Edgerouter x vpn site to site: a comprehensive guide to setting up site-to-site VPN tunnels on EdgeRouter X and EdgeRouter series in 2025

Yes, you can configure a site-to-site VPN on EdgeRouter X. In this guide, you’ll learn how to set up a robust IPsec site-to-site VPN between an EdgeRouter X and a remote gateway, including prerequisites, CLI steps, firewall and NAT considerations, testing, and common troubleshooting tips. We’ll cover practical, real-world scenarios, compare different approaches, and share battle-tested configurations you can adapt for your own network. If you’re aiming for a reliable, low-friction site-to-site connection, this guide has you covered.

• What you’ll get from this guide:
  • A clear, step-by-step path to a working site-to-site IPsec VPN on EdgeRouter X
  • Both CLI-driven and GUI-friendly options so you can choose what fits your workflow
  • How to plan subnets, avoid overlaps, and handle dynamic IPs
  • Firewalls, NAT exemptions, and routing considerations to keep traffic flowing
  • Verification commands, troubleshooting tips, and real-world gotchas
  • Advanced tips for multi-site setups, redundancy, and security hardening

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Introduction to EdgeRouter X site-to-site VPN basics

• Site-to-site VPN vs client VPN: A site-to-site VPN creates a secure tunnel between two networks, so devices on either side can communicate as if they were on the same local network. A client VPN, by contrast, lets individual users connect remotely to a single gateway. For office-to-office or data-center-to-branch deployments, site-to-site IPsec is the common choice.
• IPsec on EdgeRouter OS: EdgeRouter devices use IPsec to create encrypted tunnels. You’ll typically configure an IKE IKEv1 or IKEv2 group, an IPsec tunnel, and a pair of tunnel prefixes local and remote subnets. The tunnel can be established with a pre-shared key PSK or, in more advanced setups, with certificates.
• Why EdgeRouter X is a good fit: It’s compact, affordable, and flexible for small-to-medium sites. A well-tuned EdgeRouter X can handle straightforward site-to-site VPNs with stable throughput suitable for many branch-to-branch workloads.

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EdgeRouter X overview and site-to-site VPN basics

• EdgeRouter X is designed for simple to moderately complex routing and security tasks. When you set up a site-to-site VPN, you’re essentially creating a trusted, encrypted path between networks for example, 10.0.0.0/24 on your side and 192.168.1.0/24 on the partner side.
• Core concepts you’ll work with:
  • IKE group: The first negotiation step, defining how peers authenticate and how keys are exchanged. Common choices are aes256 and sha256 with a chosen DH group.
  • ESP group: The actual data tunnel parameters encryption, hashing, and lifetime that protect traffic across the tunnel.
  • Local and remote prefixes: The private networks that will be reachable via the tunnel on each side.
  • NAT traversal: If you’re behind NAT, you’ll typically enable NAT-T UDP 4500 so peers can negotiate and maintain the tunnel through NAT devices.
  • Firewall rules: You’ll create rules to allow IPsec traffic IKE’s UDP 500 and UDP 4500, plus ESP and to ensure VPN traffic flows through the right interfaces.
• Real-world constraints to consider:
  • Subnet overlaps: Make sure the local and remote subnets don’t overlap. If you must, redesign one side’s LAN or use a different tunnel subnet.
  • Public IPs: If either gateway uses a dynamic IP, plan for Dynamic DNS DDNS or a dynamic peer setting so the tunnel can re-establish when the IP changes.
  • Hardware limits: EdgeRouter X is great for small setups, but you’ll want to manage expectations about maximum VPN throughput and concurrent tunnels.

Prerequisites and planning

Before you start, gather and verify these items:

• Public IPs for both sites or DDNS names if you’re relying on dynamic addressing.
• Local subnets and remote subnets that won’t collide for example, 10.1.0.0/24 on Site A and 172.16.1.0/24 on Site B.
• A pre-shared key PSK or a certificate-based method if you’re implementing a more scalable PKI approach.
• EdgeRouter X with a recent EdgeOS/RouterOS version 2.x series is common and a stable internet connection on the WAN interface.
• Optional: a second EdgeRouter in the remote site to complete the site-to-site tunnel or an equivalent gateway that supports IPsec with similar capabilities.
• Basic firewall and NAT awareness: you’ll want rules that permit IPsec negotiation while safeguarding your LAN.

