Bug 1048947 - Multicast services need to enable igmp
Summary: Multicast services need to enable igmp
Alias: None
Product: Fedora
Classification: Fedora
Component: firewalld
Version: 20
Hardware: Unspecified
OS: Unspecified
Target Milestone: ---
Assignee: Thomas Woerner
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2014-01-06 15:12 UTC by Giovanni Campagna
Modified: 2015-06-29 14:13 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2015-06-29 14:13:12 UTC
Type: Bug

Attachments (Terms of Use)

Description Giovanni Campagna 2014-01-06 15:12:54 UTC
Description of problem:
While in theory it's not necessary, because both mdns and upnp operate on the local subnet and thus link-layer broadcasting is enough to ensure all hosts get the packets, my switch+router (Alice Gate VoIP AGPF_4.5.0sx, by Pirelli) refuses to switch packets between ethernet and wi-fi unless all hosts declare they partecipate in a multicast group using IGMP.
This means that effectively mDNS and UPnP communication is blocked, and the relevant options in the firewalld GUI have no effect.

I believe the correct solution would be for firewalld to offer a configuration option inside service XML files to mark that multicast is required.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. Enable a multicast service such as mDNS from firewall-config or firewall-cmd
2. Have a switch/router that requires IGMP for local multicast
3. Attempt to send multicast packets to the other host and to get replies (for example with "getent hosts <hostname>.local")

Actual results:
Packets are not delivered, because the hosts are not marked as inside the multicast group. wireshark shows no activity, and neither does iptables -j LOG

Expected results:
Packets are delivered fine, reach the appropriate filter rule, and then are forwarded to the application or rejected as configured.

Additional info:
A successful workaround is
firewall-cmd --permanent --direct --add-rule ipv4 filter INPUT 0 -p igmp -j ACCEPT

For the record, this problem affects old system-config-firewall on EL 6 too, and in there one can solve this problem by editing /etc/sysconfig/iptables.

Comment 1 Fedora End Of Life 2015-05-29 10:21:30 UTC
This message is a reminder that Fedora 20 is nearing its end of life.
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Comment 2 Fedora End Of Life 2015-06-29 14:13:12 UTC
Fedora 20 changed to end-of-life (EOL) status on 2015-06-23. Fedora 20 is
no longer maintained, which means that it will not receive any further
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