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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.

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Wireless IP device expansion [on hold]

I have to use a Verizon Jetpack as my internet service. We live pretty remote and no alternative for ISP. The Jetpack is limited to 10 devices (IP addresses). I want to use another router to be DHCP ...
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10 views

freeradius: assign IP from specific pool filtered by user

I'm new here. I have a freeradius 3 with sqlippool and LDAP authentication (with a "guest" file-configured user), all working fine. I have 2 sqlippools: -main_pool -guest_pool I want to do the ...
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1answer
38 views

Delete DHCP lease if DNS record is updated

Situation(Windows Environment): Three DHCP scopes with 3 different subnets. A user uses his notebook in all three subnets in one or two day's. Now, there are 3 dhcp leases at the same moment. The ...
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4 views

Why do Cisco IOS switches send packets to DHCP servers with zero giaddr field when DHCP snooping is on?

I recently troubleshooted a network where the switch had DHCP snooping turned on and even though the router which was acting as a DHCP server was connected to a trusted port, the client wasn't able to ...
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0answers
21 views

Configure multiple search suffix domains in Unifi Security Gateway (dhcp option 119 domain search)

I would like to have the DHCP server in my Unifi Security Gatway include multiple domain search entries as part of DHCP option 119 so that I can use shortnames for multiple suffixes like: host -> ...
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38 views

OpenVPN without NAT or DHCP

I am trying to setup an OpenVPN server similar to LiquidVPN.com. WIth their VPN server when a client connects it receives the public IP address of the server. All network traffic to the public IP is ...
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1answer
20 views

Enforce usage of VPN-provided DNS servers on Ubuntu 18.04

On a vanilla Ubuntu 18.04 headless server, the OpenVPN client is used to connect to a remote network in tap mode. The address, default gateway, DNS servers etc. are provided by a DHCP server on the ...
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21 views

DHCP Server (Centos 7) Dynamic and static leases present for… ignore?

I have been running my own DHCP server on Cento6, now 7 for a number of years. I've never had any real issue. Something strange happened, a device wasn't joining the network after rebooting it, so I ...
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1answer
27 views

SRX Juniper port forwarding

I am trying to punch a hole through the Juniper to allow access to a rasperry pi web camera running on a DHCP IP address and on port 8081. This is what I tried: set security zones security-zone trust ...
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1answer
40 views

DHCP Server no answer on CentOS 6.10

I have installed dhcp (4.1.1) on Centos 6.10. I am using the following configuration: #specify domain name option domain-name "example.com"; #specify DNS server ip and additional DNS server ip ...
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2answers
32 views

DHCP dnsmasq for infinite lease

I am using dnsmasq to serve IPs for about 200 vservers. Leasetime is infinite: dhcp-range=10.0.1.2,10.0.1.254,infinite I don't know why, but 1 vserver changed IP. Let's say MAC address changed. I ...
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28 views

DHCP, VLANs, APs and IP assignements

I have a debian-based isc dhcp server, that works as router/firewall too. I configured a Cambium cnPilot 610 to broadcast 2 SSIDs. Each SSID is associated to a different VLAN. So, in the port where ...
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0answers
17 views

Policies missing from DHCP scopes on Windows 2012 Server

I would like to use the Policies in DHCP. Policies should be listed just below Scope Options. It is, however, missing for me (see screen capture below). Running Windows 2012 Server. Current on ...
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1answer
32 views

Can isc-dhcp-server update bind running on a non default port?

I'm running the following on the same server: pi-hole, bind9, isc-dhcp-server and cloudflared (for DNS over HTTPS). The order goes like this: Pihole:53 -> Bind9:54 -> cloudflared:5353 I'm now ...
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27 views

DHCP & Windows Firewall

With a Windows workstation, the DHCP request is initialized by the workstation (the client). So, is an "incoming rule" (UDP, ports 68/67) useful? PS: I'm not sure how the Windows Firewall works, but ...
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1answer
71 views

Is it possible to have name-resolution from Fortigate and local DNS server?

