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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Misunderstanding of DHCP/DNS - What is the IP of a machine before DHCPOFFER/DHCPREQUEST

From what little I understand, DHCP allows for dynamic assignment of IP addresses to client machines on a network from a DHCP server. The client transmits a DHCPDISCOVER packet, followed by a ...
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1answer
28 views

Internet bandwidth split with HP1810-8G, using “DSCP QoS policies” and VLANs

I have the following scenario: We are a small company (~10 clients) with little resources and we rented out office space to another company(<5 clients). We ordered a 20 Mbit fiber connection which ...
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1answer
1k views

How could I fix “No subnet declaration for restart (0.0.0.0)”?

I have a DHCP service installed on my distribution, Backtrack 5 R2 (ubuntu 10.04) and it was working fine, but when I began to configure DNS it suddenly stoped working, how can I make it work again?? ...
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0answers
12 views

Using Microsoft DHCP with Linux PXE/TFTP/kickstart

I have a microsoft dhcp server already in the network and i have linux servers for pxe/tftp/kickstart. I would think that it would work using a ms dchp server with pxe/tftp on linux but im not sure, ...
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3answers
3k views

Clonezilla-SE with another DHCP Server in LAN

I want to install Clonezilla-Server(192.168.1.100) in a network that already have a DHCP Server (dd-wrt with dnsmasq - 192.168.1.1). I've installed Clonezilla-SE on ubuntu Server 10.10, once installed ...
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2answers
4k views

Issue with RHEL7 and disabling NetworkManager

Okay community, let's see if we can figure this one out, cause I'm out of answers. Where I work I am setting up a bunch of RedHat Enterprise Linux servers. There is a collection of RHEL6 and RHEL7 ...
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1answer
28 views

DHCP Server Not Registering PTR Records

I've got a DHCP server that's configured to "Always dynamically update DNS records". Unfortunately, it's not doing its job. The client sends an Option 81 with its FQDN and all flags at 0. The ACK back ...
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0answers
14 views

Use Framed-IP-Address RADIUS attribute for IP allocation with DHCP on Windows Server 2012R2

I have configured a DHCP server on Windows Server with an NPS Policy, connected to a FreeRADIUS2 server running on pfSense. Authentication is based on MAC address. If MAC address is not present in ...
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7answers
33k views

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 ...
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0answers
37 views

Android dhcp assigning bogus dns server [migrated]

I've been having problems with Android devices and DNS lookups on my WiFi network, so I've done some digging and found that android is assigning what appears to be a random link-local ipv6 address in ...
3
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1answer
39 views

Reaching out DHCP relayed hosts

I have one primary server (DHCP) and one secondary (DHCP-RELAY). Majority of hosts are served from primary (wirelessly), however there are a few (wired ones) which get their IPs from secondary. ...
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0answers
16 views

Access HTTP Server in the Same Subnet [on hold]

I am trying to access http server running my laptop to my android mobile. But it's not accessible. But the server is accessible from other laptops. Firewall is open for the port 8080. Laptop Ip ...
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2answers
1k views

Gateway gets stripped from DHCP Reply through OpenVPN tunnel

I have a bridged OpenVPN setup. This is my server config: port 1194 proto udp dev tap0 ca /etc/openvpn/easy-rsa/keys/ca.crt cert /etc/openvpn/easy-rsa/keys/server.crt key ...
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2answers
22 views

Linux Server Update Windows Server DNS (DHCP Not Windows)

I have Linux machines that are DHCP clients that have send hostname enabled but are not updating DNS on the Windows servers. DHCP is coming from the firewall, NOT Windows. Other windows machines ...
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0answers
12 views

ESXi 5.5 - Management network with no gateway [migrated]

I'm setting up a test lab for VMware in Hyper-V. I have 3 vSwitches in Hyper-V: -EXT01 -INT01 -INT02 I've also created a W2K12 VM in Hyper-V which has the following roles installed: -AD/DNS -DHCP ...
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1answer
906 views

