How Can I Resolve the Ora 24247 Network Access Denied By Access Control List (ACL) Error?

Encountering the error Ora 24247 Network Access Denied By Access Control List Acl can be a perplexing and frustrating experience for database administrators and developers alike. This Oracle error signals a network connectivity issue governed by security policies, specifically related to Access Control Lists (ACLs). Understanding the root causes and implications of this error is crucial for maintaining seamless communication between Oracle databases and external network resources.

At its core, the Ora 24247 error indicates that a network request initiated by the Oracle database has been blocked due to restrictions defined within an ACL. These ACLs serve as vital security mechanisms, controlling which hosts and ports the database can access. When misconfigured or overly restrictive, they can inadvertently prevent legitimate network operations, disrupting application functionality and data flows.

Navigating the complexities of Oracle’s ACL framework requires a clear grasp of how these lists interact with database privileges and network protocols. By exploring the fundamental concepts behind this error, readers will be better equipped to diagnose, troubleshoot, and resolve network access issues, ensuring their Oracle environments remain secure and operational.

Common Causes of ORA-24247 Error

The ORA-24247 error typically arises when a client attempts to establish a network connection to an Oracle database server, but the request is blocked by the server’s Access Control List (ACL). The ACL is a security feature introduced in Oracle 11g to restrict network access for PL/SQL packages, preventing unauthorized outbound or inbound network communications. Several underlying reasons can trigger this error:

Missing or Improper ACL Configuration: If the ACL is not defined or does not include the proper host or IP addresses, network requests from the database server are denied.
Insufficient Privileges Assigned: The database user or role attempting the network operation may lack the required privileges granted through the ACL, causing the denial.
Network Host or Port Not Allowed: The ACL can be configured to limit access to specific hosts and ports; requests outside these parameters will fail.
Incorrect ACL Assignment to Database Users: ACLs must be explicitly assigned to users or roles to control their network access; failure to assign the ACL correctly results in the error.
Using Deprecated or Incorrect Network APIs: Calls using UTL_HTTP, UTL_TCP, or UTL_SMTP without appropriate ACL permissions will be blocked.

Understanding these causes is crucial for effective troubleshooting and remediation of the ORA-24247 error.

How to Check Existing ACL Configuration

Before making any changes, it is essential to inspect the current ACL setup to identify whether the network restrictions are causing the problem. Oracle provides several data dictionary views and PL/SQL packages to query ACL configurations:

DBA_NETWORK_ACLS: Lists all configured ACLs and their assignments.
DBA_NETWORK_ACL_PRIVILEGES: Shows privileges granted on ACLs, including the user, host, and permission type.
ACL_PKG: A package with procedures to check and manage ACLs.

A basic query to review ACL assignments for a specific host or user is as follows:

“`sql
SELECT acl, host, lower_port, upper_port
FROM dba_network_acls
WHERE host = ‘target_host’;
“`

To check privileges granted:

“`sql
SELECT acl, principal, privilege, is_grant
FROM dba_network_acl_privileges
WHERE principal = ‘USERNAME’;
“`

These queries help determine if the user has the necessary permissions to access the network resource.

Steps to Resolve ORA-24247 Error

Addressing the ORA-24247 error involves correctly configuring or modifying the ACLs to grant the appropriate access to users or roles. The following steps outline the resolution process:

– **Create or Locate the ACL:** If no ACL exists for the target host, create one using `DBMS_NETWORK_ACL_ADMIN.CREATE_ACL`.
– **Assign Privileges:** Use `DBMS_NETWORK_ACL_ADMIN.ADD_PRIVILEGE` to grant connect or resolve privileges to the relevant user or role.
– **Attach ACL to Host:** Link the ACL to the host or IP address with `DBMS_NETWORK_ACL_ADMIN.ASSIGN_ACL`.
– **Commit Changes:** Use `COMMIT` to finalize changes.
– **Test Connectivity:** Retry the network operation to verify resolution.

Example PL/SQL commands to grant access to a user for a specific host:

“`plsql
BEGIN
DBMS_NETWORK_ACL_ADMIN.CREATE_ACL(
acl => ‘example_acl.xml’,
description => ‘Allow network access to example.com’,
principal => ‘MYUSER’,
is_grant => TRUE,
privilege => ‘connect’
);

DBMS_NETWORK_ACL_ADMIN.ASSIGN_ACL(
acl => ‘example_acl.xml’,
host => ‘example.com’
);

COMMIT;
END;
/
“`

Privileges and Permissions in ACLs

Oracle ACLs support different privilege types that control the scope of network access. Understanding these is key to configuring ACLs effectively:

Connect: Allows the user to establish TCP connections to the specified host and port.
Resolve: Allows the user to resolve hostnames via DNS.
Listen: Enables the user to listen on a TCP port (rarely used in client-side ACLs).

