Guide: Getting started with OPNsense and VLANs

Might be bold to call this a guide, it’s rather my personal documentation rewritten to a quite extensive How to get started with OPNsense and VLANs. Modify for your own needs and preferences - I’ve just started and probably lack some understanding.

OPNsense dashboard

Install OPNsense⌗

Read the official documentation
Download the latest image and create a bootable USB with preferable tools, eg. tar and dd.
- tar -xvjf OPNsense-24.7-vga-amd64.img.bz2
- dd if=OPNsense-24.7-vga-amd64.img of=/dev/sdX bs=16k
Let the initial setup run, it will auto-select WAN/LAN interfaces if you’ve plugged them in - running live in memory.
Login as user installer password opnsense to start the actual installer.
- Install on ZFS (my preferred, if running virtualized with ZFS behind just choose UFS)
- Pick your drive next. After that, go with default swap (8Gb) and then accept.
- When it’s done, choose a new password and then reboot.

After it rebooted, access its webGUI on the internal IP it shows (probably 192.168.1.1) and start the initial setup wizard.

General

Hostname: OPNsense
Domain: home.arpa
TimeZone: Europe/Stockholm
DNS Servers: 9.9.9.9 and 149.112.112.112 (my preferred upstream DNS - quad9)
- Uncheck Override DNS to not let ISP DNS override yours
Unbound DNS
- Enable Resolver: check
- Enable DNSSEC Support: check

WAN: Select Type (usually DHCP) and there’s nothing more to configure, if you’re on Static IP or something else, just enter the options needed.

LAN: Same thing but for the internal network, pick your internal address here - depending on your layout with VLANs this might be used as the VLAN1 (default LAN) subnet.

Complete the initial configuration - then check for updates @System/Firmware/Updates (Go to Status -> Check for Updates) and reboot if required.

And now the most important step! DARK THEME!

Go to @System/Firmware/Plugins and filter for theme.
Install a theme (cicada, rebellion, vicuna are all dark themes).
Apply @System/Settings/General/Theme -> Save.

Now you should be up and running with the initial configuration done, let’s dive deeper!

VLANs⌗

I’ll create a setup with 4 VLANs;

10.0.10.0 Home, for all default clients, PCs, phones.
10.0.20.0 Management, for internal servers and services.
10.0.30.0 DMZ, for servers and services accessible from the internet.
10.0.40.0 Guest, for my guest Wifi.

Creating a VLAN interface and DHCP.⌗

Example setup for VLAN 10 - Home:

@Interfaces/Other Types/VLAN
Add
- Name: vlan0.10
- Interface: LAN
- Tag: 10
- Description: 10_home
@Interfaces/Assignments/Assign a new interface
- Choose vlan0.10 -interface (virtual device)
- Choose a short+descriptive description eg 10_home (default will be opt1)
- Add
- New interface added, eg 10_home - click to edit
  - Enable Interface: check
  - IPv4 Configuration Type: Static IPv4
  - IPv4 address: 10.0.10.1/24 (this is the routers IP-address on this network)
  - Save!
@Services/DHCPv4/10_home
- Enable: check
- Range: 10.0.10.100 - 10.0.10.200
- Gateway: 10.0.10.1
- DNS: leave empty for system default or set specific for VLAN
- DHCP Static Mappings
  - Add MAC + IP of preferred static lease (or do this after each client have connected).

Repeat with any other VLAN you wish to have - adjust the IP’s and names per your layout.

Firewalling VLANs⌗

Good read: homenetworkguy’s cheat-sheet

Rules are usually created on the originating interface - so to allow traffic eg. from VLAN10 to a something on VLAN20, the rule is created on the VLAN10 interface context. Rules are read from top to bottom - so if you’ve got an “allow all” rule, any block rules have to be above that. Vice versa.

OPNsense will by default set up a Default allow LAN to any rule on the LAN-interface, to allow clients on the LAN-network (192.168.1.0/24 if you’ve not changed it) to reach any other. This is fine for now, and you’d might want to set up a equal rule on your first VLAN while learning and setting up the rest.

Create an allow to ANY rule on the VLAN10 - home interface:⌗

@Firewall/Rules/10_home
Add
- Action: Pass
- Interface: 10_home
- TCP/IP Version: IPv4+IPv6
- Protocol: any
- Source: 10_home net
- Direction: in (this means entering this interface)
- Destination: any (to allow 10_home to ANY other network)
- Destination port: any
- Description: allow to ANY
Save

This is fine for the internal networks for now. I suggest to lock it down further later.

Securing it further can be done by either adding restrictions above the “allow to ANY” rule (like block traffic from 20_mgmt to 10_home) this might be fine in a default home setup, implicit allow - things not explicitly blocked will be allowed. Preferrably though a more secure way is implicit deny - anything not explicitly allo::wed will be blocked and I’ll show that with the DMZ-VLAN.

