[Blink] Blink over VPN using the wrong ip address in headers

Saúl Ibarra Corretgé saul at ag-projects.com
Wed May 11 23:29:25 CEST 2011


Hi,

On 05/11/2011 11:16 PM, Christian Kujau wrote:
> Hi,
>
> maybe this has been reported already, but I could not find any
> (searchable) archives or a bugtracker. Does a bugtacker for Blink exist?
>

No. This mailing list is currently the right place to report issues.

> This is basically the same bug that is present for another SIP client,
> called telephone: https://code.google.com/p/telephone/issues/detail?id=187
>
> In short: when I'm using Blink (0.24.0, MacOS 10.6.7) to connect to a SIP
> server via a VPN connection (Tunnelblick using OpenVPN), Blink uses my
> /local/ address within its SIP traffic instead of my VPN address.
>
> A few details on that:
>
> -------------------------------
> # ifconfig  | egrep -A1 '^(en1|tun0)'
> en1: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST>  mtu 1500
>          inet 192.168.0.103 netmask 0xffffff00 broadcast 192.168.0.255
> --
> tun0: flags=8851<UP,POINTOPOINT,RUNNING,SIMPLEX,MULTICAST>  mtu 1500
>          inet 10.9.2.70 -->  10.9.2.69 netmask 0xffffffff
> -------------------------------
>
> With the VPN being UP, I now have a second address, 10.9.2.70. This is the
> only address that could be used for my SIP server within that VPN,
> 10.0.0.54. However, tcpdump and Blink's own Activiy/SIP logs show that my
> local address, 192.168.0.103 is used instead:
>
> -------------------------------
> # tcpdump -i tun0 -tttt -v not port '53 or 123'
> tcpdump: listening on tun0, link-type NULL (BSD loopback), capture size
> 65535 bytes
> 2011-05-11 13:55:14.932116 IP (tos 0x0, ttl 64, id 27697, offset 0, flags
> [none], proto UDP (17), length 443)
>      10.9.2.70.53114>  10.0.0.54.sip: SIP, length: 415
>          REGISTER sip:10.0.0.54 SIP/2.0
>          Via: SIP/2.0/UDP 192.168.0.103:53114;rport;branch=z9hG4bKPj6ML44wC9jVdKC704G08ffgijZwcC7di.
>          Max-Forwards: 70
>          From: "ck"<sip:356 at 10.0.0.54>;tag=Ge5mGwv7mrlTA-E5SuFdTkWnQZU1EtsZ
>          To: "ck"<sip:356 at 10.0.0.54>
>          Contact:<sip:jfsgbvhp at 10.9.2.70:53114>
>          Call-ID: OMSbfSeoRs4S-YaeiBWhSq-Zho.FuHwn
>          CSeq: 1 REGISTER
>          Expires: 600
>          User-Agent: Blink 0.24.0 (MacOSX)
>          Content-Length:  0
> -------------------------------
>
> The activity log says:
>
> -------------------------------
> 2011-05-11 13:58:55   Account('356 at 10.0.0.54') activated
> 2011-05-11 13:59:05   Account('356 at 10.0.0.54') failed to register: No more
> routes to try (retrying in 49.77 seconds)
> 2011-05-11 13:59:05   Error: The account 356 at 10.0.0.54 failed to
> register(No more routes to try)
> 2011-05-11 13:59:10   Account('356 at 10.0.0.54') deactivated
> -------------------------------
>
> Is there some (secret?) setting that tells Blink which IP address to use
> for SDP/SIP messages?
>

Having the wrong IP address in the Via header is a known issue but it 
shouldn't matter since rport (RFC 3581) is requested and should be used.

When using UDP, if rport is not used responses are routed back to the 
source address and the port in the topmost Via header. Since this may 
cause trouble with NATs, if rport is being used, responses will be 
routed to the source IP and port from which the request originated.

What SIP server are you using?

-- 
Saúl Ibarra Corretgé
AG Projects



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