Presence and IntComm WG

[Jiri Kuthan <>]

At 09:49 PM 4/8/2004, Candace Holman wrote:
>I got this error when I tried to IM to Joe.  I note in noisy feedback that 
>the out_uri has a private address.

(now you see what this "noisy feedback" is good for ;))


That most likely means that the server is not configured to handle natted 
client. With a nat-ready configuration, SER replaces original SIP contacts
with transport address of SIP client. A related SER script fragment is 
attached. Note that for complete VoIP NAT traversal, media traversal is
the harder part and it takes an RTP relay too, resulting in fairly more
complex configuration.

-jiri


    if (nat_uac_test("3")) {
        append_to_reply("P-Behind-NAT: Yes\r\n");
        if (method == "REGISTER" || ! search("^Record-Route:")) {
            log("LOG: Someone trying to register from private IP, 
rewriting\n");
            # This will work only for user agents that support symmetric
            # communication. We tested quite many of them and majority is
            # smart smart enough to be symmetric. In some phones, like
            # it takes a configuration option. With Cisco 7960, it is
            # called NAT_Enable=Yes, with kphone it is called
            # "symmetric media" and "symmetric signaling". (The latter
            # not part of public released yet.)
            fix_nated_contact(); # Rewrite contact with source IP of 
signalling
            force_rport();       # Add rport parameter to topmost Via
            setflag(6); # Mark as NATed
    };