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awan_m's avatar
awan_m
Icon for Cirrostratus rankCirrostratus
Nov 28, 2024

F5 to read a combined CRL file

Hello , i have a client ssl profile which uses a crl file that is uploaded to F5 every night .

Now i have a second CRL file .

Question - can the F5 read a file that is a combination of 2 CRL files . meaning multiple begin and ends .

i understand that openssl has this limitation that it can only read the first.

-----BEGIN X509 CRL-----

-----END X509 CRL-----

-----BEGIN X509 CRL-----

-----END X509 CRL-----

 

  • awan_m  hello i   was able to find some information to help guide you to a resolution. 

    While there may not be a specific article that addresses the exact scenario of merging multiple CRL files into a single file for use with F5 BIG-IP, there are general resources and documentation that can help you understand and manage CRLs on F5 systems. Here are some useful resources:

    1. **F5 Networks Official Documentation:**
       - [Managing SSL Certificates and Keys](https://techdocs.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-ssl-administration-13-1-0.html): This guide covers various aspects of managing SSL certificates and CRLs on BIG-IP systems.
       - [K13309: Overview of the BIG-IP system’s support for certificate revocation lists (CRLs)](https://support.f5.com/csp/article/K13309): This article provides an overview of how the BIG-IP system supports CRLs.

    2. **OpenSSL Documentation:**
       - [OpenSSL Manual](https://www.openssl.org/docs/man1.1.1/man1/openssl.html): The OpenSSL documentation can provide you with detailed information on how to use OpenSSL commands to manage CRLs.

    3. **General Tutorials and Blogs:**
       - Look for general network engineering blogs and tutorials that cover SSL/TLS and CRL management. These resources can often provide step-by-step guides and practical examples.

    If you need a specific step-by-step guide, here is a general approach to merging CRLs using OpenSSL, which can then be applied to F5:

    1. **Combine the CRLs:**
       - Concatenate the two CRL files into one file:
         ```bash
         cat crl1.pem crl2.pem > combined_crl.pem
         ```

    2. **Convert to DER format and back to PEM:**
       - Convert the combined CRL to DER format:
         ```bash
         openssl crl -in combined_crl.pem -inform PEM -out combined_crl.der -outform DER
         ```
       - Convert back to PEM format:
         ```bash
         openssl crl -in combined_crl.der -inform DER -out merged_crl.pem -outform PEM
         ```

    3. **Upload and configure the F5 BIG-IP:**
       - Upload the `merged_crl.pem` file to your F5 BIG-IP system.
       - Update the client SSL profile to use the new CRL file.

    By following these steps, you can merge multiple CRL files and ensure that the F5 BIG-IP system can read and process the combined CRL correctly.

     

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    • awan_m's avatar
      awan_m
      Icon for Cirrostratus rankCirrostratus

      thanks for the response - i have tried all of that 

      i created a combined file - but F5 cannot read the full file - it only reads the first part - 

  • Can you clarify what you're referring to with "F5" and "combined CRL file"? Here are some possible contexts, and I'll tailor my answer based on your needs:

    F5 Networks (Big-IP)

    Replay

    Specific Tool/Script

    • awan_m's avatar
      awan_m
      Icon for Cirrostratus rankCirrostratus

      the query is related to CRL 

      i have 2 CRL sources - and i get 2 files 

      how do i use 2 files in a client ssl profile?

  • f51's avatar
    f51
    Icon for Cirrocumulus rankCirrocumulus

    Combining multiple Certificate Revocation Lists (CRLs) into a single file with multiple BEGIN X509 CRL and END X509 CRL sections can indeed be problematic, as many systems, including OpenSSL, typically expect a single CRL per file and may only process the first CRL they encounter.

    F5 BIG-IP systems have similar limitations when it comes to handling CRLs. The system expects a single CRL per file and may not correctly process a combined CRL file with multiple BEGIN and END sections. Therefore, you need an alternative approach to handle multiple CRLs effectively. 

    Follow Below Steps:

    Step 1: Create a Directory and Upload CRLs

    1. Create a Directory: mkdir -p /config/ssl/crl
    2. Upload CRL Files: Use the F5 GUI or SCP to upload the CRL files to the /config/ssl/crl directory.

    Step 2: Configure the Client SSL Profile

    Navigate to SSL Certificates: Go to Local Traffic > SSL Certificates > Client in the F5 GUI.

    Edit the Client SSL Profile

    Select the client SSL profile you are using.

    Under the "Certificate Revocation List (CRL) File" section, instead of specifying a single CRL file, specify the directory path.

    For example:

    • CRL File: /config/ssl/crl

    Example Commands:

    Assuming you have two CRLs, crl1.pem and crl2.pem, you can place them in the directory and configure your profile as follows:

    Upload CRLs:

    scp crl1.pem root@<f5-ip>:/config/ssl/crl/
    scp crl2.pem root@<f5-ip>:/config/ssl/crl/

    Configure Client SSL Profile:

    • In the F5 GUI, go to Local Traffic > Profiles > SSL > Client.
    • Select your client SSL profile.
    • In the "Certificate Revocation List (CRL) File" field, enter /config/ssl/crl.

    Example iRule for Custom Validation:

    If you need to perform more complex CRL validation, you can use an iRule to implement custom logic. Here’s a simple example of how you might do this:

    when CLIENTSSL_CLIENTCERT {
        # Get the client certificate
        set cert [SSL::cert 0]

        # Check if the certificate is revoked
        if { [CRL::verify $cert /config/ssl/crl/crl1.pem] == 0 || [CRL::verify $cert /config/ssl/crl/crl2.pem] == 0 } {
            # Certificate is revoked
            reject
        } else {
            # Certificate is valid
            log local0. "Client certificate is valid."
        }
    }

     

    • awan_m's avatar
      awan_m
      Icon for Cirrostratus rankCirrostratus

      Thanks for the response 

      i just tried it but the command [CRL::verify] is not being accepted - i am getting the following 

      error: /Common/crl_verify:5: error: [undefined procedure: CRL::verify][CRL::verify]

      i am running version 17

  • f51's avatar
    f51
    Icon for Cirrocumulus rankCirrocumulus

    Given the error you encountered, it seems you are trying to use a command  [CRL::verify]  that isn't supported. Instead, focus on configuring the SSL profile correctly to handle CRLs natively within the F5 BIG-IP system

    Here are the general steps to configure the SSL profile to use a CRL in F5 BIG-IP version 17:

    1. Upload the CRL File:
      • Navigate to System > File Management > SSL Certificate List.
      • Click Import.
      • Set the Type to Certificate Revocation List.
      • Specify the File Name and Source (either upload from your local machine or provide the URL if the CRL is hosted online).
    2. Configure the Client SSL Profile:
      • Navigate to Local Traffic > Profiles > SSL > Client.
      • Select or create the Client SSL profile you wish to configure.
      • In the Revocation Handling section, select the CRL you uploaded from the Certificate Revocation List dropdown.
    3. Apply the SSL Profile:
      • Ensure that the SSL profile is associated with the relevant virtual server that handles the incoming client connections.
    • awan_m's avatar
      awan_m
      Icon for Cirrostratus rankCirrostratus

      i guess you are an AI bot - as you suggested the command [CRL::verify] and then stated command is not supported - :) 

    • awan_m's avatar
      awan_m
      Icon for Cirrostratus rankCirrostratus

      so did you check before recommending -  if { [CRL::verify $cert /config/ssl/crl/crl1.pem] == 0  ?