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Manual Chapter : Securing Client-Side and Server-Side LDAP Traffic

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Manual Chapter
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Securing Client-Side and Server-Side LDAP Traffic

Overview: Securing LDAP traffic with STARTTLS encryption

You can configure STARTTLS encryption for Lightweight Directory Access Protocol (LDAP) traffic passing through the BIG-IP® system. LDAP is an industry standard application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network.

You configure the BIG-IP system for STARTTLS encryption by configuring Client LDAP and Server LDAP profiles to activate the STARTTLS communication protocol for any client or server traffic that allows or requires STARTTLS encryption.

Normally, LDAP traffic between LDAP servers and clients is unencrypted. This creates a privacy issue because LDAP traffic often passes through routers that the servers and clients do not trust, resulting in a third party potentially changing the communications between the server and client. Also, two LDAP systems do not normally authenticate each other. A more secure LDAP server might only allow communications from other known LDAP systems, or the server might act differently with unknown systems.

To mitigate these problems, the BIG-IP system includes two LDAP profiles that you can configure. When you configure a Client LDAP or Server LDAP profile, you can instruct the BIG-IP system to activate the STARTTLS communication protocol for any client or server traffic that allows or requires STARTTLS encryption. The STARTTLS protocol effectively upgrades a plain-text connection to an encrypted connection on the same port (port 389), instead of using a separate port for encrypted communication.

This illustration shows a basic configuration of a BIG-IP system that activates STARTTLS to secure LDAP traffic between a client system and the BIG-IP system, and between the BIG-IP system and an LDAP authentication server.

An LDAP/STARTTLS configuration

Sample BIG-IP configuration for LDAP traffic with STARTTLS activation

Task summary for securing client-side and server-side LDAP traffic

To configure the BIG-IP ®system to process Lightweight Directory Access Protocol (LDAP) traffic with TLS encryption, you perform a few basic tasks.

Task list

Creating a Client LDAP profile

You perform this task to specify the condition under which the BIG-IP system should activate STARTTLS encryption for client-side traffic destined for a specific virtual server.

  1. On the Main tab, click Local Traffic > Profiles > Services > Client LDAP .
    The Client LDAP list screen opens.
  2. Click Create.
    The New Client LDAP Profile screen opens.
  3. In the Name field, type a unique name for the profile.
  4. From the Parent Profile list, retain the default value, clientldap.
  5. Select the Custom check box.
  6. From the STARTTLS Activation Mode list, select a value:
    Value Description
    Allow This value activates STARTTLS encryption for any client-side traffic that allows, but does not require, STARTTLS encryption.
    Require This value activates STARTTLS encryption for any client-side traffic that requires STARTTLS encryption. All messages sent to the BIG-IP system prior to STARTTLS activation are rejected with a message stating that a stronger authentication mechanism is required.
    None This value refrains from activating STARTTLS encryption for client-side traffic. Note if you select this value, that you optionally can create an iRule that identifies client-side traffic that requires STARTTLS encryption and then dynamically activates STARTTLS for that particular traffic.
  7. Click Finished.
After you perform this task, the Client LDAP profile appears on the Client LDAP list screen.

Creating a Server LDAP profile

You perform this task to specify the condition under which the BIG-IP system should activate STARTTLS encryption for server-side traffic destined for a specific virtual server.

  1. On the Main tab, click Local Traffic > Profiles > Services > Server LDAP .
    The Server LDAP list screen opens.
  2. Click Create.
    The New Server LDAP Profile screen opens.
  3. In the Name field, type a unique name for the profile.
  4. From the Parent Profile list, retain the default value, serverldap.
  5. Select the Custom check box.
  6. From the STARTTLS Activation Mode list, select a value:
    Value Description
    Allow This value activates STARTTLS encryption for server-side traffic that allows, but does not require, STARTTLS encryption. In this case, the BIG-IP system only activates STARTTLS for server-side traffic when the BIG-IP system has activated STARTTLS on the client side and the client has acknowledged the activation.
    Require This value activates STARTTLS encryption for any server-side traffic that requires STARTTLS encryption. In this case, the BIG-IP system activates STARTTLS when a successful connection is made.
    None This value refrains from activating STARTTLS encryption for server-side traffic. Note that if you select this value, you can optionally create an iRule that identifies server-side traffic that requires STARTTLS encryption and then dynamically activates STARTTLS for that particular traffic.
  7. Click Finished.
After you perform this task, the Server LDAP profile appears on the Server LDAP list screen.

