DHCP relay

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Diese Seite wird auf folgenden Seiten eingebunden

• UTM/NET/DHCP Relay-v4 v11.7 (← liens)
• UTM/NET/DHCP Relay-v6 (page de redirection) (← liens)
• UTM (← liens)
• UTM/NET/DHCP Relay-v4 (page de redirection) (← liens)
  • DHCPRelay SERVER v4 UTMV11 (page de redirection) (← liens)
• UTM/NET/DHCP Server-v4 (inclusion) (← liens)
• UTM/NET/DHCP Relay v12.1 (← liens)
• UTM/NET/DHCP Server-v6 (inclusion) (← liens)
• UTM/NET/DHCP Relay v12.6 (← liens)
• UTM/NET/DHCP Relay v12.7.4 (← liens)
• Produkthandbuecher/UTM/G5-BlackDwarf (inclusion) (← liens)
• UTM/Changelog v12 (← liens)

{{var | Debug-Modus aktivieren--desc | Erst bei Aktivierung On werden Logmeldungen geschrieben | Log messages are only written when activated On | Dzienniki są zapisywane dopiero po aktywacji On }

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Make DHCP server available in another subnet

Last adaptation to the version: 14.1.0 (08.2025)

New:

• debug mode in the beginning of the new designed DHCP area

• Multiple DHCP server IP adresses can be specified

Last updated: 

05.2026
• Addition to the instructions for setting up a DHCP relay for only a subset of an interface’s subnets

notempty

This article refers to a Beta version

12.6 12.1 11.7

Access: UTM-IP:Port or UTM-URL:Port
Port as configured at Network / Appliance Settings / Webserver
Default-Port: 11115
i.e.: https://utm.ttt-point.de:11115
Default: https://192.168.175.1:11115 Network Network Configuration Area DHCP

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Configuration of DHCP-Relay

With the DHCP relay, devices can receive their network configuration dynamically via the network, even if the DHCP server is located in another subnet.

Setting up a DHCP relay for only one subnet of an interface

1. If there are multiple subnets on an interface and a DHCP relay is to be created for only one of these subnets, this is only possible via VLANs.
2. For this purpose, VLANs are created for the subnets of the interface. One with all subnets that should have a DHCP relay and one with the remaining subnets.
3. Then, the corresponding VLAN can be selected as the client-side interface instead of the entire interface.

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Let LAN2 be an interface with the following subnets

• Subnet A with 192.168.1.0/24
• Subnet B with 192.168.2.0/24
• Subnet C with 192.168.3.0/24

Now a DHCP relay is to be defined for subnets A and C, but not for B. For this purpose, a VLAN LAN2.1 is created, to which subnets A and C are assigned. A VLAN LAN2.2 is also created for B. So there are:

• VLAN LAN2.1 with 192.168.1.0/24 and 192.168.3.0/24
• VLAN LAN2.2 with 192.168.2.0/24

With the DHCP relay, VLAN LAN2.1 is now selected as the client-side interface instead of LAN2

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Caption	Value	Description	Network Configuration UTMuser@firewall.name.fqdn Network Network configuration DHCP relay overview
activate Debug mode: notempty New as of v12.7.1	Off
DHCP Relay IPv4 DHCP Relay IPv4
DHCP server IP addresses: notempty updated Multiple entries possible	»192.168.178.1	IP addresses of the DHCP server/s The network/s in which the servers are located must be known to the UTM.
DHCP-Relay Client Side Interfaces:	LAN2	Interfaces for which the DHCP server is to be responsible.
DHCP Relay IPv6 DHCP Relay IPv6
DHCP-Relay Server Side Interfaces:	LAN1	Interface behind which a DHCP-v6 server is located.
DHCP-Relay Client Side Interfaces:	LAN2	Interfaces for which a DHCP-v6 server is to be responsible.