[Serusers] Nathelper question

[Alex Bligh]

--On 10 July 2004 15:31 +1000 Zeus Ng <zeus.ng at isquare.com.au> wrote:

>  if (method=="INVITE") {
>    if (isflagset(4) && isflagset(5)) { /* NAT source & NAT dest. */
>      if (!exec_msg('echo $SIP_RURI | cut -d: -f2 | cut -d@ -f2 | grep
> "$SIP_SRCIP" > /dev/null')) {
>        xlog("L_NOTICE", "UAs behind different NAT devices, forcing
> rtpproxy\n");
>        force_rtp_proxy();
>        t_on_reply("2");
>      } else {
>        xlog("L_NOTICE", "UAs behind same NAT devices\n");
>        t_on_reply("3");
>      }
>      ... Other situation, NAT -> Public, Public -> NAT ...
>  }
>

For the sake of pedantry, I think that test will give a false positive
(i.e. wrongly treat caller and callee as being behind the same NAT)
in situations similar to:

10.0.0.1 A -> NAT1 -192.168.0.1 \
                                |--> NAT3 --> 195.1.1.1 Internet
10.0.0.2 B -> NAT2 -192.168.0.2 /

Alex