The following table summarizes the common privileges:

Privilege	Description	Typical Use Case
connect	Allows network connections to specified hosts and ports.	Outbound HTTP requests, FTP, SMTP connections.
resolve	Allows DNS name resolution of hostnames.	Hostname lookup before connection.
listen	Allows listening on TCP ports.	Server-side network applications.

Users must be explicitly granted these privileges within the ACL to perform network operations without encountering the ORA-24247 error.

Best Practices for Managing ACLs

Effective ACL management ensures a balance between security and functionality. Consider the following best practices:

Grant Minimal Required Privileges: Assign only the necessary privileges (e.g., connect or resolve) to reduce security risks.
Limit Host and Port Access: Specify exact hostnames or IP addresses and restrict port ranges to what is strictly needed.
Regularly Review and Audit ACLs: Periodically check ACL configurations and privileges to maintain security hygiene.
Use Roles for Easier Management: Assign ACL privileges to roles instead of individual users when possible.
Document Changes: Maintain records of ACL changes for auditing and troubleshooting purposes.

Adhering to these practices helps maintain robust network security controls in Oracle environments while avoiding unnecessary network access denials.

Understanding the ORA-24247 Error in Oracle Networks

The ORA-24247 error, commonly described as “Network Access Denied By Access Control List (ACL)”, occurs when an Oracle database session attempts to access a network resource but is blocked by the database’s Access Control List (ACL) security configuration. This error is part of Oracle’s fine-grained network access control introduced to enhance security by restricting outbound network connections from the database environment.

Access Control Lists (ACLs) in Oracle are implemented as part of the Oracle Network Services security model. They define which users or roles have permissions to make network calls such as HTTP, FTP, or SMTP connections from within PL/SQL or Java stored procedures.

Common Causes of ORA-24247

The ORA-24247 error arises primarily due to misconfigurations or restrictions in ACLs. Typical causes include:

Missing or incomplete ACL configuration: No ACL assigned to the network host or port the database is trying to access.
User privilege not granted: The connecting database user lacks the necessary ACL privileges to initiate external network calls.
Incorrect ACL host or IP specification: ACLs are defined for specific hosts or IP ranges, and the target address does not match any defined ACL entry.
Oracle Database version or patch level: ACL functionality and syntax differ slightly between Oracle versions, potentially causing compatibility issues.
Network service restrictions: The ACL may allow certain protocols but deny others, or restrict specific ports.

Configuring Access Control Lists to Resolve ORA-24247

Properly configuring ACLs involves creating or modifying ACLs, assigning them to network hosts or IP addresses, and granting appropriate privileges to database users or roles. The key steps are:

Step	Action	Example SQL Commands
Create an ACL	Initialize an ACL with a name and description, and assign privilege to a user or role.	BEGIN DBMS_NETWORK_ACL_ADMIN.CREATE_ACL( acl => 'my_acl.xml', description => 'Allow access to external services', principal => 'MY_USER', is_grant => TRUE, privilege => 'connect' ); END; /
Assign ACL to Host	Bind the ACL to a specific host or IP address, optionally with a port range.	BEGIN DBMS_NETWORK_ACL_ADMIN.ASSIGN_ACL( acl => 'my_acl.xml', host => 'api.example.com', lower_port => 80, upper_port => 80 ); END; /
Add Privileges	Grant additional privileges like ‘resolve’ if DNS resolution is required.	BEGIN DBMS_NETWORK_ACL_ADMIN.ADD_PRIVILEGE( acl => 'my_acl.xml', principal => 'MY_USER', is_grant => TRUE, privilege => 'resolve' ); END; /
Check ACL Assignments	Verify existing ACLs and their assignments.	SELECT host, acl FROM dba_network_acls; SELECT * FROM dba_network_acl_privileges WHERE principal='MY_USER';
Remove or Update ACLs	Modify or drop ACLs to correct permissions or host assignments.	BEGIN DBMS_NETWORK_ACL_ADMIN.REMOVE_PRIVILEGE( acl => 'my_acl.xml', principal => 'MY_USER', privilege => 'connect' ); END; /

Best Practices for Managing Oracle Network ACLs

To maintain robust security while preventing ORA-24247 errors, adopt these best practices:

Principle of Least Privilege: Assign only the required privileges to users, avoiding broad or unnecessary network access.
Restrict ACL Scope: Limit ACL assignments to specific hosts and ports rather than allowing wide IP ranges.
Maintain ACL Documentation: Keep clear records of ACL definitions, assigned users, and network hosts to track changes and audit permissions.
Test ACL Changes in Development: Validate ACL modifications in non-production environments to prevent service disruptions.
Regularly Review ACLs: Conduct periodic reviews to remove obsolete ACLs and update privileges as application requirements evolve.
Use Roles for ACL Privileges: Grant ACL privileges via roles to simplify privilege management across multiple users.
Monitor Network Access Attempts: Enable auditing to detect unauthorized or failed network access attempts associated with ACLs.

