The ephemeral ports you mention are used ONLY if you do not do BIND call on socket for outgoing connection.

If before doing CONNECT you do BIND, the local port number will be one specified in BIND.

Following small program demonstrates it.

#!/usr/bin/python

import socket

import threading

READER_ADDR = ("127.0.0.1", 23008)

WRITER1_ADDR = ("127.0.0.1", 23001)

WRITER2_ADDR = ("127.0.0.1", 23002)

LISTEN_SOCK = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)

LISTEN_SOCK.bind(READER_ADDR)

LISTEN_SOCK.listen(3)

DONE = False

class wait_conn(threading.Thread):

def run(self):

while not DONE:

s, a = LISTEN_SOCK.accept()

print("Incomming connection from: ", s.getpeername())

s.close()

t = wait_conn()

t.start()

w1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)

w1.bind(WRITER1_ADDR)

w1.connect(READER_ADDR)

w1.close()

w2 = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)

w2.bind(WRITER2_ADDR)

w2.connect(READER_ADDR)

w2.close()

DONE = True

t.join(1.0)

LISTEN_SOCK.close()

2018-06-20 15:19 GMT+02:00 Daniel-Constantin Mierla <notifications@github.com>:

By default, Kamailio is reusing the tcp connection when possible.

Again, about the local port for tcp connections, read more about tcp protocol and how a connection is identified (some references about ephemeral ports are also there) -- practically it is the tcp stack implementation/operating system kernel that does the selection of the local port, impossible to ensure it from user space.

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