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Security
You can secure your Informix® database server and the data that is stored in your Informix databases. You can encrypt data, secure connections, control user privileges and access, and audit data security.
Security in HCL Informix®
The Informix® Security Guide documents methods for keeping your data secure by preventing unauthorized viewing and altering of data or database objects, including how to use the secure-auditing facility of the database server.
Securing data
Connection security
You can administer the security of the connections to the database server by using authentication and authorization processes.
Limiting denial-of-service flood attacks
Informix® has multiple listener threads (listen_authenticate) to limit denial-of-service (DOS) attacks.
LISTEN_TIMEOUT and MAX_INCOMPLETE_CONNECTIONS configuration parameters
You can use configuration parameters to reduce the risk of a hostile, denial-of-service (DOS) flood attack.

Security
You can secure your Informix® database server and the data that is stored in your Informix databases. You can encrypt data, secure connections, control user privileges and access, and audit data security.
- Security in HCL Informix®
  The Informix® Security Guide documents methods for keeping your data secure by preventing unauthorized viewing and altering of data or database objects, including how to use the secure-auditing facility of the database server.
  - Securing data
    - HCL Informix® directory security
      utilities and product directories are secure by default.
    - Network data encryption
      Use network encryption to encrypt data transmitted between server and client, and between server and other server.
    - Column-level encryption
      You can use column-level encryption to store sensitive data in an encrypted format. After encrypting sensitive data, such as credit card numbers, only users who can provide a secret password can decrypt the data.
    - Connection security
      You can administer the security of the connections to the database server by using authentication and authorization processes.
      - Authentication mechanisms
        You can configure the Informix® server authentication mechanisms to meet varying requirements, such as different security methods required for local and remote connections, database access by users without operating system accounts on the servers host computer, and non-root installation.
      - Internal users (UNIX™, Linux™)
        The DBSA can grant database access to users that do not authenticate on the OS of the host computer by mapping PAM-authenticated users to OS-level entities or by configuring the server to perform internal authentication.
      - Guest account (Windows™)
        Disable the Windows™ Guest account to prevent anonymous logins.
      - Trusted-context objects and trusted connections
        You can use trusted-context objects and trusted connections to increase system performance and security within a three-tier application model.
      - Pluggable authentication modules (UNIX™ or Linux™)
        A Pluggable Authentication Module (PAM) is a well-defined framework for supporting different authentication modules that were originally developed by Sun Microsystems. PAM is supported in both 32- and 64-bit modes on Solaris, Linux™, HP-UX and AIX®.
      - LDAP authentication support on Windows™
      - Authentication module deployment
      - Simple password encryption
        The simple password communication support module (SPWDCSM) provides password encryption.
      - Single sign-on
        Single sign-on is an authentication feature that bypasses the requirement to provide user name and password after a user logs into the client computer's operating system.
      - Securing local connections to a host
        The database server administrator (DBSA) can use the SECURITY_LOCALCONNECTION configuration parameter to set up security checking for local connections with the same host.
      - Limiting denial-of-service flood attacks
        Informix® has multiple listener threads (listen_authenticate) to limit denial-of-service (DOS) attacks.
        LISTEN_TIMEOUT and MAX_INCOMPLETE_CONNECTIONS configuration parameters
        You can use configuration parameters to reduce the risk of a hostile, denial-of-service (DOS) flood attack.
    - Discretionary access control
      Discretionary access control verifies whether the user who is attempting to perform an operation has been granted the required privileges to perform that operation.
    - Label-Based Access Control
      You can use label-based access control (LBAC), an implementation of multi-level security (MLS), to control who has read access and who has write access to individual rows and columns of data.
  - Auditing data security

LISTEN_TIMEOUT and MAX_INCOMPLETE_CONNECTIONS configuration parameters

You can use configuration parameters to reduce the risk of a hostile, denial-of-service (DOS) flood attack.

You can customize the following configuration parameters:

LISTEN_TIMEOUT. Sets the incomplete connection timeout period. The default incomplete connection timeout period is 60 seconds.
MAX_INCOMPLETE_CONNECTIONS. Restricts the number of incomplete requests for connections. The default maximum number of incomplete connections is 1024.

If you do not set the LISTEN_TIMEOUT and MAX_INCOMPLETE_CONNECTIONS configuration parameters and a flood of unauthorized attacks occurs, the Listener VP might become insecure and it might not be able to listen to a valid request in a timely manner.

If you set the LISTEN_TIMEOUT and MAX_INCOMPLETE_CONNECTIONS configuration parameters, and then someone tries to break into the system and reaches the maximum limit specified, the following information in the online message log is the notification that the system is under attack:

%d incomplete connection at this time. 
System is under attack through invalid clients 
on the listener port.

Depending on the machine capability of holding the threads (in number), you can configure MAX_INCOMPLETE_CONNECTIONS to a higher value and depending on the network traffic, you can set LISTEN_TIMEOUT to a lower value to reduce the chance that the attack can reach the maximum limit.

You can use the onmode -wm or onmode -wf commands to change the values of these configuration parameters while the server is online. For more information, see the Informix® Administrator's Reference.