multicast 224.0.0.22 incorrectly flagged by !RFC1918 alias

CatSpecial202

Hello, I had a log today that doesn't make sense . The firewall System Logs are reporting that I'm having 224.0.0.22 IGMP is being blocked by a rule that does not have this IP as blokced.

Here you can see the list the IGMP block:

This is the rule that the log is flagging as blocking:

NOCling

No its correct, this IP Space is not Part of the RFC1918.
https://www.rfc-editor.org/rfc/rfc1918.html

There you find more informations:
https://www.rfc-editor.org/rfc/rfc5771.html

w0w

@NOCling
Maybe I misunderstood the question, but this is exactly what he's talking about. If this IP is not part of RFC1918, then why is it being blocked by the rule for RFC1918?

keyser

@CatSpecial202 The traffic is not being blocked because it is considered part of the RFC1918 space. Your rule is not a block rule, but rather a PASS rule (!RFC1918).
The traffic is blocked by your rule though - but thats because the IGMP multicast packets that was intended to be passed by the rule has IP options enabled that the default IP options filtering in the rule denies. Hence it blocks the traffic. Seach for IGMP filtering blocks traffic on this forum to understand the problem and configure your rule accordingly.

Fx: this thread https://forum.netgate.com/topic/187896/how-to-stop-logging-blocked-lan-igmp