Using Proxy pass and to facilitate logon to Webmin administration page.

In order to get Webmin to work behind a proxy, listening on port 80 HTTP, I had to use something like this:

when HTTP_REQUEST {
     Replace relevant headers to server
    HTTP::header replace Host "10.70.0.99:10000"
    HTTP::header replace Referer "https://10.70.0.99:10000/"
}
when HTTP_RESPONSE {
     replace redirect headers
    if { [HTTP::header exists Location] } {
        HTTP::header replace Location [string map {"https://10.70.0.99:10000" "http://10.80.0.197"} [HTTP::header Location]]
    }

     replace cookies
    foreach x [HTTP::cookie names] {
        set thisval [HTTP::cookie value $x]
        set thispath [HTTP::cookie path $x]
        HTTP::cookie remove $x
        HTTP::cookie insert name $x value $thisval path $thispath
    }
}

where in my lab, 10.70.0.99:10000 is webmin, and 10.80.0.197 is the HTTP virtual server.

In order to do the same but listening on port 443 HTTPS:

when HTTP_REQUEST {
     Replace relevant headers to server
    HTTP::header replace Host "10.70.0.99:10000"
    HTTP::header replace Referer "https://10.70.0.99:10000/"
}
when HTTP_RESPONSE {
     replace redirect headers
    if { [HTTP::header exists Location] } {
        HTTP::header replace Location [string map {"https://10.70.0.99:10000" "https://simpleserver.domain.com"} [HTTP::header Location]]
    }
}

where again 10.70.0.99:10000 is webmin and https://simpleserver.domain.com is the HTTPS virtual server.