Step-by-step configuration EdgeRouter X CLI

Note: The exact syntax can vary slightly between EdgeRouter OS versions. Use these as a solid starting point and adapt to your environment.

1. Define IKE group IKEv2 is preferred if supported by both sides. otherwise IKEv1 is fine

• Example:
  • set vpn ipsec ike-group IKE-GROUP1 proposal 1 encryption ‘aes256’
  • set vpn ipsec ike-group IKE-GROUP1 proposal 1 hash ‘sha256’
  • set vpn ipsec ike-group IKE-GROUP1 proposal 1 dh-group ‘2’
  • set vpn ipsec ike-group IKE-GROUP1 lifetime ‘3600’

2. Define ESP IPsec data proposal

• set vpn ipsec esp-group ESP-GROUP1 proposal 1 encryption ‘aes256’
• set vpn ipsec esp-group ESP-GROUP1 proposal 1 hash ‘sha256’
• set vpn ipsec esp-group ESP-GROUP1 lifetime ‘3600’

3. Configure the site-to-site peer remote gateway

• Example remote gateway IP: 203.0.113.2, local/public IP: 203.0.113.1:
  • set vpn ipsec site-to-site peer 203.0.113.2 authentication mode ‘pre-shared-secret’
  • set vpn ipsec site-to-site peer 203.0.113.2 authentication pre-shared-secret ‘your-psk-here’
  • set vpn ipsec site-to-site peer 203.0.113.2 ike-group ‘IKE-GROUP1’
  • set vpn ipsec site-to-site peer 203.0.113.2 esp-group ‘ESP-GROUP1’
  • set vpn ipsec site-to-site peer 203.0.113.2 local-address ‘203.0.113.1’

4. Define the tunnel subnets local and remote

• set vpn ipsec site-to-site peer 203.0.113.2 tunnel 1 local prefix ‘10.0.0.0/24’
• set vpn ipsec site-to-site peer 203.0.113.2 tunnel 1 remote prefix ‘192.168.1.0/24’

5. Enable NAT exemptions for VPN traffic

• The goal is to ensure that traffic between the two subnets isn’t translated to your public NAT. Create firewall rules that allow IKE/ESP and disable NAT on traffic crossing the tunnel.
• Example firewall/VPN considerations:
  • set firewall name VPN-INPUT rule 10 action ‘accept’
  • set firewall name VPN-INPUT rule 10 protocol ‘udp’
  • set firewall name VPN-INPUT rule 10 destination-port ‘500’
  • set firewall name VPN-INPUT rule 20 protocol ‘udp’
  • set firewall name VPN-INPUT rule 20 destination-port ‘4500’
  • set firewall name VPN-INPUT rule 30 protocol ‘esp’
  • Apply the firewall to the appropriate input path WAN-facing interface so it protects while allowing IPsec negotiation.

6. Apply the VPN interface to the WAN

• Depending on your setup, you may also need to ensure that the IPsec interface is properly bound to the WAN interface so that traffic can flow across the tunnel. You’ll typically see a line like:
  • set vpn ipsec interfaces interface eth0
  • or configure a VPN firewall on the WAN as described above

7. Save and apply

• commit
• save

Notes:

• If you’re behind a NAT device and your peer is also behind NAT, enable NAT-T so IPsec can traverse NAT. This is usually the default in modern EdgeRouter configurations, but verify that UDP 4500 is allowed through any intermediate devices.
• If you’re using dynamic IPs on either side, you can use a DNS name for the remote gateway and a script or DDNS client to update the IP address when it changes. Some administrators prefer configuring a dynamic peer with a hostname and letting the device re-negotiate when the IP updates.

