[sr-dev] why new tcp connection?

[Juha Heinanen]

Andrei Pelinescu-Onciul writes:

 > Yes, it should do either that, or add an alias parameter to its Via
 > (assuming that the port in Via _is_ 5074).
 > If it does add "alias" to the Via, make sure you have
 > tcp_accept_aliases=yes in the config.

twinkle does not add alias param to via so looks like its tcp
implementation is broken.  this comes from source tcp port 34136 to port
5060 at sr:

+++ 6-11-2009 12:06:27.976341 INFO SIP ::send_sip_tcp
Send to: tcp:192.98.101.10:5060
REGISTER sip:test.fi SIP/2.0
Via: SIP/2.0/TCP 192.98.101.10:5074;rport;branch=z9hG4bKtabgdwsf
Max-Forwards: 70
To: "Juha Heinanen" <sip:jh at test.fi>
From: "Juha Heinanen" <sip:jh at test.fi>;tag=hqmmp
Call-ID: bmybrkvktynbuma at localhost
CSeq: 668 REGISTER
Contact: <sip:jh_test_fi at 192.98.101.10:5074;transport=tcp>;expires=3600

 > > or should sr figure out that twinkle in fact is behind the tcp
 > > connection it created when it registered itself no matter what the port in
 > > contact uri is?
 > 
 > You can force that, using force_tcp_alias() (adds src_ip:port_in_via as
 > an alias for src_ip:src_port).

can force_tcp_alias() be called on any register over tcp or should it be
tested first that there is no alias in via and that port in register
contact uri does not match source port?

 > In general, especially if you have NATed UACs, it's better to always have
 > force_tcp_alias() in the config. It will cause problems only if you have
 >  non-NATed broken UACs that don't expect/support symmetric signalling
 >  over TCP (e.g. open a new connection for each new request and expect
 >  only replies to that request on the connection).

ok.

 > OTOH if you  don't force_tcp_alias() and the UACs don't add alias to the
 > Via, it's a very slim chance that NATed UACs will work over tcp.

i'll test next what happens when i put twinkle behind nat.

-- juha