This is quite difficult. For example, on a server with a single IP address may run several SIP proxy instances with different purposes. Each of these proxies uses another listening port, e.g: 1.1.1.1:5061, 1.1.1.1:6061, 1.1.1.1:7061.
On 13.02.2012 18:07, Bruno Bresciani wrote:
Hi all,
There is the possibility to kamailio reuse the TLS connection created by
other SIP server? When kamailio use t_relay function to send a SIP
request message to other server, kamailio verify if already exist some
connection established with the destiny and use it even if this
connection was created by the other SIP server.
In short, I want to keep only one connection between kamailio and SIP
server. Sometimes kamailio will be a client and others a server.
If on of these proxies establish a TCP connection to another proxy, e.g. 2.2.2.2:5061, it uses an ephemeral source-port. Thus, for the TLS-server (the receiver of the TLS connection) there is no way to know which of these SIP proxies on 1.1.1.1 established the connection. There are lots more issues e.g. with certificate validation - a proxy may use various certificates for several domains. Maybe you can overcome these problems if all the proxies are controlled by you, but in an open environment this kind of connection reuse does not work.
Thus: connection reuse can only be used for transactions in the same direction with the same target domain. For example if you have a proxy at 1.1.1.1:5061 authoritative for a.example.com and b.example.com and you have a proxy at 2.2.2.2:5061 authoritative for y.example.com and z.example.com then you will end up with 4 TLS connections:
1. 1.1.1.1 as TLS client to a.example.com
2. 1.1.1.1 as TLS client to b.example.com
3. 2.2.2.2 as TLS client to y.example.com
4. 2.2.2.2 as TLS client to z.example.com
Unless you have s strange setup with strange requirements I do not see any benefit in forcing all messages into a single TLS connection.
regards
Klaus