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Last adaptation to the version: 14.0.3
- Setzten einer extc-Variablen bei mehr 1000 benötigten Leases
- Adjustment in IP address allocation when Rejecting Unknown Clients is used.
- Detailed logging in the DHCP settings
- 01.2026
- Hinweis zu dynamischen Leases
Prepare IP address ranges
UTMuser@firewall.name.fqdnNetwork 
Network interfaces
For the firewall to function as a DHCP server in a network, a fixed IP from the network range must be configured on the corresponding interface. In this example, IP addresses are assigned in network 192.168.222.0/24. To achieve this, an IP from this network is added to the interface. LAN3 → → IP addresses → In the selection box, enter or select the IP address from the desired network with the desired subnet mask, if applicable. Here 192.168.222.1/24
Set up DHCP server
UTMuser@firewall.name.fqdnNetwork 
DHCP-Pools
Multiple DHCP pools can be added
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If more than 1000 IP addresses (across all pools together) are required via DHCP, the number of possible leases must be increased.
This is done in the menu Area Extc Variables with the variable MAXLEASES.
The value 0 corresponds to the default value of the service: 1000 leases.
- Multiple DHCP pools can be added
- Dabei steht nur der erste Pool je Subnetz für dynamische Leases zur Verfügung.
Weitere Pools sind ausschließlich für statische Leases nutzbarBeispiel:
Pool_1: 192.168.14.20 - 192.168.14.50
Pool_2: 192.168.14.100 - 192.168.14.150
- Sind 31 Leases per DHCP vergeben worden, werden keine weiteren dynamischen Leases mehr zugewiesen.
- Der 32. Client erhält keine IP-Adresse mehr dynamisch zugewiesen und hat damit keine Netzwerk-Kommunikation.
- Ist einem Client über die MAC-Adresse ein statisches Lease mit der Adresse 192.168.14.101 zugeordnet, wird diese zugewiesen.
- After clicking , the setup wizard opens and the DHCP parameters can be specified
In the example, the following IP addresses are assigned
Pool start address:
Pool end address:
Either the IP of a public DNS server or the IP of the firewall itself can be entered here. In this example, the clients use the firewall itself as DNS.notempty
Caution: Normally, the IP of the firewall is always entered here.notempty
Edit pool
After the pool has been created correctly, the pool start and end address can be changed and other parameters of the DHCP pool can be set up to be passed to the DHCP client.
General
UTMuser@firewall.name.fqdnNetworkNetwork configuration 
Edit pool general area
Changes to the pool range start and pool range end possible
Options - DHCP Optionen
| Option | Option number | Value | Description | UTMuser@firewall.name.fqdnNetworkNetwork configuration  Edit pool general area
|
|---|---|---|---|---|
| Router: | 3 | »192.168.222.1 | Router configured as in step 3 | |
| Domain name: | 15 | securepoint.local | Name of the domain in which the DHCP leases are assigned | |
| Domain name server: | 5 | »192.168.222.1 | Name server as configured in step 2 | |
| Netbios name server: | 44 | NetBIOS over TCP/IP Name Server Option | ||
| SMTP-Server: | 69 | Simple Mail Transport Protocol (SMTP) Server Option | ||
| NTP Server: | 41 | Servers should be listed in order of preference. | ||
| Vendor Encapsulated Options: | 43 | Values must be given coded. | ||
| TFTP Server Name: | 66 | profile.gigaset.net | The IPv4 address, or the hostname of the TFTP server option tftp-server-name text; | |
| Bootfile Name: | 67 | The name of the bootfile file option bootfile-name text; | ||
| Default URL: | 114 | https://teamwork.gigaset.com/gigawiki/display/GPPPO/DHCP+option+114 | Default URL option default-url string; | |
| VLAN ID: | 132 | The ID of the VLAN used option vlan-id code 132 = text; option vlan-id "128"; | ||
| Next Server: | The IPv4 address of the Next server | |||
| Default Lease Time: | 51 | 600 Seconds | Default validity period of the IP address if the client has not requested an explicit duration. | |
| Maximal Lease Time: | 7200 Seconds | Maximum validity period of the IP address in seconds that the client may receive when explicitly requested. | ||
| Reject unknown clients: | No | If activated Yes, an IP address is only assigned if there is a entry at Static DHCP tab for the MAC address of the client. notempty Changed standard behaviourab v12.7: The static lease entry for the DHCP must be in the same pool to be considered known. The static lease entry for the DHCP must be in the same pool to be considered known. | ||
DHCP Setup
The button opens a dialogue for the DHCP settings.
| Caption | Value | Description | UTMuser@firewall.name.fqdnNetworkNetwork configuration  DHCP Setup
|
|---|---|---|---|
| Ignore other SDHCP-Servers: | Off | When activated, other DHCP servers notempty New: IPv4 and IPv6 | |
| Enable detailed logging: notempty New |
Off | When activated, all DHCP requests are recorded in the syslog. | |
Static DHCP
If hosts are to be assigned predefined IP addresses ( fixed IPs bound to the MAC address, but assigned by the UTM), these IPs can be reserved with static leases:
Configuration under Area Static DHCP button
| Host: | MaxMustermann-Laptop | Meaningful host name | UTMuser@firewall.name.fqdnNetworkNetwork configuration  Dialogue Add lease
|
| Ethernet: | 12:34:56:78:90:AB | MAC address of the host | |
| IP: | IP address to be reserved exclusively for this host | ||
| Save and close | Saves and accepts the lease and closes the creation dialogue. | ||
|
notempty Important: Leases must necessarily be in an existing DHCP pool! |
UTMuser@firewall.name.fqdnNetwork  Static DHCP
| ||
|
notempty Joint use of static and dynamic IP addresses within a pool is possible. | |||
Static leases outside a pool
| Existing static leases that are not within a DHCP pool must be changed! If such leases are detected after an update, a message is displayed prompting to adjust the DHCP settings. It ist now possible that either
|
 | ||
Widget
In the administrator interface of the UTM, there is a DHCP widget that provides an overview of the existing DHCP connections.
Further information can be found in the Wiki article UTM Widgets.