Create a RFC1918 (private networks) alias⌗

We’ll create an alias to use in our rules, to not have to create separate rules for every network.

@Firewall/Aliases -> Add
- Name: RFC1918
- Type: Network(s)
- Content: 192.168.0.0/16 100.64.0.0./10 127.0.0.0/8 10.0.0.0/8 172.16.0.0/12
- Description: Group of Private Networks

Create rules on the DMZ interface to only allow traffic to/from internet.⌗

I only run IPv4, so I wont create any IPv6 rules.

Allow HTTP+HTTPS to internet (non-private networks)

@Firewall/Rules/30_dmz
Add
- Action: Pass
- Interface: 30_dmz
- Protocol: TCP
- Source: any
- Destination / Invert: check (to invert the match)
- Destination: RFC1918
- Destination port range: HTTP-HTTP
- Description: Allow HTTP to non-private network
Save

Clone this rule, then edit and change Destination port range to HTTPS-HTTPS and edit the description.

Allow DNS to internal network

@Firewall/Rules/30_dmz
Add
- Action: Pass
- Interface: 30_dmz
- Protocol: TCP/UDP
- Source: any
- Destination: 30_dmz net
- Destination port: DNS-DNS
- Description: Allow to internal DNS
Save

That’s it. The machines in the DMZ-network will reach internet and local dns but nothing else.

What if we’d like a specific machine on the DMZ (reverse proxy?) to reach a web service on the management network?

Example rule to allow specific DMZ-machine to specific Mgmt-service

@Firewall/Rules/30_dmz
Add
- Action: Pass
- Interface: 30_dmz
- Protocol: TCP
- Source: 10.0.30.111
- Destination: 10.0.20.222
- Destination port: 8080
- Description: Allow proxy to internal Mgmt web
Save

Now to allow this to be reached from the internet we need to do some NAT.

Port Forwarding from Internet to DMZ Reverse Proxy⌗

So let’s assume we’ve got a reverse proxy listening on port 80+443 at the IP 10.0.30.111.

@Firewall/NAT/Port Forward
Add
- Interface WAN
- Protocol: TCP
- Destination: WAN address (this means traffic entering the firewall on the WAN address)
- Destination port range: HTTP-HTTP
- Redirect target IP: Single host or Network, 10.0.30.111
- Redirect target port: HTTP
- Description: HTTP to DMZ
- Filter rule association: Add associated filter rule (this will automatically create rules on the WAN interface to allow the traffic)
Save

Clone this and edit to change HTTP to HTTPS.

Then check @Firewall/Rules/WAN to see the rules “HTTP(S) to DMZ” added. If you chose None at Filter rule association or if they’re missing add them manually.

Unbound DNS⌗

Unbound is a validating, recursive, caching DNS resolver.

Unbound will allow us to block unwanted dns queries, make queries faster by caching and being a recursive DNS, more secure by DNS over TLS and also allow us to set up internal overrides/rewrites.

@Services/Unbound DNS First make sure it’s enabled @./General -> Enable Unbound.

Enable DoT @./DNS over TLS
- Add
  - Server IP: 9.9.9.9
  - Verify CN: dns.quad9.net
- Add (secondary)
  - Server IP: 149.112.112.112
  - Verify CN: dns.quad9.net
- Apply
Enable Blocklists @./Blocklist
- Enable: check
- Type of DNSBL: Toggle preferred lists
  - Start with some Abuse.ch, OISD, AdAway, AdGuard, Blocklist.site and then add more for testing.
- Whitelist Domains: Here you can whitelist specific domains if you find them blocked.
Set local rewrites @./Overrides
- Add
  - Host: dash
  - Domain: home.arpa
  - IP address: 10.0.30.100 (internal reverse proxy, as an example)
- Apply (this will now rewrite dash.home.arpa to 10.0.30.100)

Check Register DHCP Static Mappings @Unbound DNS/General to automatically map static DHCP-client names to be resolved by the DNS.
Example: a client named stormy will be reachable by stormy.home.arpa or even just stormy when the @System/Settings/General/DNS search domain is set to home.arpa.

If you’ve already got an internal service like AdGuard Home or PiHole, you could forward your queries to that instance.

@./Query Forwarding
Add
- Server IP: 10.0.30.100 (as an example)
- Server Port: 53 (or 853 if the internal service uses DoT)
Apply

Add Cron job to update Unbound Blocklists.

@System/Settings/Cron
Add
- Set Minutes,Hours,DotM,Months,DotW to 0,0,*,*,* to run at 00:00 every day.
- Command: Update Unbound DNSBLs
- Description: Update Unbound BLs

Wireguard⌗

WireGuard® is an extremely simple yet fast and modern VPN that utilizes state-of-the-art cryptography.

