Author giangipy
Recipients giangipy, ned.deily, ronaldoussoren
Date 2021-05-01.21:16:26
SpamBayes Score -1.0
Marked as misclassified Yes
Message-id <>
I am connecting to a server using a multicast UDP socket.

Running two instances of the code below, in two shell windows on the same computer, it works on both Windows 10 and Ubuntu 18.04, but it fails on Mac OS 10.15.7, reporting:

>>> sock.bind(('', MCAST_PORT))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OSError: [Errno 48] Address already in use


import socket 


MCAST_PORT = 10000

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_IF, socket.inet_aton(CLIENT_IP))
sock.setsockopt(socket.SOL_IP, socket.IP_ADD_MEMBERSHIP, socket.inet_aton(MCAST_ADDR) + socket.inet_aton(CLIENT_IP))
sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 2)
sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_IF, socket.inet_aton(CLIENT_IP))
sock.bind(('', MCAST_PORT))
Date User Action Args
2021-05-01 21:16:26giangipysetrecipients: + giangipy, ronaldoussoren, ned.deily
2021-05-01 21:16:26giangipysetmessageid: <>
2021-05-01 21:16:26giangipylinkissue44005 messages
2021-05-01 21:16:26giangipycreate