Mikrotik - Creating DHCP Proxies for dhcpd

DHCP Proxies come in handy when provisioning to multiple networks while not maintaining multiple VLANs on the DHCP-Server itself. The easiest way to accomplish this is by running multiple DHCP-Proxies on the router/firewall (in my case, a MikroTik router).

Some Presets for DHCP:

- Server IP: 172.31.10.8

- Networks: 172.31.20.0/24, 172.31.30.0/24

First, let's set up the subnets on the DHCP-Server:

 [archy@dhcp-server ~]$ sudo vim /etc/dhcp/dhcpd.conf

 subnet 172.31.20.0 netmask 255.255.255.0 {  
      range 172.31.20.100 172.31.20.199;  
      option subnet-mask 255.255.255.0;  
      option domain-name-servers 172.31.10.5, 172.31.10.6;  
      option ntp-servers 172.31.10.5, 172.31.0.6;  
      option routers 172.31.20.254;  
      option broadcast-address 172.31.20.255;  
      filename "pxelinux.0";  
      next-server 172.31.10.10;  
      }  
 subnet 172.31.30.0 netmask 255.255.255.0 {  
      range 172.31.30.100 172.31.30.199;  
      option subnet-mask 255.255.255.0;  
      option domain-name-servers 172.31.10.5, 172.31.10.6;  
      option ntp-servers 172.31.10.5, 172.31.0.6;  
      option routers 172.31.30.254;  
      option broadcast-address 172.31.30.255;  
      filename "pxelinux.0";  
      next-server 172.31.10.10;  
      }

There are some extra options set, such as internal DNS- and NTP-Servers, as well as the PXE-Server which is a foreman in my case. To activate the changes, restart the dhcpd.service

 [archy@dhcp-server ~]$ sudo systemctl restart dhcpd.service

Now that the dhcpd-side is set-up, let's continue with the router. Since I'm using RouterOS(MikroTik), I'll be using the CLI because I'm most familiar with that on RouterOS.

 [archy@MikroTik] > ip dhcp-relay add name=internal dhcp-server 172.31.10.8 interface=vlan20 local-address=172.31.20.254 disabled=no  
 [archy@MikroTik] > ip dhcp-relay add name=dmz dhcp-server 172.31.10.8 interface=vlan30 local-address=172.31.30.254 disabled=no  
 [archy@MikroTik] > ip dhcp-relay print  
 Flags: X - disabled, I - invalid   
 #  NAME      INTERFACE  DHCP-SERVER   LOCAL-ADDRESS   
 0  internal  vlan20     172.31.10.8   172.31.20.254   
 1  dmz       vlan30     172.31.10.8   172.31.30.254

That concludes the DHCP-Proxy setup on the MikroTik Router. You can check if everything works as intended by provisioning a VM in one of the Subnets (assuming they're added to foreman already).

Feel free to comment and / or suggest a topic.

Comments

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