Wireguard will create an VPN tunnel to reach our home network from remote locations This will require a public domain or static IP or similar.

First create an instance:

@VPN/WireGuard/Settings
Add
- Name: WGMain
- Generate keypair
- Listen port: 51820
- Tunnel address: 10.10.0.1 (non-existing within internal networks)
Save
@./Peer Generator:
- Instance: WGMain
- Endpoint: -Public Domain/IP here-
- Name: Phone1
- Address: 10.10.0.2/32
- Generate Preshared Key
- DNS Servers: -Internal DNS here-
- QR-scan and/or copy+paste config!
- Store and generate next

Set up the wireguard interface:

@Interfaces/Assignment/ Assign a new interface
- Pick wg0 (the newly created WireGuard instance)
- Description: WG_admin
- Add, Save
- Click the new interface WG_admin and Enable Interface
- Save + Apply

Allow Wireguard on WAN

@Firewall/Rules/WAN - Add
- Pass
- Interface: WAN
- Protocol: UDP
- Destination: WAN adress
- Destination port range: other, 51820

Enable outbound internet access through Wireguard

@Firewall/NAT/Outbound
- Mode: Hybrid outbound NAT rule generation
  - Save
  - Apply
- Manual Rules - Add
  - Interface: WAN
  - Source address: WG_dmz net
  - Save
- Apply

Allow wireguard client to connect to any internal VLAN

@Firewall/Rules/WG_admin
- Pass
- Interface: WG_admin
Protocol: any
- Source: WG_admin net
- Destination: any

To ensure traffic is not fragmented and errors out, create a normalization rule:

@Firewall/Settings/Normalization
- Add
  - Interface: WireGuard (Group)
  - Max mss: 1380 (or 1360 if you use IPv6)

I still need to tinker some with this setup - read more in the official docs

Spamhous DROP-list official docs ⌗

DROP Don't Route or Peer -lists

@Firewall/Aliases -> Add a new alias:

Name	spamhaus_drop
Description	Spamhaus DROP
Type	URL Table (IPs)
Content	https://www.spamhaus.org/drop/drop.txt
Refresh Frequency	Days:1

Save and apply. Use the list in a block rule:

@Firewall/Rules/WAN
Add
- Block
- Interface: WAN
- Direction: in
- Source: spamhaus_drop
- Destination: any
- Category: Spamhaus
- Description: Spamhaus DROP
Save
Add
- Block
- Interface: WAN
- Direction: out (This is usually not preferred, but instead of setting up on every other VLAN)
- Source: any
- Destination: spamhaus_drop
- Category: Spamhaus
- Description: Spamhaus DROP
Save
Apply

Dynamic DNS - DDNS⌗

If you’ve got a dynamic IP and want your domain to always point to it, you’ll need DDNS. I use Loopia as my domain provider.

Install the plugin:

@System/Firmware/Plugins/os-ddclient
- Install

Configure the plugin:

@Services/Dynamic DNS/Settings
Add
- Service: -your provider- (loopia in my case)
- Username: -username-
- Password: -password-
- Check ip method: (loopia)
- Interface to monitor: WAN
- Force SSL: check
Save Wait for it to update, or restart the service.

Crowdsec - Intrusion Detection⌗

Crowdsec is an open-source, lightweight software, detecting peers with aggressive behaviors to prevent them from accessing your systems. read more

@Services/Crowdsec/Settings
- Enable Log Processor: check
- Enable LAPI: check
- Enable Remediation Component: check
- LAPI listen address: 127.0.0.1
- LAPI listen port: 8080
- Enable log for rules: check
- Tag for matched packets: crowdsec
@crowdsec.net web management
- Security Engines/Connect my Security Engine now
- Copy command cscli console enroll ABC123
@opnsense - SSH to opnsens (enable SSH @System/Settings/Administration -> Enable Secure Shell + Permit root user login)
- Make sure Crowdsec is up service crowdsec start
- Run the command above cscli console enroll ABC123
- Reload Crowdsec service crowdsec reload
@crowdsec.net web management - Accept enroll
@opnsense SSH - whitelist private addresses
- cscli parsers install crowdsecurity/whitelists
- cscli collections install crowdsecurity/opnsense
- cscli collections install crowdsecurity/opnsense-gui
- Reload Crowdsec service crowdsec reload

Check that firewall rules are added @Firewall/Rules/WAN -> Expand Automatically generated rules.

$crowdsec_blacklists
$crowdsec6_blacklists

Alerts and Blocks will be shown @Services/CrowdSec/Overview -> Alerts/Decisions