Hi all,
I'm facing a weird issue which I think is related to broken TCP socket
reuse logic where the wrong client is receiving incoming calls due to
the wrong socket being used for the incoming INVITE.
The scenario is when I have 2 clients registering using TLS behind NAT
at the same Public IPv4 address and both clients are using the same
private port number. So client 1 registers and the Via and contact
header looks like:
Via: SIP/2.0/TLS
192.168.42.162:5062;branch=z9hG4bK1409895926;rport;alias Contact:
<sip:201@192.168.42.162:5062;transport=tls>;reg-id=2;+sip.instance="<urn:uuid:00000000-0000-1000-8000-C074AD928AC4>"
Client 2 registers from behind the same Public IPv4 address and the Via
and contact header looks like:
Via: SIP/2.0/TLS 192.168.42.186:5062;branch=z9hG4bK-aff1f3b3 Contact:
<sip:202@192.168.42.186:5062;transport=tls>;expires=300
The location table shows Client 1 received field of 103.212.1.2:5062 and
Client 103.212.1.2:23456
When a call comes in for Client 1 the location lookup seems to return
the correct 'received' address and port (e.g. 103.212.1.2:5062) and all
the logs indicate that this is where the SIP INVITE *should* be going to
(in the $du field). However when you check the SIP traffic it selects
Client 2's socket and the traffic goes to port 23456 instead of 5062.
I think this is related somehow to the TCP port reuse logic inside
Opensips. My suspicion is that Opensips is looking at the Contact or
Via port number (which is the same for both client 1 and 2) and then
somehow mapping this to the wrong TCP received socket.
Does anybody have any suggestions here? Should I be fixing the NAT in
the Contact header (using fix_nated_contact). I read somewhere that you
shouldn't rewrite the Contact header to avoid problems with sending a
different Contact URI to the client on calls. Or is this issue more
related to the Via header and the TCP port reuse logic looking at this
port instead of the actual received port when choosing the outgoing socket?
FYI: I am using both force_rport() and fix_nated_register() for incoming
registrations from these clients and matching_mode of 0 in usrloc.
However, I am not using fix_nated_contact() for registrations.
Thanks,
Ray
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