Step-by-step configuration GUI alternative

If you prefer a GUI-based approach, here’s a high-level path you can follow in the EdgeRouter UI:

• Go to VPN > IPsec
  • Create a new IPsec peer with the remote gateway’s public IP or hostname
  • Choose IKE group and ESP group consistent with the remote side
  • Enter the pre-shared key
  • Define local and remote subnets under tunnel 1
• Create firewall rules to permit UDP 500 and UDP 4500, and ESP as needed
• Ensure NAT is not applied to traffic between the two subnets
• Test the connection and monitor the status in the IPsec status tab

Testing and verification

• After you configure the tunnel on both sides, verify with these steps:
  • Check the IPsec SA status:
    • show vpn ipsec sa
  • Check the overall VPN status:
    • show vpn ipsec status
  • Validate tunnel state:
    • show vpn ipsec tunnels
  • Ping across the tunnel:
    • ping 10.0.0.1 from a host on Site A to 192.168.1.1 a host on Site B
  • Validate routing:
    • traceroute to a remote host on the other side to ensure traffic is routing across the VPN
• Common issues and quick checks:
  • Mismatch in PSK or IKE/ESP proposals: re-check both sides for exact matches
  • Subnet overlap: review local and remote prefixes
  • Firewall blocking IKE/ESP: confirm firewall rules for UDP 500/4500 and ESP are in place
  • NAT issues: ensure VPN traffic is exempt from NAT on both sides

Performance considerations and best practices

• Real-world throughput depends on your hardware and the VPN settings. EdgeRouter X is capable of handling modest IPsec tunnels, especially with AES-GCM or AES-256 ciphers. If you’re pushing toward higher throughput, you may want to optimize cipher selection and keep the tunnel simple one or two subnets, straightforward ESP proposals.
• Security: use strong IKE and ESP proposals aes256 or aes-GCM, sha256/sha384 and prefer certificate-based authentication for larger deployments if you can manage PKI. PSKs are simple but can become cumbersome for many peers.
• Redundancy: for multiple sites or critical connections, consider a second EdgeRouter at the remote site for a backup tunnel. You can configure multiple IPsec peers with failover rules so that traffic automatically uses the remaining tunnel if one goes down.
• Dynamic IPs: dynamic DNS or a dynamic peer can help keep tunnels up when IPs change. You may need a small automation script to update the remote gateway with the new IP when it changes.
• Monitoring: set up syslog monitoring for VPN events and consider simple alerts when the tunnel goes down or the IPsec SA expires.

Advanced topics

• Multi-site VPNs: for more than two sites, you can configure hub-and-spoke or full mesh topologies. This often involves careful subnet planning and firewall rules to ensure traffic finds the right path.
• Behind NAT and VPN routing: if you have NAT on the LAN side, make sure that LAN-to-LAN traffic routed via VPN isn’t translated in a way that breaks the tunnel. NAT exemptions for VPN subnets are essential.
• Dynamic routing across VPN: you can use static routes for small networks, or integrate dynamic routing like OSPF or BGP if your EdgeRouter and peers support it. This helps with automatic path selection and route advertisement across sites.
• Certificate-based authentication: if you scale beyond a couple of sites, certificates offer better management than PSKs. This requires a small PKI setup and configuring certificate-based auth on both sides.

Common pitfalls and how to avoid them

• Subnet collision: always double-check that the local and remote subnets don’t overlap. If necessary, adjust one side’s LAN or tunnel subnets and reconfigure the tunnel.
• Mismatched IKE/ESP settings: symmetric choices across both sides are essential. If you see negotiation failures, re-check the proposals on both ends.
• Firewalls blocking IPsec: ensure the firewall rules allow UDP 500, UDP 4500, and IPsec ESP on the WAN interface and the appropriate VPN interface.
• NAT complications: ensure VPN traffic isn’t NATed by any intermediate devices or by the local firewall rules that could interfere with 10.x/192.168.x.x addressing.
• Remote device changes: if the remote gateway changes IPs, you may need to re-establish the tunnel or implement a dynamic remote address with a DDNS-managed endpoint.

Real-world tips from experience

• Keep a small, clean subnet plan: a simple two-site design minimizes headaches.
• Document every change: note the PSK, IKE/ESP proposals, and subnets in a secure internal doc.
• Test incrementally: start with a single tunnel, verify traffic, then add more tunnels as needed.
• Automate where possible: scripts to reload VPN settings after a WAN IP change can save you hours.

Frequently Asked Questions

How do I know if my EdgeRouter X can support IPsec VPNs effectively?

