---
title: Ensure An Instance is Allowed to Connect to Only Trusted IP Addresses
description: Use a system property to define a list of IP ranges that are appended to the outbound IP allow list.
locale: en-US
canonical_url: https://www.servicenow.com/docs/r/australia/platform-security/instance-security-hardening-settings/sc-ensure-an-instance-is-allowed-to-connect-to-only-trusted-ip-addresses.html
release: australia
product: Instance Security Hardening Settings
classification: instance-security-hardening-settings
topic_type: reference
last_updated: "2026-03-12"
reading_time_minutes: 2
breadcrumb: [Architecture, design, and threat modeling, Hardening settings, Platform Security]
---

# Ensure An Instance is Allowed to Connect to Only Trusted IP Addresses

Use a system property to define a list of IP ranges that are appended to the outbound IP allow list.

Use the **glide.custom.ip.outbound.authenticate.allow** system property to define a list of IP ranges that are appended to the outbound IP allow list of an instance. The property value contains a comma separated range of IP addresses in IPv4 or IPv6 format. IP ranges are specified using a hyphen \(10.0.10.14-10.0.10.19\), using CIDR notation \(10.0.10.0/24\), or consist of a single IP address \(10.0.10.5\). The instance is allowed to connect to the IP ranges in this property, unless listed in the IP deny list.

**Note:** IP ranges in this property are appended to the outbound IP allow list regardless of the value of the **glide.ip.authenticate.strict** property. The IP Address Access Controls \[ip\_access\] table provides an equivalent option to add to both the inbound/outbound allow/deny IP lists of an instance. Refer to the Steps to Configure section in [IP range based authentication](https://raw.githubusercontent.com/ServiceNow/ServiceNowDocs/australia/markdown/australia/platform-security/authentication/c_IPRangeBasedAuthentication.md).

Ensure that the **glide.custom.ip.outbound.authenticate.allow** system property value is either an empty, or a comma-separated list containing only trusted IP ranges that your want to allow your instance to access.

## More information

<table id="table_ajc_b43_3kb"><thead><tr><th>

Attribute

</th><th>

Description

</th></tr></thead><tbody><tr><td>

Configuration name

</td><td>

**glide.custom.ip.outbound.authenticate.allow**

</td></tr><tr><td>

Configuration type

</td><td>

System Properties \(/sys\_properties\_list.do\)

</td></tr><tr><td>

Data type

</td><td>

String

</td></tr><tr><td>

Recommended value

</td><td>

Empty, or a comma-separated list containing only trusted IP ranges that your want to allow your instance to access.

</td></tr><tr><td>

Default value

</td><td>

None

</td></tr><tr><td>

Fallback value

</td><td>

None

</td></tr><tr><td>

Category

</td><td>

[Architecture, design, and threat modeling](https://raw.githubusercontent.com/ServiceNow/ServiceNowDocs/australia/markdown/australia/platform-security/instance-security-hardening-settings/sc-architecture-design-threat-molding.md)

</td></tr><tr><td>

Security risk

</td><td>

-   Severity score: 4.3
-   CVSS score: Medium
-   Security risk details: If IP ranges are added to the property, it increases the risk of that an instance may connect to unauthorized or non-essential external services that should otherwise be blocked. This can weaken network-level security. In cases where additional IP ranges are necessary, be careful to include a minimal set of only trusted IPs.

</td></tr><tr><td>

Functional impact

</td><td>

There should be no functional impact. It can only be used to increase your instance's access.

</td></tr><tr><td>

Dependencies and prerequisites

</td><td>

None

</td></tr></tbody>
</table>**Parent Topic:**[Architecture, design, and threat modeling](https://raw.githubusercontent.com/ServiceNow/ServiceNowDocs/australia/markdown/australia/platform-security/instance-security-hardening-settings/sc-architecture-design-threat-molding.md)