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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.

The Dynamic Host Configuration Protocol (DHCP) is an auto configuration protocol used on IP networks and an extension of the Bootstrap Protocol. DHCP allows for computers to be configured automatically to communicate with each other over an IP network without the need for manual setup by a network administrator.

The implementation of DHCP relies on a DHCP server to hand out network configuration information to DHCP-capable clients that request an IP address (and other information required or useful in communicating with other devices on an IP network). In addition to an IP address, common configuration information served over DHCP includes a default gateway, subnet mask and DNS sever(s), though there are many more possible configurations that can be sent out using the DHCP protocol.

More in-depth detail on DHCP and its implementation can be found at Wikipedia.

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How can i locate rogue DHCP servers?

I am investigating some odd behaviour on a sub-net, where host registration doesn’t list some of the IPs that some users report having. Now that I’ve seen evince, i want to passively scan for the presence of a rouge DHCP server, not listed in my…
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Configure OpenNebula to use DHCP

I'm trying to configure OpenNebula to use the DHCP server that already exists on my network. Yes, I already know that OpenNebula manages virtual mac addresses rather than IP addresses, but that doesn't tell me how to get this working. ;) My guests…
cat pants
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OpenVPN Linux Client does not bring up tap0 interface

I have an OpenVPN client on Linux connecting to an OpenVPN server. The server assigns IPs via DHCP, thus I connect using the tap interface rather than the tun interface. OpenVPN connects, authenticates, chats with the server, and grabs a cup of…
Chris
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Samba4 Internal DNS with DHCP Server

On FreeBSD we run Samba4 as a DC and until recently had our IP addresses handed out by the routers DHCP server. We switched to running a DHCP server on the FreeBSD machine with the following configuration:- # dhcpd.conf # # Sample configuration file…
Jack
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How can I assign multiple IPv6 addresses with DHCPv6 to a single interface?

This seems to be possible based on the spec rfc 3315 page 23: Excerpt: The configuration information in an IA consists of one or more IPv6 addresses along with the times T1 and T2 for the IA. See section 22.4 for the representation of an IA in a…
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Incorrect lease times from Windows 2012 R2 DHCP

Env: Two Windows 2012 R2 DHCP servers in active/passive (hot standby) mode serving one scope. Scope lease duration: 1 day. MCLT: 1 hour. Situation: New dhcp client gets IP configuration with a lease duration of 1 day. Upon release, then renew…
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Can you use WMI to determine if a connection gets its DNS servers from DHCP?

The DNS server search order for a network interface can be read from Win32_NetworkAdapterConfiguration like this in Powershell, or programmatically using .Net ManagementObjects: > $NICs = Get-WMIObject Win32_NetworkAdapterConfiguration |…
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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 master-slave cluster. The network is of the SOHO…
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PXE DHCP configuration with existing DHCP server

How does a DHCP service need to be configured, so that it handles PXE requests while there is still another DHCP server on the network? I managed to set up a working PXE system in a separate environment (one server for DHCP, TFTP and HTTP, one…
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Set specific DHCP options on a static IP address connection

Our network has some not-commonly used DHCP options on it, including some vendor-specific options (e.g. option 002 for Time Offset set to 0x9AB0). I have one particular computer that for whatever reason I want to have a static IP address. (I want to…
Mark Henderson
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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 and two slaves. The DHCP gives the slaves address…
Vinícius Ferrão
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What would cause the hostname FQDN to repeat the suffix twice?

I have three new CentOS 6 servers that connect to a DHCP server to get an IP and to have DNS/rDNS setup to bind their FQDN and IP. Two of them are behaving as expected. One of them is appending the suffix twice. Instead of fulton.mydomain.com we get…
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dhclient not working at boot

Here's the problem: root@home:~# ping 8.8.8.8 connect: Network is unreachable root@home:~# dhclient eth0 RTNETLINK answers: File exists root@home:~# ping 8.8.8.8 PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data. 64 bytes from 8.8.8.8: icmp_req=1…
Poma
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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 according to the first three octets of mac…
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Client DHCP on Linux seems to not be updating Windows AD DNS

I have an odd DNS issue that only sometimes presents itself. I have several Linux machines, running Ubuntu (10.10, 11.10, 12.04). Most of the time they work flawlessly. Sometimes, however, the system gets an IP address from DHCP, but fails to…
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