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MattNears's avatar
MattNears
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Oct 02, 2019
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HTTP Header responce problem

Good Morning,

I have an issue with some of my response headers and an irule for replacing certain responses. The rule I have below is set agains a number of our sites but when running a header response scan some of the comments don't seem to be respected. For example the "Server" and "X-Powered-By" still come back with the actual server and IIS details. Am I missing something or have I go the argument wrong?

BTW I've new with F5's and still learning how to create these syntax so appologese if I ask what seem like dumb questions, thank in advance.

when HTTP_RESPONSE {

 

    foreach mycookie [HTTP::cookie names] {

 

                HTTP::cookie secure $mycookie enable

 

        }

 

  if { !([ HTTP::header exists "X-Frame-Options" ])} { HTTP::header insert "X-Frame-Options" "SAMEORIGIN" }

  if { !([ HTTP::header exists "X-Powered-By" ])} { HTTP::header insert "X-Powered-By" "Server" }

  if { !([ HTTP::header exists "Server" ])} { HTTP::header insert "Server" "A-Server" }

  if { !([ HTTP::header exists "Cache-Control" ])} { HTTP::header insert "Cache-Control" "no-cache" } 

  if { !([ HTTP::header exists "X-XSS-Protection" ])} { HTTP::header insert "X-XSS-Protection" "1; mode=block" }

  if { !([ HTTP::header exists "X-Content-Type-Options" ])} { HTTP::header insert "X-Content-Type-Options" "nosniff" } 

  if { !([ HTTP::header exists "Strict-Transport-Security" ])} { HTTP::header insert "Strict-Transport-Security" "max-age=15768000" } 

 

}

iRules
security
  • Enes_Afsin_Al's avatar
    Enes_Afsin_Al
    Oct 02, 2019

    Hi MattNears,

    If server's response contains "Server" header or "X-Powered-By" header or other headers in the iRule, "Server" and "X-Powered-By" headers will come back with the actual server and IIS details. You should use "else" blocks and HTTP::header replace command.

    if { !([HTTP::header exists "Server"]) } {
	HTTP::header insert "Server" "A-Server"
} else {
	HTTP::header replace "Server" "A-Server"
}

4 Replies

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  • Enes_Afsin_Al's avatar
    Enes_Afsin_Al
    Icon for MVP rankMVP
    Oct 02, 2019

    Hi MattNears,

    If server's response contains "Server" header or "X-Powered-By" header or other headers in the iRule, "Server" and "X-Powered-By" headers will come back with the actual server and IIS details. You should use "else" blocks and HTTP::header replace command.

    if { !([HTTP::header exists "Server"]) } {
	HTTP::header insert "Server" "A-Server"
} else {
	HTTP::header replace "Server" "A-Server"
}
    • MattNears's avatar
      MattNears
      Icon for Nimbostratus rankNimbostratus
      Oct 02, 2019

      Thanks, that makes sense now, I'd not realised you could combine with else statements.

  • MattNears's avatar
    MattNears
    Icon for Nimbostratus rankNimbostratus
    Oct 02, 2019

    As a side note to the above I do occasionally have issues where the set secure cookie comes back with a "no prefix" and "not a samesite" cookie error,

    Set-CookieASP.NET_SessionId=br3sthsomuihmjyey4xkqmh5; path=/; HttpOnly;Secure

    do I need to adjust the first line so all cookies are set as secure?

  • MattNears's avatar
    MattNears
    Icon for Nimbostratus rankNimbostratus
    Dec 20, 2019

    Just to resurect this thread a little and ask a new question, I managed to resolve me Secure cookie issue, found it in the cookie persistence profice and have that now working nicely.

     

    My new issue seems to be on if { !([ HTTP::header exists "X-AspNet-Version" ])} {HTTP::header remove "X-AspNet-Version" } not working and removing the header as it should. Now I did consider switching it and adding an arguement to insert a ficticious value anf then use else and remove but this hasn't worked either. I'm sure I'm missing something but just struggling to work out what I've missed.

    Any advice will be wlecome here.