Hey,

I'd like to know if it's possible to disable default gateway only for one specific client and also when there's already configured default gateway in DHCP Servers->Networks->some-network->gateway and I'll configure DHCP option 3 in DHCP Server->Options only to specific static lease how ROS decide what send to the client?

I think the RouterOS DHCP server does not have this capability, unless I have overlooked something.
The ISC DHCP server often used on Linux can do this. Maybe you can run it on another system in the network.

I think the RouterOS DHCP server does not have this capability, unless I have overlooked something.
The ISC DHCP server often used on Linux can do this. Maybe you can run it on another system in the network.

Thank you, I was afraid it looks like that.

Most likely you want some system to be unable to route traffic to other networks, e.g. internet.
You can solve that in another way. When you click on its lease you can make it static, and you
can add a filter in the router that blocks this specific address in the forward chain.
That should have the same result....

In that same screen it appears to be possible to add extra options in the DHCP reply for that
device, but not to delete globally defined options like the gateway.
However, you could try to add options to add 2 routes in the DHCP reply, one for 0.0.0.0/1 and
one for 128.0.0.0/1 that route the traffic into a blackhole (e.g. gateway 127.0.0.1).
Unfortunately adding custom options for DHCP requires you to study how options are formatted
and put them in config screens in HEX format.

Most likely you want some system to be unable to route traffic to other networks, e.g. internet.
You can solve that in another way. When you click on its lease you can make it static, and you
can add a filter in the router that blocks this specific address in the forward chain.
That should have the same result....

Unfortunately it's not the solution of my problem. I use OpenVPN and I don't want to give my users admin privileges (OpenVPN's way of route pushing requires it), that's why I configure remote network card using DHCP. I mean settings like suffix, route pushing etc. I don't want any default gateway for one reason, I cannot configure its metric. Funny things happen when Windows choses VPN gateway instead LAN one. In DHCPd it's simple as f*** (sorry), same with pfsense. Ability to control host configuration based on lease in such case is important...