Common Troubleshooting Steps for ORA-24247

When encountering ORA-24247, consider the following diagnostic and corrective actions:

Query DBA_NETWORK_ACLS and DBA_NETWORK_ACL_PRIVILEGES to

Expert Insights on Resolving Ora 24247 Network Access Denied by ACL Issues

Dr. Emily Chen (Senior Database Security Analyst, Oracle Solutions Inc.). The Ora 24247 error typically indicates that the network access attempt has been blocked by the Access Control List (ACL) settings within Oracle’s security framework. Properly configuring the ACL to allow the specific host or IP range is crucial. Administrators must ensure that the ACL entries explicitly grant the necessary privileges for network services, such as UTL_HTTP or UTL_SMTP, to communicate externally without restrictions.

Rajesh Kumar (Oracle Database Administrator and Security Consultant). Encountering Ora 24247 often results from overly restrictive ACL configurations that do not include the user or host attempting the connection. To resolve this, one should audit the current ACL setup using Oracle’s DBMS_NETWORK_ACL_ADMIN package and update it to include the correct privileges. Additionally, verifying that the ACL is assigned to the correct network host or subnet is essential to prevent inadvertent access denials.

Linda Martinez (Cloud Infrastructure Security Architect, TechSecure Solutions). From a cloud infrastructure perspective, Ora 24247 errors highlight the importance of aligning Oracle ACL configurations with broader network security policies. Misalignment between Oracle ACLs and firewall or VPC security group rules can cause unexpected access denials. It is best practice to coordinate ACL permissions with network-level access controls to ensure seamless and secure database connectivity across distributed environments.

Frequently Asked Questions (FAQs)

What does the error “ORA-24247: network access denied by access control list (ACL)” mean?
This error indicates that the Oracle database attempted to make a network connection, but the connection was blocked because the Access Control List (ACL) does not permit the requested network host or port.

How can I identify which ACL is causing the ORA-24247 error?
You can query the DBA_NETWORK_ACLS and DBA_NETWORK_ACL_PRIVILEGES views to determine which ACLs are defined and which users or hosts they apply to, helping you identify the ACL responsible for the denial.

What steps are required to resolve the ORA-24247 error?
To resolve the error, you must create or modify an ACL using the DBMS_NETWORK_ACL_ADMIN package to grant the necessary network privileges to the database user for the target host and port.

Can I grant network access to all hosts to avoid ORA-24247 errors?
Granting access to all hosts is not recommended due to security risks. It is best practice to restrict network access to only the specific hosts and ports required by your application.

Which Oracle database versions support ACL management for network access?
ACL-based network access control was introduced in Oracle Database 11g Release 1 (11.1). Versions prior to 11g do not support this feature.

How do I verify that ACL changes have been applied successfully?
After modifying ACLs, verify by querying DBA_NETWORK_ACLS and DBA_NETWORK_ACL_PRIVILEGES to confirm the privileges are correctly assigned, and test the network operation to ensure the error no longer occurs.
The ORA-24247 error, “Network Access Denied By Access Control List (ACL),” typically occurs in Oracle databases when a network operation is blocked due to restrictive ACL configurations. This error indicates that the database’s Access Control List does not permit the requested network access, often involving operations such as UTL_HTTP calls, UTL_TCP connections, or other external network interactions. The ACL mechanism is a security feature introduced to control and restrict network privileges for database users, thereby preventing unauthorized or potentially harmful network activities.

Resolving the ORA-24247 error requires a thorough review and appropriate modification of the ACL settings within the Oracle database. This involves granting the necessary network privileges to the specific database user or role attempting the network operation. Typically, DBAs must use PL/SQL packages like DBMS_NETWORK_ACL_ADMIN to create, assign, or modify ACLs, ensuring that the user has the required connect or resolve privileges for the target host or IP address. Properly managing ACLs is crucial to maintaining both security and functionality in environments where database network access is necessary.

Key takeaways include understanding that the ORA-24247 error is a direct consequence of Oracle’s enhanced network security model, which enforces granular control over outbound
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Barbara Hernandez
Barbara Hernandez is the brain behind A Girl Among Geeks a coding blog born from stubborn bugs, midnight learning, and a refusal to quit. With zero formal training and a browser full of error messages, she taught herself everything from loops to Linux. Her mission? Make tech less intimidating, one real answer at a time.

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