IPsec VPNs are natively supported on EdgeRouter OS. Performance depends on the firmware version, cipher selection, and CPU load. For light-to-moderate VPN traffic, EdgeRouter X handles typical office-site VPNs well. If you’re planning high-throughput or many concurrent tunnels, evaluate hardware limits and consider a higher-end model. K electric offices: the ultimate guide to secure electrical office infrastructure, VPN integration, and modern workflow

What’s the difference between IKEv1 and IKEv2 for site-to-site VPNs?

IKEv2 is generally faster to establish, more resilient to changes in connectivity, and simpler to configure for modern devices. IKEv1 remains compatible with many older devices. If both sides support IKEv2, go with it.

Can I use a dynamic IP at my site?

Yes, but you’ll need a dynamic DNS service on the remote side and a mechanism to update the peer when the IP changes. DDNS helps keep the tunnel reachable without manual reconfiguration.

Do I need certificates for a site-to-site VPN?

PSK is simpler for small deployments, but certificates scale better for larger networks and provide stronger authentication management. If you’re administrating a few sites, PSK is common. for many sites, consider PKI.

How do I handle overlapping subnets?

Redesign one side’s LAN or configure the tunnel with different subnets for example, changing 10.1.0.0/24 to 10.2.0.0/24. Then update the tunnel local/remote prefixes accordingly.

How can I verify the tunnel is up?

Use commands like show vpn ipsec status, show vpn ipsec sa, and show vpn ipsec tunnels. Ping across subnets to confirm end-to-end connectivity. Review logs for negotiation errors. Free vpn for chrome vpn proxy veepn edge

What about NAT on VPN traffic?

NAT should be disabled or exempted for traffic between the two VPN subnets. Add firewall rules to allow IPsec traffic and exclude VPN traffic from NAT. This ensures the original IP addresses are preserved across the tunnel.

How do I add a second VPN tunnel for redundancy?

Configure a second IPsec peer with a different remote gateway and distinct local/remote subnets if needed. Use routing rules to prefer the primary tunnel and automatically fall back to the secondary tunnel if the primary fails.

Can I run multiple site-to-site VPNs on EdgeRouter X at the same time?

Yes, you can configure multiple IPsec site-to-site peers and tunnels. Each tunnel should have its own local/remote subnet pairs and unique IKE/ESP configurations. Be mindful of firewall rules and NAT exemptions to avoid cross-tunnel interference.

How do I troubleshoot a tunnel that won’t come up?

• Verify PSK and IKE/ESP proposals match on both sides
• Check NAT-T status and firewall rules for UDP 500/4500 and ESP
• Confirm public IPs and route reachability between sites
• Review EdgeRouter logs for IPsec negotiation errors
• Confirm the correct local and remote prefixes in tunnel configurations

Useful resources and references

• EdgeRouter IPsec documentation official
• IPsec concepts guide
• Best practices for site-to-site VPN design
• Dynamic DNS and VPN integration guides
• Troubleshooting IPsec VPNs on EdgeRouter devices

Useful URLs and Resources unlinked text

• EdgeRouter IPsec documentation
• VPN site-to-site planning guides
• Dynamic DNS providers and tutorials
• Security best practices for IPsec VPNs
• Firewall rules and NAT exemption references

Frequently Asked Questions additional quick hits Is protonvpn legal worldwide: legality, privacy, features, and safe usage

• Is there a GUI path for IPsec on EdgeRouter X?
• What are the most common mistakes when configuring site-to-site VPN?
• How do I extend a site-to-site VPN to include a third site?
• Can I run IPv6 through an IPsec tunnel on EdgeRouter?
• What is the recommended IKE/ESP configuration for a mixed-vendor VPN?
• How do I rotate PSKs or certificates without downtime?
• What monitoring tools work best with IPsec on EdgeRouter?
• Are there performance tuning tips for EdgeRouter X VPNs?
• How do I segment VPN traffic with firewall zones on EdgeRouter?
• What is the recommended backup strategy for IPsec configurations?

References for further reading and deeper dives:

• EdgeRouter IPsec guide EdgeOS
• IPsec site-to-site architecture and best practices
• Dynamic DNS integration with VPNs
• Certificate-based authentication for IPsec VPNs
• Network design patterns for small-to-medium branch networks

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