Creating a custom Client SSL profile

You create a custom Client SSL profile when you want the BIG-IP system to terminate client-side SSL traffic for the purpose of:
  • Authenticating and decrypting ingress client-side SSL traffic
  • Re-encrypting egress client-side traffic
By terminating client-side SSL traffic, the BIG-IP system offloads these authentication and decryption/encryption functions from the destination server.
  1. On the Main tab, click Local Traffic > Profiles > SSL > Client .
    The Client SSL profile list screen opens.
  2. Click Create.
    The New Client SSL Profile screen opens.
  3. In the Name field, type a unique name for the profile.
  4. Select clientssl in the Parent Profile list.
  5. From the Configuration list, select Advanced.
  6. Select the Custom check box.
    The settings become available for change.
  7. Next to Client Authentication, select the Custom check box.
    The settings become available.
  8. From the Configuration list, select Advanced.
  9. Modify the settings, as required.
  10. Click Finished.

Creating a custom Server SSL profile

Create a custom server SSL profile to support SSL forward proxy.
  1. On the Main tab, click Local Traffic > Profiles > SSL > Server .
    The Server SSL profile list screen opens.
  2. Click Create.
    The New Server SSL Profile screen opens.
  3. In the Name field, type a unique name for the profile.
  4. For Parent Profile, retain the default selection, serverssl.
  5. From the Configuration list, select Advanced.
  6. Select the Custom check box.
    The settings become available for change.
  7. From the SSL Forward Proxy list, select Enabled.
    You can update this setting later, but only while the profile is not assigned to a virtual server.
  8. From the SSL Forward Proxy Bypass list, select Enabled (or retain the default value Disabled).
    The values of the SSL Forward Proxy Bypass settings in the server SSL and the client SSL profiles specified in a virtual server must match. You can update this setting later but only while the profile is not assigned to a virtual server.
  9. Scroll down to the Secure Renegotiation list and select Request.
  10. Click Finished.
The custom Server SSL profile is now listed in the SSL Server profile list.

Creating a virtual server and load-balancing pool

You use this task to create a virtual server, as well as a default pool of Simple Mail Transport Protocol (SMTP) servers. The virtual server listens for, and applies SSL security to, client-side SMTP application traffic. The virtual server then forwards the SMTP traffic on to the specified server pool.
Note: Using this task, you assign an SMTPS profile to the virtual server instead of an SMTP profile. You must also assign a Client SSL profile.
  1. On the Main tab, click Local Traffic > Virtual Servers .
    The Virtual Server List screen opens.
  2. Click Create.
    The New Virtual Server screen opens.
  3. In the Name field, type a unique name for the virtual server.
  4. In the Destination Address/Mask field, type an address, as appropriate for your network.
    The supported format is address/prefix, where the prefix length is in bits. For example, an IPv4 address/prefix is 10.0.0.1 or 10.0.0.0/24, and an IPv6 address/prefix is ffe1::0020/64 or 2001:ed8:77b5:2:10:10:100:42/64. When you use an IPv4 address without specifying a prefix, the BIG-IP system automatically uses a /32 prefix.
  5. In the Service Port field, type 25 or select SMTP from the list.
  6. From the Configuration list, select Basic.
  7. For the SSL Profile (Client) setting, in the Available box, select a profile name, and using the Move button, move the name to the Selected box.
  8. From the SMTPS Profile list, select the SMTPS profile that you previously created.
  9. In the Resources area of the screen, for the Default Pool setting, click the Create (+) button.
    The New Pool screen opens.
  10. In the Name field, type a unique name for the pool.
  11. In the Resources area, for the New Members setting, select the type of new member you are adding, then type the information in the appropriate fields, and click Add to add as many pool members as you need.
  12. Click Finished to create the pool.
    The screen refreshes, and reopens the New Virtual Server screen. The new pool name appears in the Default Pool list.
  13. Click Finished.
After performing this task, the virtual server applies the custom SMTPS and Client SSL profiles to incoming SMTP traffic.

Implementation result

After you have created the required LDAP and SSL profiles and assigned them to a virtual server, the BIG-IP® system listens for client- and server-side LDAP traffic on port 389. The BIG-IP system then activates the STARTTLS method for that traffic to provide SSL security on that same port, before forwarding the traffic on to the specified LDAP server pool.

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