DHCP option problem

[52000cc]

How can I enable DHCP options for a single host? For example, I need to assign a different gateway to a specific host.

[kaman]

Hi 52000cc,

Please refer to the below document for more information:

https://community.fortinet.com/t5/FortiGate/Technical-Tip-DHCP-Options/ta-p/197451

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Configure-DHCP-option-60-66-and-67-FortiGa...

Regards,
Aman

[ebilcari]

I did some lab tests because I was also curios and it seems that the Router/gateway option can't not be overwritten in the DHCP offer like the other options:

 

cconfig system dhcp server
..

config ip-range
 edit 2
  set start-ip 10.100.100.101
  set end-ip 10.100.100.109
  set vci-match enable
  set vci-string "udhcp 1.37.0"
next
end
config options
 edit 1
  set code 3
  set type ip
  set vci-match enable
  set vci-string "udhcp 1.37.0"
  set ip "10.100.100.254"
 next
 edit 2
  set code 150
  set type ip
  set vci-match enable
  set vci-string "udhcp 1.37.0"
  set ip "10.100.100.250"
 next
end
set vci-match enable
set vci-string "udhcp 1.37.0"

[ebilcari]

Update: If the default-gateway is removed from DHCP server configuration, FGT will send the new gateway as a custom option:

config system dhcp server
 edit 27
  unset default-gateway

This change will also affect the hosts that are not matching this VCI, if the other hosts can match with a VCI, the default gateway can be sent the same way.

[52000cc]

How can I configure the system to assign a different gateway to a host with a specific MAC address?

[Renante_Era]

since it's only one host, why not assign static IP address on that device instead of obtaining IP address from DHCP?

[52000cc]

If I set the IP address manually, it becomes very inconvenient to change it every time the machine is moved. There are several machines that need to use different gateways. I use to use Cisco setup as below..
ip dhcp pool HOSTXXX
host 192.168.1.68 255.255.255.0
client-identifier 01xx.xxxx.xxxx.xx
...

[Toshi_Esumi]

That's NOT assigning a gateway, but an IP reservation for a single host. Unlike Cisco, FGT can specify the host only by MAC address, not client-identifier.
https://community.fortinet.com/t5/FortiGate/Technical-Tip-How-to-set-DHCP-IP-reservation-on-FortiGat...

Toshi

[52000cc]

Because I forgot the exact command for this, the command I wrote only reserves the IP address. Either way, does the Fortigate not support assigning IP, gateway, DNS, etc., based on the MAC address?

[Toshi_Esumi]

Same as Cisco. Gateway, DNS, IP ranges are assigned in the main pool. Then if you need to assign a specific IP to a single host, you need to reserve the IP base on the MAC/hardware-address INSIDE the pool.

Just show us what you have configured in Cisco.

Toshi