IP addresses for firewalls
fairssl.dk and the ACME server change IP addresses on 11 November 2026. If your firewall allows our IP addresses, add the new ones before then.
If your firewall can use host names, allow fairssl.dk instead of IP addresses. The rule then follows the addresses when they change.
To fairssl.dk and the ACME server (inbound)
From 11 November 2026, fairssl.dk and the ACME server answer on these addresses. IPv4 only, port 443.
| IP address | Location |
|---|---|
| 81.27.108.46 | Copenhagen |
| 94.237.6.122 | Amsterdam |
There is no IPv6 address. If you have only allowed our IPv6 addresses, allow the two IPv4 addresses.
Current addresses (AWS)
fairssl.dk and the ACME server answer on these addresses today. You can remove them from your firewall after 11 November 2026.
- 18.158.73.4
- 3.68.15.95
- 3.69.102.239
- 2a05:d014:e9d:1800::/56
Schedule (Danish time, CET)
- Wednesday 4 November 2026 at 12:00 to Thursday 5 November at 13:00
- Test: fairssl.dk and the ACME server may answer from the new addresses. Allow them before the test.
- Wednesday 11 November 2026 at 13:00
- Final switch to the new addresses.
Traffic from us (outbound)
If your firewall only accepts certain senders, our connections to you come from these addresses.
| Used for | After the move | Today |
|---|---|---|
| API and webhooks | 81.27.109.162 94.237.111.251 | 3.120.17.163 18.159.51.226 3.121.196.143 |
| Certificate scanning and monitoring | 87.58.159.223 | 87.58.159.223 |
The addresses under "Today" change to those under "After the move" when the move is complete. 18.159.51.226 and 3.121.196.143 are not fixed and may change before then.