Forum Discussion

Rahul_More's avatar
Rahul_More
Icon for Cirrus rankCirrus
Oct 28, 2020
Solved

Remove the "Server" header

Hi Guys,   I have below irule created into LTM and enabled for virtual servers. but I need to remove the "Server" header.   Device version: BIG-IP 14.1.2.6   when HTTP_RESPONSE {    ...
ASM Advanced WAF
LTM
security
  • Rahul_More's avatar
    Rahul_More
    Nov 09, 2020

    Hi Dario and Jaikumar,

     

    Thank you for your responses and sharing all possible resolutions for this problem.

     

    I have double checked this and found., there are two different LTMs (Internal and External),. One is WAF enabled and other is not.

     

    1. When users are accessing from external network the traffic comes to the public IP address of site which is NAT'ed with the external VIP address (External LTM) and that device is WAF enabled and also ASM irule associated.
    2. In other side, when accessing from internal private network, the traffic goes to split brain DNS where local host A record is configured for another virtual server which is completely different than (Point 1) virtual server and pool member addresses.

     

    In short, The external traffic is coming to External LTM (WAF enabled) and internal private network traffic is going to Internal LTM (WAF not enabled).

     

    Hence, the HTTP "Server" header is only appearing to the internal network users and not for external clients.

     

     , The both solutions which you have provided are pretty good and for this scenario, the second solution is best one to apply.

     

    Once again thank you for all your help.

     

    Regards,

    Rahul

Dario_Garrido's avatar
Dario_Garrido
Icon for Noctilucent rankNoctilucent
Oct 28, 2020

Hello Rahul.

 

"Server" (or "X-Server") is a response header, not a request header.

REF - https://en.wikipedia.org/wiki/List_of_HTTP_header_fields

 

Regards,

Dario.

  • Rahul_More's avatar
    Rahul_More
    Icon for Cirrus rankCirrus
    Oct 28, 2020

    Hi Dario,

     

    Thanks for sharing the reference site to clear the request /response confusion.

     

    Standard Response Field:

    Server A name for the server Server: Apache/2.4.1 (Unix) Permanent

     

    Could you please help in this either modification or new irule for Server header?

     

    Regards,

    Rahul

     

    • Lidev's avatar
      Lidev
      Icon for Nacreous rankNacreous
      Oct 28, 2020

      Hi Rahul,

       

      more simple, use a Local Traffic Policy to Remove your HTTP Header like below :

      Regards

    • Dario_Garrido's avatar
      Dario_Garrido
      Icon for Noctilucent rankNoctilucent
      Oct 28, 2020

      Hello Rahul.

      The iRule you already have above should be enough.

      when HTTP_RESPONSE {
    HTTP::header remove {X-Server}
    HTTP::header remove Server
}

      Regards,

      Dario.

    • Rahul_More's avatar
      Rahul_More
      Icon for Cirrus rankCirrus
      Nov 06, 2020

      Hello Dario,

       

      I tried with above changes but still showing "Server: Microsoft-IIS/10.0" in response. The split brain DNS is configured and internal path is not WAF enabled. The response does not appear when accessing from external network.

       

      Only having issue while accessing the site from internal network.

       

      Path : Internal user > NAT'd ip via external LTM > web server

       

      Kindly suggest if any other solution

       

      Regards,

      Rahul