Forum Discussion

Sakiy's avatar
Sakiy
Icon for Altocumulus rankAltocumulus
May 12, 2022

Check for server certificate revocation

HI 

We are planning to upgrade BIG-IP 13.x to 14.x, but if we upgrade to 14.x, users will ge popup of "Revocation information for the secuirty certificate for theis site is not available. Do you want to proceed?"

From F5 support, we got advince that if Internet option "Check for server certificate revocation" is disabled, the popup can be avoided. It surely can be avoided with it, but many of our user uses unmanaged hardened device and users cannot change internet option settings. 

On the VS, private server certificate is used. All deivces has corresponding client certificate. We import CRL from private CA every half hour by using follwoing command line on BIG-IP.

tmsh modify /sys file ssl-crl [CRL name] source-path [URL for CRL]

I guess that the popup is shown because it is private certificates. THe popup can be avoided by some setting on BIG-IP side?

application delivery
  • F5_Design_Engineer's avatar
    F5_Design_Engineer
    Icon for MVP rankMVP
    Nov 17, 2023

    For DYNAMIC CRL

    ================

    if you want to use external proxy server for forwarding the CRL request to the CRL server.

    1. Crate DNS Resolver (Network-->DNS Resolvers-->DNS Resolver List-->Create)

    2. Open DNS Resolver created in step 1, go to "Forward Zones" tab and add appropriate zones with DNS servers.

    3. Create an internal proxy (GUI-->System-->Services-->Internal Proxies-->Create)

    Assign DNS Resolver created in step 1 (no external proxy) or enable "Use Proxy Server" and specify LTM pool with proxy server (external proxy server).

    4. Create Traffic Certificate Management CRL object (GUI-->System-->Certificate Management --> Traffic Certificate Management --> CRL)

    Assign internal proxy created in step 3.

    5. Assign CRL object created in step 5 to Client SSL profile with client authentication enabled:

    Open GUI-->Local Traffic-->Profiles-->SSL-->Client-->profile_name

    Go to Client Authentication section and set:

    Client Certificate to request/require this will enable client authentication

    Trusted Certificate Authorities to CA that you want to trust

    CRL to object created in step 2.

     

    Include root certificates to Advertised and Trusted bundle

    From v15.1 onwards client SSL profiles support CRL validator objects as per this bug report:

    Bug ID 743758 (f5.com)

    In F5 in the client SSL profiles , please search for the following setting:

     

    Notify Certificate Status to Virtual Server Introduced in BIG-IP 13.0.0, this option specifies whether to propagate the status of the certificates associated with this client SSL profile to the virtual servers that are using this client SSL profile. Disabled by default.

    Note: This option is used to communicate SSL certificate revocation status to the virtual server. This is typically implemented in conjunction with an OCSP stapling configuration.

    This option is disabled by default.

     

    You have to enable it on your CLIENT SSL profile by checking the option button

     

     

    For that you have to import the CRL list and then apply that to the CRL option in the CLIET SSL profile

     
     

     

    For STATIC CRL

    ===============

    Having a CRL loaded as a local file into the BIGIP is probably the easiest way to get it to check a CRL since you are avoiding the use of MS Enterprise/Datacenter Servers with OCSP. I also had various issues that the F5 tech support could not explain with CRLDP and MS cert services. So the CRL is an easy fix for a lab environment. I also could not find the proper method to do this in the online knowledge-base for F5’s product either.

    For starters, you need to get a copy of the CRL from your MS Certificate Server.

    Download CRL
    1) Browse to http://SERVERNAME/CertSrv Sign in if needed.
    2) Click on Download a CA certificate, certificate chain, or CRL.
    3) Select DER format and click on Download Latest Base CRL
    4) Save the file to your machine.

    Load the CRL to the BIGIP
    1) Open up your BIGIP Admin Gui
    2) Navigate to Sytem -> File Management -> SSL Certificate List -> Import
    3) From the Import Type PullDown, Select ‘Certificate Revocation List’
    4) Enter in the Name you want use when referencing this File in BIGIP. Select Create New or Overwrite as needed.
    5) Use the Browse Button to select the cert file called ‘certcrl.crl’
    6) Click Import to finish the Process.

     
     

     

    Now that the CRL is imported, it can be used in any SSL Client Profile in the Certificate Revocation List (CRL) Dropdown.

    This CRL is static. Any newly revoked certs on the MS Server will, of course, not be seen by the F5 until the CRL file 

    https://my.f5.com/manage/s/article/K14783

    HTH

    🙏

     

     

    HTH

    🙏