Can you advise on moving to a hybrid DNS? Currently, all our LAN machines receive their IP address from our Fortigate 60D (each machine is either allocated an IP address from the Fortigate DHCP, or ...
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0answers
40 views

Dynamic DNS, basic configuration not working

I'm trying to implement DDns, where DHCP daemon updates dns records instead of myself. From what I understand, it should work. But it doesn't. I would be very grateful, if somebody points out my ...
5
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2answers
126 views

Registering linux hostnames on windows DNS

How do I register DHCP linux client's hostnames in a windows server DNS? I have a small-business mixed network with: DCHP Windows workstations (Example hostname: win1) About 10 machines Machines ...
0
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1answer
24 views

Get mac address based on ip in filter wireshark

i am a test engineer writing some test cases. I am trying to write a test which has to be performed in wireshark. However, my collegues aren't that "into wireshark" and i would like to keep it as ...
1
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1answer
57 views

DHCP conflicts on two Ubuntu 18.04 servers

I have two machines running Ubuntu 18.04 server edition. Networking go through netplan. They get their IPv4 from a DHCP server v6.3 running on Windows Server 2012 R2. For some reason, they don't ...
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0answers
28 views

How to use omshell with ICS DHCP?

In /etc/dhcp/dhcpd.conf have added omapi-port 7911; omapi-key testkey; key testkey { algorithm hmac-sha256; secret QUt1z1O3fxqgSDKILAMXFA==; } but it won't let me connect when I do # systemctl ...
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1answer
42 views

can pfSense captive portal grant internet access to IP which is assigned by Windows DHCP server only?

In our organization we have a wifi access point and IP addresses are assigned by a Windows DHCP server. We have MAC filtering enabled for internet access in the DHCP server but the issue is that if ...
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0answers
25 views

Windows server dhcp issues when changing vlan

I have an issue with my dhcp server under windows 2012R2. I have many subnets requesting IP to my dhcp server: 10.20.20.0/24 10.20.21.0/24 10.20.22.0/24 10.20.23.0/24 10.20.24.0/24 Each one of them ...
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1answer
55 views

DHCP not sharing Internet access

I have several Virtual Machines in Vmware ESXi 6.5 with 2 Network Groups. Created a DHCP Server Machine on CentOs with 2 networks interface. 1 / vm network from which it takes a network and has IP ...
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0answers
36 views

Why restriction on minimum lease time in DHCP protocol removed in RFC 2131 [duplicate]

While going through RFC 2131 for DHCP I came across a section which titles 1.1 Changes to RFC 1541 under which it mentions that The minimum lease time restriction has been removed I went through RFC ...
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0answers
34 views

Is the latest dhcp spec (rfc4361) invisable to admins?

When having an old Winsdows 2003 dhcp server, which doesn't understand the dhcp identifier OS'es such as Fedora 29 and Ubuntu 18.04 server sends. Which looks like 10,11/09/18,12:28:17,Assign,192.168....
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1answer
37 views

windows machine gets assigned wrong netmask

I have a Debian based DHCP server. It assigns correct netmask 225.225.225.0 for all devices (WiFi router, voip, scanner) except for the windows machines. They all get assigned 224.0.0.0 for some ...
2
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1answer
30 views

Resolution error of specific IP addersses

I have a network with the following topology: +-----------+ +-----------+ |192.168.1.1+---+--->192.168.1.7| +-----------+ | +-----------+ server | windows | ...
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1answer
26 views

Migrating DHCP from one server and subnet to another, one subnet fails to retrieve addresses

I just attempted to migrate the DHCP service from a 2008r2 server on vlan1 to a 2012r2 server on vlan20. We had the dhcp helpers assigned on the core switch, firewall dhcp relays setup for the any ...
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1answer
48 views

Exclude subnets from distribution?

In Windows' DHCP server it is possible to exclude an entire subnet from being given out to clients which doesn't have a reservation. They call this "IP addresses excluded from distribution". Now I ...
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1answer
90 views

OpenVPN: Addressing remote LANs

I've been trying to solve this problem for a while now, but to no avail. We basically have an OpenVPN server to which our end devices need to connect. Some of those devices can directly connect to the ...
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0answers
72 views

IPV6 Small Business Implementation - Windows DHCP/DNS, PFSense, IPV6

I have some confusion about IPV6 on a Small Business Network. I'm sure one part or the other is covered extensively, but I can't seem to find answers. (Background info) I have a home network that ...
0
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2answers
82 views

