---
title: "Firewall configuration: Blocked ports on firewall"
slug: "oas-ag-firewall-configuration-open-port-numbers-on-firewall-3-28"
updated: 2025-07-04T10:04:20Z
published: 2025-07-07T13:24:13Z
canonical: "docs.onespan.com/oas-ag-firewall-configuration-open-port-numbers-on-firewall-3-28"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.onespan.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Firewall configuration: Blocked ports on firewall

OneSpan Authentication Server uses several different ports to communicate (see [Ports used by OneSpan Authentication Server](/sec/docs/oas-aref-firewall-configuration-open-port-numbers-on-firewall-3-28)). If these are blocked by a firewall, some features will not work correctly.

We recommend using a software firewall on OneSpan Authentication Server and segmenting the OneSpan Authentication Server network with a hardware firewall.