pfSense

Example rules:

pass in quick inet proto igmp
pass in quick inet proto igmp allow-opts

• IGMP packets are matched by the first rule; if the first rule is removed, the second rule will match.
• Logging is respected for both the first and second rule - i.e. a log entry is only created if log is added to the rule.
• The log entry shows pass or block as determined by the rule action:
  

  Apr 12 10:24:55 router filterlog[89591]: 89,,,1712938789,vmx1,match,pass,in,4,0x0,,1,61477,0,none,2,igmp,32,10.0.5.50,224.0.0.251,datalength=8 

• IGMP packets are matched by the first rule; if the first rule is removed, the second rule will match.
• Logging is only respected for the second rule; a log entry is always created for the first rule.
• The log entry always shows block for the first rule:
  

  Apr 12 09:56:49 gw filterlog[8789]: 338,,,1712937337,igc0.5,ip-option,block,in,4,0x0,,1,32022,0,none,2,igmp,32,10.0.5.50,224.0.0.252,datalength=8