DHCP Blocking

RouterOS General
1

Hy
I have a Question about configuring microtik
Im Starting a small ISP Projekt, by this Projekt i use for Start a CSr160 Board
The current state ( IP’s are changed for Privacy):
Backbone: IP Range 99.99.222.1/24

Mikrotik IP : 99.99.222.223
Ether 1,ether2,ether3,ether4 Bridgend IP Firewall:no
Ether 5 Managementsubnet 192.168.70.1/24 with masquerade and dhcp

I Have a ip net from 99.99.222.222-99.99.222.254 for my devices ( Public IP) : the client receive a ip from DHCP 99.99.222.1
the goal is that the DHCP on the99.99.222.1 is blocked on ether1 (WAN) and a Several DHCP on my Routerboard (99.99.222.223) Give the IP’s from 99.99.222.224-99.99.222.254 to the clients
Also it shoult not go a dhcp packet to the upper Network (99.99.222.1)

I Testet with this http://forum.mikrotik.com/t/blocking-dhcp-with-bridge-firewall/92079/1
but ists not working…
i thest the rules in ip firewll and also in Bridge filter

Can someone Help me?


Thanks

2

I solved it:

Both are possible
Filter by ip firewall and bridge filter

My fault was that my understanding of the dataflow where wrong:
By a simple bridge config the packets passes thru the device : also a forward chain is required.

I have blocked the data to dst 255.255.255.255 and port 67-68 and it works.

3

I think for your ISP project to become successful, you need to understand routing.
Do not use a bridge like you did!
That will also automatically solve the issue you asked about, since a router will not pass the 255.255.255.255 broadcasts over to the other side.