Hi all, I was recently setting up avahi-daemon on a Linux system that uses a 4.9.11 kernel and noticed that avahi failed to advertise services on IPv4, but had no such problems with IPv6. Looking through the logs I found this:
Oct 26 08:19:51 avahi-daemon[280]: Joining mDNS multicast group on interface eth0.IPv4 with address 192.168.0.125. Oct 26 08:19:51 avahi-daemon[280]: IP_ADD_MEMBERSHIP failed: No buffer space available which is apparently due to /proc/sys/net/ipv4/igmp_max_memberships being 0. Indeed, it looks like there was a change in kernel 4.6 [1] that causes igmp_max_memberships to be 0 if CONFIG_IP_MULTICAST is not enabled. Apparently this has been later reverted [2]. Enabling CONFIG_IP_MULTICAST in the offending kernel fixes the problem obviously but I have noticed that even if CONFIG_IP_MULTICAST is not enabled in the kernel, I can just do echo 20 > /proc/sys/net/ipv4/igmp_max_memberships, and with that avahi-daemon can already advertise services over IPv4. So the question is: Is CONFIG_IP_MULTICAST needed for proper operation of avahi-daemon ? What are the possible implications if CONFIG_IP_MULTICAST is _not_ enabled? [1]: https://bugzilla.kernel.org/show_bug.cgi?id=119251 [2]: https://lkml.org/lkml/2017/8/11/839 Thank you, Guillermo Rodriguez Garcia guille.rodrig...@gmail.com -- Guillermo Rodriguez Garcia guille.rodrig...@gmail.com _______________________________________________ avahi mailing list avahi@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/avahi