What You’ll Need
- CSV spreadsheet of your reserved IPs (if you have any)
This is what the headers look like, add more hosts via rows:
Importing the CSV
In OPNsense, open the webpage under Services > Dnsmasq DNS & DHCP > Hosts. There should be an import button in the UI, just upload the CSV file and you should be good.
Setting DHCP Ranges
Under Services > Dnsmasq DNS & DHCP > DHCP Ranges, click add and fill in the values. Reference your old configuration with ISC and you should be fine.
NOTE: Theres no need to set Tags. Don’t set constructors if using IPv4
TIP: Once you have 1 range set, you can just clone them and create new ones pretty quick. Same with setting DNS later.
Setting DNS
I don’t use the native OPNsense DNS server (unbound), instead I use pihole on my main server so I’m not sure how this part goes with a local unbound service.
Under Services > Dnsmasq DNS & DHCP > DHCP Options, add a new option (not Boot).
| Option name | value |
|---|---|
| Type | Set |
| Option | dns-server [6] |
| Option6 | None |
| Interface | Whatever interface you are setting |
| Tag | None |
| Value | DNS Server IPs |
| Force | unchecked |
| Description | This is my description |
Clone this as many times as needed, setting a new interface each time.
Enabling and Testing Dnsmasq
Head to System > Diagnostics > Services and turn off “DHCPv4 Server” and turn on “Dnsmasq DNS/DHCP.”
To test this, on Windows you’ll enter the command ipconfig /renew.
On Linux the command will depend on which DHCP client you are using.
By default in Debian it is dhclient:
# dhclient -r interface_name && dhclient interface_name
If your IP does not change (for reserved IPs) or the DNS server is set correctly, then you have successfully migrated
RIP ISC
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