Port 500: IKE (IPsec)
Key exchange for IPsec VPNs.
- Port
- 500
- Protocol
- UDP
- Service
- IKE (IPsec)
- Exposure
- Expose only with access controls
What is port 500 used for?
Site-to-site and remote-access VPN.
Is it safe to expose port 500 to the internet?
Needed on a VPN gateway. Allow only known peers where possible.
If port 500 seems closed or unreachable
- Check that the IKE (IPsec) service is running and listening on port 500, not only on 127.0.0.1.
- Check the firewall on the host itself (Windows Defender Firewall, iptables, nftables, ufw) for a rule that allows UDP 500.
- If the host is behind a router, confirm the forwarding rule points to the correct internal address and that your internet provider does not use carrier-grade NAT.
- Test from outside your own network. A port can be open locally and blocked at the edge, or the other way round.
Using port 500 safely
Port 500 can be exposed when the host exists to provide this service, but add controls: restrict source addresses where you can, require strong authentication and encryption, and monitor the logs for repeated failures.
Check whether port 500 is open on your host
The check connects from our server, so it shows what the internet can reach.
Open the port checker