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Firewall Rules for Active Directory Certificate Services

  • Article

 

Below is a list of ports that need to be opened on Active Directory Certificate Services servers to enable HTTP and DCOM based enrollment

The information was developed by Microsoft Consultant Services during one of our customer engagements

Protocol

Port

From

To

Action

Comments

Kerberos

464

Certificate Enrollment Web Services

 

 

Domain Controllers (DC)

Allow

Source Certificate Enrollment Web Services

Destination: DC

Service: Kerberos (network port tcp/464)

LDAP

389

Certificate Enrollment Web Services

 

 

Domain Controllers (DC)

Allow

Source Certificate Enrollment Web Services

Destination: DC

Service: LDAP (network port tcp/389)

LDAP

636

Certificate Enrollment Web Services

 

 

Domain Controllers (DC)

Allow

Source Certificate Enrollment Web Services

Destination: DC

Service: LDAP (network port tcp/636)

DCOM/RPC

Random port above port 1023

· Certificate Enrollment Web Services

· All XP clients requesting certs

 

CA

Allow

Please see for details on RPC/DCOM configuration: https://support.microsoft.com/kb/154596/en-us

HTTPS

443

All clients requesting certs

Certificate Enrollment Web Services

 

 

Allow

Source: Windows 7 client

Destination:

 

Service: https (network port tcp/443)

Certificate Enrollment Web Services

Comments

  • Anonymous
    January 01, 2003
    For DCOM/RPC between a 2008R2 CA and 2008R2 webserver, you dont need "Random port above port 1023". Port 49152-65535 is enough. But if you still have one of them as 2003, you need the whole range.

  • Anonymous
    January 01, 2003
    If you use 2008 or later on both web server and CA, port 49152-65535 is enough. support.microsoft.com/.../832017

  • Anonymous
    January 01, 2003
    I still get these errors on the Domain Controllers running 2008 R2 to a 2003 Enterprise CA. I have TCP 135 (RPC) open already, but I highly suspect it maybe the "Random port above port 1023" requirement as noted in the table. I hate to have to open up all ports above this. Any other way to make this a specific port? I can map the cahost computer from domain controller as \cahost and I will see CertEnroll Share. Event ID: 13 User: SYSTEM Source: CertificateServicesClient-CertEnroll Certificate enrollment for Local system failed to enroll for a DomainController certificate with request ID N/A from cahostname.my-domain.comcahostname (The RPC server is unavailable. 0x800706ba (WIN32: 1722)). Event ID: 6 User: N/A Source: CertificateServicesClient-AutoEnrollment Automatic certificate enrollment for local system failed (0x800706ba) The RPC server is unavailable.

    • Anonymous
      October 20, 2017
      Port 135 is only the port RPC advertises what various RPC-based services it supports. The actual services themselves each sit on a random port between 49152 and 65535 (for Win 2008 and above), which is why this large port range must be open (and why firewall admins hate RPC).

  • Anonymous
    January 01, 2003
    I just removed port 440 based on the result of an internal conversation about that port not being needed.

  • Anonymous
    June 27, 2010
    Port number without specified protocol is useless. Is it TCP or UDP ?

  • Anonymous
    June 27, 2010
    Just a minor correction. Should DCOM/RPC state: "Random port above port 1023" rather than "1024". I believe RPC uses >=1024 (includes 1024). Otherwise, good summary. Siki

  • Anonymous
    September 20, 2010
    Hello! Doesn't RPC TCP 135 (RPC Endpoint Mapper) also have to be open? How else can clients find out what random port above 1023 is being used at any given time? It is possible to set the random port being used by the CA server to a fixed value (with DCOM, Static Endpoint), is this supported by Microsoft? I love this blog, keep it updated! Sincerly Yours Tom Aafloen, Sweden

  • Anonymous
    December 16, 2010
    Thanks a lot for your article. Not found out There !!!

  • Anonymous
    June 09, 2011
    When did kerberos start using tcp/440? My understandin was it used tcp/88, upd/88 and tcp/464.

  • Anonymous
    December 19, 2011
    The comment has been removed

  • Anonymous
    January 13, 2012
    I can submit and retrieve certs just fine with https. I have also successfully automated the process with certutil. It works perfect on a regular workgroup server - but on the same network. What must be done to do so from a workgroup machine that is outisde the network? 443 access only. THANKS!

  • Anonymous
    January 30, 2012
    Has anyone got any relevant information regarding port usage when certificates are requested via MMC and the Certificates snap-in?

  • Anonymous
    October 26, 2012
    Following the article at the following URL: blogs.technet.com/.../how-to-troubleshoot-certificate-enrollment-in-the-mmc-certificate-snap-in.aspx It appears that port 135 - TCP has to be open for RPC EPM. Basically for mmc and auto-enrollment scenarios.

  • Anonymous
    May 28, 2014
    You can configure the CA server to use a static listening port for DCOM/RPC. This means that you only need to open a single port in your firewall (for DCOM/RPC). The link in the comments column above shows how to decrease the RPC/DCOM port span, but that affects all DCOM/RPC on that server. Isn't it better to lock the CA service to a specific port instead?
    I've blogged about it here:
    http://mssec.se/2014/02/20/configure-ad-cs-to-use-a-static-dcom-port/

  • Anonymous
    August 07, 2015
    The comment has been removed

  • Anonymous
    August 11, 2015
    When using a Windows Server 2008 R2 client that autoenrolls to retrieve a certificate from a Windows CA, are the firewall config changes being discussed here enough to cause the client to speak RPC DCOM to the CA when asking for a certificate, or are there other config changes I need to make this happen ??

  • Anonymous
    March 31, 2017
    I am using stand alone Root and Subordinate CAs, No Ad integration..In that case what are the port requirements