[Interest] QUdpSocket multicast on multiple network interfaces

Tom Isaacson Tom.Isaacson at navico.com
Thu Feb 20 00:27:38 CET 2014

We're using Qt 4.8.2 on an embedded Linux device. We've always had Ethernet (eth0) and we use QUdpSocket to send a multicast message on the network:

    m_pUdpSocket = new QUdpSocket(this);
    m_pUdpSocket->writeDatagram(json.toAscii(), m_cMulticastAddr, m_cMulticastPort);

This works fine, but recently we've started testing with a Wifi interface as well. What we've found is that this code only transmits the multicast on Ethernet and ignores the Wifi. From the application we have to create a second QUdpSocket and bind it to the IP address of the Wifi interface. I would have expected Qt to transmit on all available network interfaces.
- Is this a known bug? If so, is it fixed in a later release?
- Is this working as intended?


Tom Isaacson

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