Libvirt networking: Set default gateway for guest VMs via DHCP

Is it possible to set a default gateway for the guest VMs via DHCP in libvirt? I have the following config <ip address='192.168.123.1' netmask='255.255.255.0'> <dhcp> <range ...
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1answer
49 views

IP phones get DHCP NAK from superscope configured DHCP server

We are experiencing a strange problem with our 2012R2 DHCP server. Setup looks like this: Superscope with two scopes: SCOPE 1 - 192.168.100.0/24 (for PC) SCOPE 2 - 192.168.101.0/24 (for IP phones) No ...
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2answers
117 views

KVM: Hosts with private and public IPs

We have a small block of static IPs (e.g. 203.0.113.0/29). We currently only use 203.0.113.2 for a mail server. We'd like to add some other public servers, and if possible would like to have them ...
2
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1answer
64 views

How to share VPN and DHCP server across multiple hosts?

I need to set up a small computer network for what is effectively a satellite office for a business. The small network consists of several workstations and a server. The server machine has two ...
3
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2answers
876 views

How to add another address range to DHCP server

Short version Long Version Window Server 2012 DHCP server is currently configured as: Subnet: 10.0.x.x (e.g. 10.0.0.0/16) Dynamic IP Range: 10.0.0.12 - 10.0.0.120 This is done to limit dynamically ...
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0answers
177 views

Dynamic DNS client records not being updated correctly

Our network is running Windows and macOS clients all of which are joined to Active Directory. The Macs are all running Windows via Bootcamp. We were having issues which were being caused by our macOS ...
0
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0answers
30 views

DHCP request on ethernet cable reconnect with Ubuntu 16.04 Server

I have Ubuntu 16.04 Server here. My Ethernet interface is configured to use DHCP via /etc/network/interfaces and also I enabled "allow-hotplug" for the interface. It works. I can boot without cable ...
0
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1answer
37 views

Specific dhcp administration across multiple dhcp servers

Currently we have multiple DCs in our primary site and a remote location which has its own DC. All of those DCs are on the same domain, though. The remote IT team wants to be able to manage their ...
3
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3answers
884 views

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 ...
0
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0answers
42 views

Clients cannot get IPs after lease expires

Got a strange issue involving our wireless network. We have Ubiquiti AP's and have two different networks. One, our internal network gets IP's from our on-site DHCP server. The other network for ...
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0answers
34 views

Weird answer of linux DHCP server to gratitious ARP causes DHCP failure

This is a problem, that I ran into recently on a quite heavily configured linux server. This machine runs Samba as an Active Directory Domain Controller, a mail server, a web server, two virtual ...
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1answer
77 views

Mint & Ubuntu don't work on LAN, work on other networks

Good evening, We have 15-20 devices running on our office LAN. Suddenly last week, the internet (both wired and wireless) suddenly cut-off on both of 2 Mint desktops. By cut-off i mean that the wifi ...
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1answer
107 views

With static IP on Hyper-V ping to VM fails

I have configured a VM on Hyper-v. With the VM network adapter configured to receive DHCP the ping works fine but when I set it to static IP address ping from host to VM always returns time out .I am ...
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2answers
37 views

Moving from a dual ISP set up to a single ISP facility with mixed IP handling (DHCP with Static IPs)

First time posting a question here, please bear with me. I've been assigned to manage the migration of all our computers and servers from a facility where we have 2 ISP's to a facility where we're ...
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0answers
25 views

SonicWALL TZ205 IP Helper policy

Network connection: SonicWALL TZ205 port X1 is connected to ISP. Port X0 is connected to a Netgear switch. Windows Server 2012 R2 (AD DC, DNS & DHCP services) is connected to the Netgear ...
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1answer
68 views

How to get an DHCP allocated IP address without a reboot?

I have a server which currently staticly addressed with an entry in its /etc/hosts file, e.g.: 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost ...
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1answer
17 views

Server 2016, Using Different Bootfiles to Deploy Company Specific Images

I have a switch with 3 VLANs. I have a WDS server (with DHCP and DNS) with 3 virtual NICs, each NIC is tied to one of those VLANs. Each VLAN corresponds to a company that we work with. I have 3 scopes ...
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1answer
103 views

How to get the number of devices connected to openwrt in realtime?

I tryed cat /tmp/dhcp.leases | wc -l but have a time delay. Is there any way to get the number of devices in real time, including wired and wireless devices?