Questions tagged [dhcp]
DHCP stands for Dynamic Host Configuration Protocol and is an auto configuration protocol used on IP networks and an extension of the Bootstrap Protocol.
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Can I have multiple DHCP servers on one network?
This is a Canonical Question about Redundant DHCP Servers.
Is it possible to have more than one DHCP server on the same LAN? What are the implications of doing this?
What happens if there is more ...
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How do I find if there is a rogue DHCP server on my Network?
What's the best approach towards determining if I have a rogue DHCP server inside my network?
I'm wondering how most admins approach these kinds of problems. I found DHCP Probe through searching, ...
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Command line program to test DHCP service
Is there a simple ping-like command to test whether a DHCP service is running on a network? ...on Linux
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How do I force Linux to reacquire a new IP address from the DHCP server?
The environment is Debian, although the answer will apply to all distributions.
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How do I request a new IP address from my DHCP server using Ubuntu Server?
I know there is a simple command for this, but how do I tell my Ubuntu server instance to request a new IP address from the DHCP server on eth0?
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KVM/libvirt: How to configure static guest IP addresses on the virtualisation host
What I'd like to do is to set the guests' network configuration (IP address, subnet, gateway, broadcast address) from the host system. The used network setup is in bridge mode. How can I configure the ...
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dhclient: What does "RTNETLINK answers: File exists" Mean?
I wanted to update the DHCP lease of an Amazon EC2 instance, so I executed the following command:
user@host:~$ sudo dhclient
Following that, the system's DHCP lease is updated successfully updated. ...
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How do you get dnsmasq to specify alternate DNS servers?
I'm working on a network with ~10 kubuntu desktops (and numerous servers and IP phones) and am trying to get dnsmasq to specify another dns server as a failover. I tried using
server=192.168.0.90
...
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Any way to find unused IP addresses on my network?
How can I locate unused IP addresses on my network? The DHCP server keeps assigning the same address and I need a different IP address to test my application with. The software would need to run on ...
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How does a computer obtain an IP address via DHCP?
How does the computer know which device on the network to query? How does the default gateway factor into this? Pretty much, what is the chain of events that occurs when a computer tries to obtain an ...
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Why does it take seconds to obtain IP address via DHCP?
Out of curiosity, why does it often take seconds to obtain network configuration via DHCP when the CPU is capable of processing millions of operations per second and ping to the router takes a couple ...
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How do I determine what my DHCP server is?
I have a sad network left behind by some careless administrators - I am in the process of figuring out exactly what services are running where, not excluding the possibility that some services are ...
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Locate rogue DHCP server [duplicate]
Possible Duplicate:
How do I find if there is a rogue DHCP server on my Network?
I know this is a serious long shot, but here we go.
In the past week or so, for users connected to a particular ...
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1 Year DHCP Lease
Just a little background I'm a fairly young I.T. Tech working in a school only and only been working in the as a technician for a few years so I would still consider myself a "newbie"
Anyway, My boss ...
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Why can Windows machines resolve local names when Linux can't?
I have a small network with Windows and Linux machines connected to a D-Link DIR-825 router.
The Windows machines on the network can reach all other machines by name while the Linux machines only can ...
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What is a good DHCP lease timeout configuration
I have generally seen that DHCP lease times are quite long (a day plus) on most defaults. I have a client that seems to have the following problem. They have a DHCP server in a router that is near-...
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What are the possible issues in using very short DHCP lease time (< 1min)?
We have a network setup for a demo, which lasts about 15mn. Our DHCP server is configured to assign ~ 100 addresses (max number of simultaneous connections or our AP) ... but since people might come ...
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How do I protect a low budget network from rogue DHCP servers?
I am helping a friend manage a shared internet connection in an apartment buildling with 80 apartments - 8 stairways with 10 apartments in each.
The network is laid out with the internet router at ...
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dnsmasq: mapping 2 MAC addresses to the same IP address
Is it possible to map 2 different MAC addresses to the same IP address?
For my backup, I need to connect back from the server to the portable, and I would like to have the same IP both for the ...
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How to renew dhcp ip address in ubuntu?
This is a simple question in ubuntu server
How do I renew a dhcp assigned IP address?
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IPv4 To IPv6 Migration Advice
I'm currently working on adding IPv6 capabilities to our network, and I have some questions on what is considered best practice in 2020 to convert some of the IPv4 concepts we are used to into the ...
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DHCP Options for Network Time Server
It looks like there are two options for providing network time settings to a DHCP client; option 004 and option 042. The description for 004 is "Time Server", while 042 specifies NTP. Is there a ...
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Domain connection shows as "unauthenticated"
I have seen various different questions for this problem floating around but either the circumstances arent the same or the solution doesnt work so thought i would post it to see if anybody has any ...
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Why use DHCPv6 over Stateless Address Autoconfiguration?
IPv6 and RFC 2462 provide a means for hosts to configure their own IP addresses via stateless address autoconfiguration. To me this seems like the bee's knees, and it leaves me wondering why someone ...
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Reverse DNS records not registered when using DHCP
I've stumbled upon a strange behaviour with Windows machines, which seems to be fairly consistent between all Windows versions from Vista/2008 to 8.1/2012 R2; it doesn't happen instead when using ...
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Difference between DHCP options 'Domain-Name' and 'Domain-Search'
What is the difference between the two?
I had thought that domain-name would put the client on the specified domain (ie. If the domain-name was set to "foo.bar" the clients FQDN would be '...
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Howto setup Cobbler with PXE if you can't change the dhcp server?