Windows 2012 DHCP Failover: Scope refuses failover config Error: 20044

I have a scope configured on a Windows 2012 DHCP server (primary in a hot standby config) with two Cisco Vendor class options. I've added the Vendor class options, identically, to the standby server. ...
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5answers
1k views

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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5answers
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How do I MAC filter with DHCP server

I want to Only allow certain MAC addresses to get a IP from my DHCP server, currently I use dnsmasq and I rather not change dhcp server but I'm open to other software aswell. However, I need to be ...
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1answer
3k views

IP served by OpenVPN doesn't take ipp.txt into account

I'm facing some troubles right now with an OpenVPN server an former colleague set up (I'm not too into it ATM). We're using OpenVPN for a private network of ~200 clients (to be more specific, only 15 ...
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0answers
42 views

DHCP clients geting ip address after booting in DHCP environment [closed]

Our DHCP server does not assign IP addresses to clients during their boot process. DHCP clients get their IP addresses after booting their operating system. Windows clients boot up completely, then ...
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1answer
1k views

dnsmasq(as DHCP server) isn't working in KVM+libvirt envirmont

I'm using dnsmasq as DHCP server in VM environment. But It didn't working. I disabled basic DHCP feature in libvirt. <network> <name>default</name> ...
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2answers
3k views

CentOS 7 is not setting my gateway from DHCP

I have a Minimal Install of CentOS 7. I have disabled the Network Manager as I want to setup my network the "old school" way. systemctl stop NetworkManager systemctl disable NetworkManager ...
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1answer
36 views

DHCP with fixed IP hosts (Ubuntu)

I'm managing an office system that assigns IPs based on the MAC address. The fixed hosts are added in a dhcpd-hosts.conf file which is included in dhcpd.conf. There are some PCs that are not in the ...
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2answers
2k views

Juniper SSG5 DHCP IP Pool is full. Unable to offer IP address to client

hope we have some Juniper guys around, I have configured a Juniper SSG5 as our main firewall/router the DHCP server set on interface bgroup1 to have a rang from 10.10.10.76 to 10.10.10.210 All ...
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6answers
4k views

Why do partially failed/failing switches fail to pass DHCP?

I've noticed this several times: a switch starts to behave oddly. Usually if the switch doesn't fail outright, what tends to get noticed is that DHCP doesn't work. We had a Linksys SRW-224P fail ...
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1answer
38 views

lan to wan connection refused by windows firewall

I have plenty of experience with LAN's and bridges however this is my first time using a WAN style setup... here is a diagram of my network WAN (public ip & 10.1.10.1)---COMP1 (10.1.10.2) ...
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2answers
56 views

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
32 views

Router behind router [migrated]

To extend my wireless upstairs I salvaged a second router and have been trying to set it up so that: SSID matches with primary router Password matches with primary router Secondary router: Dlink ...
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0answers
15 views

DHCP Config for Server 2012 R2

This question may have been covered before, but it is rather complex and haven't found a similar post, so please be kind! I think my issue is rather unique, so I'll try to explain as best I can. I'm ...
2
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0answers
57 views

DHCP Failover works but no DNS available

I have a DHCP failover (load balance) configured. DHCP failover works but the clients are not getting any DNS entries. We have 2 DNS servers using AD-integrated zones, and the failover is between ...
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1answer
1k views

Disable LDAP service in CentOS 6.3

What command needed to disable LDAP service in CentOS 6.3. I tried: authconfig --disableldap but it doesn't work. I am trying to run ISC-DHCP in my machine but it always shows Not searching ...
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3answers
36 views

Can the firewall prevent the DHCP to give an address, how to fix this?

