Questions tagged [dhcp]

For questions about DHCP in in relation to network devices. For instance, you are setting up DHCP on a layer 3 switch.

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Communication between subnets on Sonicwall firewall

I have a Sonicwall TZ-350. X0 is the default LAN with IP 192.168.10.1, and X1 is the WAN. I've set up a second local subnet on X2 with IP 192.168.20.1 for a single NAS device (no switch; the device is ...
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63 views

How does Network Layer behave when client received a unicast DHCP offer?

I went through various stack exchange post to understand the concept of DHCP offer when it comes as a unicast to client from the DHCP server. A server can send a unicast DHCP offer since it knows the ...
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70 views

Configue IOS DHCP server to respond to Option 60 class

I have a number of small networks each with about half-a-dozen mostly-fixed hosts. The routers on each network provide DHCP service for the occasional visiting engineer's laptop. I am adding IP ...
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129 views

How to implement port security in SDN using pox controller and ovs?

How can I defend against DHCP starvation attacks or MAC spoofing in an SDN environment?
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347 views

Cisco ASA L2TP remote-access VPN with addresses assigned by DHCP

I have an ASA with a working Cisco VPN Client configuration set up. I am trying to phase out the Cisco VPN Client, initially in favour of L2TP. The Cisco Client policy has end-users fetch their ...
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2k views

DHCP Relay on Cisco ASA over site-to-site VPN

How do I get the DHCP relay function of a Cisco ASA working over a site-to-site VPN? The ops center is behind a 5510 ASA with a 3560 core switch. The DHCP server is at IP 10.0.10.153. The remote ...
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305 views

Cisco 1841/WAP4410N Wireless Access Issue

In our environment, we have a Cisco 1841 which, among other things, performs DHCP services for a small manufacturing facility. We have 100 available DHCP addresses in the pool. That device connects to ...
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2k views

What is the safest method to decrease DHCP lease time while not risking clients receiving already-used IP addresses?

Our wireless in our NYC office has a guest SSID that has no auth. Understandably, we get a LOT of users on this network. Lately, our IP space has been filling very fast at events and I'd like to ...
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23 views

Cisco FTD DHCP option codes

I have a Cisco ASA 5515-X that is currently running ASA with the FirePOWER module, which cannot sent option code 60 in the DHCP request. My ISP requires me to send this. Does anyone have FTD 6.4 (or ...
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22 views

DHCP helper flow in incorrect config

Discovered a configuration error in our network and would like to double check if the conclusions I drew from it are correct. Incorrect configuration: dhcp helper set on VLAN xyz to point at DHCP01 ...
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15 views

Next-server option missing in dhcp server on EXOS switch

I'm trying to utilize the build-in DHCP server on our EXOS switch. Address pools work as intended. So far so good. But I also need to boot our FOG iPXE server through it. The configuration of the ...
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Cisco RV345P - disable DNS names for DHCP bindings

This is about Cisco RV345P router (non-IOS, it's the Web interface kind). When the hosts on our office LAN obtain address from DHCP their host name is automatically registered in a local DNS resolver ...
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147 views

Best practice / advice for cisco 3560 behind Virtualised OPNsense

Currently I run the below scheme. The problem is that when ESXi is down it takes down all the network with it, so I have to boot up another router to log in to it. WAN > OPNsense (in ESXi)> ...
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32 views

VLAN DHCP Relay Agent how to set

dhcp server V10 10.10.10.10 V10 10.10.10.0 V20 10.10.20.0 V30 10.10.30.0 PC1 - V10 PC2 - V10 PC3 - V20 PC4 - V20 PC5 - V30 PC6 - V30 SW1 int f1/0 no sw ip addr 50.50.90.100 255.255.255.0 int f1/...
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Why DHCP client doesn't issue a DHCPREQUEST as it has received a DHCPOFFER?

In GNS3 (and using Cisco routers), I've created four subnetworks like the following: The goal is to set up a DHCP server on router R1 and a DHCP relay agent on router R2 in order to make it available ...
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59 views

There have DHCP relay for different vlans issue in my MX-480 router

I have the network topology: in this topology, in my router, I set the DHCP relay: admin@MX-RE0# show forwarding-options dhcp-relay server-group { smart_group { 103.57.xxx.19; } } ...