In the past I've setup a PXE server several times by making the normal dhcp server return everything needed for network booting: both the regular ip config AND bootinfo in a single dhcp setup. That ...
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Find out the DNS server for a DHCP connection in Linux
I know they're defined in /etc/resolv.conf, but what if it's not there? And more specifically, how do you find the DNS server returned by DHCP?
In GNOME you can use the NetworkManager applet to see ...
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How do I manually release a DHCP lease on the DHCP server itself?
I have been doing some VM testing. I have created and destroyed a large number of VMs on my subnet to test fresh provisioning via puppet. However, it looks like Ubuntu doesn't free a DHCP lease when ...
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VLAN tags not shown in packet capture (Linux) via tcpdump
I am adding a tagged VLAN onto eth0:
#ip link add link eth0 name eth0.20 type vlan id 20
This results in:
#ip link
2: eth0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast ...
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Per-client DNS servers with DNSMasq
I am running TomatoUSB with DNSMasq to provide DHCP and DNS services for my local network.
What I would like to achieve is to provide alternative DNS servers for one or two specific clients on the ...
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Phones on some switches cannot complete DHCP process
Background
I have a Windows DHCP server (Server 2008 R2) handing out addresses for several scopes. One of those scopes is for some Mitel IP Phones. The phones are configured to use dhcp option 125 to ...
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Assigning a fixed IP address to a machine in a DHCP network
I want to assign a fixed private IP address to a server so that local computers can always access it.
Currently, the DHCP address of the server is something like 192.168.1.66.
Should I simply assign ...
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How to request dhcp (using dhclient) on a virtual interface (i.e. eth0:1)
This seems to work fine:
dhclient eth0
ifconfig eth0:1 192.168.1.105 up
But not this:
ifconfig eth0 192.168.1.105 up
dhclient eth0:1
Is there any way to get dhcp on a virtual address?
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Windows DHCP Server - get notification when a non-AD joined device gets an IP address
SCENARIO
To simplify this down to it's easiest example:
I have a Windows 2008 R2 standard DC with the DHCP server role. It hands out IPs via various IPv4 scopes, no problem there.
WHAT I'D LIKE
I ...
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Is there a downside to always updating DNS from DHCP?
I've got a Windows 2012 Domain Controller running DNS and DHCP servers. The default setting appears to be Dynamically update DNS A and PTR records only if requested by the DHCP clients.
(This is ...
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What does a DHCP-client consider to be the "best" answer?
We have training rooms where normally Windows XP is installed (via PXE). The "normal" DNS/DHCP infrastructure are Windows-Servers. The training room has its own VLAN (different from the Windows ...
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DHCP addressing vs Static addressing for Servers
I'm having a "lively" debate with a work associate about the reasons for or against using DHCP on servers in a network environment. The network environment in particular is a relatively small network, ...
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Register A records for my Linux box on my Windows 2008 DNS/DHCP server
I've a network which is mainly Windows: Windows 2008 server (with DNS/DHCP as well as AD), and various mainly Windows machines (servers, XP, 7). I know trying to add few Linux boxes, and can't make ...
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How does my DHCP server know my machine's hostname when I didn't define one in dhclient.conf?
I'm trying to resolve some funky DNS issues related to DHCP on our network (I suspect we have more than one DHCP server running at the moment), and while trying to figure that out, I noticed something ...
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Multiple VLANs, multiple subnets, single DHCP server?
At my job we are prepping to transition from multiple LANs connected over slow VPN connections to a single MAN connected over fiber, and I've got a few questions.
First of all, we are planning on ...
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PXE Booting Virtualbox guests in internal networking mode?
I am not sure if this is just specific to my distro's packages or is a vbox limitation. So, any help would be appreciated.
Ok, so I have a network of VMs, with one VM acting as a NAT for the other ...
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How to set up Google ShortName service for my domain, so that the FQDN isn't needed
The blog post "A 'tinyurl' service for your domain" explains how to set up a ShortName service for your domain using Google Apps. For example, if your domain is example.com and you use Google Apps, ...
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Use Windows DHCP/DHCPv6 server without setting a static address
You cannot set the Windows DHCP/DHCPv6 server to listen on dynamic addresses or all addresses, only static addresses. Is there a technical reason for this limitation? Is there any workaround?
My ...
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How to ignore a set of Mac addresses in dhcpd.conf?
Is it possible in dhcpd.conf to ignore requests from a set of MAC addresses?
Something like this:
host vminstances {
hardware ethernet d0:0d:*;
ignore booting;
}
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How to make a Macintosh register a Hostname to the DHCP Server?
I have a MacBook running Snow Leopard in our company's internal network, which is basically a Windows domain network. Our TO department complains about my MacBook not specifying a name to the DHCP ...
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How to add a static secondary IP to a DHCP interface using netplan?
My server has a file /etc/netplan/50-cloud-init.yaml with the following content:
# This file is generated from information provided by
# the datasource. Changes to it will not persist across an ...
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Force the DHCP server to renew the IP address of a client machine, without doing anything in client machine
I would like to know, if there is a way I could force the DHCP server to renew the IP address of a client machine instantly, without me going to the client machine? In fact, imagine, I don't have ...
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libvirt: Change dhcp-setup without restarting
I'm using libvirt and kvm to virtualize my server. I configured libvirt to start a dhcp-server on the bridge-network-interface to give the vm's their ips. Every VM's gets always the same ip based on ...
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How can I configure my DHCP server to distribute IP routes?
I have a DHCP server (Linux, IPCop, dnsmasq) running on my default gateway server 192.168.0.1. I have a VPN endpoint on another server in the network (192.168.0.4). Is it possible to configure the ...
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