I am not getting an IP in the subnet 10.0.0.0/24 where the DHCP is working and should serve an IP, I am getting instead only an IP in the subnet 169.254.0.0/16(link local address) that is probably ...
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0answers
17 views

DHCP, IP conflict on LAN (pfsense)

On my router I occasinally get a log with multible entries like this. It is a LAN with DHCP so I guess here should be no conflict at all... Is there a nature to this? May 11 09:24:36 220002 ...
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2answers
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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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0answers
29 views

Configure WiFi and LAN network to use the same Kerio DHCP server

We have a local network in the company: An Ubuntu server hosted for VPS. Kerio Control Appliance 8.5 installed on VPS as internet & DHCP server . WiFi modem connected to eth0 of Kerio. eth1 of ...
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0answers
19 views

Virtualbox vm lstp client login blank for lstp server on ubuntu 14.04 , what I'm missing here..?

I am trying to configure a lstp server ( ip of lstp server : 172.16.40.0 ) on a 64bit ubuntu 14.04 and check it network booting virtualbox vm (harddisk less vm) I configured everything according to ...
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1answer
38 views

Is it possible to bring down a network with DHCP discover?

When a DHCP server receives a DHCP discover message it broadcasts the offer across the entire network. If a malicious machine joined a network and somehow began spamming DHCP discover messages, would ...
2
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1answer
988 views

Windows 7 Client gets incorrect IPv6 Prefix Length

I am currently setting up IPv6 and DHCPv6 for Server 2008 R2 on my private network for testing. I was able to get DHCPv6 to work by configuring a static, then setting up the scope. I was also able to ...
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0answers
29 views

cisco ip helpder-address not working

I have 3 Cisco Catalyst switches: 2 3750 series and one 3550. The appear to suffer from the same problem. If I define a VLAN, configure a DHCP address assignment on it and then issue a command for it ...
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3answers
657 views

DNS name resolution not working with DHCP assigned IP address on Linux?

If the DNS name is not properly registered to the DNS server through DHCP server for linux machine, which fault is this ? from the DHCP console it is blank with no hostname ? If anyone know how to ...
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1answer
1k views

Retrieving kickstart and other .img file in pxe remote installation in CentOS

I am trying to installation CentOS through pxe tftp installation. Installation starts but it fails to download image files from the http server. but file are accessible on the http server. Logs from ...
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0answers
14 views

How to set up a simple Cisco ISG config for controlling internet access

First off, here is my config so far. http://pastebin.com/fV2NGCE2 I've gone through a few guides online and the 15.2s manual and the xe3 manual for Cisco's ISG (intelligent services gateway) and ...
1
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1answer
1k views

Client see Windows Deployment Services but still get “selected boot device failed” error

Like the title says I can't Windows Deployment Services working. The client laptop has an ethernet IP address of 10.0.4.94. On the secondary DHCP server I've set option 60 to PXEClient, option 66 to ...
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0answers
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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 ...
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0answers
12 views

Openwrt bridging issue between wireless and ethernet port [migrated]

I've this scenario: an AP connected to the STA wirelessly, the AP is a DHCP server I have following configurations in /etc/config/network of the AP: config interface lan option ifname 'eth1 ...
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9answers
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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 ...
4
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3answers
3k views

Is it possible to detect Android and iOS devices based on DHCP requests?

I want to configure DHCP server in a way that it puts "regular" smartphones and tablets into a separate subnet. Is it possible to detect if the DHCP request comes from an Android or iOS device based ...
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1answer
17 views

Why does starting openvpn client, then dhcpcd give different routing table than the reverse order? [closed]

I am connecting through a router in my home, and tunneling all traffic via openvpn through a remote server. When I first connect with dhcpcd, then start openvpn, my routes look like this (on a linux ...
2
votes
4answers
2k views

How can I avoid Mac OS X temporarily setting its IP in the “link-local” range (169.254.x.x) at boot time?

I have a DNS and DHCP server (Linux machine) managing my LAN addresses and names. Everything is configured and fully working once the clients are up and running, having every Mac OS X client a DHCP ...
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1answer
25 views

How to move company voip phones to a different subnet by modifying DHCP of a Cisco Switch?

Our company has replaced its old voip phones with new ones which are the NEC phones. We are done with the configuration part, and the phones are working fine. But I want the phones to be in a ...