alert icmp $EXTERNAL_NET any -> $HOME_NET any (msg:"GPL SCAN icmpenum v1.1.1"; dsize:0; icmp_id:666 ; icmp_seq:0; id:666; itype:8; reference:arachnids,450; classtype:attempted-recon; sid:2100471; rev:4; metadata:created_at 2010_09_23, signature_severity Informational, updated_at 2019_07_26;)