IKEv2 Monitoring

To monitor IKEv2, you run the same two exchanges a real client runs: IKE_SA_INIT on UDP/500 to negotiate keys, then IKE_AUTH to prove your username and password and verify the gateway's identity. TunnelHQ performs that full exchange on every check, from multiple regions, and alerts within a second when authentication breaks. Free for 5 monitors.

Why UDP/500 replies don't mean IKEv2 works

IKEv2 is a two-phase protocol, and the split is exactly why port-level monitoring gives false confidence. The first exchange, IKE_SA_INIT, negotiates cryptographic proposals, performs the Diffie-Hellman exchange, and swaps nonces. It is deliberately unauthenticated. Any client on the internet can complete it, and most IPsec stacks will answer it even when the gateway is unusable in every way that matters.

Everything that actually breaks for users lives in the second exchange, IKE_AUTH:

• The gateway's certificate expired. iOS, macOS, and Windows built-in clients hard-fail on this
• The EAP backend (RADIUS, Active Directory, LDAP) is down, so every username/password authentication fails while IKE_SA_INIT still completes cleanly
• The server identity no longer matches what clients expect after a certificate renewal changed the SAN
• A crypto-policy tightening removed the proposals older clients offer

There's a second trap: NAT traversal. Real-world clients are almost always behind NAT, which moves IKE and ESP traffic to UDP/4500. If UDP/4500 is filtered somewhere but UDP/500 isn't, a naive check against 500 stays green while every phone and laptop in the field fails to connect.

How TunnelHQ monitors IKEv2

1. Add host and credentials

IKEv2 is credential-based in TunnelHQ. There's no config file or URI to paste. A monitor needs three fields, plus one optional:

2. Full IKE_SA_INIT + IKE_AUTH on every check

Each check negotiates the IKE SA from scratch. Diffie-Hellman, nonces, proposal selection, then authenticates with your username and password the way built-in OS clients do. A check only counts as "up" when the gateway accepts the authentication, not when it merely answers packets.

3. Gateway identity verification

The remote_id field mirrors what strongSwan calls the remote identity: the name the gateway must present during IKE_AUTH. If your gateway identifies as vpn.example.com but its renewed certificate says something else, real clients refuse to connect. TunnelHQ applies the same strictness, so identity drift is caught the first check after it happens.

4. Regional checks and sub-second alerts

Checks run from US, EU, APAC, and SA nodes. On a state change, alerts go out within a second via email, Slack, Telegram, Discord, and webhooks.

Common IKEv2 failure modes TunnelHQ catches

• Gateway certificate expiry. The single most common "VPN suddenly stopped for everyone" cause
• RADIUS or AD outage behind the gateway. IKE_SA_INIT fine, IKE_AUTH failing
• Identity mismatch after certificate renewal (remote_id no longer matches)
• Proposal mismatch after a strongSwan or OS security-baseline update
• UDP/500 or UDP/4500 filtered on a specific path or region
• Address-pool exhaustion, where authentication is refused because no virtual IP is left to assign

Automate checks with the REST API

Create the same check programmatically. The fields map 1:1 to the monitor form:

curl -X POST https://tunnelhq.com/api/v1/check/public \
  -H "Content-Type: application/json" \
  -d '{
    "protocol": "ikev2",
    "host": "vpn.example.com",
    "username": "monitor",
    "password": "S3parate-Mon-Acct",
    "remote_id": "vpn.example.com"
  }'

Or try one interactively first in the free protocol tester. Click the IKEv2 chip, enter host and credentials, get a result in seconds.

Pricing for IKEv2 monitoring

IKEv2 is one of the 11 protocols TunnelHQ monitors, on every plan.

See full plan comparison →

IKEv2 monitoring FAQ

Which IKEv2 servers does this work with?

Any standards-compliant IKEv2 gateway that accepts username/password (EAP) authentication: strongSwan, Libreswan, Windows Server RRAS, MikroTik, and commercial VPN appliances. If the built-in iOS or Windows client can connect with a username and password, TunnelHQ can monitor it.

Do I need to give TunnelHQ a certificate or private key?

No. IKEv2 monitors need host, username, and password, with an optional remote_id. Credentials are encrypted with AES-256-GCM at rest. Best practice: create a dedicated monitoring account so you can rotate or revoke it independently of real users.

What does remote_id default to?

The host. Set it explicitly only when your gateway presents an identity different from its DNS name, which is common when one gateway serves several hostnames.

We also run an SSL VPN. Can TunnelHQ monitor both?

Yes. Many teams pair IKEv2 (native OS clients) with an OpenConnect / AnyConnect-compatible SSL VPN for restrictive networks, or with OpenVPN. Each protocol gets its own protocol-correct check under one dashboard.