on other remote machine. Oct 6 10:09:46 2012 dhcpd: DHCPDISCOVER from 00:1e:68:06:eb:37 (oguz-U300) via 172.16.17.81 ...