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Forum Discussion

Bubbagump_12531's avatar
Bubbagump_12531
Icon for Nimbostratus rankNimbostratus
Oct 30, 2013

Prevent X-Forwarded-For spoofing

We insert an X-Forwarded-For header to pass back to our web servers. One application we have looks to this header to allow or deny certain servers access to us. However, we want to prevent spoofing t...
application delivery
deployment
devops
iRules
security
Kevin_Stewart's avatar
Kevin_Stewart
Icon for Employee rankEmployee
Oct 30, 2013

The XFF option in the HTTP profile is an insert, so yes it will allow spoofing. What you need is a replace function:

when HTTP_REQUEST {
    foreach x [HTTP::header names] {
        if { $x equals "X-FORWARDED-FOR" } {
            HTTP::header remove X-FORWARDED-FOR
            HTTP::header replace X-FORWARDED-FOR [IP::client_addr]
        }
    }   
}