class SourcePortAdapter(HTTPAdapter):
 """"Transport adapter" that allows us to set the source port."""

 def __init__(self, port, *args, **kwargs):
  self.poolmanager = None
  self._source_port = port
  super().__init__(*args, **kwargs)

 def init_poolmanager(self, connections, maxsize, block=DEFAULT_POOLBLOCK, **pool_kwargs):
  self.poolmanager = PoolManager(
   num_pools=connections, maxsize=maxsize,
   block=block, source_address=('', self._source_port))

s = requests.Session()
s.mount('https://baidu.com', SourcePortAdapter(54321))
s.get('https://baidu.com')

c = pycurl.Curl()
c.setopt(c.URL, 'https://curl.haxx.se/dev/')
c.setopt(c.LOCALPORT, 54321)
c.setopt(c.LOCALPORTRANGE, [52314,56321,5532])
c.perform()
c.close()

curl --local-port 12520 http://baidu.com