irule redirection

Reformatted:

when HTTP_REQUEST {
    if { ( [IP::addr [IP::client_addr] equals x.x.x.x]) } { 
        if { [HTTP::uri] equals "/index.htm" } { 
            log local0. "Client: [IP::client_addr]" 
            HTTP::redirect "http://[getfield [HTTP::host] ":" 1]/index_new.htm" 
        } 
    } 
    else { 
       log local0. "not redirecting client: [IP::client_addr]" 
    }
}

Although this isn't your issue, I will say that the

IP::addr [IP::client_addr] ...

construct is not needed.

IP::client_addr

evaluates to a string, so, if you're comparing it to a single host address,

equals

is sufficient.

I recommend logging both the client addres and the Request-URI before the logic. Also, you may wish to consider using

HTTP::path

rather than

HTTP::uri

. The latter would include, for example, any query parameters. So, you might try something like this:

when HTTP_REQUEST {
    log local0. "Received request from ([IP::client_addr]) for ([HTTP::path])"
    if { [IP::client_addr] eq "x.x.x.x" and [HTTP::path] equals "/index.htm" } {
        log local0. "  .. match branch"
        HTTP::redirect "http://[getfield [HTTP::host] : 1]/index_new.htm"
    }
    else {
        log local0. "  .. miss branch"
    }
}