# How to Configure a Site-to-Site IPsec VPN on pfSense?

## Objective

To establish a secure IPsec Site-to-Site VPN tunnel between two pfSense firewalls.

## Prerequisites

* Non-overlapping LAN subnets.
* Pre-Shared Key (PSK).
* Internet connectivity on both sites.

## Client-Side Requirements

* WAN IP address.
* LAN subnet(s) for Phase 2.
* Matching Phase 1 settings (IKE version, PSK, encryption).
* Matching Phase 2 settings (subnets, encryption, PFS).
* Confirm NAT or routing requirements.

## Step 1: Configure Phase 1 (IKE)

* Navigate to VPN > IPsec > Add P1.
* Set Key Exchange Version: IKEv2.
* Remote Gateway: Client WAN IP.
* Authentication Method: Mutual PSK.
* Pre-Shared Key: \[Client-provided key].
* Encryption: AES-256, SHA256, DH Group 20, Lifetime: 28800 seconds.
* Save and Apply.

![](/files/d18e1fac06abcfb6b141d8159e705621ad75482f)

<figure><img src="/files/38e39a128f944e4e92a1af4aaa26dcbff9667c35" alt=""><figcaption></figcaption></figure>

## Step 2: Configure Phase 2 (ESP)

* Local Network: Site A LAN subnet.
* Remote Network: Site B LAN subnet.
* Encryption: AES-256, SHA256.
* Lifetime: 3600 seconds.
* Save and Apply.

## Step 3: Firewall Rules

* Navigate to Firewall > Rules > IPsec.
* Add rules to allow traffic between LAN subnets.
* Action: Pass, Interface: IPsec, Protocol: Any, Source: Local LAN subnet, Destination: Remote LAN subnet.
* Save and Apply.

  <figure><img src="/files/29fefefa2ddfb2f069fa73c94465c593ef3e1836" alt=""><figcaption></figcaption></figure>

<figure><img src="/files/ade625a4bd387c5c5df0adf5aeaf81bfff3f896c" alt=""><figcaption></figcaption></figure>

## Step 4: Test the Tunnel

* Go to Status > IPsec and verify the tunnel is established.
* Test connectivity: Ping from Site A LAN to Site B LAN.
* Use Diagnostics > Traceroute if needed.

  <figure><img src="/files/ea2e5841312a7a04324535d02f9b89ac0aca290a" alt=""><figcaption></figcaption></figure>

## Troubleshooting

* Ensure Phase 1 and Phase 2 settings match exactly on both ends.
* Check firewall rules and NAT settings.
* Verify routing and DNS.

## Best Practices

* Use strong encryption (AES-256, SHA256).
* Enable Dead Peer Detection.
* Monitor tunnel status regularly.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.acecloud.ai/knowledge-base/tutorials/how-to-configure-a-site-to-site-ipsec-vpn-on-pfsense.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.