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Qasim's avatar
Qasim
Icon for Cirrostratus rankCirrostratus
Jul 12, 2019
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What LTM do to HTTP Header?

Hi,   I need to read up on LTMs as its a basic theory question but wondering if you can help me in the meanwhile: my understanding is that LTM receives traffic on a particular VIP, replaces the he...
  • Lee_Sutcliffe's avatar
    Lee_Sutcliffe
    Jul 12, 2019

    It's not something that can be turned on with a check box, you need to either:

    • Use and iRule (one above is not re-writing the Host)
    • Use a Local Traffic Policy
    • Use an HTTP profile to erase a header

     

    Are you sure F5 is rewriting the Host? Can you share you VS config?

Qasim's avatar
Qasim
Icon for Cirrostratus rankCirrostratus
Jul 12, 2019

Thank Lee once again.

if I was to enable the re-write, what would I need to do? is it like a checkbox somewhere? wondering if this has been enabled for a service I am t-shooting right now.

 the current IRULE only redirects so can't be the irule:

when HTTP_REQUEST {

  switch -glob [HTTP::host] {

uat-services-hccf.abc.co.uk { pool EXT_UAT_abc_443_POOL }

thanks.

  • Lee_Sutcliffe's avatar
    Lee_Sutcliffe
    Icon for Nacreous rankNacreous
    Jul 12, 2019

    It's not something that can be turned on with a check box, you need to either:

    • Use and iRule (one above is not re-writing the Host)
    • Use a Local Traffic Policy
    • Use an HTTP profile to erase a header

     

    Are you sure F5 is rewriting the Host? Can you share you VS config?

    • Qasim's avatar
      Qasim
      Icon for Cirrostratus rankCirrostratus
      Jul 12, 2019

      I am not sure as I don;t have access to the logs but was just wondering whether that the case and if I can confirm it from the config.

       

      SO it won't replace the header even if offload SSL

    • Lee_Sutcliffe's avatar
      Lee_Sutcliffe
      Icon for Nacreous rankNacreous
      Jul 12, 2019

      As I've mentioned previously, the three places you could have header re-writes are mentioned above.

      Take a look at all iRules on the VS, the HTTP profile and if you have any traffic policies assigned. F5 won't log that it is re-writing the header unless you tell it to.

       

      Remember, F5 is a simple TCP proxy, what comes in one end is sent out the other on a new connection. So unless you have configured something, it will not change anything in the payload